[PATCH 5/9] unwind: split unwind codes into front-end and back-end
Masatake YAMATO
yamato at redhat.com
Tue Mar 13 17:28:10 UTC 2018
So the back-end can replaceable.
* unwind.c: Move all libunwind related code to unwind-libunwind.c.
Put codes to implement the abstract interface are here.
* unwind.h: New file. Declares types for defining a unwinder.
* unwind-libunwind.c: New file defining unwinder adapted to unwind.h.
Mostly derived libunwind related code from unwind.c.
* Makefile.am (USE_LIBUNWIND): Reintroduced condition.
libunwind related compiler flags are set here.
(CAN_UNWIND): Move libunwind related flags to USE_LIBUNWIND.
(strace_SOURCES): Add unwind.h in CAN_UNWIND condition, a new
header file. Add unwind-libunwind.c in USE_LIBUNWIND.
Signed-off-by: Masatake YAMATO <yamato at redhat.com>
---
Makefile.am | 14 +++-
unwind-libunwind.c | 174 +++++++++++++++++++++++++++++++++++++++++++
unwind.c | 214 +++++++++++++++--------------------------------------
unwind.h | 74 ++++++++++++++++++
4 files changed, 319 insertions(+), 157 deletions(-)
create mode 100644 unwind-libunwind.c
create mode 100644 unwind.h
diff --git a/Makefile.am b/Makefile.am
index 00c7b4bc..a4d274a5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -339,10 +339,9 @@ strace_SOURCES = \
# end of strace_SOURCES
if CAN_UNWIND
-strace_SOURCES += unwind.c
-strace_CPPFLAGS += $(libunwind_CPPFLAGS)
-strace_LDFLAGS += $(libunwind_LDFLAGS)
-strace_LDADD += $(libunwind_LIBS)
+strace_SOURCES += \
+ unwind.c \
+ unwind.h
if USE_DEMANGLE
strace_CPPFLAGS += $(libiberty_CPPFLAGS)
strace_LDFLAGS += $(libiberty_LDFLAGS)
@@ -350,6 +349,13 @@ strace_LDADD += $(libiberty_LIBS)
endif
endif
+if USE_LIBUNWIND
+strace_SOURCES += unwind-libunwind.c
+strace_CPPFLAGS += $(libunwind_CPPFLAGS)
+strace_LDFLAGS += $(libunwind_LDFLAGS)
+strace_LDADD += $(libunwind_LIBS)
+endif
+
@CODE_COVERAGE_RULES@
CODE_COVERAGE_BRANCH_COVERAGE = 1
CODE_COVERAGE_GENHTML_OPTIONS = $(CODE_COVERAGE_GENHTML_OPTIONS_DEFAULT) \
diff --git a/unwind-libunwind.c b/unwind-libunwind.c
new file mode 100644
index 00000000..49e2c66e
--- /dev/null
+++ b/unwind-libunwind.c
@@ -0,0 +1,174 @@
+/*
+ * Copyright (c) 2013 Luca Clementi <luca.clementi at 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((struct UPT_info *)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("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;
+ 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_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,
+ (struct UPT_info *)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);
+}
+
+static void
+tcb_flush_cache(struct tcb *tcp)
+{
+ unw_flush_cache(libunwind_as, 0, 0);
+}
+
+const struct unwind_unwinder_t unwinder_libunwind = {
+ .name = "libunwind",
+ .init = init,
+ .tcb_init = tcb_init,
+ .tcb_fin = tcb_fin,
+ .tcb_walk = tcb_walk,
+ .tcb_flush_cache = tcb_flush_cache,
+};
diff --git a/unwind.c b/unwind.c
index f5b25fa3..83c5cff4 100644
--- a/unwind.c
+++ b/unwind.c
@@ -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 +52,39 @@ 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[] = "???";
+#ifdef USE_LIBUNWIND
+extern const struct unwind_unwinder_t unwinder_libunwind;
+#endif
+static const struct unwind_unwinder_t *unwinder;
+
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);
+#ifdef USE_LIBUNWIND
+ unwinder = &unwinder_libunwind;
+#endif
+
+ if (!unwinder)
+ error_msg_and_die("bug: no unwinder");
+
+ 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
@@ -100,123 +94,10 @@ unwind_tcb_fin(struct tcb *tcp)
free(tcp->unwind_queue);
tcp->unwind_queue = NULL;
- _UPT_destroy((struct UPT_info *)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,
- (struct UPT_info *)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
*/
@@ -229,10 +110,10 @@ 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 \
@@ -249,11 +130,24 @@ 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
@@ -278,15 +172,29 @@ 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)
@@ -311,7 +219,7 @@ 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)
{
@@ -338,7 +246,7 @@ 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,
@@ -401,11 +309,11 @@ unwind_tcb_print(struct tcb *tcp)
queue_print(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, 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 */
@@ -433,11 +341,11 @@ 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,
- queue);
+ unwinder->tcb_walk(tcp, queue_put_call, queue_put_error,
+ queue);
debug_func_msg("tcp=%p, queue=%p", tcp, queue->head);
break;
default:
diff --git a/unwind.h b/unwind.h
new file mode 100644
index 00000000..59603321
--- /dev/null
+++ b/unwind.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2013 Luca Clementi <luca.clementi at 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
+
+/* Interface for backends (unwinders) See defs.h for the frontend. */
+
+#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 a context data attached to tcb. */
+ void * (*tcb_init)(struct tcb *);
+ void (*tcb_fin)(struct tcb *);
+
+ /* Walk stack */
+ void (*tcb_walk)(struct tcb *,
+ unwind_call_action_fn,
+ unwind_error_action_fn,
+ void *);
+
+ /* Rebuild unwinder internal cache. Called when mmap cache
+ * subsystem detects the change of memory mapping of target
+ * process.
+ */
+ void (*tcb_flush_cache)(struct tcb *);
+};
+
+#endif /* !STRACE_UNWIND_H */
--
2.14.3
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