blob: 797a287a81935d13bec05b91458db7991ef94464 [file] [log] [blame]
/*
* Copyright (c) 2013 Luca Clementi <luca.clementi@gmail.com>
*
* 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 <limits.h>
#include <libunwind-ptrace.h>
#define DPRINTF(F, A, ...) if (debug_flag) fprintf(stderr, " [unwind(" A ")] " F "\n", __VA_ARGS__)
/*
* Кeep a sorted array of cache entries,
* so that we can binary search through it.
*/
struct mmap_cache_t {
/**
* example entry:
* 7fabbb09b000-7fabbb09f000 r--p 00179000 fc:00 1180246 /lib/libc-2.11.1.so
*
* start_addr is 0x7fabbb09b000
* end_addr is 0x7fabbb09f000
* mmap_offset is 0x179000
* binary_filename is "/lib/libc-2.11.1.so"
*/
unsigned long start_addr;
unsigned long end_addr;
unsigned long mmap_offset;
char* binary_filename;
bool deleted;
};
/*
* Type used in stacktrace walker
*/
typedef void (*call_action_fn)(void *data,
char *binary_filename,
char *symbol_name,
unw_word_t function_off_set,
unsigned long true_offset);
typedef void (*error_action_fn)(void *data,
const char *error,
unsigned long true_offset);
/*
* Type used in stacktrace capturing
*/
struct call_t {
struct call_t* next;
char *output_line;
};
struct queue_t {
struct call_t *tail;
struct call_t *head;
};
static void queue_print(struct queue_t *queue);
static void delete_mmap_cache(struct tcb *tcp, const char *caller);
static unw_addr_space_t libunwind_as;
static unsigned int mmap_cache_generation;
void
unwind_init(void)
{
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);
}
void
unwind_tcb_init(struct tcb *tcp)
{
tcp->libunwind_ui = _UPT_create(tcp->pid);
if (!tcp->libunwind_ui)
die_out_of_memory();
tcp->queue = malloc(sizeof(*tcp->queue));
if (!tcp->queue)
die_out_of_memory();
tcp->queue->head = NULL;
tcp->queue->tail = NULL;
}
void
unwind_tcb_fin(struct tcb *tcp)
{
queue_print(tcp->queue);
free(tcp->queue);
tcp->queue = NULL;
delete_mmap_cache(tcp, __FUNCTION__);
_UPT_destroy(tcp->libunwind_ui);
tcp->libunwind_ui = NULL;
}
/*
* caching of /proc/ID/maps for each process to speed up stack tracing
*
* The cache must be refreshed after some syscall: mmap, mprotect, munmap, execve
*/
static void
build_mmap_cache(struct tcb* tcp)
{
unsigned long start_addr, end_addr, mmap_offset;
char filename[sizeof ("/proc/0123456789/maps")];
char buffer[PATH_MAX + 80];
char binary_path[PATH_MAX];
struct mmap_cache_t *cur_entry, *prev_entry;
/* start with a small dynamically-allocated array and then expand it */
size_t cur_array_size = 10;
struct mmap_cache_t *cache_head;
FILE *fp;
const char *deleted = " (deleted)";
size_t blen;
size_t dlen;
unw_flush_cache (libunwind_as, 0, 0);
sprintf(filename, "/proc/%d/maps", tcp->pid);
fp = fopen(filename, "r");
if (!fp) {
perror_msg("fopen: %s", filename);
return;
}
cache_head = calloc(cur_array_size, sizeof(*cache_head));
if (!cache_head)
die_out_of_memory();
while (fgets(buffer, sizeof(buffer), fp) != NULL) {
binary_path[0] = '\0'; // 'reset' it just to be paranoid
sscanf(buffer, "%lx-%lx %*c%*c%*c%*c %lx %*x:%*x %*d %[^\n]",
&start_addr, &end_addr, &mmap_offset, binary_path);
/* ignore special 'fake files' like "[vdso]", "[heap]", "[stack]", */
if (binary_path[0] == '[') {
continue;
}
if (binary_path[0] == '\0') {
continue;
}
if (end_addr < start_addr)
perror_msg_and_die("%s: unrecognized maps file format",
filename);
cur_entry = &cache_head[tcp->mmap_cache_size];
cur_entry->start_addr = start_addr;
cur_entry->end_addr = end_addr;
cur_entry->mmap_offset = mmap_offset;
cur_entry->binary_filename = strdup(binary_path);
dlen = strlen(deleted);
blen = strlen(binary_path);
if (blen >= dlen && strcmp(binary_path + blen - dlen, deleted) == 0)
cur_entry->deleted = true;
else
cur_entry->deleted = false;
/*
* sanity check to make sure that we're storing
* non-overlapping regions in ascending order
*/
if (tcp->mmap_cache_size > 0) {
prev_entry = &cache_head[tcp->mmap_cache_size - 1];
if (prev_entry->start_addr >= cur_entry->start_addr)
perror_msg_and_die("Overlaying memory region in %s",
filename);
if (prev_entry->end_addr > cur_entry->start_addr)
perror_msg_and_die("Overlaying memory region in %s",
filename);
}
tcp->mmap_cache_size++;
/* resize doubling its size */
if (tcp->mmap_cache_size >= cur_array_size) {
cur_array_size *= 2;
cache_head = realloc(cache_head, cur_array_size * sizeof(*cache_head));
if (!cache_head)
die_out_of_memory();
}
}
fclose(fp);
tcp->mmap_cache = cache_head;
tcp->mmap_cache_generation = mmap_cache_generation;
DPRINTF("tgen=%u, ggen=%u, tcp=%p, cache=%p",
"cache-build",
tcp->mmap_cache_generation,
mmap_cache_generation,
tcp, tcp->mmap_cache);
}
/* deleting the cache */
static void
delete_mmap_cache(struct tcb *tcp, const char *caller)
{
unsigned int i;
DPRINTF("tgen=%u, ggen=%u, tcp=%p, cache=%p, caller=%s",
"cache-delete",
tcp->mmap_cache_generation,
mmap_cache_generation,
tcp, tcp->mmap_cache, caller);
for (i = 0; i < tcp->mmap_cache_size; i++) {
free(tcp->mmap_cache[i].binary_filename);
tcp->mmap_cache[i].binary_filename = NULL;
}
free(tcp->mmap_cache);
tcp->mmap_cache = NULL;
tcp->mmap_cache_size = 0;
}
static bool
rebuild_cache_if_invalid(struct tcb *tcp, const char *caller)
{
if ((tcp->mmap_cache_generation != mmap_cache_generation)
&& tcp->mmap_cache)
delete_mmap_cache(tcp, caller);
if (!tcp->mmap_cache)
build_mmap_cache(tcp);
if (!tcp->mmap_cache || !tcp->mmap_cache_size)
return false;
else
return true;
}
void
unwind_cache_invalidate(struct tcb* tcp)
{
mmap_cache_generation++;
DPRINTF("tgen=%u, ggen=%u, tcp=%p, cache=%p", "increment",
tcp->mmap_cache_generation,
mmap_cache_generation,
tcp,
tcp->mmap_cache);
}
/*
* walking the stack
*/
static void
stacktrace_walk(struct tcb *tcp,
call_action_fn call_action,
error_action_fn error_action,
void *data)
{
unw_word_t ip;
unw_cursor_t cursor;
unw_word_t function_off_set;
int stack_depth = 0, ret_val;
/* these are used for the binary search through the mmap_chace */
unsigned int lower, upper, mid;
size_t symbol_name_size = 40;
char * symbol_name;
struct mmap_cache_t* cur_mmap_cache;
unsigned long true_offset;
bool berror_expected = false;
if (!tcp->mmap_cache)
error_msg_and_die("bug: mmap_cache is NULL");
if (tcp->mmap_cache_size == 0)
error_msg_and_die("bug: mmap_cache is empty");
symbol_name = malloc(symbol_name_size);
if (!symbol_name)
die_out_of_memory();
if (unw_init_remote(&cursor, libunwind_as, tcp->libunwind_ui) < 0)
perror_msg_and_die("Can't initiate libunwind");
do {
/* looping on the stack frame */
if (unw_get_reg(&cursor, UNW_REG_IP, &ip) < 0) {
perror_msg("Can't walk the stack of process %d", tcp->pid);
break;
}
lower = 0;
upper = tcp->mmap_cache_size - 1;
while (lower <= upper) {
/* find the mmap_cache and print the stack frame */
mid = (upper + lower) / 2;
cur_mmap_cache = &tcp->mmap_cache[mid];
if (ip >= cur_mmap_cache->start_addr &&
ip < cur_mmap_cache->end_addr) {
for (;;) {
symbol_name[0] = '\0';
ret_val = unw_get_proc_name(&cursor, symbol_name,
symbol_name_size, &function_off_set);
if (ret_val != -UNW_ENOMEM)
break;
symbol_name_size *= 2;
symbol_name = realloc(symbol_name, symbol_name_size);
if (!symbol_name)
die_out_of_memory();
}
if (cur_mmap_cache->deleted)
berror_expected = true;
true_offset = ip - cur_mmap_cache->start_addr +
cur_mmap_cache->mmap_offset;
if (symbol_name[0]) {
call_action(data,
cur_mmap_cache->binary_filename,
symbol_name,
function_off_set,
true_offset);
} else {
call_action(data,
cur_mmap_cache->binary_filename,
symbol_name,
0,
true_offset);
}
break; /* stack frame printed */
}
else if (mid == 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,
"backtracing_error", 0);
goto ret;
}
else if (ip < cur_mmap_cache->start_addr)
upper = mid;
else
lower = mid + 1;
}
if (lower > upper) {
error_action(data,
berror_expected
?"expected_backtracing_error"
:"unexpected_backtracing_error",
ip);
goto ret;
}
ret_val = unw_step(&cursor);
if (++stack_depth > 255) {
error_action(data,
"too many stack frames", 0);
break;
}
} while (ret_val > 0);
ret:
free(symbol_name);
}
/*
* printing an entry in stack to stream or buffer
*/
/*
* we want to keep the format used by backtrace_symbols from the glibc
*
* ./a.out() [0x40063d]
* ./a.out() [0x4006bb]
* ./a.out() [0x4006c6]
* /lib64/libc.so.6(__libc_start_main+0xed) [0x7fa2f8a5976d]
* ./a.out() [0x400569]
*/
#define STACK_ENTRY_SYMBOL_FMT \
" > %s(%s+0x%lx) [0x%lx]\n", \
binary_filename, \
symbol_name, \
function_off_set, \
true_offset
#define STACK_ENTRY_NOSYMBOL_FMT \
" > %s() [0x%lx]\n", \
binary_filename, true_offset
#define STACK_ENTRY_BUG_FMT \
" > BUG IN %s\n"
#define STACK_ENTRY_ERROR_WITH_OFFSET_FMT \
" > %s [0x%lx]\n", error, true_offset
#define STACK_ENTRY_ERROR_FMT \
" > %s\n", error
static void
print_call_cb(void *dummy,
char *binary_filename,
char *symbol_name,
unw_word_t function_off_set,
unsigned long true_offset)
{
if (symbol_name)
tprintf(STACK_ENTRY_SYMBOL_FMT);
else if (binary_filename)
tprintf(STACK_ENTRY_NOSYMBOL_FMT);
else
tprintf(STACK_ENTRY_BUG_FMT, __FUNCTION__);
line_ended();
}
static void
print_error_cb(void *dummy,
const char *error,
unsigned long true_offset)
{
if (true_offset)
tprintf(STACK_ENTRY_ERROR_WITH_OFFSET_FMT);
else
tprintf(STACK_ENTRY_ERROR_FMT);
line_ended();
}
static char *
sprint_call_or_error(char *binary_filename,
char *symbol_name,
unw_word_t function_off_set,
unsigned long true_offset,
const char *error)
{
char *output_line = NULL;
int n;
if (symbol_name)
n = asprintf(&output_line, STACK_ENTRY_SYMBOL_FMT);
else if (binary_filename)
n = asprintf(&output_line, STACK_ENTRY_NOSYMBOL_FMT);
else if (error)
n = true_offset
? asprintf(&output_line, STACK_ENTRY_ERROR_WITH_OFFSET_FMT)
: asprintf(&output_line, STACK_ENTRY_ERROR_FMT);
else
n = asprintf(&output_line, STACK_ENTRY_BUG_FMT, __FUNCTION__);
if (n < 0)
error_msg_and_die("error in asprintf");
return output_line;
}
/*
* queue manipulators
*/
static void
queue_put(struct queue_t *queue,
char *binary_filename,
char *symbol_name,
unw_word_t function_off_set,
unsigned long true_offset,
const char *error)
{
struct call_t *call;
call = malloc(sizeof(*call));
if (!call)
die_out_of_memory();
call->output_line = sprint_call_or_error(binary_filename,
symbol_name,
function_off_set,
true_offset,
error);
call->next = NULL;
if (!queue->head) {
queue->head = call;
queue->tail = call;
} else {
queue->tail->next = call;
queue->tail = call;
}
}
static void
queue_put_call(void *queue,
char *binary_filename,
char *symbol_name,
unw_word_t function_off_set,
unsigned long true_offset)
{
queue_put(queue,
binary_filename,
symbol_name,
function_off_set,
true_offset,
NULL);
}
static void
queue_put_error(void *queue,
const char *error,
unw_word_t ip)
{
queue_put(queue, NULL, NULL, 0, ip, error);
}
static void
queue_print(struct queue_t *queue)
{
struct call_t *call, *tmp;
queue->tail = NULL;
call = queue->head;
queue->head = NULL;
while (call) {
tmp = call;
call = call->next;
tprints(tmp->output_line);
line_ended();
free(tmp->output_line);
tmp->output_line = NULL;
tmp->next = NULL;
free(tmp);
}
}
/*
* printing stack
*/
void
unwind_print_stacktrace(struct tcb* tcp)
{
if (tcp->queue->head) {
DPRINTF("tcp=%p, queue=%p", "queueprint", tcp, tcp->queue->head);
queue_print(tcp->queue);
}
else if (rebuild_cache_if_invalid(tcp, __FUNCTION__)) {
DPRINTF("tcp=%p, queue=%p", "stackprint", tcp, tcp->queue->head);
stacktrace_walk(tcp, print_call_cb, print_error_cb, NULL);
}
}
/*
* capturing stack
*/
void
unwind_capture_stacktrace(struct tcb *tcp)
{
if (tcp->queue->head)
error_msg_and_die("bug: unprinted entries in queue");
if (rebuild_cache_if_invalid(tcp, __FUNCTION__)) {
stacktrace_walk(tcp, queue_put_call, queue_put_error,
tcp->queue);
DPRINTF("tcp=%p, queue=%p", "captured", tcp, tcp->queue->head);
}
}