#include <limits.h>
#include <libunwind-ptrace.h>
+#ifdef _LARGEFILE64_SOURCE
+# ifdef HAVE_FOPEN64
+# define fopen_for_input fopen64
+# else
+# define fopen_for_input fopen
+# endif
+#else
+# define fopen_for_input fopen
+#endif
+
+#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
+ * 7fabbb09b000-7fabbb09f000 r-xp 00179000 fc:00 1180246 /lib/libc-2.11.1.so
*
* start_addr is 0x7fabbb09b000
* end_addr is 0x7fabbb09f000
unsigned long start_addr;
unsigned long end_addr;
unsigned long mmap_offset;
- char* binary_filename;
+ char *binary_filename;
+};
+
+/*
+ * Type used in stacktrace walker
+ */
+typedef void (*call_action_fn)(void *data,
+ const char *binary_filename,
+ const char *symbol_name,
+ unw_word_t function_offset,
+ 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
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)
{
- unwind_cache_invalidate(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
+ * The cache must be refreshed after syscalls that affect memory mappings,
+ * e.g. mmap, mprotect, munmap, execve.
*/
static void
-alloc_mmap_cache(struct tcb* tcp)
+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;
+ FILE *fp;
+ struct mmap_cache_t *cache_head;
/* 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;
+ char filename[sizeof("/proc/4294967296/maps")];
+ char buffer[PATH_MAX + 80];
+
+ unw_flush_cache(libunwind_as, 0, 0);
- sprintf(filename, "/proc/%d/maps", tcp->pid);
- fp = fopen(filename, "r");
+ sprintf(filename, "/proc/%u/maps", tcp->pid);
+ fp = fopen_for_input(filename, "r");
if (!fp) {
perror_msg("fopen: %s", filename);
return;
die_out_of_memory();
while (fgets(buffer, sizeof(buffer), fp) != NULL) {
- binary_path[0] = '\0'; // 'reset' it just to be paranoid
+ struct mmap_cache_t *entry;
+ unsigned long start_addr, end_addr, mmap_offset;
+ char exec_bit;
+ char binary_path[PATH_MAX];
- 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] == '[') {
+ if (sscanf(buffer, "%lx-%lx %*c%*c%c%*c %lx %*x:%*x %*d %[^\n]",
+ &start_addr, &end_addr, &exec_bit,
+ &mmap_offset, binary_path) != 5)
continue;
- }
- if (binary_path[0] == '\0') {
+ /* ignore mappings that have no PROT_EXEC bit set */
+ if (exec_bit != 'x')
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);
+ if (end_addr < start_addr) {
+ error_msg("%s: unrecognized file format", filename);
+ break;
+ }
/*
* 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);
+ entry = &cache_head[tcp->mmap_cache_size - 1];
+ if (entry->start_addr == start_addr &&
+ entry->end_addr == end_addr) {
+ /* duplicate entry, e.g. [vsyscall] */
+ continue;
+ }
+ if (start_addr <= entry->start_addr ||
+ start_addr < entry->end_addr) {
+ error_msg("%s: overlapping memory region",
+ filename);
+ continue;
+ }
}
- 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));
+ cache_head = realloc(cache_head,
+ cur_array_size * sizeof(*cache_head));
if (!cache_head)
die_out_of_memory();
}
+
+ entry = &cache_head[tcp->mmap_cache_size];
+ entry->start_addr = start_addr;
+ entry->end_addr = end_addr;
+ entry->mmap_offset = mmap_offset;
+ entry->binary_filename = strdup(binary_path);
+ if (!entry->binary_filename)
+ die_out_of_memory();
+ tcp->mmap_cache_size++;
}
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 */
-void
-unwind_cache_invalidate(struct tcb* tcp)
+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;
tcp->mmap_cache_size = 0;
}
-/* use libunwind to unwind the stack and print a backtrace */
+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_print_stacktrace(struct tcb* tcp)
+unwind_cache_invalidate(struct tcb* tcp)
+{
+#if SUPPORTED_PERSONALITIES > 1
+ if (tcp->currpers != DEFAULT_PERSONALITY) {
+ /* disable strack trace */
+ return;
+ }
+#endif
+ mmap_cache_generation++;
+ DPRINTF("tgen=%u, ggen=%u, tcp=%p, cache=%p", "increment",
+ tcp->mmap_cache_generation,
+ mmap_cache_generation,
+ tcp,
+ tcp->mmap_cache);
+}
+
+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;
+ }
+ *size *= 2;
+ *name = realloc(*name, *size);
+ if (!*name)
+ die_out_of_memory();
+ }
+}
+
+static int
+print_stack_frame(struct tcb *tcp,
+ call_action_fn call_action,
+ error_action_fn error_action,
+ void *data,
+ unw_cursor_t *cursor,
+ char **symbol_name,
+ size_t *symbol_name_size)
{
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;
+ int lower = 0;
+ int upper = (int) tcp->mmap_cache_size - 1;
+
+ if (unw_get_reg(cursor, UNW_REG_IP, &ip) < 0) {
+ perror_msg("Can't walk the stack of process %d", tcp->pid);
+ return -1;
+ }
+
+ while (lower <= upper) {
+ struct mmap_cache_t *cur_mmap_cache;
+ int mid = (upper + lower) / 2;
+
+ cur_mmap_cache = &tcp->mmap_cache[mid];
+
+ if (ip >= cur_mmap_cache->start_addr &&
+ ip < cur_mmap_cache->end_addr) {
+ unsigned long true_offset;
+ unw_word_t function_offset;
+
+ get_symbol_name(cursor, symbol_name, symbol_name_size,
+ &function_offset);
+ true_offset = ip - cur_mmap_cache->start_addr +
+ cur_mmap_cache->mmap_offset;
+ call_action(data,
+ cur_mmap_cache->binary_filename,
+ *symbol_name,
+ function_offset,
+ true_offset);
+ return 0;
+ }
+ else if (ip < cur_mmap_cache->start_addr)
+ upper = mid - 1;
+ else
+ lower = mid + 1;
+ }
+
+ /*
+ * 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;
+}
+
+/*
+ * walking the stack
+ */
+static void
+stacktrace_walk(struct tcb *tcp,
+ call_action_fn call_action,
+ error_action_fn error_action,
+ void *data)
+{
+ char *symbol_name;
size_t symbol_name_size = 40;
- char * symbol_name;
- struct mmap_cache_t* cur_mmap_cache;
- unsigned long true_offset;
+ unw_cursor_t cursor;
+ int stack_depth;
if (!tcp->mmap_cache)
- alloc_mmap_cache(tcp);
- if (!tcp->mmap_cache || !tcp->mmap_cache_size)
- return;
+ 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)
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);
+ 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);
- 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();
- }
-
- true_offset = ip - cur_mmap_cache->start_addr +
- cur_mmap_cache->mmap_offset;
- if (symbol_name[0]) {
- /*
- * 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]
- */
- tprintf(" > %s(%s+0x%lx) [0x%lx]\n",
- cur_mmap_cache->binary_filename,
- symbol_name, function_off_set, true_offset);
- } else {
- tprintf(" > %s() [0x%lx]\n",
- cur_mmap_cache->binary_filename, true_offset);
- }
- line_ended();
- 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)
- tprintf(" > backtracing_error\n");
- line_ended();
- goto ret;
- }
- else if (ip < cur_mmap_cache->start_addr)
- upper = mid;
- else
- lower = mid + 1;
+ free(symbol_name);
+}
- }
- if (lower > upper) {
- tprintf(" > backtracing_error [0x%lx]\n", ip);
- line_ended();
- goto ret;
- }
+/*
+ * 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, \
+ (unsigned long) function_offset, \
+ 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
- ret_val = unw_step(&cursor);
+static void
+print_call_cb(void *dummy,
+ const char *binary_filename,
+ const char *symbol_name,
+ unw_word_t function_offset,
+ 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__);
- if (++stack_depth > 255) {
- tprintf("> too many stack frames\n");
- line_ended();
- break;
- }
- } while (ret_val > 0);
-ret:
- free(symbol_name);
+ 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(const char *binary_filename,
+ const char *symbol_name,
+ unw_word_t function_offset,
+ 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,
+ const char *binary_filename,
+ const char *symbol_name,
+ unw_word_t function_offset,
+ 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_offset,
+ 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,
+ const char *binary_filename,
+ const char *symbol_name,
+ unw_word_t function_offset,
+ unsigned long true_offset)
+{
+ queue_put(queue,
+ binary_filename,
+ symbol_name,
+ function_offset,
+ true_offset,
+ NULL);
+}
+
+static void
+queue_put_error(void *queue,
+ const char *error,
+ unsigned long 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 SUPPORTED_PERSONALITIES > 1
+ if (tcp->currpers != DEFAULT_PERSONALITY) {
+ /* disable strack trace */
+ return;
+ }
+#endif
+ 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 SUPPORTED_PERSONALITIES > 1
+ if (tcp->currpers != DEFAULT_PERSONALITY) {
+ /* disable strack trace */
+ return;
+ }
+#endif
+ 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);
+ }
}
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