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- /* Code dealing with dummy stack frames, for GDB, the GNU debugger.
- Copyright (C) 1986-2022 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).data ());
- 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_printf (file, "%s: id=%s, ptid=%s\n",
- host_address_to_string (s),
- s->id.id.to_string ().c_str (),
- s->id.thread->ptid.to_string ().c_str ());
- }
- 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");
- }
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