blob: 95381e24912e46f34526754005120288c1805f3d [file] [log] [blame]
/*
* Copyright 2006 The Android Open Source Project
*/
#include <dirent.h>
#include <sys/ptrace.h>
#include <stdint.h>
#include <thread_db.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#define DEBUG 0
#if DEBUG
# include <string.h> /* for strerror() */
# define D(...) fprintf(stderr, "libthread_db:%s: ", __FUNCTION__), fprintf(stderr, __VA_ARGS__)
#else
# define D(...) do{}while(0)
#endif
extern int ps_pglobal_lookup (void *, const char *obj, const char *name, void **sym_addr);
struct ps_prochandle
{
pid_t pid;
};
/*
* This is the list of "special" symbols we care about whose addresses are
* cached by gdbserver from the host at init time.
*/
enum {
SYM_TD_CREATE,
SYM_THREAD_LIST,
NUM_SYMS
};
static char const * gSymbols[] = {
[SYM_TD_CREATE] = "_thread_created_hook",
NULL
};
char const **
td_symbol_list(void)
{
return gSymbols;
}
/* Extract the permitted capabilities of a given task */
static int
_get_task_permitted_caps(int pid, int tid, uint64_t *cap)
{
char path[64];
char buff[1024];
int len;
int fd;
int result = -1;
char* perm;
char* end;
/* Open task status file */
snprintf(path, sizeof path, "/proc/%d/task/%d/status", pid, tid);
fd = open(path, O_RDONLY);
if (fd < 0) {
D("Could not open %s: %s\n", path, strerror(errno));
return -1;
}
/* Read its content, up to sizeof buff-1, then zero-terminate */
do {
len = read(fd, buff, sizeof buff-1);
} while (len < 0 && errno == EINTR);
if (len < 0) {
D("Could not read %s: %s\n", path, strerror(errno));
goto EXIT;
}
buff[len] = 0;
/* Look for "CapPrm: " in it */
perm = strstr(buff, "CapPrm:");
if (perm == NULL) {
D("Could not find CapPrm in %s!\n---- cut here ----\n%.*s\n----- cut here -----\n",
path, len, buff);
errno = EINVAL;
goto EXIT;
}
/* Now read the hexadecimal value after 'CapPrm: ' */
errno = 0;
*cap = (uint64_t) strtoull(perm+8, &end, 16);
if (errno == 0) {
D("Found CapPerm of %lld in %s\n", *cap, path);
result = 0;
} else {
D("Cannot read CapPerm from %s: '%.*s'\n", path, 24, perm);
}
EXIT:
close(fd);
return result;
}
td_err_e
td_ta_new(struct ps_prochandle const * proc_handle, td_thragent_t ** agent_out)
{
td_thragent_t * agent;
/* Platforms before Android 2.3 contain a system bug that prevents
* gdbserver to attach to all threads in a target process when
* it is run as the same userID than the target (works fine if
* run as root).
*
* Due to the way gdbserver is coded, this makes gdbserver exit()
* immediately (see linux_attach_lwp in linux-low.c). Even if we
* modify the source code to not exit(), then signals will not
* be properly rerouted to gdbserver, preventing breakpoints from
* working correctly.
*
* The following code is here to test for this problematic condition.
* If it is detected, we return TD_NOLIBTHREAD to indicate that there
* are no threads to attach to (gdbserver will attach to the main thread
* though).
*/
do {
char path[64];
DIR* dir;
struct dirent *entry;
pid_t my_pid = getpid();
int target_pid = proc_handle->pid;
uint64_t my_caps, tid_caps;
D("Probing system for platform bug.\n");
/* nothing to do if we run as root */
if (geteuid() == 0) {
D("Running as root, nothing to do.\n");
break;
}
/* First, get our own permitted capabilities */
if (_get_task_permitted_caps(my_pid, my_pid, &my_caps) < 0) {
/* something is really fishy here */
D("Could not get gdbserver permitted caps!\n");
return TD_NOLIBTHREAD;
}
/* Now, for each thread in the target process, compare the
* permitted capabilities set to our own. If they differ,
* the thread attach will fail. Booo...
*/
snprintf(path, sizeof path, "/proc/%d/task", target_pid);
dir = opendir(path);
if (!dir) {
D("Could not open %s: %s\n", path, strerror(errno));
break;
}
while ((entry = readdir(dir)) != NULL) {
int tid;
if (entry->d_name[0] == '.') /* skip . and .. */
continue;
tid = atoi(entry->d_name);
if (tid == 0) /* should not happen - be safe */
continue;
if (_get_task_permitted_caps(target_pid, tid, &tid_caps) < 0) {
/* again, something is fishy */
D("Could not get permitted caps for thread %d\n", tid);
closedir(dir);
return TD_NOLIBTHREAD;
}
if (tid_caps != my_caps) {
/* AAAARGH !! The permitted capabilities set differ. */
D("AAAAAH, Can't debug threads!\n");
fprintf(stderr, "Thread debugging is unsupported on this Android platform!\n");
closedir(dir);
return TD_NOLIBTHREAD;
}
}
closedir(dir);
D("Victory: We can debug theads!\n");
} while (0);
/* We now return to our regularly scheduled program */
agent = (td_thragent_t *)malloc(sizeof(td_thragent_t));
if (!agent) {
return TD_MALLOC;
}
agent->pid = proc_handle->pid;
*agent_out = agent;
return TD_OK;
}
td_err_e
td_ta_set_event(td_thragent_t const * agent, td_thr_events_t * events)
{
return TD_OK;
}
static td_thrhandle_t gEventMsgHandle;
static int
_event_getmsg_helper(td_thrhandle_t const * handle, void * bkpt_addr)
{
void * pc;
pc = (void *)ptrace(PTRACE_PEEKUSR, handle->tid, (void *)60 /* r15/pc */, NULL);
if (pc == bkpt_addr) {
// The hook function takes the id of the new thread as it's first param,
// so grab it from r0.
gEventMsgHandle.pid = ptrace(PTRACE_PEEKUSR, handle->tid, (void *)0 /* r0 */, NULL);
gEventMsgHandle.tid = gEventMsgHandle.pid;
return 0x42;
}
return 0;
}
td_err_e
td_ta_event_getmsg(td_thragent_t const * agent, td_event_msg_t * event)
{
td_err_e err;
void * bkpt_addr;
err = ps_pglobal_lookup(NULL, NULL, gSymbols[SYM_TD_CREATE], &bkpt_addr);
if (err) {
return err;
}
err = td_ta_thr_iter(agent, _event_getmsg_helper, bkpt_addr, 0, 0, NULL, 0);
if (err != 0x42) {
return TD_NOMSG;
}
event->event = TD_CREATE;
event->th_p = &gEventMsgHandle; // Nasty hack, but it's the only way!
return TD_OK;
}
td_err_e
td_thr_get_info(td_thrhandle_t const * handle, td_thrinfo_t * info)
{
info->ti_tid = handle->tid;
info->ti_lid = handle->tid; // Our pthreads uses kernel ids for tids
info->ti_state = TD_THR_SLEEP; /* XXX this needs to be read from /proc/<pid>/task/<tid>.
This is only used to see if the thread is a zombie or not */
return TD_OK;
}
td_err_e
td_thr_event_enable(td_thrhandle_t const * handle, td_event_e event)
{
// I don't think we need to do anything here...
return TD_OK;
}
td_err_e
td_ta_event_addr(td_thragent_t const * agent, td_event_e event, td_notify_t * notify_out)
{
int32_t err;
/*
* This is nasty, ps_pglobal_lookup is implemented in gdbserver and looks up
* the symbol from it's cache, which is populated at start time with the
* symbols returned from td_symbol_list via calls back to the host.
*/
switch (event) {
case TD_CREATE:
err = ps_pglobal_lookup(NULL, NULL, gSymbols[SYM_TD_CREATE], &notify_out->u.bptaddr);
if (err) {
return TD_NOEVENT;
}
return TD_OK;
}
return TD_NOEVENT;
}
td_err_e
td_ta_thr_iter(td_thragent_t const * agent, td_thr_iter_f * func, void * cookie,
td_thr_state_e state, int32_t prio, sigset_t * sigmask, uint32_t user_flags)
{
td_err_e err = TD_OK;
char path[32];
DIR * dir;
struct dirent * entry;
td_thrhandle_t handle;
snprintf(path, sizeof(path), "/proc/%d/task/", agent->pid);
dir = opendir(path);
if (!dir) {
return TD_NOEVENT;
}
handle.pid = agent->pid;
while ((entry = readdir(dir)) != NULL) {
if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) {
continue;
}
handle.tid = atoi(entry->d_name);
err = func(&handle, cookie);
if (err) {
break;
}
}
closedir(dir);
return err;
}