blob: 19353eb97dcc48f9c26fa65a22539d6b447b0ae8 [file] [log] [blame]
/* BSD Kernel Data Access Library (libkvm) interface.
Copyright (C) 2004-2024 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/>. */
#define _KMEMUSER
#include "cli/cli-cmds.h"
#include "command.h"
#include "filenames.h"
#include "frame.h"
#include "regcache.h"
#include "target.h"
#include "process-stratum-target.h"
#include "value.h"
#include "gdbcore.h"
#include "inferior.h"
#include "gdbthread.h"
#include "gdbsupport/pathstuff.h"
#include "gdbsupport/gdb_tilde_expand.h"
#include <fcntl.h>
#include <kvm.h>
#ifdef HAVE_NLIST_H
#include <nlist.h>
#endif
#include <paths.h>
#include "readline/readline.h"
#include <sys/param.h>
#include <sys/proc.h>
#ifdef HAVE_SYS_USER_H
#include <sys/user.h>
#endif
#include "bsd-kvm.h"
/* Kernel memory device file. */
static std::string bsd_kvm_corefile;
/* Kernel memory interface descriptor. */
static kvm_t *core_kd;
/* Address of process control block. */
static struct pcb *bsd_kvm_paddr;
/* Pointer to architecture-specific function that reconstructs the
register state from PCB and supplies it to REGCACHE. */
static int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb);
/* This is the ptid we use while we're connected to kvm. The kvm
target currently doesn't export any view of the running processes,
so this represents the kernel task. */
static ptid_t bsd_kvm_ptid;
/* The libkvm target. */
static const target_info bsd_kvm_target_info = {
"kvm",
N_("Kernel memory interface"),
N_("Use a kernel virtual memory image as a target.\n\
Optionally specify the filename of a core dump.")
};
class bsd_kvm_target final : public process_stratum_target
{
public:
bsd_kvm_target () = default;
const target_info &info () const override
{ return bsd_kvm_target_info; }
void close () override;
void fetch_registers (struct regcache *, int) override;
enum target_xfer_status xfer_partial (enum target_object object,
const char *annex,
gdb_byte *readbuf,
const gdb_byte *writebuf,
ULONGEST offset, ULONGEST len,
ULONGEST *xfered_len) override;
void files_info () override;
bool thread_alive (ptid_t ptid) override;
std::string pid_to_str (ptid_t) override;
bool has_memory () override { return true; }
bool has_stack () override { return true; }
bool has_registers () override { return true; }
};
/* Target ops for libkvm interface. */
static bsd_kvm_target bsd_kvm_ops;
static void
bsd_kvm_target_open (const char *arg, int from_tty)
{
char errbuf[_POSIX2_LINE_MAX];
kvm_t *temp_kd;
std::string filename;
target_preopen (from_tty);
if (arg)
{
filename = gdb_tilde_expand (arg);
if (!IS_ABSOLUTE_PATH (filename))
filename = gdb_abspath (filename);
}
const char *execfile = current_program_space->exec_filename ();
temp_kd = kvm_openfiles (execfile, filename.c_str (), NULL,
write_files ? O_RDWR : O_RDONLY, errbuf);
if (temp_kd == NULL)
error (("%s"), errbuf);
bsd_kvm_corefile = filename;
current_inferior ()->unpush_target (&bsd_kvm_ops);
core_kd = temp_kd;
current_inferior ()->push_target (&bsd_kvm_ops);
thread_info *thr = add_thread_silent (&bsd_kvm_ops, bsd_kvm_ptid);
switch_to_thread (thr);
target_fetch_registers (get_thread_regcache (thr), -1);
reinit_frame_cache ();
print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1);
}
void
bsd_kvm_target::close ()
{
if (core_kd)
{
if (kvm_close (core_kd) == -1)
warning (("%s"), kvm_geterr(core_kd));
core_kd = NULL;
}
bsd_kvm_corefile.clear ();
switch_to_no_thread ();
exit_inferior (current_inferior ());
}
static LONGEST
bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len,
gdb_byte *readbuf, const gdb_byte *writebuf)
{
ssize_t nbytes = len;
if (readbuf)
nbytes = kvm_read (core_kd, addr, readbuf, nbytes);
if (writebuf && nbytes > 0)
nbytes = kvm_write (core_kd, addr, writebuf, nbytes);
return nbytes;
}
enum target_xfer_status
bsd_kvm_target::xfer_partial (enum target_object object,
const char *annex, gdb_byte *readbuf,
const gdb_byte *writebuf,
ULONGEST offset, ULONGEST len, ULONGEST *xfered_len)
{
switch (object)
{
case TARGET_OBJECT_MEMORY:
{
LONGEST ret = bsd_kvm_xfer_memory (offset, len, readbuf, writebuf);
if (ret < 0)
return TARGET_XFER_E_IO;
else if (ret == 0)
return TARGET_XFER_EOF;
else
{
*xfered_len = (ULONGEST) ret;
return TARGET_XFER_OK;
}
}
default:
return TARGET_XFER_E_IO;
}
}
void
bsd_kvm_target::files_info ()
{
if (bsd_kvm_corefile != _PATH_MEM)
gdb_printf (_("\tUsing the kernel crash dump %s.\n"),
bsd_kvm_corefile.c_str ());
else
gdb_printf (_("\tUsing the currently running kernel.\n"));
}
/* Fetch process control block at address PADDR. */
static int
bsd_kvm_fetch_pcb (struct regcache *regcache, struct pcb *paddr)
{
struct pcb pcb;
if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)
error (("%s"), kvm_geterr (core_kd));
gdb_assert (bsd_kvm_supply_pcb);
return bsd_kvm_supply_pcb (regcache, &pcb);
}
void
bsd_kvm_target::fetch_registers (struct regcache *regcache, int regnum)
{
struct nlist nl[2];
if (bsd_kvm_paddr)
{
bsd_kvm_fetch_pcb (regcache, bsd_kvm_paddr);
return;
}
/* On dumping core, BSD kernels store the faulting context (PCB)
in the variable "dumppcb". */
memset (nl, 0, sizeof nl);
nl[0].n_name = (char *) "_dumppcb";
if (kvm_nlist (core_kd, nl) == -1)
error (("%s"), kvm_geterr (core_kd));
if (nl[0].n_value != 0)
{
/* Found dumppcb. If it contains a valid context, return
immediately. */
if (bsd_kvm_fetch_pcb (regcache, (struct pcb *) nl[0].n_value))
return;
}
/* Traditional BSD kernels have a process proc0 that should always
be present. The address of proc0's PCB is stored in the variable
"proc0paddr". */
memset (nl, 0, sizeof nl);
nl[0].n_name = (char *) "_proc0paddr";
if (kvm_nlist (core_kd, nl) == -1)
error (("%s"), kvm_geterr (core_kd));
if (nl[0].n_value != 0)
{
struct pcb *paddr;
/* Found proc0paddr. */
if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
error (("%s"), kvm_geterr (core_kd));
bsd_kvm_fetch_pcb (regcache, paddr);
return;
}
#ifdef HAVE_STRUCT_THREAD_TD_PCB
/* In FreeBSD kernels for 5.0-RELEASE and later, the PCB no longer
lives in `struct proc' but in `struct thread'. The `struct
thread' for the initial thread for proc0 can be found in the
variable "thread0". */
memset (nl, 0, sizeof nl);
nl[0].n_name = (char *) "_thread0";
if (kvm_nlist (core_kd, nl) == -1)
error (("%s"), kvm_geterr (core_kd));
if (nl[0].n_value != 0)
{
struct pcb *paddr;
/* Found thread0. */
nl[0].n_value += offsetof (struct thread, td_pcb);
if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
error (("%s"), kvm_geterr (core_kd));
bsd_kvm_fetch_pcb (regcache, paddr);
return;
}
#endif
/* i18n: PCB == "Process Control Block". */
error (_("Cannot find a valid PCB"));
}
/* Kernel memory interface commands. */
struct cmd_list_element *bsd_kvm_cmdlist;
static void
bsd_kvm_cmd (const char *arg, int fromtty)
{
/* ??? Should this become an alias for "target kvm"? */
}
#ifndef HAVE_STRUCT_THREAD_TD_PCB
static void
bsd_kvm_proc_cmd (const char *arg, int fromtty)
{
CORE_ADDR addr;
if (arg == NULL)
error_no_arg (_("proc address"));
if (core_kd == NULL)
error (_("No kernel memory image."));
addr = parse_and_eval_address (arg);
#ifdef HAVE_STRUCT_LWP
addr += offsetof (struct lwp, l_addr);
#else
addr += offsetof (struct proc, p_addr);
#endif
if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)
error (("%s"), kvm_geterr (core_kd));
target_fetch_registers (get_thread_regcache (inferior_thread ()), -1);
reinit_frame_cache ();
print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1);
}
#endif
static void
bsd_kvm_pcb_cmd (const char *arg, int fromtty)
{
if (arg == NULL)
/* i18n: PCB == "Process Control Block". */
error_no_arg (_("pcb address"));
if (core_kd == NULL)
error (_("No kernel memory image."));
bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg);
target_fetch_registers (get_thread_regcache (inferior_thread ()), -1);
reinit_frame_cache ();
print_stack_frame (get_selected_frame (NULL), 0, SRC_AND_LOC, 1);
}
bool
bsd_kvm_target::thread_alive (ptid_t ptid)
{
return true;
}
std::string
bsd_kvm_target::pid_to_str (ptid_t ptid)
{
return "<kvm>";
}
/* Add the libkvm interface to the list of all possible targets and
register CUPPLY_PCB as the architecture-specific process control
block interpreter. */
void
bsd_kvm_add_target (int (*supply_pcb)(struct regcache *, struct pcb *))
{
gdb_assert (bsd_kvm_supply_pcb == NULL);
bsd_kvm_supply_pcb = supply_pcb;
add_target (bsd_kvm_target_info, bsd_kvm_target_open);
add_prefix_cmd ("kvm", class_obscure, bsd_kvm_cmd, _("\
Generic command for manipulating the kernel memory interface."),
&bsd_kvm_cmdlist, 0, &cmdlist);
#ifndef HAVE_STRUCT_THREAD_TD_PCB
add_cmd ("proc", class_obscure, bsd_kvm_proc_cmd,
_("Set current context from proc address"), &bsd_kvm_cmdlist);
#endif
add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,
/* i18n: PCB == "Process Control Block". */
_("Set current context from pcb address"), &bsd_kvm_cmdlist);
/* Some notes on the ptid usage on this target.
The pid field represents the kvm inferior instance. Currently,
we don't support multiple kvm inferiors, but we start at 1
anyway. The lwp field is set to != 0, in case the core wants to
refer to the whole kvm inferior with ptid(1,0,0).
If kvm is made to export running processes as gdb threads,
the following form can be used:
ptid (1, 1, 0) -> kvm inferior 1, in kernel
ptid (1, 1, 1) -> kvm inferior 1, process 1
ptid (1, 1, 2) -> kvm inferior 1, process 2
ptid (1, 1, n) -> kvm inferior 1, process n */
bsd_kvm_ptid = ptid_t (1, 1, 0);
}