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platform_system_core/debuggerd/utility.c
Jeff Brown 19b39f371b Improve backtrace formatting. 
Show the symbol offset, when available.

Centralized formatting of native stack traces in libcorkscrew.
It's handy for automated tools if all stacks look the same.
Since we already made them all look them same, we might as well
do the formatting in just one place.

Do not strip the Thumb bit on ARM.  This fixes an off-by-one
issue that could happen when resolving a PC that was at the
very beginning of a Thumb function, since the symbol table would
have the Thumb bit set but since we stripped the bit from our
PC, we would be looking for an address one byte before the
one listed in the symbol table.  It's also quite useful to see
whether a given function is executing in Thumb mode just by glancing
at the PC.

Change-Id: Icaa29add85ce0bcafe24d5ce2098e138d809e2ab
2011-11-22 12:13:46 -08:00

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/* system/debuggerd/utility.c
**
** Copyright 2008, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
#include <signal.h>
#include <string.h>
#include <cutils/logd.h>
#include <sys/ptrace.h>
#include <errno.h>
#include <corkscrew/demangle.h>
#include "utility.h"
#define STACK_DEPTH 32
#define STACK_WORDS 16
void _LOG(int tfd, bool in_tombstone_only, const char *fmt, ...) {
char buf[512];
va_list ap;
va_start(ap, fmt);
if (tfd >= 0) {
int len;
vsnprintf(buf, sizeof(buf), fmt, ap);
len = strlen(buf);
if(tfd >= 0) write(tfd, buf, len);
}
if (!in_tombstone_only)
__android_log_vprint(ANDROID_LOG_INFO, "DEBUG", fmt, ap);
va_end(ap);
}
bool signal_has_address(int sig) {
switch (sig) {
case SIGILL:
case SIGFPE:
case SIGSEGV:
case SIGBUS:
return true;
default:
return false;
}
}
static void dump_backtrace(const ptrace_context_t* context __attribute((unused)),
int tfd, pid_t tid __attribute((unused)), bool at_fault,
const backtrace_frame_t* backtrace, size_t frames) {
_LOG(tfd, !at_fault, "\nbacktrace:\n");
backtrace_symbol_t backtrace_symbols[STACK_DEPTH];
get_backtrace_symbols_ptrace(context, backtrace, frames, backtrace_symbols);
for (size_t i = 0; i < frames; i++) {
char line[MAX_BACKTRACE_LINE_LENGTH];
format_backtrace_line(i, &backtrace[i], &backtrace_symbols[i],
line, MAX_BACKTRACE_LINE_LENGTH);
_LOG(tfd, !at_fault, " %s\n", line);
}
free_backtrace_symbols(backtrace_symbols, frames);
}
static void dump_stack_segment(const ptrace_context_t* context, int tfd, pid_t tid,
bool only_in_tombstone, uintptr_t* sp, size_t words, int label) {
for (size_t i = 0; i < words; i++) {
uint32_t stack_content;
if (!try_get_word_ptrace(tid, *sp, &stack_content)) {
break;
}
const map_info_t* mi;
const symbol_t* symbol;
find_symbol_ptrace(context, stack_content, &mi, &symbol);
if (symbol) {
char* demangled_name = demangle_symbol_name(symbol->name);
const char* symbol_name = demangled_name ? demangled_name : symbol->name;
uint32_t offset = stack_content - (mi->start + symbol->start);
if (!i && label >= 0) {
if (offset) {
_LOG(tfd, only_in_tombstone, " #%02d %08x %08x %s (%s+%u)\n",
label, *sp, stack_content, mi ? mi->name : "", symbol_name, offset);
} else {
_LOG(tfd, only_in_tombstone, " #%02d %08x %08x %s (%s)\n",
label, *sp, stack_content, mi ? mi->name : "", symbol_name);
}
} else {
if (offset) {
_LOG(tfd, only_in_tombstone, " %08x %08x %s (%s+%u)\n",
*sp, stack_content, mi ? mi->name : "", symbol_name, offset);
} else {
_LOG(tfd, only_in_tombstone, " %08x %08x %s (%s)\n",
*sp, stack_content, mi ? mi->name : "", symbol_name);
}
}
free(demangled_name);
} else {
if (!i && label >= 0) {
_LOG(tfd, only_in_tombstone, " #%02d %08x %08x %s\n",
label, *sp, stack_content, mi ? mi->name : "");
} else {
_LOG(tfd, only_in_tombstone, " %08x %08x %s\n",
*sp, stack_content, mi ? mi->name : "");
}
}
*sp += sizeof(uint32_t);
}
}
static void dump_stack(const ptrace_context_t* context, int tfd, pid_t tid, bool at_fault,
const backtrace_frame_t* backtrace, size_t frames) {
bool have_first = false;
size_t first, last;
for (size_t i = 0; i < frames; i++) {
if (backtrace[i].stack_top) {
if (!have_first) {
have_first = true;
first = i;
}
last = i;
}
}
if (!have_first) {
return;
}
_LOG(tfd, !at_fault, "\nstack:\n");
// Dump a few words before the first frame.
bool only_in_tombstone = !at_fault;
uintptr_t sp = backtrace[first].stack_top - STACK_WORDS * sizeof(uint32_t);
dump_stack_segment(context, tfd, tid, only_in_tombstone, &sp, STACK_WORDS, -1);
// Dump a few words from all successive frames.
// Only log the first 3 frames, put the rest in the tombstone.
for (size_t i = first; i <= last; i++) {
const backtrace_frame_t* frame = &backtrace[i];
if (sp != frame->stack_top) {
_LOG(tfd, only_in_tombstone, " ........ ........\n");
sp = frame->stack_top;
}
if (i - first == 3) {
only_in_tombstone = true;
}
if (i == last) {
dump_stack_segment(context, tfd, tid, only_in_tombstone, &sp, STACK_WORDS, i);
if (sp < frame->stack_top + frame->stack_size) {
_LOG(tfd, only_in_tombstone, " ........ ........\n");
}
} else {
size_t words = frame->stack_size / sizeof(uint32_t);
if (words == 0) {
words = 1;
} else if (words > STACK_WORDS) {
words = STACK_WORDS;
}
dump_stack_segment(context, tfd, tid, only_in_tombstone, &sp, words, i);
}
}
}
void dump_backtrace_and_stack(const ptrace_context_t* context, int tfd, pid_t tid,
bool at_fault) {
backtrace_frame_t backtrace[STACK_DEPTH];
ssize_t frames = unwind_backtrace_ptrace(tid, context, backtrace, 0, STACK_DEPTH);
if (frames > 0) {
dump_backtrace(context, tfd, tid, at_fault, backtrace, frames);
dump_stack(context, tfd, tid, at_fault, backtrace, frames);
}
}
void dump_memory(int tfd, pid_t tid, uintptr_t addr, bool at_fault) {
char code_buffer[64]; /* actual 8+1+((8+1)*4) + 1 == 45 */
char ascii_buffer[32]; /* actual 16 + 1 == 17 */
uintptr_t p, end;
p = addr & ~3;
p -= 32;
if (p > addr) {
/* catch underflow */
p = 0;
}
end = p + 80;
/* catch overflow; 'end - p' has to be multiples of 16 */
while (end < p)
end -= 16;
/* Dump the code around PC as:
* addr contents ascii
* 00008d34 ef000000 e8bd0090 e1b00000 512fff1e ............../Q
* 00008d44 ea00b1f9 e92d0090 e3a070fc ef000000 ......-..p......
*/
while (p < end) {
char* asc_out = ascii_buffer;
sprintf(code_buffer, "%08x ", p);
int i;
for (i = 0; i < 4; i++) {
/*
* If we see (data == -1 && errno != 0), we know that the ptrace
* call failed, probably because we're dumping memory in an
* unmapped or inaccessible page. I don't know if there's
* value in making that explicit in the output -- it likely
* just complicates parsing and clarifies nothing for the
* enlightened reader.
*/
long data = ptrace(PTRACE_PEEKTEXT, tid, (void*)p, NULL);
sprintf(code_buffer + strlen(code_buffer), "%08lx ", data);
int j;
for (j = 0; j < 4; j++) {
/*
* Our isprint() allows high-ASCII characters that display
* differently (often badly) in different viewers, so we
* just use a simpler test.
*/
char val = (data >> (j*8)) & 0xff;
if (val >= 0x20 && val < 0x7f) {
*asc_out++ = val;
} else {
*asc_out++ = '.';
}
}
p += 4;
}
*asc_out = '\0';
_LOG(tfd, !at_fault, " %s %s\n", code_buffer, ascii_buffer);
}
}
void dump_nearby_maps(const ptrace_context_t* context, int tfd, pid_t tid) {
siginfo_t si;
memset(&si, 0, sizeof(si));
if (ptrace(PTRACE_GETSIGINFO, tid, 0, &si)) {
_LOG(tfd, false, "cannot get siginfo for %d: %s\n",
tid, strerror(errno));
return;
}
if (!signal_has_address(si.si_signo)) {
return;
}
uintptr_t addr = (uintptr_t) si.si_addr;
addr &= ~0xfff; /* round to 4K page boundary */
if (addr == 0) { /* null-pointer deref */
return;
}
_LOG(tfd, false, "\nmemory map around fault addr %08x:\n", (int)si.si_addr);
/*
* Search for a match, or for a hole where the match would be. The list
* is backward from the file content, so it starts at high addresses.
*/
bool found = false;
map_info_t* map = context->map_info_list;
map_info_t *next = NULL;
map_info_t *prev = NULL;
while (map != NULL) {
if (addr >= map->start && addr < map->end) {
found = true;
next = map->next;
break;
} else if (addr >= map->end) {
/* map would be between "prev" and this entry */
next = map;
map = NULL;
break;
}
prev = map;
map = map->next;
}
/*
* Show "next" then "match" then "prev" so that the addresses appear in
* ascending order (like /proc/pid/maps).
*/
if (next != NULL) {
_LOG(tfd, false, " %08x-%08x %s\n", next->start, next->end, next->name);
} else {
_LOG(tfd, false, " (no map below)\n");
}
if (map != NULL) {
_LOG(tfd, false, " %08x-%08x %s\n", map->start, map->end, map->name);
} else {
_LOG(tfd, false, " (no map for address)\n");
}
if (prev != NULL) {
_LOG(tfd, false, " %08x-%08x %s\n", prev->start, prev->end, prev->name);
} else {
_LOG(tfd, false, " (no map above)\n");
}
}
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