glebfm/strace
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

unwind: split unwind code into front-end and back-end

Browse Source 
This opens the way for alternative unwinder back-ends.

* unwind.h: New file, defines the unwinder back-end interface.
* unwind.c: Move all libunwind related code ...
* unwind-libunwind.c: ... here.
* Makefile.am [USE_LIBUNWIND] (strace_SOURCES): Add unwind.h
and unwind-libunwind.c.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
This commit is contained in:
Masatake YAMATO 2018-03-14 02:28:10 +09:00 committed by Dmitry V. Levin
parent 6b94271548
commit dd7e62f1e7
4 changed files with 300 additions and 153 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Makefile.am
View File

@ -350,7 +350,7 @@ strace_SOURCES = \
strace_SOURCES_check = bpf_attr_check.c
if USE_LIBUNWIND
strace_SOURCES += unwind.c
strace_SOURCES += unwind.c unwind.h unwind-libunwind.c
strace_CPPFLAGS += $(libunwind_CPPFLAGS)
strace_LDFLAGS += $(libunwind_LDFLAGS)
strace_LDADD += $(libunwind_LIBS)

174
unwind-libunwind.c Normal file
View File

@ -0,0 +1,174 @@
/*
* Copyright (c) 2013 Luca Clementi <luca.clementi@gmail.com>
* Copyright (c) 2013-2018 The strace developers.
*
* 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 "unwind.h"
#include "mmap_cache.h"
#include <libunwind-ptrace.h>
static unw_addr_space_t libunwind_as;
static void
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);
}
static void *
tcb_init(struct tcb *tcp)
{
void *r = _UPT_create(tcp->pid);
if (!r)
perror_msg_and_die("_UPT_create");
return r;
}
static void
tcb_fin(struct tcb *tcp)
{
_UPT_destroy(tcp->unwind_ctx);
}
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;
}
*name = xgrowarray(*name, size, 1);
}
}
static int
print_stack_frame(struct tcb *tcp,
unwind_call_action_fn call_action,
unwind_error_action_fn error_action,
void *data,
unw_cursor_t *cursor,
char **symbol_name,
size_t *symbol_name_size)
{
unw_word_t ip;
struct mmap_cache_t *cur_mmap_cache;
if (unw_get_reg(cursor, UNW_REG_IP, &ip) < 0) {
perror_msg("cannot walk the stack of process %d", tcp->pid);
return -1;
}
cur_mmap_cache = mmap_cache_search(tcp, ip);
if (cur_mmap_cache
/* ignore mappings that have no PROT_EXEC bit set */
&& (cur_mmap_cache->protections & MMAP_CACHE_PROT_EXECUTABLE)) {
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;
}
/*
* 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;
}
static void
tcb_walk(struct tcb *tcp,
unwind_call_action_fn call_action,
unwind_error_action_fn error_action,
void *data)
{
char *symbol_name;
size_t symbol_name_size = 40;
unw_cursor_t cursor;
int stack_depth;
if (!tcp->mmap_cache)
error_func_msg_and_die("mmap_cache is NULL");
if (tcp->mmap_cache_size == 0)
error_func_msg_and_die("mmap_cache is empty");
symbol_name = xmalloc(symbol_name_size);
if (unw_init_remote(&cursor, libunwind_as, tcp->unwind_ctx) < 0)
perror_func_msg_and_die("cannot initialize libunwind");
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);
free(symbol_name);
}
static void
tcb_flush_cache(struct tcb *tcp)
{
unw_flush_cache(libunwind_as, 0, 0);
}
const struct unwind_unwinder_t unwinder = {
.name = "libunwind",
.init = init,
.tcb_init = tcb_init,
.tcb_fin = tcb_fin,
.tcb_walk = tcb_walk,
.tcb_flush_cache = tcb_flush_cache,
};

201
unwind.c
View File

@ -27,7 +27,7 @@
#include "defs.h"
#include "mmap_cache.h"
#include <libunwind-ptrace.h>
#include "unwind.h"
#ifdef USE_DEMANGLE
# if defined HAVE_DEMANGLE_H
@ -37,18 +37,6 @@
# endif
#endif
/*
* 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
*/
@ -64,33 +52,27 @@ struct unwind_queue_t {
static void queue_print(struct unwind_queue_t *queue);
static unw_addr_space_t libunwind_as;
static const char asprintf_error_str[] = "???";
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);
if (unwinder.init)
unwinder.init();
mmap_cache_enable();
}
void
unwind_tcb_init(struct tcb *tcp)
{
if (tcp->unwind_ctx)
if (tcp->unwind_queue)
return;
tcp->unwind_ctx = _UPT_create(tcp->pid);
if (!tcp->unwind_ctx)
perror_msg_and_die("_UPT_create");
tcp->unwind_queue = xmalloc(sizeof(*tcp->unwind_queue));
tcp->unwind_queue->head = NULL;
tcp->unwind_queue->tail = NULL;
tcp->unwind_ctx = unwinder.tcb_init(tcp);
}
void
@ -100,122 +82,10 @@ unwind_tcb_fin(struct tcb *tcp)
free(tcp->unwind_queue);
tcp->unwind_queue = NULL;
_UPT_destroy(tcp->unwind_ctx);
unwinder.tcb_fin(tcp);
tcp->unwind_ctx = NULL;
}
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;
}
*name = xgrowarray(*name, size, 1);
}
}
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;
struct mmap_cache_t *cur_mmap_cache;
if (unw_get_reg(cursor, UNW_REG_IP, &ip) < 0) {
perror_msg("Can't walk the stack of process %d", tcp->pid);
return -1;
}
cur_mmap_cache = mmap_cache_search(tcp, ip);
if (cur_mmap_cache
/* ignore mappings that have no PROT_EXEC bit set */
&& (cur_mmap_cache->protections & MMAP_CACHE_PROT_EXECUTABLE)) {
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;
#ifdef USE_DEMANGLE
char *demangled_name =
cplus_demangle(*symbol_name,
DMGL_AUTO | DMGL_PARAMS);
#endif
call_action(data,
cur_mmap_cache->binary_filename,
#ifdef USE_DEMANGLE
demangled_name ? demangled_name :
#endif
*symbol_name,
function_offset,
true_offset);
#ifdef USE_DEMANGLE
free(demangled_name);
#endif
return 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, "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;
unw_cursor_t cursor;
int stack_depth;
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 = xmalloc(symbol_name_size);
if (unw_init_remote(&cursor, libunwind_as, tcp->unwind_ctx) < 0)
perror_msg_and_die("Can't initiate libunwind");
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);
free(symbol_name);
}
/*
* printing an entry in stack to stream or buffer
*/
@ -228,10 +98,10 @@ stacktrace_walk(struct tcb *tcp,
* /lib64/libc.so.6(__libc_start_main+0xed) [0x7fa2f8a5976d]
* ./a.out() [0x400569]
*/
#define STACK_ENTRY_SYMBOL_FMT \
#define STACK_ENTRY_SYMBOL_FMT(SYM) \
" > %s(%s+0x%lx) [0x%lx]\n", \
binary_filename, \
symbol_name, \
(SYM), \
(unsigned long) function_offset, \
true_offset
#define STACK_ENTRY_NOSYMBOL_FMT \
@ -248,11 +118,24 @@ static void
print_call_cb(void *dummy,
const char *binary_filename,
const char *symbol_name,
unw_word_t function_offset,
unwind_function_offset_t function_offset,
unsigned long true_offset)
{
if (symbol_name && (symbol_name[0] != '\0'))
tprintf(STACK_ENTRY_SYMBOL_FMT);
if (symbol_name && (symbol_name[0] != '\0')) {
#ifdef USE_DEMANGLE
char *demangled_name =
cplus_demangle(symbol_name,
DMGL_AUTO | DMGL_PARAMS);
#endif
tprintf(STACK_ENTRY_SYMBOL_FMT(
#ifdef USE_DEMANGLE
demangled_name ? demangled_name :
#endif
symbol_name));
#ifdef USE_DEMANGLE
free(demangled_name);
#endif
}
else if (binary_filename)
tprintf(STACK_ENTRY_NOSYMBOL_FMT);
else
@ -277,15 +160,29 @@ print_error_cb(void *dummy,
static char *
sprint_call_or_error(const char *binary_filename,
const char *symbol_name,
unw_word_t function_offset,
unwind_function_offset_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);
if (symbol_name) {
#ifdef USE_DEMANGLE
char *demangled_name =
cplus_demangle(symbol_name,
DMGL_AUTO | DMGL_PARAMS);
#endif
n = asprintf(&output_line,
STACK_ENTRY_SYMBOL_FMT(
#ifdef USE_DEMANGLE
demangled_name ? demangled_name :
#endif
symbol_name));
#ifdef USE_DEMANGLE
free(demangled_name);
#endif
}
else if (binary_filename)
n = asprintf(&output_line, STACK_ENTRY_NOSYMBOL_FMT);
else if (error)
@ -310,7 +207,7 @@ static void
queue_put(struct unwind_queue_t *queue,
const char *binary_filename,
const char *symbol_name,
unw_word_t function_offset,
unwind_function_offset_t function_offset,
unsigned long true_offset,
const char *error)
{
@ -337,7 +234,7 @@ static void
queue_put_call(void *queue,
const char *binary_filename,
const char *symbol_name,
unw_word_t function_offset,
unwind_function_offset_t function_offset,
unsigned long true_offset)
{
queue_put(queue,
@ -398,12 +295,12 @@ unwind_tcb_print(struct tcb *tcp)
queue_print(tcp->unwind_queue);
} else switch (mmap_cache_rebuild_if_invalid(tcp, __func__)) {
case MMAP_CACHE_REBUILD_RENEWED:
unw_flush_cache(libunwind_as, 0, 0);
unwinder.tcb_flush_cache(tcp);
ATTRIBUTE_FALLTHROUGH;
case MMAP_CACHE_REBUILD_READY:
debug_func_msg("walk: tcp=%p, queue=%p",
tcp, tcp->unwind_queue->head);
stacktrace_walk(tcp, print_call_cb, print_error_cb, NULL);
unwinder.tcb_walk(tcp, print_call_cb, print_error_cb, NULL);
break;
default:
/* Do nothing */
@ -428,11 +325,11 @@ unwind_tcb_capture(struct tcb *tcp)
switch (mmap_cache_rebuild_if_invalid(tcp, __func__)) {
case MMAP_CACHE_REBUILD_RENEWED:
unw_flush_cache(libunwind_as, 0, 0);
unwinder.tcb_flush_cache(tcp);
ATTRIBUTE_FALLTHROUGH;
case MMAP_CACHE_REBUILD_READY:
stacktrace_walk(tcp, queue_put_call, queue_put_error,
tcp->unwind_queue);
unwinder.tcb_walk(tcp, queue_put_call, queue_put_error,
tcp->unwind_queue);
debug_func_msg("tcp=%p, queue=%p",
tcp, tcp->unwind_queue->head);
break;

76
unwind.h Normal file
View File

@ -0,0 +1,76 @@
/*
* Unwinder backends interface.
*
* Copyright (c) 2013 Luca Clementi <luca.clementi@gmail.com>
* Copyright (c) 2013-2018 The strace developers.
*
* 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.
*/
#ifndef STRACE_UNWIND_H
#define STRACE_UNWIND_H
#include "defs.h"
/*
* Type used in stacktrace walker.
*/
/* This storage be enough large to store unw_word_t. */
typedef unsigned long unwind_function_offset_t;
typedef void (*unwind_call_action_fn)(void *data,
const char *binary_filename,
const char *symbol_name,
unwind_function_offset_t function_offset,
unsigned long true_offset);
typedef void (*unwind_error_action_fn)(void *data,
const char *error,
unsigned long true_offset);
struct unwind_unwinder_t {
const char *name;
/* Initialize the unwinder. */
void (*init)(void);
/* Make/destroy the context data attached to tcb. */
void * (*tcb_init)(struct tcb *);
void (*tcb_fin)(struct tcb *);
/* Walk the stack. */
void (*tcb_walk)(struct tcb *,
unwind_call_action_fn,
unwind_error_action_fn,
void *);
/*
* Rebuild the unwinder internal cache. Called when mmap cache
* subsystem detects a change of tracee memory mapping.
*/
void (*tcb_flush_cache)(struct tcb *);
};
extern const struct unwind_unwinder_t unwinder;
#endif /* !STRACE_UNWIND_H */