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/* Signal trampoline unwinder, for GDB the GNU Debugger.
Copyright (C) 2004-2018 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 "tramp-frame.h"
#include "frame-unwind.h"
#include "gdbcore.h"
#include "symtab.h"
#include "objfiles.h"
#include "target.h"
#include "trad-frame.h"
#include "frame-base.h"
struct frame_data
{
const struct tramp_frame *tramp_frame;
};
struct tramp_frame_cache
{
CORE_ADDR func;
const struct tramp_frame *tramp_frame;
struct trad_frame_cache *trad_cache;
};
static struct trad_frame_cache *
tramp_frame_cache (struct frame_info *this_frame,
void **this_cache)
{
struct tramp_frame_cache *tramp_cache
= (struct tramp_frame_cache *) *this_cache;
if (tramp_cache->trad_cache == NULL)
{
tramp_cache->trad_cache = trad_frame_cache_zalloc (this_frame);
tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,
this_frame,
tramp_cache->trad_cache,
tramp_cache->func);
}
return tramp_cache->trad_cache;
}
static void
tramp_frame_this_id (struct frame_info *this_frame,
void **this_cache,
struct frame_id *this_id)
{
struct trad_frame_cache *trad_cache
= tramp_frame_cache (this_frame, this_cache);
trad_frame_get_id (trad_cache, this_id);
}
static struct value *
tramp_frame_prev_register (struct frame_info *this_frame,
void **this_cache,
int prev_regnum)
{
struct trad_frame_cache *trad_cache
= tramp_frame_cache (this_frame, this_cache);
return trad_frame_get_register (trad_cache, this_frame, prev_regnum);
}
static CORE_ADDR
tramp_frame_start (const struct tramp_frame *tramp,
struct frame_info *this_frame, CORE_ADDR pc)
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
int ti;
/* Check if we can use this trampoline. */
if (tramp->validate && !tramp->validate (tramp, this_frame, &pc))
return 0;
/* Search through the trampoline for one that matches the
instruction sequence around PC. */
for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)
{
CORE_ADDR func = pc - tramp->insn_size * ti;
int i;
for (i = 0; 1; i++)
{
gdb_byte buf[sizeof (tramp->insn[0])];
ULONGEST insn;
if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)
return func;
if (!safe_frame_unwind_memory (this_frame,
func + i * tramp->insn_size,
buf, tramp->insn_size))
break;
insn = extract_unsigned_integer (buf, tramp->insn_size, byte_order);
if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))
break;
}
}
/* Trampoline doesn't match. */
return 0;
}
static int
tramp_frame_sniffer (const struct frame_unwind *self,
struct frame_info *this_frame,
void **this_cache)
{
const struct tramp_frame *tramp = self->unwind_data->tramp_frame;
CORE_ADDR pc = get_frame_pc (this_frame);
CORE_ADDR func;
struct tramp_frame_cache *tramp_cache;
/* tausq/2004-12-12: We used to assume if pc has a name or is in a valid
section, then this is not a trampoline. However, this assumption is
false on HPUX which has a signal trampoline that has a name; it can
also be false when using an alternative signal stack. */
func = tramp_frame_start (tramp, this_frame, pc);
if (func == 0)
return 0;
tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);
tramp_cache->func = func;
tramp_cache->tramp_frame = tramp;
(*this_cache) = tramp_cache;
return 1;
}
void
tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
const struct tramp_frame *tramp_frame)
{
struct frame_data *data;
struct frame_unwind *unwinder;
int i;
/* Check that the instruction sequence contains a sentinel. */
for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
{
if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)
break;
}
gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));
data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
data->tramp_frame = tramp_frame;
unwinder->type = tramp_frame->frame_type;
unwinder->unwind_data = data;
unwinder->sniffer = tramp_frame_sniffer;
unwinder->stop_reason = default_frame_unwind_stop_reason;
unwinder->this_id = tramp_frame_this_id;
unwinder->prev_register = tramp_frame_prev_register;
frame_unwind_prepend_unwinder (gdbarch, unwinder);
}
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