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/*
* Copyright (c) 2013 Luca Clementi <luca.clementi@gmail.com>
* Copyright (c) 2013-2018 The strace developers.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "defs.h"
#include "unwind.h"
#include "mmap_cache.h"
#include <libunwind-ptrace.h>
static unw_addr_space_t libunwind_as;
static void
init(void)
{
mmap_cache_enable();
libunwind_as = unw_create_addr_space(&_UPT_accessors, 0);
if (!libunwind_as)
error_msg_and_die("failed to create address space"
" for stack tracing");
unw_set_caching_policy(libunwind_as, UNW_CACHE_GLOBAL);
}
static void *
tcb_init(struct tcb *tcp)
{
void *r = _UPT_create(tcp->pid);
if (!r)
perror_msg_and_die("_UPT_create");
return r;
}
static void
tcb_fin(struct tcb *tcp)
{
_UPT_destroy(tcp->unwind_ctx);
}
static void
get_symbol_name(unw_cursor_t *cursor, char **name,
size_t *size, unw_word_t *offset)
{
for (;;) {
int rc = unw_get_proc_name(cursor, *name, *size, offset);
if (rc == 0)
break;
if (rc != -UNW_ENOMEM) {
**name = '\0';
*offset = 0;
break;
}
*name = xgrowarray(*name, size, 1);
}
}
static int
print_stack_frame(struct tcb *tcp,
unwind_call_action_fn call_action,
unwind_error_action_fn error_action,
void *data,
unw_cursor_t *cursor,
char **symbol_name,
size_t *symbol_name_size)
{
unw_word_t ip;
if (unw_get_reg(cursor, UNW_REG_IP, &ip) < 0) {
perror_msg("cannot walk the stack of process %d", tcp->pid);
return -1;
}
struct mmap_cache_entry_t *entry = mmap_cache_search(tcp, ip);
if (entry
/* ignore mappings that have no PROT_EXEC bit set */
&& (entry->protections & MMAP_CACHE_PROT_EXECUTABLE)) {
unw_word_t function_offset;
get_symbol_name(cursor, symbol_name, symbol_name_size,
&function_offset);
unsigned long true_offset =
ip - entry->start_addr + entry->mmap_offset;
call_action(data,
entry->binary_filename,
*symbol_name,
function_offset,
true_offset);
return 0;
}
/*
* there is a bug in libunwind >= 1.0
* after a set_tid_address syscall
* unw_get_reg returns IP == 0
*/
if (ip)
error_action(data, "unexpected_backtracing_error", ip);
return -1;
}
static void
walk(struct tcb *tcp,
unwind_call_action_fn call_action,
unwind_error_action_fn error_action,
void *data)
{
char *symbol_name;
size_t symbol_name_size = 40;
unw_cursor_t cursor;
int stack_depth;
if (!tcp->mmap_cache)
error_func_msg_and_die("mmap_cache is NULL");
symbol_name = xmalloc(symbol_name_size);
if (unw_init_remote(&cursor, libunwind_as, tcp->unwind_ctx) < 0)
perror_func_msg_and_die("cannot initialize libunwind");
for (stack_depth = 0; stack_depth < 256; ++stack_depth) {
if (print_stack_frame(tcp, call_action, error_action, data,
&cursor, &symbol_name, &symbol_name_size) < 0)
break;
if (unw_step(&cursor) <= 0)
break;
}
if (stack_depth >= 256)
error_action(data, "too many stack frames", 0);
free(symbol_name);
}
static void
tcb_walk(struct tcb *tcp,
unwind_call_action_fn call_action,
unwind_error_action_fn error_action,
void *data)
{
switch (mmap_cache_rebuild_if_invalid(tcp, __func__)) {
case MMAP_CACHE_REBUILD_RENEWED:
/*
* Rebuild the unwinder internal cache.
* Called when mmap cache subsystem detects a
* change of tracee memory mapping.
*/
unw_flush_cache(libunwind_as, 0, 0);
ATTRIBUTE_FALLTHROUGH;
case MMAP_CACHE_REBUILD_READY:
walk(tcp, call_action, error_action, data);
break;
default:
/* Do nothing */
;
}
}
const struct unwind_unwinder_t unwinder = {
.name = "libunwind",
.init = init,
.tcb_init = tcb_init,
.tcb_fin = tcb_fin,
.tcb_walk = tcb_walk,
};
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