/* system/debuggerd/debuggerd.c
**
** Copyright 2006, 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 <stdio.h>
#include <errno.h>
#include <signal.h>
#include <pthread.h>
#include <stdarg.h>
#include <fcntl.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <sys/exec_elf.h>
#include <sys/stat.h>
#include <cutils/sockets.h>
#include <cutils/logd.h>
#include <cutils/properties.h>
#include <linux/input.h>
#include <private/android_filesystem_config.h>
#include "debuggerd.h"
#include "utility.h"
#define ANDROID_LOG_INFO 4
/* Log information onto the tombstone */
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);
}
// 6f000000-6f01e000 rwxp 00000000 00:0c 16389419 /system/lib/libcomposer.so
// 012345678901234567890123456789012345678901234567890123456789
// 0 1 2 3 4 5
mapinfo *parse_maps_line(char *line)
{
mapinfo *mi;
int len = strlen(line);
if(len < 1) return 0;
line[--len] = 0;
if(len < 50) return 0;
if(line[20] != 'x') return 0;
mi = malloc(sizeof(mapinfo) + (len - 47));
if(mi == 0) return 0;
mi->start = strtoul(line, 0, 16);
mi->end = strtoul(line + 9, 0, 16);
/* To be filled in parse_elf_info if the mapped section starts with
* elf_header
*/
mi->exidx_start = mi->exidx_end = 0;
mi->symbols = 0;
mi->next = 0;
strcpy(mi->name, line + 49);
return mi;
}
void dump_build_info(int tfd)
{
char fingerprint[PROPERTY_VALUE_MAX];
property_get("ro.build.fingerprint", fingerprint, "unknown");
_LOG(tfd, false, "Build fingerprint: '%s'\n", fingerprint);
}
const char *get_signame(int sig)
{
switch(sig) {
case SIGILL: return "SIGILL";
case SIGABRT: return "SIGABRT";
case SIGBUS: return "SIGBUS";
case SIGFPE: return "SIGFPE";
case SIGSEGV: return "SIGSEGV";
case SIGSTKFLT: return "SIGSTKFLT";
default: return "?";
}
}
const char *get_sigcode(int signo, int code)
{
switch (signo) {
case SIGILL:
switch (code) {
case ILL_ILLOPC: return "ILL_ILLOPC";
case ILL_ILLOPN: return "ILL_ILLOPN";
case ILL_ILLADR: return "ILL_ILLADR";
case ILL_ILLTRP: return "ILL_ILLTRP";
case ILL_PRVOPC: return "ILL_PRVOPC";
case ILL_PRVREG: return "ILL_PRVREG";
case ILL_COPROC: return "ILL_COPROC";
case ILL_BADSTK: return "ILL_BADSTK";
}
break;
case SIGBUS:
switch (code) {
case BUS_ADRALN: return "BUS_ADRALN";
case BUS_ADRERR: return "BUS_ADRERR";
case BUS_OBJERR: return "BUS_OBJERR";
}
break;
case SIGFPE:
switch (code) {
case FPE_INTDIV: return "FPE_INTDIV";
case FPE_INTOVF: return "FPE_INTOVF";
case FPE_FLTDIV: return "FPE_FLTDIV";
case FPE_FLTOVF: return "FPE_FLTOVF";
case FPE_FLTUND: return "FPE_FLTUND";
case FPE_FLTRES: return "FPE_FLTRES";
case FPE_FLTINV: return "FPE_FLTINV";
case FPE_FLTSUB: return "FPE_FLTSUB";
}
break;
case SIGSEGV:
switch (code) {
case SEGV_MAPERR: return "SEGV_MAPERR";
case SEGV_ACCERR: return "SEGV_ACCERR";
}
break;
}
return "?";
}
void dump_fault_addr(int tfd, int pid, int sig)
{
siginfo_t si;
memset(&si, 0, sizeof(si));
if(ptrace(PTRACE_GETSIGINFO, pid, 0, &si)){
_LOG(tfd, false, "cannot get siginfo: %s\n", strerror(errno));
} else {
_LOG(tfd, false, "signal %d (%s), code %d (%s), fault addr %08x\n",
sig, get_signame(sig),
si.si_code, get_sigcode(sig, si.si_code),
si.si_addr);
}
}
void dump_crash_banner(int tfd, unsigned pid, unsigned tid, int sig)
{
char data[1024];
char *x = 0;
FILE *fp;
sprintf(data, "/proc/%d/cmdline", pid);
fp = fopen(data, "r");
if(fp) {
x = fgets(data, 1024, fp);
fclose(fp);
}
_LOG(tfd, false,
"*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
dump_build_info(tfd);
_LOG(tfd, false, "pid: %d, tid: %d >>> %s <<<\n",
pid, tid, x ? x : "UNKNOWN");
if(sig) dump_fault_addr(tfd, tid, sig);
}
static void parse_elf_info(mapinfo *milist, pid_t pid)
{
mapinfo *mi;
for (mi = milist; mi != NULL; mi = mi->next) {
Elf32_Ehdr ehdr;
memset(&ehdr, 0, sizeof(Elf32_Ehdr));
/* Read in sizeof(Elf32_Ehdr) worth of data from the beginning of
* mapped section.
*/
get_remote_struct(pid, (void *) (mi->start), &ehdr,
sizeof(Elf32_Ehdr));
/* Check if it has the matching magic words */
if (IS_ELF(ehdr)) {
Elf32_Phdr phdr;
Elf32_Phdr *ptr;
int i;
ptr = (Elf32_Phdr *) (mi->start + ehdr.e_phoff);
for (i = 0; i < ehdr.e_phnum; i++) {
/* Parse the program header */
get_remote_struct(pid, (char *) (ptr+i), &phdr,
sizeof(Elf32_Phdr));
#ifdef __arm__
/* Found a EXIDX segment? */
if (phdr.p_type == PT_ARM_EXIDX) {
mi->exidx_start = mi->start + phdr.p_offset;
mi->exidx_end = mi->exidx_start + phdr.p_filesz;
break;
}
#endif
}
/* Try to load symbols from this file */
mi->symbols = symbol_table_create(mi->name);
}
}
}
void dump_crash_report(int tfd, unsigned pid, unsigned tid, bool at_fault)
{
char data[1024];
FILE *fp;
mapinfo *milist = 0;
unsigned int sp_list[STACK_CONTENT_DEPTH];
int stack_depth;
#ifdef __arm__
int frame0_pc_sane = 1;
#endif
if (!at_fault) {
_LOG(tfd, true,
"--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
_LOG(tfd, true, "pid: %d, tid: %d\n", pid, tid);
}
dump_registers(tfd, tid, at_fault);
/* Clear stack pointer records */
memset(sp_list, 0, sizeof(sp_list));
sprintf(data, "/proc/%d/maps", pid);
fp = fopen(data, "r");
if(fp) {
while(fgets(data, 1024, fp)) {
mapinfo *mi = parse_maps_line(data);
if(mi) {
mi->next = milist;
milist = mi;
}
}
fclose(fp);
}
parse_elf_info(milist, tid);
#if __arm__
/* If stack unwinder fails, use the default solution to dump the stack
* content.
*/
stack_depth = unwind_backtrace_with_ptrace(tfd, tid, milist, sp_list,
&frame0_pc_sane, at_fault);
/* The stack unwinder should at least unwind two levels of stack. If less
* level is seen we make sure at lease pc and lr are dumped.
*/
if (stack_depth < 2) {
dump_pc_and_lr(tfd, tid, milist, stack_depth, at_fault);
}
dump_stack_and_code(tfd, tid, milist, stack_depth, sp_list, at_fault);
#elif __i386__
/* If stack unwinder fails, use the default solution to dump the stack
* content.
*/
stack_depth = unwind_backtrace_with_ptrace_x86(tfd, tid, milist,at_fault);
#else
#error "Unsupported architecture"
#endif
while(milist) {
mapinfo *next = milist->next;
symbol_table_free(milist->symbols);
free(milist);
milist = next;
}
}
#define MAX_TOMBSTONES 10
#define typecheck(x,y) { \
typeof(x) __dummy1; \
typeof(y) __dummy2; \
(void)(&__dummy1 == &__dummy2); }
#define TOMBSTONE_DIR "/data/tombstones"
/*
* find_and_open_tombstone - find an available tombstone slot, if any, of the
* form tombstone_XX where XX is 00 to MAX_TOMBSTONES-1, inclusive. If no
* file is available, we reuse the least-recently-modified file.
*/
static int find_and_open_tombstone(void)
{
unsigned long mtime = ULONG_MAX;
struct stat sb;
char path[128];
int fd, i, oldest = 0;
/*
* XXX: Our stat.st_mtime isn't time_t. If it changes, as it probably ought
* to, our logic breaks. This check will generate a warning if that happens.
*/
typecheck(mtime, sb.st_mtime);
/*
* In a single wolf-like pass, find an available slot and, in case none
* exist, find and record the least-recently-modified file.
*/
for (i = 0; i < MAX_TOMBSTONES; i++) {
snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", i);
if (!stat(path, &sb)) {
if (sb.st_mtime < mtime) {
oldest = i;
mtime = sb.st_mtime;
}
continue;
}
if (errno != ENOENT)
continue;
fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0600);
if (fd < 0)
continue; /* raced ? */
fchown(fd, AID_SYSTEM, AID_SYSTEM);
return fd;
}
/* we didn't find an available file, so we clobber the oldest one */
snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", oldest);
fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
fchown(fd, AID_SYSTEM, AID_SYSTEM);
return fd;
}
/* Return true if some thread is not detached cleanly */
static bool dump_sibling_thread_report(int tfd, unsigned pid, unsigned tid)
{
char task_path[1024];
sprintf(task_path, "/proc/%d/task", pid);
DIR *d;
struct dirent *de;
int need_cleanup = 0;
d = opendir(task_path);
/* Bail early if cannot open the task directory */
if (d == NULL) {
XLOG("Cannot open /proc/%d/task\n", pid);
return false;
}
while ((de = readdir(d)) != NULL) {
unsigned new_tid;
/* Ignore "." and ".." */
if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
continue;
new_tid = atoi(de->d_name);
/* The main thread at fault has been handled individually */
if (new_tid == tid)
continue;
/* Skip this thread if cannot ptrace it */
if (ptrace(PTRACE_ATTACH, new_tid, 0, 0) < 0)
continue;
dump_crash_report(tfd, pid, new_tid, false);
need_cleanup |= ptrace(PTRACE_DETACH, new_tid, 0, 0);
}
closedir(d);
return need_cleanup != 0;
}
/* Return true if some thread is not detached cleanly */
static bool engrave_tombstone(unsigned pid, unsigned tid, int debug_uid,
int signal)
{
int fd;
bool need_cleanup = false;
mkdir(TOMBSTONE_DIR, 0755);
chown(TOMBSTONE_DIR, AID_SYSTEM, AID_SYSTEM);
fd = find_and_open_tombstone();
if (fd < 0)
return need_cleanup;
dump_crash_banner(fd, pid, tid, signal);
dump_crash_report(fd, pid, tid, true);
/*
* If the user has requested to attach gdb, don't collect the per-thread
* information as it increases the chance to lose track of the process.
*/
if ((signed)pid > debug_uid) {
need_cleanup = dump_sibling_thread_report(fd, pid, tid);
}
close(fd);
return need_cleanup;
}
static int
write_string(const char* file, const char* string)
{
int len;
int fd;
ssize_t amt;
fd = open(file, O_RDWR);
len = strlen(string);
if (fd < 0)
return -errno;
amt = write(fd, string, len);
close(fd);
return amt >= 0 ? 0 : -errno;
}
static
void init_debug_led(void)
{
// trout leds
write_string("/sys/class/leds/red/brightness", "0");
write_string("/sys/class/leds/green/brightness", "0");
write_string("/sys/class/leds/blue/brightness", "0");
write_string("/sys/class/leds/red/device/blink", "0");
// sardine leds
write_string("/sys/class/leds/left/cadence", "0,0");
}
static
void enable_debug_led(void)
{
// trout leds
write_string("/sys/class/leds/red/brightness", "255");
// sardine leds
write_string("/sys/class/leds/left/cadence", "1,0");
}
static
void disable_debug_led(void)
{
// trout leds
write_string("/sys/class/leds/red/brightness", "0");
// sardine leds
write_string("/sys/class/leds/left/cadence", "0,0");
}
extern int init_getevent();
extern void uninit_getevent();
extern int get_event(struct input_event* event, int timeout);
static void wait_for_user_action(unsigned tid, struct ucred* cr)
{
(void)tid;
/* First log a helpful message */
LOG( "********************************************************\n"
"* Process %d has been suspended while crashing. To\n"
"* attach gdbserver for a gdb connection on port 5039:\n"
"*\n"
"* adb shell gdbserver :5039 --attach %d &\n"
"*\n"
"* Press HOME key to let the process continue crashing.\n"
"********************************************************\n",
cr->pid, cr->pid);
/* wait for HOME key (TODO: something useful for devices w/o HOME key) */
if (init_getevent() == 0) {
int ms = 1200 / 10;
int dit = 1;
int dah = 3*dit;
int _ = -dit;
int ___ = 3*_;
int _______ = 7*_;
const signed char codes[] = {
dit,_,dit,_,dit,___,dah,_,dah,_,dah,___,dit,_,dit,_,dit,_______
};
size_t s = 0;
struct input_event e;
int home = 0;
init_debug_led();
enable_debug_led();
do {
int timeout = abs((int)(codes[s])) * ms;
int res = get_event(&e, timeout);
if (res == 0) {
if (e.type==EV_KEY && e.code==KEY_HOME && e.value==0)
home = 1;
} else if (res == 1) {
if (++s >= sizeof(codes)/sizeof(*codes))
s = 0;
if (codes[s] > 0) {
enable_debug_led();
} else {
disable_debug_led();
}
}
} while (!home);
uninit_getevent();
}
/* don't forget to turn debug led off */
disable_debug_led();
/* close filedescriptor */
LOG("debuggerd resuming process %d", cr->pid);
}
static void handle_crashing_process(int fd)
{
char buf[64];
struct stat s;
unsigned tid;
struct ucred cr;
int n, len, status;
int tid_attach_status = -1;
unsigned retry = 30;
bool need_cleanup = false;
char value[PROPERTY_VALUE_MAX];
property_get("debug.db.uid", value, "-1");
int debug_uid = atoi(value);
XLOG("handle_crashing_process(%d)\n", fd);
len = sizeof(cr);
n = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
if(n != 0) {
LOG("cannot get credentials\n");
goto done;
}
XLOG("reading tid\n");
fcntl(fd, F_SETFL, O_NONBLOCK);
while((n = read(fd, &tid, sizeof(unsigned))) != sizeof(unsigned)) {
if(errno == EINTR) continue;
if(errno == EWOULDBLOCK) {
if(retry-- > 0) {
usleep(100 * 1000);
continue;
}
LOG("timed out reading tid\n");
goto done;
}
LOG("read failure? %s\n", strerror(errno));
goto done;
}
snprintf(buf, sizeof buf, "/proc/%d/task/%d", cr.pid, tid);
if(stat(buf, &s)) {
LOG("tid %d does not exist in pid %d. ignoring debug request\n",
tid, cr.pid);
close(fd);
return;
}
XLOG("BOOM: pid=%d uid=%d gid=%d tid=%d\n", cr.pid, cr.uid, cr.gid, tid);
/* Note that at this point, the target thread's signal handler
* is blocked in a read() call. This gives us the time to PTRACE_ATTACH
* to it before it has a chance to really fault.
*
* After the attach, the thread is stopped, and we write to the file
* descriptor to ensure that it will run as soon as we call PTRACE_CONT
* below. See details in bionic/libc/linker/debugger.c, in function
* debugger_signal_handler().
*/
tid_attach_status = ptrace(PTRACE_ATTACH, tid, 0, 0);
int ptrace_error = errno;
if (TEMP_FAILURE_RETRY(write(fd, &tid, 1)) != 1) {
XLOG("failed responding to client: %s\n",
strerror(errno));
goto done;
}
if(tid_attach_status < 0) {
LOG("ptrace attach failed: %s\n", strerror(ptrace_error));
goto done;
}
close(fd);
fd = -1;
const int sleep_time_usec = 200000; /* 0.2 seconds */
const int max_total_sleep_usec = 3000000; /* 3 seconds */
int loop_limit = max_total_sleep_usec / sleep_time_usec;
for(;;) {
if (loop_limit-- == 0) {
LOG("timed out waiting for pid=%d tid=%d uid=%d to die\n",
cr.pid, tid, cr.uid);
goto done;
}
n = waitpid(tid, &status, __WALL | WNOHANG);
if (n == 0) {
/* not ready yet */
XLOG("not ready yet\n");
usleep(sleep_time_usec);
continue;
}
if(n < 0) {
if(errno == EAGAIN) continue;
LOG("waitpid failed: %s\n", strerror(errno));
goto done;
}
XLOG("waitpid: n=%d status=%08x\n", n, status);
if(WIFSTOPPED(status)){
n = WSTOPSIG(status);
switch(n) {
case SIGSTOP:
XLOG("stopped -- continuing\n");
n = ptrace(PTRACE_CONT, tid, 0, 0);
if(n) {
LOG("ptrace failed: %s\n", strerror(errno));
goto done;
}
continue;
case SIGILL:
case SIGABRT:
case SIGBUS:
case SIGFPE:
case SIGSEGV:
case SIGSTKFLT: {
XLOG("stopped -- fatal signal\n");
need_cleanup = engrave_tombstone(cr.pid, tid, debug_uid, n);
kill(tid, SIGSTOP);
goto done;
}
default:
XLOG("stopped -- unexpected signal\n");
goto done;
}
} else {
XLOG("unexpected waitpid response\n");
goto done;
}
}
done:
XLOG("detaching\n");
/* stop the process so we can debug */
kill(cr.pid, SIGSTOP);
/*
* If a thread has been attached by ptrace, make sure it is detached
* successfully otherwise we will get a zombie.
*/
if (tid_attach_status == 0) {
int detach_status;
/* detach so we can attach gdbserver */
detach_status = ptrace(PTRACE_DETACH, tid, 0, 0);
need_cleanup |= (detach_status != 0);
}
/*
* if debug.db.uid is set, its value indicates if we should wait
* for user action for the crashing process.
* in this case, we log a message and turn the debug LED on
* waiting for a gdb connection (for instance)
*/
if ((signed)cr.uid <= debug_uid) {
wait_for_user_action(tid, &cr);
}
/* resume stopped process (so it can crash in peace) */
kill(cr.pid, SIGCONT);
if (need_cleanup) {
LOG("debuggerd committing suicide to free the zombie!\n");
kill(getpid(), SIGKILL);
}
if(fd != -1) close(fd);
}
int main()
{
int s;
struct sigaction act;
int logsocket = -1;
/*
* debuggerd crashes can't be reported to debuggerd. Reset all of the
* crash handlers.
*/
signal(SIGILL, SIG_DFL);
signal(SIGABRT, SIG_DFL);
signal(SIGBUS, SIG_DFL);
signal(SIGFPE, SIG_DFL);
signal(SIGSEGV, SIG_DFL);
signal(SIGSTKFLT, SIG_DFL);
signal(SIGPIPE, SIG_DFL);
logsocket = socket_local_client("logd",
ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_DGRAM);
if(logsocket < 0) {
logsocket = -1;
} else {
fcntl(logsocket, F_SETFD, FD_CLOEXEC);
}
act.sa_handler = SIG_DFL;
sigemptyset(&act.sa_mask);
sigaddset(&act.sa_mask,SIGCHLD);
act.sa_flags = SA_NOCLDWAIT;
sigaction(SIGCHLD, &act, 0);
s = socket_local_server("android:debuggerd",
ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
if(s < 0) return -1;
fcntl(s, F_SETFD, FD_CLOEXEC);
LOG("debuggerd: " __DATE__ " " __TIME__ "\n");
for(;;) {
struct sockaddr addr;
socklen_t alen;
int fd;
alen = sizeof(addr);
XLOG("waiting for connection\n");
fd = accept(s, &addr, &alen);
if(fd < 0) {
XLOG("accept failed: %s\n", strerror(errno));
continue;
}
fcntl(fd, F_SETFD, FD_CLOEXEC);
handle_crashing_process(fd);
}
return 0;
}