| /* Code dealing with dummy stack frames, for GDB, the GNU debugger. |
| |
| Copyright (C) 1986-2021 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 "defs.h" |
| #include "dummy-frame.h" |
| #include "regcache.h" |
| #include "frame.h" |
| #include "inferior.h" |
| #include "frame-unwind.h" |
| #include "command.h" |
| #include "gdbcmd.h" |
| #include "observable.h" |
| #include "gdbthread.h" |
| #include "infcall.h" |
| #include "gdbarch.h" |
| |
| struct dummy_frame_id |
| { |
| /* This frame's ID. Must match the value returned by |
| gdbarch_dummy_id. */ |
| struct frame_id id; |
| |
| /* The thread this dummy_frame relates to. */ |
| thread_info *thread; |
| }; |
| |
| /* Return whether dummy_frame_id *ID1 and *ID2 are equal. */ |
| |
| static int |
| dummy_frame_id_eq (struct dummy_frame_id *id1, |
| struct dummy_frame_id *id2) |
| { |
| return frame_id_eq (id1->id, id2->id) && id1->thread == id2->thread; |
| } |
| |
| /* List of dummy_frame destructors. */ |
| |
| struct dummy_frame_dtor_list |
| { |
| /* Next element in the list or NULL if this is the last element. */ |
| struct dummy_frame_dtor_list *next; |
| |
| /* If non-NULL, a destructor that is run when this dummy frame is freed. */ |
| dummy_frame_dtor_ftype *dtor; |
| |
| /* Arbitrary data that is passed to DTOR. */ |
| void *dtor_data; |
| }; |
| |
| /* Dummy frame. This saves the processor state just prior to setting |
| up the inferior function call. Older targets save the registers |
| on the target stack (but that really slows down function calls). */ |
| |
| struct dummy_frame |
| { |
| struct dummy_frame *next; |
| |
| /* An id represents a dummy frame. */ |
| struct dummy_frame_id id; |
| |
| /* The caller's state prior to the call. */ |
| struct infcall_suspend_state *caller_state; |
| |
| /* First element of destructors list or NULL if there are no |
| destructors registered for this dummy_frame. */ |
| struct dummy_frame_dtor_list *dtor_list; |
| }; |
| |
| static struct dummy_frame *dummy_frame_stack = NULL; |
| |
| /* Push the caller's state, along with the dummy frame info, onto the |
| dummy-frame stack. */ |
| |
| void |
| dummy_frame_push (struct infcall_suspend_state *caller_state, |
| const frame_id *dummy_id, thread_info *thread) |
| { |
| struct dummy_frame *dummy_frame; |
| |
| dummy_frame = XCNEW (struct dummy_frame); |
| dummy_frame->caller_state = caller_state; |
| dummy_frame->id.id = (*dummy_id); |
| dummy_frame->id.thread = thread; |
| dummy_frame->next = dummy_frame_stack; |
| dummy_frame_stack = dummy_frame; |
| } |
| |
| /* Remove *DUMMY_PTR from the dummy frame stack. */ |
| |
| static void |
| remove_dummy_frame (struct dummy_frame **dummy_ptr) |
| { |
| struct dummy_frame *dummy = *dummy_ptr; |
| |
| while (dummy->dtor_list != NULL) |
| { |
| struct dummy_frame_dtor_list *list = dummy->dtor_list; |
| |
| dummy->dtor_list = list->next; |
| list->dtor (list->dtor_data, 0); |
| xfree (list); |
| } |
| |
| *dummy_ptr = dummy->next; |
| discard_infcall_suspend_state (dummy->caller_state); |
| xfree (dummy); |
| } |
| |
| /* Delete any breakpoint B which is a momentary breakpoint for return from |
| inferior call matching DUMMY_VOIDP. */ |
| |
| static bool |
| pop_dummy_frame_bpt (struct breakpoint *b, struct dummy_frame *dummy) |
| { |
| if (b->thread == dummy->id.thread->global_num |
| && b->disposition == disp_del && frame_id_eq (b->frame_id, dummy->id.id)) |
| { |
| while (b->related_breakpoint != b) |
| delete_breakpoint (b->related_breakpoint); |
| |
| delete_breakpoint (b); |
| |
| /* Stop the traversal. */ |
| return true; |
| } |
| |
| /* Continue the traversal. */ |
| return false; |
| } |
| |
| /* Pop *DUMMY_PTR, restoring program state to that before the |
| frame was created. */ |
| |
| static void |
| pop_dummy_frame (struct dummy_frame **dummy_ptr) |
| { |
| struct dummy_frame *dummy = *dummy_ptr; |
| |
| gdb_assert (dummy->id.thread == inferior_thread ()); |
| |
| while (dummy->dtor_list != NULL) |
| { |
| struct dummy_frame_dtor_list *list = dummy->dtor_list; |
| |
| dummy->dtor_list = list->next; |
| list->dtor (list->dtor_data, 1); |
| xfree (list); |
| } |
| |
| restore_infcall_suspend_state (dummy->caller_state); |
| |
| for (breakpoint *bp : all_breakpoints_safe ()) |
| if (pop_dummy_frame_bpt (bp, dummy)) |
| break; |
| |
| /* restore_infcall_control_state frees inf_state, |
| all that remains is to pop *dummy_ptr. */ |
| *dummy_ptr = dummy->next; |
| xfree (dummy); |
| |
| /* We've made right mess of GDB's local state, just discard |
| everything. */ |
| reinit_frame_cache (); |
| } |
| |
| /* Look up DUMMY_ID. |
| Return NULL if not found. */ |
| |
| static struct dummy_frame ** |
| lookup_dummy_frame (struct dummy_frame_id *dummy_id) |
| { |
| struct dummy_frame **dp; |
| |
| for (dp = &dummy_frame_stack; *dp != NULL; dp = &(*dp)->next) |
| { |
| if (dummy_frame_id_eq (&(*dp)->id, dummy_id)) |
| return dp; |
| } |
| |
| return NULL; |
| } |
| |
| /* Find the dummy frame by DUMMY_ID and THREAD, and pop it, restoring |
| program state to that before the frame was created. |
| On return reinit_frame_cache has been called. |
| If the frame isn't found, flag an internal error. */ |
| |
| void |
| dummy_frame_pop (frame_id dummy_id, thread_info *thread) |
| { |
| struct dummy_frame **dp; |
| struct dummy_frame_id id = { dummy_id, thread }; |
| |
| dp = lookup_dummy_frame (&id); |
| gdb_assert (dp != NULL); |
| |
| pop_dummy_frame (dp); |
| } |
| |
| /* Find the dummy frame by DUMMY_ID and PTID and drop it. Do nothing |
| if it is not found. Do not restore its state into inferior, just |
| free its memory. */ |
| |
| void |
| dummy_frame_discard (struct frame_id dummy_id, thread_info *thread) |
| { |
| struct dummy_frame **dp; |
| struct dummy_frame_id id = { dummy_id, thread }; |
| |
| dp = lookup_dummy_frame (&id); |
| if (dp) |
| remove_dummy_frame (dp); |
| } |
| |
| /* See dummy-frame.h. */ |
| |
| void |
| register_dummy_frame_dtor (frame_id dummy_id, thread_info *thread, |
| dummy_frame_dtor_ftype *dtor, void *dtor_data) |
| { |
| struct dummy_frame_id id = { dummy_id, thread }; |
| struct dummy_frame **dp, *d; |
| struct dummy_frame_dtor_list *list; |
| |
| dp = lookup_dummy_frame (&id); |
| gdb_assert (dp != NULL); |
| d = *dp; |
| list = XNEW (struct dummy_frame_dtor_list); |
| list->next = d->dtor_list; |
| d->dtor_list = list; |
| list->dtor = dtor; |
| list->dtor_data = dtor_data; |
| } |
| |
| /* See dummy-frame.h. */ |
| |
| int |
| find_dummy_frame_dtor (dummy_frame_dtor_ftype *dtor, void *dtor_data) |
| { |
| struct dummy_frame *d; |
| |
| for (d = dummy_frame_stack; d != NULL; d = d->next) |
| { |
| struct dummy_frame_dtor_list *list; |
| |
| for (list = d->dtor_list; list != NULL; list = list->next) |
| if (list->dtor == dtor && list->dtor_data == dtor_data) |
| return 1; |
| } |
| return 0; |
| } |
| |
| /* There may be stale dummy frames, perhaps left over from when an uncaught |
| longjmp took us out of a function that was called by the debugger. Clean |
| them up at least once whenever we start a new inferior. */ |
| |
| static void |
| cleanup_dummy_frames (inferior *inf) |
| { |
| while (dummy_frame_stack != NULL) |
| remove_dummy_frame (&dummy_frame_stack); |
| } |
| |
| /* Return the dummy frame cache, it contains both the ID, and a |
| pointer to the regcache. */ |
| struct dummy_frame_cache |
| { |
| struct frame_id this_id; |
| readonly_detached_regcache *prev_regcache; |
| }; |
| |
| static int |
| dummy_frame_sniffer (const struct frame_unwind *self, |
| struct frame_info *this_frame, |
| void **this_prologue_cache) |
| { |
| /* When unwinding a normal frame, the stack structure is determined |
| by analyzing the frame's function's code (be it using brute force |
| prologue analysis, or the dwarf2 CFI). In the case of a dummy |
| frame, that simply isn't possible. The PC is either the program |
| entry point, or some random address on the stack. Trying to use |
| that PC to apply standard frame ID unwind techniques is just |
| asking for trouble. */ |
| |
| /* Don't bother unless there is at least one dummy frame. */ |
| if (dummy_frame_stack != NULL) |
| { |
| struct dummy_frame *dummyframe; |
| /* Use an architecture specific method to extract this frame's |
| dummy ID, assuming it is a dummy frame. */ |
| struct frame_id this_id |
| = gdbarch_dummy_id (get_frame_arch (this_frame), this_frame); |
| struct dummy_frame_id dummy_id = { this_id, inferior_thread () }; |
| |
| /* Use that ID to find the corresponding cache entry. */ |
| for (dummyframe = dummy_frame_stack; |
| dummyframe != NULL; |
| dummyframe = dummyframe->next) |
| { |
| if (dummy_frame_id_eq (&dummyframe->id, &dummy_id)) |
| { |
| struct dummy_frame_cache *cache; |
| |
| cache = FRAME_OBSTACK_ZALLOC (struct dummy_frame_cache); |
| cache->prev_regcache = get_infcall_suspend_state_regcache |
| (dummyframe->caller_state); |
| cache->this_id = this_id; |
| (*this_prologue_cache) = cache; |
| return 1; |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /* Given a call-dummy dummy-frame, return the registers. Here the |
| register value is taken from the local copy of the register buffer. */ |
| |
| static struct value * |
| dummy_frame_prev_register (struct frame_info *this_frame, |
| void **this_prologue_cache, |
| int regnum) |
| { |
| struct dummy_frame_cache *cache |
| = (struct dummy_frame_cache *) *this_prologue_cache; |
| struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| struct value *reg_val; |
| |
| /* The dummy-frame sniffer always fills in the cache. */ |
| gdb_assert (cache != NULL); |
| |
| /* Describe the register's location. Generic dummy frames always |
| have the register value in an ``expression''. */ |
| reg_val = value_zero (register_type (gdbarch, regnum), not_lval); |
| |
| /* Use the regcache_cooked_read() method so that it, on the fly, |
| constructs either a raw or pseudo register from the raw |
| register cache. */ |
| cache->prev_regcache->cooked_read (regnum, |
| value_contents_writeable (reg_val)); |
| return reg_val; |
| } |
| |
| /* Assuming that THIS_FRAME is a dummy, return its ID. That ID is |
| determined by examining the NEXT frame's unwound registers using |
| the method dummy_id(). As a side effect, THIS dummy frame's |
| dummy cache is located and saved in THIS_PROLOGUE_CACHE. */ |
| |
| static void |
| dummy_frame_this_id (struct frame_info *this_frame, |
| void **this_prologue_cache, |
| struct frame_id *this_id) |
| { |
| /* The dummy-frame sniffer always fills in the cache. */ |
| struct dummy_frame_cache *cache |
| = (struct dummy_frame_cache *) *this_prologue_cache; |
| |
| gdb_assert (cache != NULL); |
| (*this_id) = cache->this_id; |
| } |
| |
| const struct frame_unwind dummy_frame_unwind = |
| { |
| "dummy", |
| DUMMY_FRAME, |
| default_frame_unwind_stop_reason, |
| dummy_frame_this_id, |
| dummy_frame_prev_register, |
| NULL, |
| dummy_frame_sniffer, |
| }; |
| |
| /* See dummy-frame.h. */ |
| |
| struct frame_id |
| default_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame) |
| { |
| CORE_ADDR sp, pc; |
| |
| sp = get_frame_sp (this_frame); |
| pc = get_frame_pc (this_frame); |
| return frame_id_build (sp, pc); |
| } |
| |
| static void |
| fprint_dummy_frames (struct ui_file *file) |
| { |
| struct dummy_frame *s; |
| |
| for (s = dummy_frame_stack; s != NULL; s = s->next) |
| { |
| gdb_print_host_address (s, file); |
| fprintf_unfiltered (file, ":"); |
| fprintf_unfiltered (file, " id=%s", s->id.id.to_string ().c_str ()); |
| fprintf_unfiltered (file, ", ptid=%s", |
| target_pid_to_str (s->id.thread->ptid).c_str ()); |
| fprintf_unfiltered (file, "\n"); |
| } |
| } |
| |
| static void |
| maintenance_print_dummy_frames (const char *args, int from_tty) |
| { |
| if (args == NULL) |
| fprint_dummy_frames (gdb_stdout); |
| else |
| { |
| stdio_file file; |
| |
| if (!file.open (args, "w")) |
| perror_with_name (_("maintenance print dummy-frames")); |
| fprint_dummy_frames (&file); |
| } |
| } |
| |
| void _initialize_dummy_frame (); |
| void |
| _initialize_dummy_frame () |
| { |
| add_cmd ("dummy-frames", class_maintenance, maintenance_print_dummy_frames, |
| _("Print the contents of the internal dummy-frame stack."), |
| &maintenanceprintlist); |
| |
| gdb::observers::inferior_created.attach (cleanup_dummy_frames, "dummy-frame"); |
| } |