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/* Copyright (C) 2009-2017 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 <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include JIT_READER_H /* Please see jit-reader.exp for an explanation. */
#include "jithost.h"
GDB_DECLARE_GPL_COMPATIBLE_READER;
enum register_mapping
{
AMD64_RA = 16,
AMD64_RBP = 6,
AMD64_RSP = 7,
};
struct reader_state
{
uintptr_t code_begin;
uintptr_t code_end;
};
static enum gdb_status
read_debug_info (struct gdb_reader_funcs *self,
struct gdb_symbol_callbacks *cbs,
void *memory, long memory_sz)
{
struct jithost_abi *symfile = memory;
struct gdb_object *object = cbs->object_open (cbs);
struct gdb_symtab *symtab = cbs->symtab_open (cbs, object, "");
GDB_CORE_ADDR begin = (GDB_CORE_ADDR) symfile->begin;
GDB_CORE_ADDR end = (GDB_CORE_ADDR) symfile->end;
struct reader_state *state = (struct reader_state *) self->priv_data;
/* Record the function's range, for the unwinder. */
state->code_begin = begin;
state->code_end = end;
cbs->block_open (cbs, symtab, NULL, begin, end, "jit_function_00");
cbs->symtab_close (cbs, symtab);
cbs->object_close (cbs, object);
return GDB_SUCCESS;
}
static void
free_reg_value (struct gdb_reg_value *value)
{
free (value);
}
static void
write_register (struct gdb_unwind_callbacks *callbacks, int dw_reg,
uintptr_t value)
{
const int size = sizeof (uintptr_t);
struct gdb_reg_value *reg_val =
malloc (sizeof (struct gdb_reg_value) + size - 1);
reg_val->defined = 1;
reg_val->free = free_reg_value;
memcpy (reg_val->value, &value, size);
callbacks->reg_set (callbacks, dw_reg, reg_val);
}
static int
read_register (struct gdb_unwind_callbacks *callbacks, int dw_reg,
uintptr_t *value)
{
const int size = sizeof (uintptr_t);
struct gdb_reg_value *reg_val = callbacks->reg_get (callbacks, dw_reg);
if (reg_val->size != size || !reg_val->defined)
{
reg_val->free (reg_val);
return 0;
}
memcpy (value, reg_val->value, size);
reg_val->free (reg_val);
return 1;
}
/* Read the stack pointer into *VALUE. IP is the address the inferior
is currently stopped at. Takes care of demangling the stack
pointer if necessary. */
static int
read_sp (struct gdb_reader_funcs *self, struct gdb_unwind_callbacks *cbs,
uintptr_t ip, uintptr_t *value)
{
struct reader_state *state = (struct reader_state *) self->priv_data;
uintptr_t sp;
if (!read_register (cbs, AMD64_RSP, &sp))
return GDB_FAIL;
/* If stopped at the instruction after the "xor $-1, %rsp", demangle
the stack pointer back. */
if (ip == state->code_begin + 5)
sp ^= (uintptr_t) -1;
*value = sp;
return GDB_SUCCESS;
}
static enum gdb_status
unwind_frame (struct gdb_reader_funcs *self, struct gdb_unwind_callbacks *cbs)
{
const int word_size = sizeof (uintptr_t);
uintptr_t prev_sp, this_sp;
uintptr_t prev_ip, this_ip;
uintptr_t prev_bp, this_bp;
struct reader_state *state = (struct reader_state *) self->priv_data;
if (!read_register (cbs, AMD64_RA, &this_ip))
return GDB_FAIL;
if (this_ip >= state->code_end || this_ip < state->code_begin)
return GDB_FAIL;
/* Unwind RBP in order to make the unwinder that tries to unwind
from the just-unwound frame happy. */
if (!read_register (cbs, AMD64_RBP, &this_bp))
return GDB_FAIL;
/* RBP is unmodified. */
prev_bp = this_bp;
/* Fetch the demangled stack pointer. */
if (!read_sp (self, cbs, this_ip, &this_sp))
return GDB_FAIL;
/* The return address is saved on the stack. */
if (cbs->target_read (this_sp, &prev_ip, word_size) == GDB_FAIL)
return GDB_FAIL;
prev_sp = this_sp + word_size;
write_register (cbs, AMD64_RA, prev_ip);
write_register (cbs, AMD64_RSP, prev_sp);
write_register (cbs, AMD64_RBP, prev_bp);
return GDB_SUCCESS;
}
static struct gdb_frame_id
get_frame_id (struct gdb_reader_funcs *self, struct gdb_unwind_callbacks *cbs)
{
struct reader_state *state = (struct reader_state *) self->priv_data;
struct gdb_frame_id frame_id;
uintptr_t ip;
uintptr_t sp;
read_register (cbs, AMD64_RA, &ip);
read_sp (self, cbs, ip, &sp);
frame_id.code_address = (GDB_CORE_ADDR) state->code_begin;
frame_id.stack_address = (GDB_CORE_ADDR) sp;
return frame_id;
}
static void
destroy_reader (struct gdb_reader_funcs *self)
{
free (self->priv_data);
free (self);
}
struct gdb_reader_funcs *
gdb_init_reader (void)
{
struct reader_state *state = calloc (1, sizeof (struct reader_state));
struct gdb_reader_funcs *reader_funcs =
malloc (sizeof (struct gdb_reader_funcs));
reader_funcs->reader_version = GDB_READER_INTERFACE_VERSION;
reader_funcs->priv_data = state;
reader_funcs->read = read_debug_info;
reader_funcs->unwind = unwind_frame;
reader_funcs->get_frame_id = get_frame_id;
reader_funcs->destroy = destroy_reader;
return reader_funcs;
}
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