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/* Tracepoint code for remote server for GDB.
Copyright (C) 2009-2024 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "tracepoint.h"
#include "gdbthread.h"
#include "gdbsupport/rsp-low.h"
#include <ctype.h>
#include <fcntl.h>
#include <unistd.h>
#include <chrono>
#include <inttypes.h>
#include "ax.h"
#include "tdesc.h"
#define IPA_SYM_STRUCT_NAME ipa_sym_addresses
#include "gdbsupport/agent.h"
#define DEFAULT_TRACE_BUFFER_SIZE 5242880 /* 5*1024*1024 */
/* This file is built for both GDBserver, and the in-process
agent (IPA), a shared library that includes a tracing agent that is
loaded by the inferior to support fast tracepoints. Fast
tracepoints (or more accurately, jump based tracepoints) are
implemented by patching the tracepoint location with a jump into a
small trampoline function whose job is to save the register state,
call the in-process tracing agent, and then execute the original
instruction that was under the tracepoint jump (possibly adjusted,
if PC-relative, or some such).
The current synchronization design is pull based. That means,
GDBserver does most of the work, by peeking/poking at the inferior
agent's memory directly for downloading tracepoint and associated
objects, and for uploading trace frames. Whenever the IPA needs
something from GDBserver (trace buffer is full, tracing stopped for
some reason, etc.) the IPA calls a corresponding hook function
where GDBserver has placed a breakpoint.
Each of the agents has its own trace buffer. When browsing the
trace frames built from slow and fast tracepoints from GDB (tfind
mode), there's no guarantee the user is seeing the trace frames in
strict chronological creation order, although, GDBserver tries to
keep the order relatively reasonable, by syncing the trace buffers
at appropriate times.
*/
#ifdef IN_PROCESS_AGENT
static void trace_vdebug (const char *, ...) ATTRIBUTE_PRINTF (1, 2);
static void
trace_vdebug (const char *fmt, ...)
{
char buf[1024];
va_list ap;
va_start (ap, fmt);
vsprintf (buf, fmt, ap);
fprintf (stderr, PROG "/tracepoint: %s\n", buf);
va_end (ap);
}
#define trace_debug(fmt, args...) \
do { \
if (debug_threads) \
trace_vdebug ((fmt), ##args); \
} while (0)
#else
#define trace_debug(fmt, args...) \
do { \
threads_debug_printf ((fmt), ##args); \
} while (0)
#endif
/* Prefix exported symbols, for good citizenship. All the symbols
that need exporting are defined in this module. Note that all
these symbols must be tagged with IP_AGENT_EXPORT_*. */
#ifdef IN_PROCESS_AGENT
# define gdb_tp_heap_buffer IPA_SYM_EXPORTED_NAME (gdb_tp_heap_buffer)
# define gdb_jump_pad_buffer IPA_SYM_EXPORTED_NAME (gdb_jump_pad_buffer)
# define gdb_jump_pad_buffer_end IPA_SYM_EXPORTED_NAME (gdb_jump_pad_buffer_end)
# define gdb_trampoline_buffer IPA_SYM_EXPORTED_NAME (gdb_trampoline_buffer)
# define gdb_trampoline_buffer_end IPA_SYM_EXPORTED_NAME (gdb_trampoline_buffer_end)
# define gdb_trampoline_buffer_error IPA_SYM_EXPORTED_NAME (gdb_trampoline_buffer_error)
# define collecting IPA_SYM_EXPORTED_NAME (collecting)
# define gdb_collect_ptr IPA_SYM_EXPORTED_NAME (gdb_collect_ptr)
# define stop_tracing IPA_SYM_EXPORTED_NAME (stop_tracing)
# define flush_trace_buffer IPA_SYM_EXPORTED_NAME (flush_trace_buffer)
# define about_to_request_buffer_space IPA_SYM_EXPORTED_NAME (about_to_request_buffer_space)
# define trace_buffer_is_full IPA_SYM_EXPORTED_NAME (trace_buffer_is_full)
# define stopping_tracepoint IPA_SYM_EXPORTED_NAME (stopping_tracepoint)
# define expr_eval_result IPA_SYM_EXPORTED_NAME (expr_eval_result)
# define error_tracepoint IPA_SYM_EXPORTED_NAME (error_tracepoint)
# define tracepoints IPA_SYM_EXPORTED_NAME (tracepoints)
# define tracing IPA_SYM_EXPORTED_NAME (tracing)
# define trace_buffer_ctrl IPA_SYM_EXPORTED_NAME (trace_buffer_ctrl)
# define trace_buffer_ctrl_curr IPA_SYM_EXPORTED_NAME (trace_buffer_ctrl_curr)
# define trace_buffer_lo IPA_SYM_EXPORTED_NAME (trace_buffer_lo)
# define trace_buffer_hi IPA_SYM_EXPORTED_NAME (trace_buffer_hi)
# define traceframe_read_count IPA_SYM_EXPORTED_NAME (traceframe_read_count)
# define traceframe_write_count IPA_SYM_EXPORTED_NAME (traceframe_write_count)
# define traceframes_created IPA_SYM_EXPORTED_NAME (traceframes_created)
# define trace_state_variables IPA_SYM_EXPORTED_NAME (trace_state_variables)
# define get_raw_reg_ptr IPA_SYM_EXPORTED_NAME (get_raw_reg_ptr)
# define get_trace_state_variable_value_ptr \
IPA_SYM_EXPORTED_NAME (get_trace_state_variable_value_ptr)
# define set_trace_state_variable_value_ptr \
IPA_SYM_EXPORTED_NAME (set_trace_state_variable_value_ptr)
# define ust_loaded IPA_SYM_EXPORTED_NAME (ust_loaded)
# define helper_thread_id IPA_SYM_EXPORTED_NAME (helper_thread_id)
# define cmd_buf IPA_SYM_EXPORTED_NAME (cmd_buf)
# define ipa_tdesc_idx IPA_SYM_EXPORTED_NAME (ipa_tdesc_idx)
#endif
#ifndef IN_PROCESS_AGENT
/* Addresses of in-process agent's symbols GDBserver cares about. */
struct ipa_sym_addresses
{
CORE_ADDR addr_gdb_tp_heap_buffer;
CORE_ADDR addr_gdb_jump_pad_buffer;
CORE_ADDR addr_gdb_jump_pad_buffer_end;
CORE_ADDR addr_gdb_trampoline_buffer;
CORE_ADDR addr_gdb_trampoline_buffer_end;
CORE_ADDR addr_gdb_trampoline_buffer_error;
CORE_ADDR addr_collecting;
CORE_ADDR addr_gdb_collect_ptr;
CORE_ADDR addr_stop_tracing;
CORE_ADDR addr_flush_trace_buffer;
CORE_ADDR addr_about_to_request_buffer_space;
CORE_ADDR addr_trace_buffer_is_full;
CORE_ADDR addr_stopping_tracepoint;
CORE_ADDR addr_expr_eval_result;
CORE_ADDR addr_error_tracepoint;
CORE_ADDR addr_tracepoints;
CORE_ADDR addr_tracing;
CORE_ADDR addr_trace_buffer_ctrl;
CORE_ADDR addr_trace_buffer_ctrl_curr;
CORE_ADDR addr_trace_buffer_lo;
CORE_ADDR addr_trace_buffer_hi;
CORE_ADDR addr_traceframe_read_count;
CORE_ADDR addr_traceframe_write_count;
CORE_ADDR addr_traceframes_created;
CORE_ADDR addr_trace_state_variables;
CORE_ADDR addr_get_raw_reg_ptr;
CORE_ADDR addr_get_trace_state_variable_value_ptr;
CORE_ADDR addr_set_trace_state_variable_value_ptr;
CORE_ADDR addr_ust_loaded;
CORE_ADDR addr_ipa_tdesc_idx;
};
static struct
{
const char *name;
int offset;
} symbol_list[] = {
IPA_SYM(gdb_tp_heap_buffer),
IPA_SYM(gdb_jump_pad_buffer),
IPA_SYM(gdb_jump_pad_buffer_end),
IPA_SYM(gdb_trampoline_buffer),
IPA_SYM(gdb_trampoline_buffer_end),
IPA_SYM(gdb_trampoline_buffer_error),
IPA_SYM(collecting),
IPA_SYM(gdb_collect_ptr),
IPA_SYM(stop_tracing),
IPA_SYM(flush_trace_buffer),
IPA_SYM(about_to_request_buffer_space),
IPA_SYM(trace_buffer_is_full),
IPA_SYM(stopping_tracepoint),
IPA_SYM(expr_eval_result),
IPA_SYM(error_tracepoint),
IPA_SYM(tracepoints),
IPA_SYM(tracing),
IPA_SYM(trace_buffer_ctrl),
IPA_SYM(trace_buffer_ctrl_curr),
IPA_SYM(trace_buffer_lo),
IPA_SYM(trace_buffer_hi),
IPA_SYM(traceframe_read_count),
IPA_SYM(traceframe_write_count),
IPA_SYM(traceframes_created),
IPA_SYM(trace_state_variables),
IPA_SYM(get_raw_reg_ptr),
IPA_SYM(get_trace_state_variable_value_ptr),
IPA_SYM(set_trace_state_variable_value_ptr),
IPA_SYM(ust_loaded),
IPA_SYM(ipa_tdesc_idx),
};
static struct ipa_sym_addresses ipa_sym_addrs;
static int read_inferior_integer (CORE_ADDR symaddr, int *val);
/* Returns true if both the in-process agent library and the static
tracepoints libraries are loaded in the inferior, and agent has
capability on static tracepoints. */
static int
in_process_agent_supports_ust (void)
{
int loaded = 0;
if (!agent_loaded_p ())
{
warning ("In-process agent not loaded");
return 0;
}
if (agent_capability_check (AGENT_CAPA_STATIC_TRACE))
{
/* Agent understands static tracepoint, then check whether UST is in
fact loaded in the inferior. */
if (read_inferior_integer (ipa_sym_addrs.addr_ust_loaded, &loaded))
{
warning ("Error reading ust_loaded in lib");
return 0;
}
return loaded;
}
else
return 0;
}
static void
write_e_ipa_not_loaded (char *buffer)
{
sprintf (buffer,
"E.In-process agent library not loaded in process. "
"Fast and static tracepoints unavailable.");
}
/* Write an error to BUFFER indicating that UST isn't loaded in the
inferior. */
static void
write_e_ust_not_loaded (char *buffer)
{
#ifdef HAVE_UST
sprintf (buffer,
"E.UST library not loaded in process. "
"Static tracepoints unavailable.");
#else
sprintf (buffer, "E.GDBserver was built without static tracepoints support");
#endif
}
/* If the in-process agent library isn't loaded in the inferior, write
an error to BUFFER, and return 1. Otherwise, return 0. */
static int
maybe_write_ipa_not_loaded (char *buffer)
{
if (!agent_loaded_p ())
{
write_e_ipa_not_loaded (buffer);
return 1;
}
return 0;
}
/* If the in-process agent library and the ust (static tracepoints)
library aren't loaded in the inferior, write an error to BUFFER,
and return 1. Otherwise, return 0. */
static int
maybe_write_ipa_ust_not_loaded (char *buffer)
{
if (!agent_loaded_p ())
{
write_e_ipa_not_loaded (buffer);
return 1;
}
else if (!in_process_agent_supports_ust ())
{
write_e_ust_not_loaded (buffer);
return 1;
}
return 0;
}
/* Cache all future symbols that the tracepoints module might request.
We can not request symbols at arbitrary states in the remote
protocol, only when the client tells us that new symbols are
available. So when we load the in-process library, make sure to
check the entire list. */
void
tracepoint_look_up_symbols (void)
{
int i;
if (agent_loaded_p ())
return;
for (i = 0; i < sizeof (symbol_list) / sizeof (symbol_list[0]); i++)
{
CORE_ADDR *addrp =
(CORE_ADDR *) ((char *) &ipa_sym_addrs + symbol_list[i].offset);
if (look_up_one_symbol (symbol_list[i].name, addrp, 1) == 0)
{
threads_debug_printf ("symbol `%s' not found", symbol_list[i].name);
return;
}
}
agent_look_up_symbols (NULL);
}
#endif
/* GDBserver places a breakpoint on the IPA's version (which is a nop)
of the "stop_tracing" function. When this breakpoint is hit,
tracing stopped in the IPA for some reason. E.g., due to
tracepoint reaching the pass count, hitting conditional expression
evaluation error, etc.
The IPA's trace buffer is never in circular tracing mode: instead,
GDBserver's is, and whenever the in-process buffer fills, it calls
"flush_trace_buffer", which triggers an internal breakpoint.
GDBserver reacts to this breakpoint by pulling the meanwhile
collected data. Old frames discarding is always handled on the
GDBserver side. */
#ifdef IN_PROCESS_AGENT
/* See target.h. */
int
read_inferior_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
{
memcpy (myaddr, (void *) (uintptr_t) memaddr, len);
return 0;
}
/* Call this in the functions where GDBserver places a breakpoint, so
that the compiler doesn't try to be clever and skip calling the
function at all. This is necessary, even if we tell the compiler
to not inline said functions. */
#if defined(__GNUC__)
# define UNKNOWN_SIDE_EFFECTS() asm ("")
#else
# define UNKNOWN_SIDE_EFFECTS() do {} while (0)
#endif
/* This is needed for -Wmissing-declarations. */
IP_AGENT_EXPORT_FUNC void stop_tracing (void);
IP_AGENT_EXPORT_FUNC void
stop_tracing (void)
{
/* GDBserver places breakpoint here. */
UNKNOWN_SIDE_EFFECTS();
}
/* This is needed for -Wmissing-declarations. */
IP_AGENT_EXPORT_FUNC void flush_trace_buffer (void);
IP_AGENT_EXPORT_FUNC void
flush_trace_buffer (void)
{
/* GDBserver places breakpoint here. */
UNKNOWN_SIDE_EFFECTS();
}
#endif
#ifndef IN_PROCESS_AGENT
static int
tracepoint_handler (CORE_ADDR address)
{
trace_debug ("tracepoint_handler: tracepoint at 0x%s hit",
paddress (address));
return 0;
}
/* Breakpoint at "stop_tracing" in the inferior lib. */
static struct breakpoint *stop_tracing_bkpt;
static int stop_tracing_handler (CORE_ADDR);
/* Breakpoint at "flush_trace_buffer" in the inferior lib. */
static struct breakpoint *flush_trace_buffer_bkpt;
static int flush_trace_buffer_handler (CORE_ADDR);
static void download_trace_state_variables (void);
static void upload_fast_traceframes (void);
static int run_inferior_command (char *cmd, int len);
static int
read_inferior_integer (CORE_ADDR symaddr, int *val)
{
return read_inferior_memory (symaddr, (unsigned char *) val,
sizeof (*val));
}
struct tracepoint;
static int tracepoint_send_agent (struct tracepoint *tpoint);
static int
read_inferior_uinteger (CORE_ADDR symaddr, unsigned int *val)
{
return read_inferior_memory (symaddr, (unsigned char *) val,
sizeof (*val));
}
static int
read_inferior_data_pointer (CORE_ADDR symaddr, CORE_ADDR *val)
{
void *pval = (void *) (uintptr_t) val;
int ret;
ret = read_inferior_memory (symaddr, (unsigned char *) &pval, sizeof (pval));
*val = (uintptr_t) pval;
return ret;
}
static int
write_inferior_data_pointer (CORE_ADDR symaddr, CORE_ADDR val)
{
void *pval = (void *) (uintptr_t) val;
return target_write_memory (symaddr,
(unsigned char *) &pval, sizeof (pval));
}
static int
write_inferior_integer (CORE_ADDR symaddr, int val)
{
return target_write_memory (symaddr, (unsigned char *) &val, sizeof (val));
}
static int
write_inferior_int8 (CORE_ADDR symaddr, int8_t val)
{
return target_write_memory (symaddr, (unsigned char *) &val, sizeof (val));
}
static int
write_inferior_uinteger (CORE_ADDR symaddr, unsigned int val)
{
return target_write_memory (symaddr, (unsigned char *) &val, sizeof (val));
}
static CORE_ADDR target_malloc (ULONGEST size);
#define COPY_FIELD_TO_BUF(BUF, OBJ, FIELD) \
do { \
memcpy (BUF, &(OBJ)->FIELD, sizeof ((OBJ)->FIELD)); \
BUF += sizeof ((OBJ)->FIELD); \
} while (0)
#endif
/* Base action. Concrete actions inherit this. */
struct tracepoint_action
{
char type;
};
/* An 'M' (collect memory) action. */
struct collect_memory_action
{
struct tracepoint_action base;
ULONGEST addr;
ULONGEST len;
int32_t basereg;
};
/* An 'R' (collect registers) action. */
struct collect_registers_action
{
struct tracepoint_action base;
};
/* An 'X' (evaluate expression) action. */
struct eval_expr_action
{
struct tracepoint_action base;
struct agent_expr *expr;
};
/* An 'L' (collect static trace data) action. */
struct collect_static_trace_data_action
{
struct tracepoint_action base;
};
#ifndef IN_PROCESS_AGENT
static CORE_ADDR
m_tracepoint_action_download (const struct tracepoint_action *action)
{
CORE_ADDR ipa_action = target_malloc (sizeof (struct collect_memory_action));
target_write_memory (ipa_action, (unsigned char *) action,
sizeof (struct collect_memory_action));
return ipa_action;
}
static char *
m_tracepoint_action_send (char *buffer, const struct tracepoint_action *action)
{
struct collect_memory_action *maction
= (struct collect_memory_action *) action;
COPY_FIELD_TO_BUF (buffer, maction, addr);
COPY_FIELD_TO_BUF (buffer, maction, len);
COPY_FIELD_TO_BUF (buffer, maction, basereg);
return buffer;
}
static CORE_ADDR
r_tracepoint_action_download (const struct tracepoint_action *action)
{
CORE_ADDR ipa_action = target_malloc (sizeof (struct collect_registers_action));
target_write_memory (ipa_action, (unsigned char *) action,
sizeof (struct collect_registers_action));
return ipa_action;
}
static char *
r_tracepoint_action_send (char *buffer, const struct tracepoint_action *action)
{
return buffer;
}
static CORE_ADDR download_agent_expr (struct agent_expr *expr);
static CORE_ADDR
x_tracepoint_action_download (const struct tracepoint_action *action)
{
CORE_ADDR ipa_action = target_malloc (sizeof (struct eval_expr_action));
CORE_ADDR expr;
target_write_memory (ipa_action, (unsigned char *) action,
sizeof (struct eval_expr_action));
expr = download_agent_expr (((struct eval_expr_action *) action)->expr);
write_inferior_data_pointer (ipa_action
+ offsetof (struct eval_expr_action, expr),
expr);
return ipa_action;
}
/* Copy agent expression AEXPR to buffer pointed by P. If AEXPR is NULL,
copy 0 to P. Return updated header of buffer. */
static char *
agent_expr_send (char *p, const struct agent_expr *aexpr)
{
/* Copy the length of condition first, and then copy its
content. */
if (aexpr == NULL)
{
memset (p, 0, 4);
p += 4;
}
else
{
memcpy (p, &aexpr->length, 4);
p +=4;
memcpy (p, aexpr->bytes, aexpr->length);
p += aexpr->length;
}
return p;
}
static char *
x_tracepoint_action_send ( char *buffer, const struct tracepoint_action *action)
{
struct eval_expr_action *eaction = (struct eval_expr_action *) action;
return agent_expr_send (buffer, eaction->expr);
}
static CORE_ADDR
l_tracepoint_action_download (const struct tracepoint_action *action)
{
CORE_ADDR ipa_action
= target_malloc (sizeof (struct collect_static_trace_data_action));
target_write_memory (ipa_action, (unsigned char *) action,
sizeof (struct collect_static_trace_data_action));
return ipa_action;
}
static char *
l_tracepoint_action_send (char *buffer, const struct tracepoint_action *action)
{
return buffer;
}
static char *
tracepoint_action_send (char *buffer, const struct tracepoint_action *action)
{
switch (action->type)
{
case 'M':
return m_tracepoint_action_send (buffer, action);
case 'R':
return r_tracepoint_action_send (buffer, action);
case 'X':
return x_tracepoint_action_send (buffer, action);
case 'L':
return l_tracepoint_action_send (buffer, action);
}
error ("Unknown trace action '%c'.", action->type);
}
static CORE_ADDR
tracepoint_action_download (const struct tracepoint_action *action)
{
switch (action->type)
{
case 'M':
return m_tracepoint_action_download (action);
case 'R':
return r_tracepoint_action_download (action);
case 'X':
return x_tracepoint_action_download (action);
case 'L':
return l_tracepoint_action_download (action);
}
error ("Unknown trace action '%c'.", action->type);
}
#endif
/* This structure describes a piece of the source-level definition of
the tracepoint. The contents are not interpreted by the target,
but preserved verbatim for uploading upon reconnection. */
struct source_string
{
/* The type of string, such as "cond" for a conditional. */
char *type;
/* The source-level string itself. For the sake of target
debugging, we store it in plaintext, even though it is always
transmitted in hex. */
char *str;
/* Link to the next one in the list. We link them in the order
received, in case some make up an ordered list of commands or
some such. */
struct source_string *next;
};
enum tracepoint_type
{
/* Trap based tracepoint. */
trap_tracepoint,
/* A fast tracepoint implemented with a jump instead of a trap. */
fast_tracepoint,
/* A static tracepoint, implemented by a program call into a tracing
library. */
static_tracepoint
};
struct tracepoint_hit_ctx;
typedef enum eval_result_type (*condfn) (unsigned char *,
ULONGEST *);
/* The definition of a tracepoint. */
/* Tracepoints may have multiple locations, each at a different
address. This can occur with optimizations, template
instantiation, etc. Since the locations may be in different
scopes, the conditions and actions may be different for each
location. Our target version of tracepoints is more like GDB's
notion of "breakpoint locations", but we have almost nothing that
is not per-location, so we bother having two kinds of objects. The
key consequence is that numbers are not unique, and that it takes
both number and address to identify a tracepoint uniquely. */
struct tracepoint
{
/* The number of the tracepoint, as specified by GDB. Several
tracepoint objects here may share a number. */
uint32_t number;
/* Address at which the tracepoint is supposed to trigger. Several
tracepoints may share an address. */
CORE_ADDR address;
/* Tracepoint type. */
enum tracepoint_type type;
/* True if the tracepoint is currently enabled. */
int8_t enabled;
/* The number of single steps that will be performed after each
tracepoint hit. */
uint64_t step_count;
/* The number of times the tracepoint may be hit before it will
terminate the entire tracing run. */
uint64_t pass_count;
/* Pointer to the agent expression that is the tracepoint's
conditional, or NULL if the tracepoint is unconditional. */
struct agent_expr *cond;
/* The list of actions to take when the tracepoint triggers. */
uint32_t numactions;
struct tracepoint_action **actions;
/* Count of the times we've hit this tracepoint during the run.
Note that while-stepping steps are not counted as "hits". */
uint64_t hit_count;
/* Cached sum of the sizes of traceframes created by this point. */
uint64_t traceframe_usage;
CORE_ADDR compiled_cond;
/* Link to the next tracepoint in the list. */
struct tracepoint *next;
#ifndef IN_PROCESS_AGENT
/* The list of actions to take when the tracepoint triggers, in
string/packet form. */
char **actions_str;
/* The collection of strings that describe the tracepoint as it was
entered into GDB. These are not used by the target, but are
reported back to GDB upon reconnection. */
struct source_string *source_strings;
/* The number of bytes displaced by fast tracepoints. It may subsume
multiple instructions, for multi-byte fast tracepoints. This
field is only valid for fast tracepoints. */
uint32_t orig_size;
/* Only for fast tracepoints. */
CORE_ADDR obj_addr_on_target;
/* Address range where the original instruction under a fast
tracepoint was relocated to. (_end is actually one byte past
the end). */
CORE_ADDR adjusted_insn_addr;
CORE_ADDR adjusted_insn_addr_end;
/* The address range of the piece of the jump pad buffer that was
assigned to this fast tracepoint. (_end is actually one byte
past the end).*/
CORE_ADDR jump_pad;
CORE_ADDR jump_pad_end;
/* The address range of the piece of the trampoline buffer that was
assigned to this fast tracepoint. (_end is actually one byte
past the end). */
CORE_ADDR trampoline;
CORE_ADDR trampoline_end;
/* The list of actions to take while in a stepping loop. These
fields are only valid for patch-based tracepoints. */
int num_step_actions;
struct tracepoint_action **step_actions;
/* Same, but in string/packet form. */
char **step_actions_str;
/* Handle returned by the breakpoint or tracepoint module when we
inserted the trap or jump, or hooked into a static tracepoint.
NULL if we haven't inserted it yet. */
void *handle;
#endif
};
#ifndef IN_PROCESS_AGENT
/* Given `while-stepping', a thread may be collecting data for more
than one tracepoint simultaneously. On the other hand, the same
tracepoint with a while-stepping action may be hit by more than one
thread simultaneously (but not quite, each thread could be handling
a different step). Each thread holds a list of these objects,
representing the current step of each while-stepping action being
collected. */
struct wstep_state
{
struct wstep_state *next;
/* The tracepoint number. */
int tp_number;
/* The tracepoint's address. */
CORE_ADDR tp_address;
/* The number of the current step in this 'while-stepping'
action. */
long current_step;
};
#endif
extern "C" {
/* The linked list of all tracepoints. Marked explicitly as used as
the in-process library doesn't use it for the fast tracepoints
support. */
IP_AGENT_EXPORT_VAR struct tracepoint *tracepoints;
/* The first tracepoint to exceed its pass count. */
IP_AGENT_EXPORT_VAR struct tracepoint *stopping_tracepoint;
/* True if the trace buffer is full or otherwise no longer usable. */
IP_AGENT_EXPORT_VAR int trace_buffer_is_full;
/* The first error that occurred during expression evaluation. */
/* Stored as an int to avoid the IPA ABI being dependent on whatever
the compiler decides to use for the enum's underlying type. Holds
enum eval_result_type values. */
IP_AGENT_EXPORT_VAR int expr_eval_result = expr_eval_no_error;
}
#ifndef IN_PROCESS_AGENT
/* Pointer to the last tracepoint in the list, new tracepoints are
linked in at the end. */
static struct tracepoint *last_tracepoint;
static const char * const eval_result_names[] =
{
#define AX_RESULT_TYPE(ENUM,STR) STR,
#include "ax-result-types.def"
#undef AX_RESULT_TYPE
};
#endif
/* The tracepoint in which the error occurred. */
extern "C" {
IP_AGENT_EXPORT_VAR struct tracepoint *error_tracepoint;
}
struct trace_state_variable
{
/* This is the name of the variable as used in GDB. The target
doesn't use the name, but needs to have it for saving and
reconnection purposes. */
char *name;
/* This number identifies the variable uniquely. Numbers may be
assigned either by the target (in the case of builtin variables),
or by GDB, and are presumed unique during the course of a trace
experiment. */
int number;
/* The variable's initial value, a 64-bit signed integer always. */
LONGEST initial_value;
/* The variable's value, a 64-bit signed integer always. */
LONGEST value;
/* Pointer to a getter function, used to supply computed values. */
LONGEST (*getter) (void);
/* Link to the next variable. */
struct trace_state_variable *next;
};
/* Linked list of all trace state variables. */
#ifdef IN_PROCESS_AGENT
static struct trace_state_variable *alloced_trace_state_variables;
#endif
IP_AGENT_EXPORT_VAR struct trace_state_variable *trace_state_variables;
/* The results of tracing go into a fixed-size space known as the
"trace buffer". Because usage follows a limited number of
patterns, we manage it ourselves rather than with malloc. Basic
rules are that we create only one trace frame at a time, each is
variable in size, they are never moved once created, and we only
discard if we are doing a circular buffer, and then only the oldest
ones. Each trace frame includes its own size, so we don't need to
link them together, and the trace frame number is relative to the
first one, so we don't need to record numbers. A trace frame also
records the number of the tracepoint that created it. The data
itself is a series of blocks, each introduced by a single character
and with a defined format. Each type of block has enough
type/length info to allow scanners to jump quickly from one block
to the next without reading each byte in the block. */
/* Trace buffer management would be simple - advance a free pointer
from beginning to end, then stop - were it not for the circular
buffer option, which is a useful way to prevent a trace run from
stopping prematurely because the buffer filled up. In the circular
case, the location of the first trace frame (trace_buffer_start)
moves as old trace frames are discarded. Also, since we grow trace
frames incrementally as actions are performed, we wrap around to
the beginning of the trace buffer. This is per-block, so each
block within a trace frame remains contiguous. Things get messy
when the wrapped-around trace frame is the one being discarded; the
free space ends up in two parts at opposite ends of the buffer. */
#ifndef ATTR_PACKED
# if defined(__GNUC__)
# define ATTR_PACKED __attribute__ ((packed))
# else
# define ATTR_PACKED /* nothing */
# endif
#endif
/* The data collected at a tracepoint hit. This object should be as
small as possible, since there may be a great many of them. We do
not need to keep a frame number, because they are all sequential
and there are no deletions; so the Nth frame in the buffer is
always frame number N. */
struct traceframe
{
/* Number of the tracepoint that collected this traceframe. A value
of 0 indicates the current end of the trace buffer. We make this
a 16-bit field because it's never going to happen that GDB's
numbering of tracepoints reaches 32,000. */
int tpnum : 16;
/* The size of the data in this trace frame. We limit this to 32
bits, even on a 64-bit target, because it's just implausible that
one is validly going to collect 4 gigabytes of data at a single
tracepoint hit. */
unsigned int data_size : 32;
/* The base of the trace data, which is contiguous from this point. */
unsigned char data[0];
} ATTR_PACKED;
/* The size of the EOB marker, in bytes. A traceframe with zeroed
fields (and no data) marks the end of trace data. */
#define TRACEFRAME_EOB_MARKER_SIZE offsetof (struct traceframe, data)
/* This flag is true if the trace buffer is circular, meaning that
when it fills, the oldest trace frames are discarded in order to
make room. */
#ifndef IN_PROCESS_AGENT
static int circular_trace_buffer;
#endif
/* Size of the trace buffer. */
static LONGEST trace_buffer_size;
extern "C" {
/* Pointer to the block of memory that traceframes all go into. */
IP_AGENT_EXPORT_VAR unsigned char *trace_buffer_lo;
/* Pointer to the end of the trace buffer, more precisely to the byte
after the end of the buffer. */
IP_AGENT_EXPORT_VAR unsigned char *trace_buffer_hi;
}
/* Control structure holding the read/write/etc. pointers into the
trace buffer. We need more than one of these to implement a
transaction-like mechanism to guarantees that both GDBserver and the
in-process agent can try to change the trace buffer
simultaneously. */
struct trace_buffer_control
{
/* Pointer to the first trace frame in the buffer. In the
non-circular case, this is equal to trace_buffer_lo, otherwise it
moves around in the buffer. */
unsigned char *start;
/* Pointer to the free part of the trace buffer. Note that we clear
several bytes at and after this pointer, so that traceframe
scans/searches terminate properly. */
unsigned char *free;
/* Pointer to the byte after the end of the free part. Note that
this may be smaller than trace_buffer_free in the circular case,
and means that the free part is in two pieces. Initially it is
equal to trace_buffer_hi, then is generally equivalent to
trace_buffer_start. */
unsigned char *end_free;
/* Pointer to the wraparound. If not equal to trace_buffer_hi, then
this is the point at which the trace data breaks, and resumes at
trace_buffer_lo. */
unsigned char *wrap;
};
/* Same as above, to be used by GDBserver when updating the in-process
agent. */
struct ipa_trace_buffer_control
{
uintptr_t start;
uintptr_t free;
uintptr_t end_free;
uintptr_t wrap;
};
/* We have possibly both GDBserver and an inferior thread accessing
the same IPA trace buffer memory. The IPA is the producer (tries
to put new frames in the buffer), while GDBserver occasionally
consumes them, that is, flushes the IPA's buffer into its own
buffer. Both sides need to update the trace buffer control
pointers (current head, tail, etc.). We can't use a global lock to
synchronize the accesses, as otherwise we could deadlock GDBserver
(if the thread holding the lock stops for a signal, say). So
instead of that, we use a transaction scheme where GDBserver writes
always prevail over the IPAs writes, and, we have the IPA detect
the commit failure/overwrite, and retry the whole attempt. This is
mainly implemented by having a global token object that represents
who wrote last to the buffer control structure. We need to freeze
any inferior writing to the buffer while GDBserver touches memory,
so that the inferior can correctly detect that GDBserver had been
there, otherwise, it could mistakingly think its commit was
successful; that's implemented by simply having GDBserver set a
breakpoint the inferior hits if it is the critical region.
There are three cycling trace buffer control structure copies
(buffer head, tail, etc.), with the token object including an index
indicating which is current live copy. The IPA tentatively builds
an updated copy in a non-current control structure, while GDBserver
always clobbers the current version directly. The IPA then tries
to atomically "commit" its version; if GDBserver clobbered the
structure meanwhile, that will fail, and the IPA restarts the
allocation process.
Listing the step in further detail, we have:
In-process agent (producer):
- passes by `about_to_request_buffer_space' breakpoint/lock
- reads current token, extracts current trace buffer control index,
and starts tentatively updating the rightmost one (0->1, 1->2,
2->0). Note that only one inferior thread is executing this code
at any given time, due to an outer lock in the jump pads.
- updates counters, and tries to commit the token.
- passes by second `about_to_request_buffer_space' breakpoint/lock,
leaving the sync region.
- checks if the update was effective.
- if trace buffer was found full, hits flush_trace_buffer
breakpoint, and restarts later afterwards.
GDBserver (consumer):
- sets `about_to_request_buffer_space' breakpoint/lock.
- updates the token unconditionally, using the current buffer
control index, since it knows that the IP agent always writes to
the rightmost, and due to the breakpoint, at most one IP thread
can try to update the trace buffer concurrently to GDBserver, so
there will be no danger of trace buffer control index wrap making
the IPA write to the same index as GDBserver.
- flushes the IP agent's trace buffer completely, and updates the
current trace buffer control structure. GDBserver *always* wins.
- removes the `about_to_request_buffer_space' breakpoint.
The token is stored in the `trace_buffer_ctrl_curr' variable.
Internally, it's bits are defined as:
|-------------+-----+-------------+--------+-------------+--------------|
| Bit offsets | 31 | 30 - 20 | 19 | 18-8 | 7-0 |
|-------------+-----+-------------+--------+-------------+--------------|
| What | GSB | PC (11-bit) | unused | CC (11-bit) | TBCI (8-bit) |
|-------------+-----+-------------+--------+-------------+--------------|
GSB - GDBserver Stamp Bit
PC - Previous Counter
CC - Current Counter
TBCI - Trace Buffer Control Index
An IPA update of `trace_buffer_ctrl_curr' does:
- read CC from the current token, save as PC.
- updates pointers
- atomically tries to write PC+1,CC
A GDBserver update of `trace_buffer_ctrl_curr' does:
- reads PC and CC from the current token.
- updates pointers
- writes GSB,PC,CC
*/
/* These are the bits of `trace_buffer_ctrl_curr' that are reserved
for the counters described below. The cleared bits are used to
hold the index of the items of the `trace_buffer_ctrl' array that
is "current". */
#define GDBSERVER_FLUSH_COUNT_MASK 0xfffffff0
/* `trace_buffer_ctrl_curr' contains two counters. The `previous'
counter, and the `current' counter. */
#define GDBSERVER_FLUSH_COUNT_MASK_PREV 0x7ff00000
#define GDBSERVER_FLUSH_COUNT_MASK_CURR 0x0007ff00
/* When GDBserver update the IP agent's `trace_buffer_ctrl_curr', it
always stamps this bit as set. */
#define GDBSERVER_UPDATED_FLUSH_COUNT_BIT 0x80000000
#ifdef IN_PROCESS_AGENT
IP_AGENT_EXPORT_VAR struct trace_buffer_control trace_buffer_ctrl[3];
IP_AGENT_EXPORT_VAR unsigned int trace_buffer_ctrl_curr;
# define TRACE_BUFFER_CTRL_CURR \
(trace_buffer_ctrl_curr & ~GDBSERVER_FLUSH_COUNT_MASK)
#else
/* The GDBserver side agent only needs one instance of this object, as
it doesn't need to sync with itself. Define it as array anyway so
that the rest of the code base doesn't need to care for the
difference. */
static trace_buffer_control trace_buffer_ctrl[1];
# define TRACE_BUFFER_CTRL_CURR 0
#endif
/* These are convenience macros used to access the current trace
buffer control in effect. */
#define trace_buffer_start (trace_buffer_ctrl[TRACE_BUFFER_CTRL_CURR].start)
#define trace_buffer_free (trace_buffer_ctrl[TRACE_BUFFER_CTRL_CURR].free)
#define trace_buffer_end_free \
(trace_buffer_ctrl[TRACE_BUFFER_CTRL_CURR].end_free)
#define trace_buffer_wrap (trace_buffer_ctrl[TRACE_BUFFER_CTRL_CURR].wrap)
/* Macro that returns a pointer to the first traceframe in the buffer. */
#define FIRST_TRACEFRAME() ((struct traceframe *) trace_buffer_start)
/* Macro that returns a pointer to the next traceframe in the buffer.
If the computed location is beyond the wraparound point, subtract
the offset of the wraparound. */
#define NEXT_TRACEFRAME_1(TF) \
(((unsigned char *) (TF)) + sizeof (struct traceframe) + (TF)->data_size)
#define NEXT_TRACEFRAME(TF) \
((struct traceframe *) (NEXT_TRACEFRAME_1 (TF) \
- ((NEXT_TRACEFRAME_1 (TF) >= trace_buffer_wrap) \
? (trace_buffer_wrap - trace_buffer_lo) \
: 0)))
/* The difference between these counters represents the total number
of complete traceframes present in the trace buffer. The IP agent
writes to the write count, GDBserver writes to read count. */
IP_AGENT_EXPORT_VAR unsigned int traceframe_write_count;
IP_AGENT_EXPORT_VAR unsigned int traceframe_read_count;
/* Convenience macro. */
#define traceframe_count \
((unsigned int) (traceframe_write_count - traceframe_read_count))
/* The count of all traceframes created in the current run, including
ones that were discarded to make room. */
IP_AGENT_EXPORT_VAR int traceframes_created;
#ifndef IN_PROCESS_AGENT
/* Read-only regions are address ranges whose contents don't change,
and so can be read from target memory even while looking at a trace
frame. Without these, disassembly for instance will likely fail,
because the program code is not usually collected into a trace
frame. This data structure does not need to be very complicated or
particularly efficient, it's only going to be used occasionally,
and only by some commands. */
struct readonly_region
{
/* The bounds of the region. */
CORE_ADDR start, end;
/* Link to the next one. */
struct readonly_region *next;
};
/* Linked list of readonly regions. This list stays in effect from
one tstart to the next. */
static struct readonly_region *readonly_regions;
#endif
/* The global that controls tracing overall. */
IP_AGENT_EXPORT_VAR int tracing;
#ifndef IN_PROCESS_AGENT
/* Controls whether tracing should continue after GDB disconnects. */
int disconnected_tracing;
/* The reason for the last tracing run to have stopped. We initialize
to a distinct string so that GDB can distinguish between "stopped
after running" and "stopped because never run" cases. */
static const char *tracing_stop_reason = "tnotrun";
static int tracing_stop_tpnum;
/* 64-bit timestamps for the trace run's start and finish, expressed
in microseconds from the Unix epoch. */
static LONGEST tracing_start_time;
static LONGEST tracing_stop_time;
/* The (optional) user-supplied name of the user that started the run.
This is an arbitrary string, and may be NULL. */
static char *tracing_user_name;
/* Optional user-supplied text describing the run. This is
an arbitrary string, and may be NULL. */
static char *tracing_notes;
/* Optional user-supplied text explaining a tstop command. This is an
arbitrary string, and may be NULL. */
static char *tracing_stop_note;
#endif
/* Functions local to this file. */
/* Base "class" for tracepoint type specific data to be passed down to
collect_data_at_tracepoint. */
struct tracepoint_hit_ctx
{
enum tracepoint_type type;
};
#ifdef IN_PROCESS_AGENT
/* Fast/jump tracepoint specific data to be passed down to
collect_data_at_tracepoint. */
struct fast_tracepoint_ctx
{
struct tracepoint_hit_ctx base;
struct regcache regcache;
int regcache_initted;
unsigned char *regspace;
unsigned char *regs;
struct tracepoint *tpoint;
};
/* Static tracepoint specific data to be passed down to
collect_data_at_tracepoint. */
struct static_tracepoint_ctx
{
struct tracepoint_hit_ctx base;
/* The regcache corresponding to the registers state at the time of
the tracepoint hit. Initialized lazily, from REGS. */
struct regcache regcache;
int regcache_initted;
/* The buffer space REGCACHE above uses. We use a separate buffer
instead of letting the regcache malloc for both signal safety and
performance reasons; this is allocated on the stack instead. */
unsigned char *regspace;
/* The register buffer as passed on by lttng/ust. */
struct registers *regs;
/* The "printf" formatter and the args the user passed to the marker
call. We use this to be able to collect "static trace data"
($_sdata). */
const char *fmt;
va_list *args;
/* The GDB tracepoint matching the probed marker that was "hit". */
struct tracepoint *tpoint;
};
#else
/* Static tracepoint specific data to be passed down to
collect_data_at_tracepoint. */
struct trap_tracepoint_ctx
{
struct tracepoint_hit_ctx base;
struct regcache *regcache;
};
#endif
#ifndef IN_PROCESS_AGENT
static CORE_ADDR traceframe_get_pc (struct traceframe *tframe);
static int traceframe_read_tsv (int num, LONGEST *val);
#endif
static int condition_true_at_tracepoint (struct tracepoint_hit_ctx *ctx,
struct tracepoint *tpoint);
#ifndef IN_PROCESS_AGENT
static void clear_readonly_regions (void);
static void clear_installed_tracepoints (void);
#endif
static void collect_data_at_tracepoint (struct tracepoint_hit_ctx *ctx,
CORE_ADDR stop_pc,
struct tracepoint *tpoint);
#ifndef IN_PROCESS_AGENT
static void collect_data_at_step (struct tracepoint_hit_ctx *ctx,
CORE_ADDR stop_pc,
struct tracepoint *tpoint, int current_step);
static void compile_tracepoint_condition (struct tracepoint *tpoint,
CORE_ADDR *jump_entry);
#endif
static void do_action_at_tracepoint (struct tracepoint_hit_ctx *ctx,
CORE_ADDR stop_pc,
struct tracepoint *tpoint,
struct traceframe *tframe,
struct tracepoint_action *taction);
#ifndef IN_PROCESS_AGENT
static struct tracepoint *fast_tracepoint_from_ipa_tpoint_address (CORE_ADDR);
static void install_tracepoint (struct tracepoint *, char *own_buf);
static void download_tracepoint (struct tracepoint *);
static int install_fast_tracepoint (struct tracepoint *, char *errbuf);
static void clone_fast_tracepoint (struct tracepoint *to,
const struct tracepoint *from);
#endif
static LONGEST get_timestamp (void);
#if defined(__GNUC__)
# define memory_barrier() asm volatile ("" : : : "memory")
#else
# define memory_barrier() do {} while (0)
#endif
/* We only build the IPA if this builtin is supported, and there are
no uses of this in GDBserver itself, so we're safe in defining this
unconditionally. */
#define cmpxchg(mem, oldval, newval) \
__sync_val_compare_and_swap (mem, oldval, newval)
/* Record that an error occurred during expression evaluation. */
static void
record_tracepoint_error (struct tracepoint *tpoint, const char *which,
enum eval_result_type rtype)
{
trace_debug ("Tracepoint %d at %s %s eval reports error %d",
tpoint->number, paddress (tpoint->address), which, rtype);
#ifdef IN_PROCESS_AGENT
/* Only record the first error we get. */
if (cmpxchg (&expr_eval_result,
expr_eval_no_error,
rtype) != expr_eval_no_error)
return;
#else
if (expr_eval_result != expr_eval_no_error)
return;
#endif
error_tracepoint = tpoint;
}
/* Trace buffer management. */
static void
clear_trace_buffer (void)
{
trace_buffer_start = trace_buffer_lo;
trace_buffer_free = trace_buffer_lo;
trace_buffer_end_free = trace_buffer_hi;
trace_buffer_wrap = trace_buffer_hi;
/* A traceframe with zeroed fields marks the end of trace data. */
((struct traceframe *) trace_buffer_free)->tpnum = 0;
((struct traceframe *) trace_buffer_free)->data_size = 0;
traceframe_read_count = traceframe_write_count = 0;
traceframes_created = 0;
}
#ifndef IN_PROCESS_AGENT
static void
clear_inferior_trace_buffer (void)
{
CORE_ADDR ipa_trace_buffer_lo;
CORE_ADDR ipa_trace_buffer_hi;
struct traceframe ipa_traceframe = { 0 };
struct ipa_trace_buffer_control ipa_trace_buffer_ctrl;
read_inferior_data_pointer (ipa_sym_addrs.addr_trace_buffer_lo,
&ipa_trace_buffer_lo);
read_inferior_data_pointer (ipa_sym_addrs.addr_trace_buffer_hi,
&ipa_trace_buffer_hi);
ipa_trace_buffer_ctrl.start = ipa_trace_buffer_lo;
ipa_trace_buffer_ctrl.free = ipa_trace_buffer_lo;
ipa_trace_buffer_ctrl.end_free = ipa_trace_buffer_hi;
ipa_trace_buffer_ctrl.wrap = ipa_trace_buffer_hi;
/* A traceframe with zeroed fields marks the end of trace data. */
target_write_memory (ipa_sym_addrs.addr_trace_buffer_ctrl,
(unsigned char *) &ipa_trace_buffer_ctrl,
sizeof (ipa_trace_buffer_ctrl));
write_inferior_uinteger (ipa_sym_addrs.addr_trace_buffer_ctrl_curr, 0);
/* A traceframe with zeroed fields marks the end of trace data. */
target_write_memory (ipa_trace_buffer_lo,
(unsigned char *) &ipa_traceframe,
sizeof (ipa_traceframe));
write_inferior_uinteger (ipa_sym_addrs.addr_traceframe_write_count, 0);
write_inferior_uinteger (ipa_sym_addrs.addr_traceframe_read_count, 0);
write_inferior_integer (ipa_sym_addrs.addr_traceframes_created, 0);
}
#endif
static void
init_trace_buffer (LONGEST bufsize)
{
size_t alloc_size;
trace_buffer_size = bufsize;
/* Make sure to internally allocate at least space for the EOB
marker. */
alloc_size = (bufsize < TRACEFRAME_EOB_MARKER_SIZE
? TRACEFRAME_EOB_MARKER_SIZE : bufsize);
trace_buffer_lo = (unsigned char *) xrealloc (trace_buffer_lo, alloc_size);
trace_buffer_hi = trace_buffer_lo + trace_buffer_size;
clear_trace_buffer ();
}
#ifdef IN_PROCESS_AGENT
/* This is needed for -Wmissing-declarations. */
IP_AGENT_EXPORT_FUNC void about_to_request_buffer_space (void);
IP_AGENT_EXPORT_FUNC void
about_to_request_buffer_space (void)
{
/* GDBserver places breakpoint here while it goes about to flush
data at random times. */
UNKNOWN_SIDE_EFFECTS();
}
#endif
/* Carve out a piece of the trace buffer, returning NULL in case of
failure. */
static void *
trace_buffer_alloc (size_t amt)
{
unsigned char *rslt;
struct trace_buffer_control *tbctrl;
unsigned int curr;
#ifdef IN_PROCESS_AGENT
unsigned int prev, prev_filtered;
unsigned int commit_count;
unsigned int commit;
unsigned int readout;
#else
struct traceframe *oldest;
unsigned char *new_start;
#endif
trace_debug ("Want to allocate %ld+%ld bytes in trace buffer",
(long) amt, (long) sizeof (struct traceframe));
/* Account for the EOB marker. */
amt += TRACEFRAME_EOB_MARKER_SIZE;
#ifdef IN_PROCESS_AGENT
again:
memory_barrier ();
/* Read the current token and extract the index to try to write to,
storing it in CURR. */
prev = trace_buffer_ctrl_curr;
prev_filtered = prev & ~GDBSERVER_FLUSH_COUNT_MASK;
curr = prev_filtered + 1;
if (curr > 2)
curr = 0;
about_to_request_buffer_space ();
/* Start out with a copy of the current state. GDBserver may be
midway writing to the PREV_FILTERED TBC, but, that's OK, we won't
be able to commit anyway if that happens. */
trace_buffer_ctrl[curr]
= trace_buffer_ctrl[prev_filtered];
trace_debug ("trying curr=%u", curr);
#else
/* The GDBserver's agent doesn't need all that syncing, and always
updates TCB 0 (there's only one, mind you). */
curr = 0;
#endif
tbctrl = &trace_buffer_ctrl[curr];
/* Offsets are easier to grok for debugging than raw addresses,
especially for the small trace buffer sizes that are useful for
testing. */
trace_debug ("Trace buffer [%d] start=%d free=%d endfree=%d wrap=%d hi=%d",
curr,
(int) (tbctrl->start - trace_buffer_lo),
(int) (tbctrl->free - trace_buffer_lo),
(int) (tbctrl->end_free - trace_buffer_lo),
(int) (tbctrl->wrap - trace_buffer_lo),
(int) (trace_buffer_hi - trace_buffer_lo));
/* The algorithm here is to keep trying to get a contiguous block of
the requested size, possibly discarding older traceframes to free
up space. Since free space might come in one or two pieces,
depending on whether discarded traceframes wrapped around at the
high end of the buffer, we test both pieces after each
discard. */
while (1)
{
/* First, if we have two free parts, try the upper one first. */
if (tbctrl->end_free < tbctrl->free)
{
if (tbctrl->free + amt <= trace_buffer_hi)
/* We have enough in the upper part. */
break;
else
{
/* Our high part of free space wasn't enough. Give up
on it for now, set wraparound. We will recover the
space later, if/when the wrapped-around traceframe is
discarded. */
trace_debug ("Upper part too small, setting wraparound");
tbctrl->wrap = tbctrl->free;
tbctrl->free = trace_buffer_lo;
}
}
/* The normal case. */
if (tbctrl->free + amt <= tbctrl->end_free)
break;
#ifdef IN_PROCESS_AGENT
/* The IP Agent's buffer is always circular. It isn't used
currently, but `circular_trace_buffer' could represent
GDBserver's mode. If we didn't find space, ask GDBserver to
flush. */
flush_trace_buffer ();
memory_barrier ();
if (tracing)
{
trace_debug ("gdbserver flushed buffer, retrying");
goto again;
}
/* GDBserver cancelled the tracing. Bail out as well. */
return NULL;
#else
/* If we're here, then neither part is big enough, and
non-circular trace buffers are now full. */
if (!circular_trace_buffer)
{
trace_debug ("Not enough space in the trace buffer");
return NULL;
}
trace_debug ("Need more space in the trace buffer");
/* If we have a circular buffer, we can try discarding the
oldest traceframe and see if that helps. */
oldest = FIRST_TRACEFRAME ();
if (oldest->tpnum == 0)
{
/* Not good; we have no traceframes to free. Perhaps we're
asking for a block that is larger than the buffer? In
any case, give up. */
trace_debug ("No traceframes to discard");
return NULL;
}
/* We don't run this code in the in-process agent currently.
E.g., we could leave the in-process agent in autonomous
circular mode if we only have fast tracepoints. If we do
that, then this bit becomes racy with GDBserver, which also
writes to this counter. */
--traceframe_write_count;
new_start = (unsigned char *) NEXT_TRACEFRAME (oldest);
/* If we freed the traceframe that wrapped around, go back
to the non-wrap case. */
if (new_start < tbctrl->start)
{
trace_debug ("Discarding past the wraparound");
tbctrl->wrap = trace_buffer_hi;
}
tbctrl->start = new_start;
tbctrl->end_free = tbctrl->start;
trace_debug ("Discarded a traceframe\n"
"Trace buffer [%d], start=%d free=%d "
"endfree=%d wrap=%d hi=%d",
curr,
(int) (tbctrl->start - trace_buffer_lo),
(int) (tbctrl->free - trace_buffer_lo),
(int) (tbctrl->end_free - trace_buffer_lo),
(int) (tbctrl->wrap - trace_buffer_lo),
(int) (trace_buffer_hi - trace_buffer_lo));
/* Now go back around the loop. The discard might have resulted
in either one or two pieces of free space, so we want to try
both before freeing any more traceframes. */
#endif
}
/* If we get here, we know we can provide the asked-for space. */
rslt = tbctrl->free;
/* Adjust the request back down, now that we know we have space for
the marker, but don't commit to AMT yet, we may still need to
restart the operation if GDBserver touches the trace buffer
(obviously only important in the in-process agent's version). */
tbctrl->free += (amt - sizeof (struct traceframe));
/* Or not. If GDBserver changed the trace buffer behind our back,
we get to restart a new allocation attempt. */
#ifdef IN_PROCESS_AGENT
/* Build the tentative token. */
commit_count = (((prev & GDBSERVER_FLUSH_COUNT_MASK_CURR) + 0x100)
& GDBSERVER_FLUSH_COUNT_MASK_CURR);
commit = (((prev & GDBSERVER_FLUSH_COUNT_MASK_CURR) << 12)
| commit_count
| curr);
/* Try to commit it. */
readout = cmpxchg (&trace_buffer_ctrl_curr, prev, commit);
if (readout != prev)
{
trace_debug ("GDBserver has touched the trace buffer, restarting."
" (prev=%08x, commit=%08x, readout=%08x)",
prev, commit, readout);
goto again;
}
/* Hold your horses here. Even if that change was committed,
GDBserver could come in, and clobber it. We need to hold to be
able to tell if GDBserver clobbers before or after we committed
the change. Whenever GDBserver goes about touching the IPA
buffer, it sets a breakpoint in this routine, so we have a sync
point here. */
about_to_request_buffer_space ();
/* Check if the change has been effective, even if GDBserver stopped
us at the breakpoint. */
{
unsigned int refetch;
memory_barrier ();
refetch = trace_buffer_ctrl_curr;
if (refetch == commit
|| ((refetch & GDBSERVER_FLUSH_COUNT_MASK_PREV) >> 12) == commit_count)
{
/* effective */
trace_debug ("change is effective: (prev=%08x, commit=%08x, "
"readout=%08x, refetch=%08x)",
prev, commit, readout, refetch);
}
else
{
trace_debug ("GDBserver has touched the trace buffer, not effective."
" (prev=%08x, commit=%08x, readout=%08x, refetch=%08x)",
prev, commit, readout, refetch);
goto again;
}
}
#endif
/* We have a new piece of the trace buffer. Hurray! */
/* Add an EOB marker just past this allocation. */
((struct traceframe *) tbctrl->free)->tpnum = 0;
((struct traceframe *) tbctrl->free)->data_size = 0;
/* Adjust the request back down, now that we know we have space for
the marker. */
amt -= sizeof (struct traceframe);
if (debug_threads)
{
trace_debug ("Allocated %d bytes", (int) amt);
trace_debug ("Trace buffer [%d] start=%d free=%d "
"endfree=%d wrap=%d hi=%d",
curr,
(int) (tbctrl->start - trace_buffer_lo),
(int) (tbctrl->free - trace_buffer_lo),
(int) (tbctrl->end_free - trace_buffer_lo),
(int) (tbctrl->wrap - trace_buffer_lo),
(int) (trace_buffer_hi - trace_buffer_lo));
}
return rslt;
}
#ifndef IN_PROCESS_AGENT
/* Return the total free space. This is not necessarily the largest
block we can allocate, because of the two-part case. */
static int
free_space (void)
{
if (trace_buffer_free <= trace_buffer_end_free)
return trace_buffer_end_free - trace_buffer_free;
else
return ((trace_buffer_end_free - trace_buffer_lo)
+ (trace_buffer_hi - trace_buffer_free));
}
/* An 'S' in continuation packets indicates remainder are for
while-stepping. */
static int seen_step_action_flag;
/* Create a tracepoint (location) with given number and address. Add this
new tracepoint to list and sort this list. */
static struct tracepoint *
add_tracepoint (int num, CORE_ADDR addr)
{
struct tracepoint *tpoint, **tp_next;
tpoint = XNEW (struct tracepoint);
tpoint->number = num;
tpoint->address = addr;
tpoint->numactions = 0;
tpoint->actions = NULL;
tpoint->actions_str = NULL;
tpoint->cond = NULL;
tpoint->num_step_actions = 0;
tpoint->step_actions = NULL;
tpoint->step_actions_str = NULL;
/* Start all off as regular (slow) tracepoints. */
tpoint->type = trap_tracepoint;
tpoint->orig_size = -1;
tpoint->source_strings = NULL;
tpoint->compiled_cond = 0;
tpoint->handle = NULL;
tpoint->next = NULL;
/* Find a place to insert this tracepoint into list in order to keep
the tracepoint list still in the ascending order. There may be
multiple tracepoints at the same address as TPOINT's, and this
guarantees TPOINT is inserted after all the tracepoints which are
set at the same address. For example, fast tracepoints A, B, C are
set at the same address, and D is to be insert at the same place as
well,
-->| A |--> | B |-->| C |->...
One jump pad was created for tracepoint A, B, and C, and the target
address of A is referenced/used in jump pad. So jump pad will let
inferior jump to A. If D is inserted in front of A, like this,
-->| D |-->| A |--> | B |-->| C |->...
without updating jump pad, D is not reachable during collect, which
is wrong. As we can see, the order of B, C and D doesn't matter, but
A should always be the `first' one. */
for (tp_next = &tracepoints;
(*tp_next) != NULL && (*tp_next)->address <= tpoint->address;
tp_next = &(*tp_next)->next)
;
tpoint->next = *tp_next;
*tp_next = tpoint;
last_tracepoint = tpoint;
seen_step_action_flag = 0;
return tpoint;
}
#ifndef IN_PROCESS_AGENT
/* Return the tracepoint with the given number and address, or NULL. */
static struct tracepoint *
find_tracepoint (int id, CORE_ADDR addr)
{
struct tracepoint *tpoint;
for (tpoint = tracepoints; tpoint; tpoint = tpoint->next)
if (tpoint->number == id && tpoint->address == addr)
return tpoint;
return NULL;
}
/* Remove TPOINT from global list. */
static void
remove_tracepoint (struct tracepoint *tpoint)
{
struct tracepoint *tp, *tp_prev;
for (tp = tracepoints, tp_prev = NULL; tp && tp != tpoint;
tp_prev = tp, tp = tp->next)
;
if (tp)
{
if (tp_prev)
tp_prev->next = tp->next;
else
tracepoints = tp->next;
xfree (tp);
}
}
/* There may be several tracepoints with the same number (because they
are "locations", in GDB parlance); return the next one after the
given tracepoint, or search from the beginning of the list if the
first argument is NULL. */
static struct tracepoint *
find_next_tracepoint_by_number (struct tracepoint *prev_tp, int num)
{
struct tracepoint *tpoint;
if (prev_tp)
tpoint = prev_tp->next;
else
tpoint = tracepoints;
for (; tpoint; tpoint = tpoint->next)
if (tpoint->number == num)
return tpoint;
return NULL;
}
#endif
/* Append another action to perform when the tracepoint triggers. */
static void
add_tracepoint_action (struct tracepoint *tpoint, const char *packet)
{
const char *act;
if (*packet == 'S')
{
seen_step_action_flag = 1;
++packet;
}
act = packet;
while (*act)
{
const char *act_start = act;
struct tracepoint_action *action = NULL;
switch (*act)
{
case 'M':
{
struct collect_memory_action *maction =
XNEW (struct collect_memory_action);
ULONGEST basereg;
int is_neg;
maction->base.type = *act;
action = &maction->base;
++act;
is_neg = (*act == '-');
if (*act == '-')
++act;
act = unpack_varlen_hex (act, &basereg);
++act;
act = unpack_varlen_hex (act, &maction->addr);
++act;
act = unpack_varlen_hex (act, &maction->len);
maction->basereg = (is_neg
? - (int) basereg
: (int) basereg);
trace_debug ("Want to collect %s bytes at 0x%s (basereg %d)",
pulongest (maction->len),
paddress (maction->addr), maction->basereg);
break;
}
case 'R':
{
struct collect_registers_action *raction =
XNEW (struct collect_registers_action);
raction->base.type = *act;
action = &raction->base;
trace_debug ("Want to collect registers");
++act;
/* skip past hex digits of mask for now */
while (isxdigit(*act))
++act;
break;
}
case 'L':
{
struct collect_static_trace_data_action *raction =
XNEW (struct collect_static_trace_data_action);
raction->base.type = *act;
action = &raction->base;
trace_debug ("Want to collect static trace data");
++act;
break;
}
case 'S':
trace_debug ("Unexpected step action, ignoring");
++act;
break;
case 'X':
{
struct eval_expr_action *xaction = XNEW (struct eval_expr_action);
xaction->base.type = *act;
action = &xaction->base;
trace_debug ("Want to evaluate expression");
xaction->expr = gdb_parse_agent_expr (&act);
break;
}
default:
trace_debug ("unknown trace action '%c', ignoring...", *act);
break;
case '-':
break;
}
if (action == NULL)
break;
if (seen_step_action_flag)
{
tpoint->num_step_actions++;
tpoint->step_actions
= XRESIZEVEC (struct tracepoint_action *, tpoint->step_actions,
tpoint->num_step_actions);
tpoint->step_actions_str
= XRESIZEVEC (char *, tpoint->step_actions_str,
tpoint->num_step_actions);
tpoint->step_actions[tpoint->num_step_actions - 1] = action;
tpoint->step_actions_str[tpoint->num_step_actions - 1]
= savestring (act_start, act - act_start);
}
else
{
tpoint->numactions++;
tpoint->actions
= XRESIZEVEC (struct tracepoint_action *, tpoint->actions,
tpoint->numactions);
tpoint->actions_str
= XRESIZEVEC (char *, tpoint->actions_str, tpoint->numactions);
tpoint->actions[tpoint->numactions - 1] = action;
tpoint->actions_str[tpoint->numactions - 1]
= savestring (act_start, act - act_start);
}
}
}
#endif
/* Find or create a trace state variable with the given number. */
static struct trace_state_variable *
get_trace_state_variable (int num)
{
struct trace_state_variable *tsv;
#ifdef IN_PROCESS_AGENT
/* Search for an existing variable. */
for (tsv = alloced_trace_state_variables; tsv; tsv = tsv->next)
if (tsv->number == num)
return tsv;
#endif
/* Search for an existing variable. */
for (tsv = trace_state_variables; tsv; tsv = tsv->next)
if (tsv->number == num)
return tsv;
return NULL;
}
/* Find or create a trace state variable with the given number. */
static struct trace_state_variable *
create_trace_state_variable (int num, int gdb)
{
struct trace_state_variable *tsv;
tsv = get_trace_state_variable (num);
if (tsv != NULL)
return tsv;
/* Create a new variable. */
tsv = XNEW (struct trace_state_variable);
tsv->number = num;
tsv->initial_value = 0;
tsv->value = 0;
tsv->getter = NULL;
tsv->name = NULL;
#ifdef IN_PROCESS_AGENT
if (!gdb)
{
tsv->next = alloced_trace_state_variables;
alloced_trace_state_variables = tsv;
}
else
#endif
{
tsv->next = trace_state_variables;
trace_state_variables = tsv;
}
return tsv;
}
/* This is needed for -Wmissing-declarations. */
IP_AGENT_EXPORT_FUNC LONGEST get_trace_state_variable_value (int num);
IP_AGENT_EXPORT_FUNC LONGEST
get_trace_state_variable_value (int num)
{
struct trace_state_variable *tsv;
tsv = get_trace_state_variable (num);
if (!tsv)
{
trace_debug ("No trace state variable %d, skipping value get", num);
return 0;
}
/* Call a getter function if we have one. While it's tempting to
set up something to only call the getter once per tracepoint hit,
it could run afoul of thread races. Better to let the getter
handle it directly, if necessary to worry about it. */
if (tsv->getter)
tsv->value = (tsv->getter) ();
trace_debug ("get_trace_state_variable_value(%d) ==> %s",
num, plongest (tsv->value));
return tsv->value;
}
/* This is needed for -Wmissing-declarations. */
IP_AGENT_EXPORT_FUNC void set_trace_state_variable_value (int num,
LONGEST val);
IP_AGENT_EXPORT_FUNC void
set_trace_state_variable_value (int num, LONGEST val)
{
struct trace_state_variable *tsv;
tsv = get_trace_state_variable (num);
if (!tsv)
{
trace_debug ("No trace state variable %d, skipping value set", num);
return;
}
tsv->value = val;
}
LONGEST
agent_get_trace_state_variable_value (int num)
{
return get_trace_state_variable_value (num);
}
void
agent_set_trace_state_variable_value (int num, LONGEST val)
{
set_trace_state_variable_value (num, val);
}
static void
set_trace_state_variable_name (int num, const char *name)
{
struct trace_state_variable *tsv;
tsv = get_trace_state_variable (num);
if (!tsv)
{
trace_debug ("No trace state variable %d, skipping name set", num);
return;
}
tsv->name = (char *) name;
}
static void
set_trace_state_variable_getter (int num, LONGEST (*getter) (void))
{
struct trace_state_variable *tsv;
tsv = get_trace_state_variable (num);
if (!tsv)
{
trace_debug ("No trace state variable %d, skipping getter set", num);
return;
}
tsv->getter = getter;
}
/* Add a raw traceframe for the given tracepoint. */
static struct traceframe *
add_traceframe (struct tracepoint *tpoint)
{
struct traceframe *tframe;
tframe
= (struct traceframe *) trace_buffer_alloc (sizeof (struct traceframe));
if (tframe == NULL)
return NULL;
tframe->tpnum = tpoint->number;
tframe->data_size = 0;
return tframe;
}
/* Add a block to the traceframe currently being worked on. */
static unsigned char *
add_traceframe_block (struct traceframe *tframe,
struct tracepoint *tpoint, int amt)
{
unsigned char *block;
if (!tframe)
return NULL;
block = (unsigned char *) trace_buffer_alloc (amt);
if (!block)
return NULL;
gdb_assert (tframe->tpnum == tpoint->number);
tframe->data_size += amt;
tpoint->traceframe_usage += amt;
return block;
}
/* Flag that the current traceframe is finished. */
static void
finish_traceframe (struct traceframe *tframe)
{
++traceframe_write_count;
++traceframes_created;
}
#ifndef IN_PROCESS_AGENT
/* Given a traceframe number NUM, find the NUMth traceframe in the
buffer. */
static struct traceframe *
find_traceframe (int num)
{
struct traceframe *tframe;
int tfnum = 0;
for (tframe = FIRST_TRACEFRAME ();
tframe->tpnum != 0;
tframe = NEXT_TRACEFRAME (tframe))
{
if (tfnum == num)
return tframe;
++tfnum;
}
return NULL;
}
static CORE_ADDR
get_traceframe_address (struct traceframe *tframe)
{
CORE_ADDR addr;
struct tracepoint *tpoint;
addr = traceframe_get_pc (tframe);
if (addr)
return addr;
/* Fallback strategy, will be incorrect for while-stepping frames
and multi-location tracepoints. */
tpoint = find_next_tracepoint_by_number (NULL, tframe->tpnum);
return tpoint->address;
}
/* Search for the next traceframe whose address is inside or outside
the given range. */
static struct traceframe *
find_next_traceframe_in_range (CORE_ADDR lo, CORE_ADDR hi, int inside_p,
int *tfnump)
{
client_state &cs = get_client_state ();
struct traceframe *tframe;
CORE_ADDR tfaddr;
*tfnump = cs.current_traceframe + 1;
tframe = find_traceframe (*tfnump);
/* The search is not supposed to wrap around. */
if (!tframe)
{
*tfnump = -1;
return NULL;
}
for (; tframe->tpnum != 0; tframe = NEXT_TRACEFRAME (tframe))
{
tfaddr = get_traceframe_address (tframe);
if (inside_p
? (lo <= tfaddr && tfaddr <= hi)
: (lo > tfaddr || tfaddr > hi))
return tframe;
++*tfnump;
}
*tfnump = -1;
return NULL;
}
/* Search for the next traceframe recorded by the given tracepoint.
Note that for multi-location tracepoints, this will find whatever
location appears first. */
static struct traceframe *
find_next_traceframe_by_tracepoint (int num, int *tfnump)
{
client_state &cs = get_client_state ();
struct traceframe *tframe;
*tfnump = cs.current_traceframe + 1;
tframe = find_traceframe (*tfnump);
/* The search is not supposed to wrap around. */
if (!tframe)
{
*tfnump = -1;
return NULL;
}
for (; tframe->tpnum != 0; tframe = NEXT_TRACEFRAME (tframe))
{
if (tframe->tpnum == num)
return tframe;
++*tfnump;
}
*tfnump = -1;
return NULL;
}
#endif
#ifndef IN_PROCESS_AGENT
/* Clear all past trace state. */
static void
cmd_qtinit (char *packet)
{
client_state &cs = get_client_state ();
struct trace_state_variable *tsv, *prev, *next;
/* Can't do this command without a pid attached. */
if (current_thread == NULL)
{
write_enn (packet);
return;
}
/* Make sure we don't try to read from a trace frame. */
cs.current_traceframe = -1;
stop_tracing ();
trace_debug ("Initializing the trace");
clear_installed_tracepoints ();
clear_readonly_regions ();
tracepoints = NULL;
last_tracepoint = NULL;
/* Clear out any leftover trace state variables. Ones with target
defined getters should be kept however. */
prev = NULL;
tsv = trace_state_variables;
while (tsv)
{
trace_debug ("Looking at var %d", tsv->number);
if (tsv->getter == NULL)
{
next = tsv->next;
if (prev)
prev->next = next;
else
trace_state_variables = next;
trace_debug ("Deleting var %d", tsv->number);
free (tsv);
tsv = next;
}
else
{
prev = tsv;
tsv = tsv->next;
}
}
clear_trace_buffer ();
clear_inferior_trace_buffer ();
write_ok (packet);
}
/* Unprobe the UST marker at ADDRESS. */
static void
unprobe_marker_at (CORE_ADDR address)
{
char cmd[IPA_CMD_BUF_SIZE];
sprintf (cmd, "unprobe_marker_at:%s", paddress (address));
run_inferior_command (cmd, strlen (cmd) + 1);
}
/* Restore the program to its pre-tracing state. This routine may be called
in error situations, so it needs to be careful about only restoring
from known-valid bits. */
static void
clear_installed_tracepoints (void)
{
struct tracepoint *tpoint;
struct tracepoint *prev_stpoint;
target_pause_all (true);
prev_stpoint = NULL;
/* Restore any bytes overwritten by tracepoints. */
for (tpoint = tracepoints; tpoint; tpoint = tpoint->next)
{
/* Catch the case where we might try to remove a tracepoint that
was never actually installed. */
if (tpoint->handle == NULL)
{
trace_debug ("Tracepoint %d at 0x%s was "
"never installed, nothing to clear",
tpoint->number, paddress (tpoint->address));
continue;
}
switch (tpoint->type)
{
case trap_tracepoint:
{
struct breakpoint *bp
= (struct breakpoint *) tpoint->handle;
delete_breakpoint (bp);
}
break;
case fast_tracepoint:
{
struct fast_tracepoint_jump *jump
= (struct fast_tracepoint_jump *) tpoint->handle;
delete_fast_tracepoint_jump (jump);
}
break;
case static_tracepoint:
if (prev_stpoint != NULL
&& prev_stpoint->address == tpoint->address)
/* Nothing to do. We already unprobed a tracepoint set at
this marker address (and there can only be one probe
per marker). */
;
else
{
unprobe_marker_at (tpoint->address);
prev_stpoint = tpoint;
}
break;
}
tpoint->handle = NULL;
}
target_unpause_all (true);
}
/* Parse a packet that defines a tracepoint. */
static void
cmd_qtdp (char *own_buf)
{
int tppacket;
/* Whether there is a trailing hyphen at the end of the QTDP packet. */
int trail_hyphen = 0;
ULONGEST num;
ULONGEST addr;
ULONGEST count;
struct tracepoint *tpoint;
const char *packet = own_buf;
packet += strlen ("QTDP:");
/* A hyphen at the beginning marks a packet specifying actions for a
tracepoint already supplied. */
tppacket = 1;
if (*packet == '-')
{
tppacket = 0;
++packet;
}
packet = unpack_varlen_hex (packet, &num);
++packet; /* skip a colon */
packet = unpack_varlen_hex (packet, &addr);
++packet; /* skip a colon */
/* See if we already have this tracepoint. */
tpoint = find_tracepoint (num, addr);
if (tppacket)
{
/* Duplicate tracepoints are never allowed. */
if (tpoint)
{
trace_debug ("Tracepoint error: tracepoint %d"
" at 0x%s already exists",
(int) num, paddress (addr));
write_enn (own_buf);
return;
}
tpoint = add_tracepoint (num, addr);
tpoint->enabled = (*packet == 'E');
++packet; /* skip 'E' */
++packet; /* skip a colon */
packet = unpack_varlen_hex (packet, &count);
tpoint->step_count = count;
++packet; /* skip a colon */
packet = unpack_varlen_hex (packet, &count);
tpoint->pass_count = count;
/* See if we have any of the additional optional fields. */
while (*packet == ':')
{
++packet;
if (*packet == 'F')
{
tpoint->type = fast_tracepoint;
++packet;
packet = unpack_varlen_hex (packet, &count);
tpoint->orig_size = count;
}
else if (*packet == 'S')
{
tpoint->type = static_tracepoint;
++packet;
}
else if (*packet == 'X')
{
tpoint->cond = gdb_parse_agent_expr (&packet);
}
else if (*packet == '-')
break;
else if (*packet == '\0')
break;
else
trace_debug ("Unknown optional tracepoint field");
}
if (*packet == '-')
{
trail_hyphen = 1;
trace_debug ("Also has actions\n");
}
trace_debug ("Defined %stracepoint %d at 0x%s, "
"enabled %d step %" PRIu64 " pass %" PRIu64,
tpoint->type == fast_tracepoint ? "fast "
: tpoint->type == static_tracepoint ? "static " : "",
tpoint->number, paddress (tpoint->address), tpoint->enabled,
tpoint->step_count, tpoint->pass_count);
}
else if (tpoint)
add_tracepoint_action (tpoint, packet);
else
{
trace_debug ("Tracepoint error: tracepoint %d at 0x%s not found",
(int) num, paddress (addr));
write_enn (own_buf);
return;
}
/* Install tracepoint during tracing only once for each tracepoint location.
For each tracepoint loc, GDB may send multiple QTDP packets, and we can
determine the last QTDP packet for one tracepoint location by checking
trailing hyphen in QTDP packet. */
if (tracing && !trail_hyphen)
{
struct tracepoint *tp = NULL;
/* Pause all threads temporarily while we patch tracepoints. */
target_pause_all (false);
/* download_tracepoint will update global `tracepoints'
list, so it is unsafe to leave threads in jump pad. */
target_stabilize_threads ();
/* Freeze threads. */
target_pause_all (true);
if (tpoint->type != trap_tracepoint)
{
/* Find another fast or static tracepoint at the same address. */
for (tp = tracepoints; tp; tp = tp->next)
{
if (tp->address == tpoint->address && tp->type == tpoint->type
&& tp->number != tpoint->number)
break;
}
/* TPOINT is installed at the same address as TP. */
if (tp)
{
if (tpoint->type == fast_tracepoint)
clone_fast_tracepoint (tpoint, tp);
else if (tpoint->type == static_tracepoint)
tpoint->handle = (void *) -1;
}
}
if (use_agent && tpoint->type == fast_tracepoint
&& agent_capability_check (AGENT_CAPA_FAST_TRACE))
{
/* Download and install fast tracepoint by agent. */
if (tracepoint_send_agent (tpoint) == 0)
write_ok (own_buf);
else
{
write_enn (own_buf);
remove_tracepoint (tpoint);
}
}
else
{
download_tracepoint (tpoint);
if (tpoint->type == trap_tracepoint || tp == NULL)
{
install_tracepoint (tpoint, own_buf);
if (strcmp (own_buf, "OK") != 0)
remove_tracepoint (tpoint);
}
else
write_ok (own_buf);
}
target_unpause_all (true);
return;
}
write_ok (own_buf);
}
static void
cmd_qtdpsrc (char *own_buf)
{
ULONGEST num, addr, start, slen;
struct tracepoint *tpoint;
const char *packet = own_buf;
const char *saved;
char *srctype, *src;
size_t nbytes;
struct source_string *last, *newlast;
packet += strlen ("QTDPsrc:");
packet = unpack_varlen_hex (packet, &num);
++packet; /* skip a colon */
packet = unpack_varlen_hex (packet, &addr);
++packet; /* skip a colon */
/* See if we already have this tracepoint. */
tpoint = find_tracepoint (num, addr);
if (!tpoint)
{
trace_debug ("Tracepoint error: tracepoint %d at 0x%s not found",
(int) num, paddress (addr));
write_enn (own_buf);
return;
}
saved = packet;
packet = strchr (packet, ':');
srctype = (char *) xmalloc (packet - saved + 1);
memcpy (srctype, saved, packet - saved);
srctype[packet - saved] = '\0';
++packet;
packet = unpack_varlen_hex (packet, &start);
++packet; /* skip a colon */
packet = unpack_varlen_hex (packet, &slen);
++packet; /* skip a colon */
src = (char *) xmalloc (slen + 1);
nbytes = hex2bin (packet, (gdb_byte *) src, strlen (packet) / 2);
src[nbytes] = '\0';
newlast = XNEW (struct source_string);
newlast->type = srctype;
newlast->str = src;
newlast->next = NULL;
/* Always add a source string to the end of the list;
this keeps sequences of actions/commands in the right
order. */
if (tpoint->source_strings)
{
for (last = tpoint->source_strings; last->next; last = last->next)
;
last->next = newlast;
}
else
tpoint->source_strings = newlast;
write_ok (own_buf);
}
static void
cmd_qtdv (char *own_buf)
{
ULONGEST num, val, builtin;
char *varname;
size_t nbytes;
struct trace_state_variable *tsv;
const char *packet = own_buf;
packet += strlen ("QTDV:");
packet = unpack_varlen_hex (packet, &num);
++packet; /* skip a colon */
packet = unpack_varlen_hex (packet, &val);
++packet; /* skip a colon */
packet = unpack_varlen_hex (packet, &builtin);
++packet; /* skip a colon */
nbytes = strlen (packet) / 2;
varname = (char *) xmalloc (nbytes + 1);
nbytes = hex2bin (packet, (gdb_byte *) varname, nbytes);
varname[nbytes] = '\0';
tsv = create_trace_state_variable (num, 1);
tsv->initial_value = (LONGEST) val;
tsv->name = varname;
set_trace_state_variable_value (num, (LONGEST) val);
write_ok (own_buf);
}
static void
cmd_qtenable_disable (char *own_buf, int enable)
{
const char *packet = own_buf;
ULONGEST num, addr;
struct tracepoint *tp;
packet += strlen (enable ? "QTEnable:" : "QTDisable:");
packet = unpack_varlen_hex (packet, &num);
++packet; /* skip a colon */
packet = unpack_varlen_hex (packet, &addr);
tp = find_tracepoint (num, addr);
if (tp)
{
if ((enable && tp->enabled) || (!enable && !tp->enabled))
{
trace_debug ("Tracepoint %d at 0x%s is already %s",
(int) num, paddress (addr),
enable ? "enabled" : "disabled");
write_ok (own_buf);
return;
}
trace_debug ("%s tracepoint %d at 0x%s",
enable ? "Enabling" : "Disabling",
(int) num, paddress (addr));
tp->enabled = enable;
if (tp->type == fast_tracepoint || tp->type == static_tracepoint)
{
int offset = offsetof (struct tracepoint, enabled);
CORE_ADDR obj_addr = tp->obj_addr_on_target + offset;
int ret = write_inferior_int8 (obj_addr, enable);
if (ret)
{
trace_debug ("Cannot write enabled flag into "
"inferior process memory");
write_enn (own_buf);
return;
}
}
write_ok (own_buf);
}
else
{
trace_debug ("Tracepoint %d at 0x%s not found",
(int) num, paddress (addr));
write_enn (own_buf);
}
}
static void
cmd_qtv (char *own_buf)
{
client_state &cs = get_client_state ();
ULONGEST num;
LONGEST val = 0;
int err;
char *packet = own_buf;
packet += strlen ("qTV:");
unpack_varlen_hex (packet, &num);
if (cs.current_traceframe >= 0)
{
err = traceframe_read_tsv ((int) num, &val);
if (err)
{
strcpy (own_buf, "U");
return;
}
}
/* Only make tsv's be undefined before the first trace run. After a
trace run is over, the user might want to see the last value of
the tsv, and it might not be available in a traceframe. */
else if (!tracing && strcmp (tracing_stop_reason, "tnotrun") == 0)
{
strcpy (own_buf, "U");
return;
}
else
val = get_trace_state_variable_value (num);
sprintf (own_buf, "V%s", phex_nz (val, 0));
}
/* Clear out the list of readonly regions. */
static void
clear_readonly_regions (void)
{
struct readonly_region *roreg;
while (readonly_regions)
{
roreg = readonly_regions;
readonly_regions = readonly_regions->next;
free (roreg);
}
}
/* Parse the collection of address ranges whose contents GDB believes
to be unchanging and so can be read directly from target memory
even while looking at a traceframe. */
static void
cmd_qtro (char *own_buf)
{
ULONGEST start, end;
struct readonly_region *roreg;
const char *packet = own_buf;
trace_debug ("Want to mark readonly regions");
clear_readonly_regions ();
packet += strlen ("QTro");
while (*packet == ':')
{
++packet; /* skip a colon */
packet = unpack_varlen_hex (packet, &start);
++packet; /* skip a comma */
packet = unpack_varlen_hex (packet, &end);
roreg = XNEW (struct readonly_region);
roreg->start = start;
roreg->end = end;
roreg->next = readonly_regions;
readonly_regions = roreg;
trace_debug ("Added readonly region from 0x%s to 0x%s",
paddress (roreg->start), paddress (roreg->end));
}
write_ok (own_buf);
}
/* Test to see if the given range is in our list of readonly ranges.
We only test for being entirely within a range, GDB is not going to
send a single memory packet that spans multiple regions. */
int
in_readonly_region (CORE_ADDR addr, ULONGEST length)
{
struct readonly_region *roreg;
for (roreg = readonly_regions; roreg; roreg = roreg->next)
if (roreg->start <= addr && (addr + length - 1) <= roreg->end)
return 1;
return 0;
}
static CORE_ADDR gdb_jump_pad_head;
/* Return the address of the next free jump space. */
static CORE_ADDR
get_jump_space_head (void)
{
if (gdb_jump_pad_head == 0)
{
if (read_inferior_data_pointer (ipa_sym_addrs.addr_gdb_jump_pad_buffer,
&gdb_jump_pad_head))
{
internal_error ("error extracting jump_pad_buffer");
}
}
return gdb_jump_pad_head;
}
/* Reserve USED bytes from the jump space. */
static void
claim_jump_space (ULONGEST used)
{
trace_debug ("claim_jump_space reserves %s bytes at %s",
pulongest (used), paddress (gdb_jump_pad_head));
gdb_jump_pad_head += used;
}
static CORE_ADDR trampoline_buffer_head = 0;
static CORE_ADDR trampoline_buffer_tail;
/* Reserve USED bytes from the trampoline buffer and return the
address of the start of the reserved space in TRAMPOLINE. Returns
non-zero if the space is successfully claimed. */
int
claim_trampoline_space (ULONGEST used, CORE_ADDR *trampoline)
{
if (!trampoline_buffer_head)
{
if (read_inferior_data_pointer (ipa_sym_addrs.addr_gdb_trampoline_buffer,
&trampoline_buffer_tail))
{
internal_error ("error extracting trampoline_buffer");
}
if (read_inferior_data_pointer (ipa_sym_addrs.addr_gdb_trampoline_buffer_end,
&trampoline_buffer_head))
{
internal_error ("error extracting trampoline_buffer_end");
}
}
/* Start claiming space from the top of the trampoline space. If
the space is located at the bottom of the virtual address space,
this reduces the possibility that corruption will occur if a null
pointer is used to write to memory. */
if (trampoline_buffer_head - trampoline_buffer_tail < used)
{
trace_debug ("claim_trampoline_space failed to reserve %s bytes",
pulongest (used));
return 0;
}
trampoline_buffer_head -= used;
trace_debug ("claim_trampoline_space reserves %s bytes at %s",
pulongest (used), paddress (trampoline_buffer_head));
*trampoline = trampoline_buffer_head;
return 1;
}
/* Returns non-zero if there is space allocated for use in trampolines
for fast tracepoints. */
int
have_fast_tracepoint_trampoline_buffer (char *buf)
{
CORE_ADDR trampoline_end, errbuf;
if (read_inferior_data_pointer (ipa_sym_addrs.addr_gdb_trampoline_buffer_end,
&trampoline_end))
{
internal_error ("error extracting trampoline_buffer_end");
}
if (buf)
{
buf[0] = '\0';
strcpy (buf, "was claiming");
if (read_inferior_data_pointer (ipa_sym_addrs.addr_gdb_trampoline_buffer_error,
&errbuf))
{
internal_error ("error extracting errbuf");
}
read_inferior_memory (errbuf, (unsigned char *) buf, 100);
}
return trampoline_end != 0;
}
/* Ask the IPA to probe the marker at ADDRESS. Returns -1 if running
the command fails, or 0 otherwise. If the command ran
successfully, but probing the marker failed, ERROUT will be filled
with the error to reply to GDB, and -1 is also returned. This
allows directly passing IPA errors to GDB. */
static int
probe_marker_at (CORE_ADDR address, char *errout)
{
char cmd[IPA_CMD_BUF_SIZE];
int err;
sprintf (cmd, "probe_marker_at:%s", paddress (address));
err = run_inferior_command (cmd, strlen (cmd) + 1);
if (err == 0)
{
if (*cmd == 'E')
{
strcpy (errout, cmd);
return -1;
}
}
return err;
}
static void
clone_fast_tracepoint (struct tracepoint *to, const struct tracepoint *from)
{
to->jump_pad = from->jump_pad;
to->jump_pad_end = from->jump_pad_end;
to->trampoline = from->trampoline;
to->trampoline_end = from->trampoline_end;
to->adjusted_insn_addr = from->adjusted_insn_addr;
to->adjusted_insn_addr_end = from->adjusted_insn_addr_end;
to->handle = from->handle;
gdb_assert (from->handle);
inc_ref_fast_tracepoint_jump ((struct fast_tracepoint_jump *) from->handle);
}
#define MAX_JUMP_SIZE 20
/* Install fast tracepoint. Return 0 if successful, otherwise return
non-zero. */
static int
install_fast_tracepoint (struct tracepoint *tpoint, char *errbuf)
{
CORE_ADDR jentry, jump_entry;
CORE_ADDR trampoline;
CORE_ADDR collect;
ULONGEST trampoline_size;
int err = 0;
/* The jump to the jump pad of the last fast tracepoint
installed. */
unsigned char fjump[MAX_JUMP_SIZE];
ULONGEST fjump_size;
if (tpoint->orig_size < target_get_min_fast_tracepoint_insn_len ())
{
trace_debug ("Requested a fast tracepoint on an instruction "
"that is of less than the minimum length.");
return 0;
}
if (read_inferior_data_pointer (ipa_sym_addrs.addr_gdb_collect_ptr,
&collect))
{
error ("error extracting gdb_collect_ptr");
return 1;
}
jentry = jump_entry = get_jump_space_head ();
trampoline = 0;
trampoline_size = 0;
/* Install the jump pad. */
err = target_install_fast_tracepoint_jump_pad
(tpoint->obj_addr_on_target, tpoint->address, collect,
ipa_sym_addrs.addr_collecting, tpoint->orig_size, &jentry,
&trampoline, &trampoline_size, fjump, &fjump_size,
&tpoint->adjusted_insn_addr, &tpoint->adjusted_insn_addr_end, errbuf);
if (err)
return 1;
/* Wire it in. */
tpoint->handle = set_fast_tracepoint_jump (tpoint->address, fjump,
fjump_size);
if (tpoint->handle != NULL)
{
tpoint->jump_pad = jump_entry;
tpoint->jump_pad_end = jentry;
tpoint->trampoline = trampoline;
tpoint->trampoline_end = trampoline + trampoline_size;
/* Pad to 8-byte alignment. */
jentry = ((jentry + 7) & ~0x7);
claim_jump_space (jentry - jump_entry);
}
return 0;
}
/* Install tracepoint TPOINT, and write reply message in OWN_BUF. */
static void
install_tracepoint (struct tracepoint *tpoint, char *own_buf)
{
tpoint->handle = NULL;
*own_buf = '\0';
if (tpoint->type == trap_tracepoint)
{
/* Tracepoints are installed as memory breakpoints. Just go
ahead and install the trap. The breakpoints module
handles duplicated breakpoints, and the memory read
routine handles un-patching traps from memory reads. */
tpoint->handle = set_breakpoint_at (tpoint->address,
tracepoint_handler);
}
else if (tpoint->type == fast_tracepoint || tpoint->type == static_tracepoint)
{
if (!agent_loaded_p ())
{
trace_debug ("Requested a %s tracepoint, but fast "
"tracepoints aren't supported.",
tpoint->type == static_tracepoint ? "static" : "fast");
write_e_ipa_not_loaded (own_buf);
return;
}
if (tpoint->type == static_tracepoint
&& !in_process_agent_supports_ust ())
{
trace_debug ("Requested a static tracepoint, but static "
"tracepoints are not supported.");
write_e_ust_not_loaded (own_buf);
return;
}
if (tpoint->type == fast_tracepoint)
install_fast_tracepoint (tpoint, own_buf);
else
{
if (probe_marker_at (tpoint->address, own_buf) == 0)
tpoint->handle = (void *) -1;
}
}
else
internal_error ("Unknown tracepoint type");
if (tpoint->handle == NULL)
{
if (*own_buf == '\0')
write_enn (own_buf);
}
else
write_ok (own_buf);
}
static void download_tracepoint_1 (struct tracepoint *tpoint);
static void
cmd_qtstart (char *packet)
{
struct tracepoint *tpoint, *prev_ftpoint, *prev_stpoint;
CORE_ADDR tpptr = 0, prev_tpptr = 0;
trace_debug ("Starting the trace");
/* Pause all threads temporarily while we patch tracepoints. */
target_pause_all (false);
/* Get threads out of jump pads. Safe to do here, since this is a
top level command. And, required to do here, since we're
deleting/rewriting jump pads. */
target_stabilize_threads ();
/* Freeze threads. */
target_pause_all (true);
/* Sync the fast tracepoints list in the inferior ftlib. */
if (agent_loaded_p ())
download_trace_state_variables ();
/* No previous fast tpoint yet. */
prev_ftpoint = NULL;
/* No previous static tpoint yet. */
prev_stpoint = NULL;
*packet = '\0';
if (agent_loaded_p ())
{
/* Tell IPA about the correct tdesc. */
if (write_inferior_integer (ipa_sym_addrs.addr_ipa_tdesc_idx,
target_get_ipa_tdesc_idx ()))
error ("Error setting ipa_tdesc_idx variable in lib");
}
/* Start out empty. */
if (agent_loaded_p ())
write_inferior_data_pointer (ipa_sym_addrs.addr_tracepoints, 0);
/* Download and install tracepoints. */
for (tpoint = tracepoints; tpoint; tpoint = tpoint->next)
{
/* Ensure all the hit counts start at zero. */
tpoint->hit_count = 0;
tpoint->traceframe_usage = 0;
if (tpoint->type == trap_tracepoint)
{
/* Tracepoints are installed as memory breakpoints. Just go
ahead and install the trap. The breakpoints module
handles duplicated breakpoints, and the memory read
routine handles un-patching traps from memory reads. */
tpoint->handle = set_breakpoint_at (tpoint->address,
tracepoint_handler);
}
else if (tpoint->type == fast_tracepoint
|| tpoint->type == static_tracepoint)
{
if (maybe_write_ipa_not_loaded (packet))
{
trace_debug ("Requested a %s tracepoint, but fast "
"tracepoints aren't supported.",
tpoint->type == static_tracepoint
? "static" : "fast");
break;
}
if (tpoint->type == fast_tracepoint)
{
int use_agent_p
= use_agent && agent_capability_check (AGENT_CAPA_FAST_TRACE);
if (prev_ftpoint != NULL
&& prev_ftpoint->address == tpoint->address)
{
if (use_agent_p)
tracepoint_send_agent (tpoint);
else
download_tracepoint_1 (tpoint);
clone_fast_tracepoint (tpoint, prev_ftpoint);
}
else
{
/* Tracepoint is installed successfully? */
int installed = 0;
/* Download and install fast tracepoint by agent. */
if (use_agent_p)
installed = !tracepoint_send_agent (tpoint);
else
{
download_tracepoint_1 (tpoint);
installed = !install_fast_tracepoint (tpoint, packet);
}
if (installed)
prev_ftpoint = tpoint;
}
}
else
{
if (!in_process_agent_supports_ust ())
{
trace_debug ("Requested a static tracepoint, but static "
"tracepoints are not supported.");
break;
}
download_tracepoint_1 (tpoint);
/* Can only probe a given marker once. */
if (prev_stpoint != NULL
&& prev_stpoint->address == tpoint->address)
tpoint->handle = (void *) -1;
else
{
if (probe_marker_at (tpoint->address, packet) == 0)
{
tpoint->handle = (void *) -1;
/* So that we can handle multiple static tracepoints
at the same address easily. */
prev_stpoint = tpoint;
}
}
}
prev_tpptr = tpptr;
tpptr = tpoint->obj_addr_on_target;
if (tpoint == tracepoints)
/* First object in list, set the head pointer in the
inferior. */
write_inferior_data_pointer (ipa_sym_addrs.addr_tracepoints, tpptr);
else
write_inferior_data_pointer (prev_tpptr
+ offsetof (struct tracepoint, next),
tpptr);
}
/* Any failure in the inner loop is sufficient cause to give
up. */
if (tpoint->handle == NULL)
break;
}
/* Any error in tracepoint insertion is unacceptable; better to
address the problem now, than end up with a useless or misleading
trace run. */
if (tpoint != NULL)
{
clear_installed_tracepoints ();
if (*packet == '\0')
write_enn (packet);
target_unpause_all (true);
return;
}
stopping_tracepoint = NULL;
trace_buffer_is_full = 0;
expr_eval_result = expr_eval_no_error;
error_tracepoint = NULL;
tracing_start_time = get_timestamp ();
/* Tracing is now active, hits will now start being logged. */
tracing = 1;
if (agent_loaded_p ())
{
if (write_inferior_integer (ipa_sym_addrs.addr_tracing, 1))
{
internal_error ("Error setting tracing variable in lib");
}
if (write_inferior_data_pointer (ipa_sym_addrs.addr_stopping_tracepoint,
0))
{
internal_error ("Error clearing stopping_tracepoint variable"
" in lib");
}
if (write_inferior_integer (ipa_sym_addrs.addr_trace_buffer_is_full, 0))
{
internal_error ("Error clearing trace_buffer_is_full variable"
" in lib");
}
stop_tracing_bkpt = set_breakpoint_at (ipa_sym_addrs.addr_stop_tracing,
stop_tracing_handler);
if (stop_tracing_bkpt == NULL)
error ("Error setting stop_tracing breakpoint");
flush_trace_buffer_bkpt
= set_breakpoint_at (ipa_sym_addrs.addr_flush_trace_buffer,
flush_trace_buffer_handler);
if (flush_trace_buffer_bkpt == NULL)
error ("Error setting flush_trace_buffer breakpoint");
}
target_unpause_all (true);
write_ok (packet);
}
/* End a tracing run, filling in a stop reason to report back to GDB,
and removing the tracepoints from the code. */
void
stop_tracing (void)
{
if (!tracing)
{
trace_debug ("Tracing is already off, ignoring");
return;
}
trace_debug ("Stopping the trace");
/* Pause all threads before removing fast jumps from memory,
breakpoints, and touching IPA state variables (inferior memory).
Some thread may hit the internal tracing breakpoints, or be
collecting this moment, but that's ok, we don't release the
tpoint object's memory or the jump pads here (we only do that
when we're sure we can move all threads out of the jump pads).
We can't now, since we may be getting here due to the inferior
agent calling us. */
target_pause_all (true);
/* Stop logging. Tracepoints can still be hit, but they will not be
recorded. */
tracing = 0;
if (agent_loaded_p ())
{
if (write_inferior_integer (ipa_sym_addrs.addr_tracing, 0))
{
internal_error ("Error clearing tracing variable in lib");
}
}
tracing_stop_time = get_timestamp ();
tracing_stop_reason = "t???";
tracing_stop_tpnum = 0;
if (stopping_tracepoint)
{
trace_debug ("Stopping the trace because "
"tracepoint %d was hit %" PRIu64 " times",
stopping_tracepoint->number,
stopping_tracepoint->pass_count);
tracing_stop_reason = "tpasscount";
tracing_stop_tpnum = stopping_tracepoint->number;
}
else if (trace_buffer_is_full)
{
trace_debug ("Stopping the trace because the trace buffer is full");
tracing_stop_reason = "tfull";
}
else if (expr_eval_result != expr_eval_no_error)
{
trace_debug ("Stopping the trace because of an expression eval error");
tracing_stop_reason = eval_result_names[expr_eval_result];
tracing_stop_tpnum = error_tracepoint->number;
}
#ifndef IN_PROCESS_AGENT
else if (!gdb_connected ())
{
trace_debug ("Stopping the trace because GDB disconnected");
tracing_stop_reason = "tdisconnected";
}
#endif
else
{
trace_debug ("Stopping the trace because of a tstop command");
tracing_stop_reason = "tstop";
}
stopping_tracepoint = NULL;
error_tracepoint = NULL;
/* Clear out the tracepoints. */
clear_installed_tracepoints ();
if (agent_loaded_p ())
{
/* Pull in fast tracepoint trace frames from the inferior lib
buffer into our buffer, even if our buffer is already full,
because we want to present the full number of created frames
in addition to what fit in the trace buffer. */
upload_fast_traceframes ();
}
if (stop_tracing_bkpt != NULL)
{
delete_breakpoint (stop_tracing_bkpt);
stop_tracing_bkpt = NULL;
}
if (flush_trace_buffer_bkpt != NULL)
{
delete_breakpoint (</