From a16a4e10e140094ca7b83dc5a65c1ddc68470a5e Mon Sep 17 00:00:00 2001 From: Christopher Ferris Date: Tue, 1 Oct 2013 17:54:11 -0700 Subject: Fix problems in libbacktrace. - Add a wait for stop to backtrace_test. There is a possible race condition that is exposed when using libunwind. - Fix a few calls to unwind function calls. Bug: 8410085 Change-Id: I7487d687f6d4b7b05b8a96ad1c5f7183681e5c95 --- libbacktrace/backtrace_test.c | 22 ++++++++++++++++++++++ libbacktrace/unwind_local.c | 13 ++++++++++--- libbacktrace/unwind_remote.c | 13 ++++++++++--- 3 files changed, 42 insertions(+), 6 deletions(-) (limited to 'libbacktrace') diff --git a/libbacktrace/backtrace_test.c b/libbacktrace/backtrace_test.c index 34d3519..6155c9b 100644 --- a/libbacktrace/backtrace_test.c +++ b/libbacktrace/backtrace_test.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include @@ -29,6 +30,8 @@ #define FINISH(pid) dump_frames(&backtrace); if (pid < 0) exit(1); else return false; +#define WAIT_INTERVAL_USECS 1000 + // Prototypes for functions in the test library. int test_level_one(int, int, int, int, bool (*)(pid_t)); @@ -52,6 +55,21 @@ void dump_frames(const backtrace_t* backtrace) { } } +void wait_for_stop(pid_t pid, size_t max_usecs_to_wait) { + siginfo_t si; + size_t usecs_waited = 0; + + while (ptrace(PTRACE_GETSIGINFO, pid, 0, &si) < 0 && (errno == EINTR || errno == ESRCH)) { + if (usecs_waited >= max_usecs_to_wait) { + printf("The process did not get to a stopping point in %zu usecs.\n", + usecs_waited); + break; + } + usleep(WAIT_INTERVAL_USECS); + usecs_waited += WAIT_INTERVAL_USECS; + } +} + bool check_frame(const backtrace_t* backtrace, size_t frame_num, const char* expected_name) { if (backtrace->frames[frame_num].proc_name == NULL) { @@ -153,6 +171,10 @@ void verify_proc_test(pid_t pid, bool (*verify_func)(pid_t)) { kill(pid, SIGKILL); exit(1); } + + // Wait up to 1 second for the process to get to a point that we can trace it. + wait_for_stop(pid, 1000000); + bool pass = verify_func(pid); if (ptrace(PTRACE_DETACH, pid, 0, 0) != 0) { printf("Failed to detach from pid %d\n", pid); diff --git a/libbacktrace/unwind_local.c b/libbacktrace/unwind_local.c index e0b72d8..d467d8a 100644 --- a/libbacktrace/unwind_local.c +++ b/libbacktrace/unwind_local.c @@ -48,6 +48,7 @@ static bool local_get_frames(backtrace_t* backtrace) { bool returnValue = true; backtrace->num_frames = 0; uintptr_t map_start; + unw_word_t value; do { frame = &backtrace->frames[backtrace->num_frames]; frame->stack_size = 0; @@ -56,18 +57,21 @@ static bool local_get_frames(backtrace_t* backtrace) { frame->proc_name = NULL; frame->proc_offset = 0; - ret = unw_get_reg(&cursor, UNW_REG_IP, &frame->pc); + ret = unw_get_reg(&cursor, UNW_REG_IP, &value); if (ret < 0) { ALOGW("get_frames: Failed to read IP %d\n", ret); returnValue = false; break; } - ret = unw_get_reg(&cursor, UNW_REG_SP, &frame->sp); + frame->pc = (uintptr_t)value; + ret = unw_get_reg(&cursor, UNW_REG_SP, &value); if (ret < 0) { ALOGW("get_frames: Failed to read IP %d\n", ret); returnValue = false; break; } + frame->sp = (uintptr_t)value; + if (backtrace->num_frames) { backtrace_frame_data_t* prev = &backtrace->frames[backtrace->num_frames-1]; prev->stack_size = frame->sp - prev->sp; @@ -111,8 +115,11 @@ char* local_get_proc_name(const backtrace_t* backtrace, uintptr_t pc, unw_context_t* context = (unw_context_t*)backtrace->private_data; char buf[512]; + *offset = 0; + unw_word_t value; if (unw_get_proc_name_by_ip(unw_local_addr_space, pc, buf, sizeof(buf), - offset, context) >= 0 && buf[0] != '\0') { + &value, context) >= 0 && buf[0] != '\0') { + *offset = (uintptr_t)value; char* symbol = demangle_symbol_name(buf); if (!symbol) { symbol = strdup(buf); diff --git a/libbacktrace/unwind_remote.c b/libbacktrace/unwind_remote.c index ebbde2e..1c624d7 100644 --- a/libbacktrace/unwind_remote.c +++ b/libbacktrace/unwind_remote.c @@ -46,6 +46,7 @@ static bool remote_get_frames(backtrace_t* backtrace) { bool returnValue = true; backtrace->num_frames = 0; uintptr_t map_start; + unw_word_t value; do { frame = &backtrace->frames[backtrace->num_frames]; frame->stack_size = 0; @@ -54,18 +55,21 @@ static bool remote_get_frames(backtrace_t* backtrace) { frame->proc_name = NULL; frame->proc_offset = 0; - ret = unw_get_reg(&cursor, UNW_REG_IP, &frame->pc); + ret = unw_get_reg(&cursor, UNW_REG_IP, &value); if (ret < 0) { ALOGW("remote_get_frames: Failed to read IP %d\n", ret); returnValue = false; break; } - ret = unw_get_reg(&cursor, UNW_REG_SP, &frame->sp); + frame->pc = (uintptr_t)value; + ret = unw_get_reg(&cursor, UNW_REG_SP, &value); if (ret < 0) { ALOGW("remote_get_frames: Failed to read SP %d\n", ret); returnValue = false; break; } + frame->sp = (uintptr_t)value; + if (backtrace->num_frames) { backtrace_frame_data_t* prev = &backtrace->frames[backtrace->num_frames-1]; prev->stack_size = frame->sp - prev->sp; @@ -139,8 +143,11 @@ char* remote_get_proc_name(const backtrace_t* backtrace, uintptr_t pc, backtrace_private_t* data = (backtrace_private_t*)backtrace->private_data; char buf[512]; - if (unw_get_proc_name_by_ip(data->addr_space, pc, buf, sizeof(buf), offset, + *offset = 0; + unw_word_t value; + if (unw_get_proc_name_by_ip(data->addr_space, pc, buf, sizeof(buf), &value, data->upt_info) >= 0 && buf[0] != '\0') { + *offset = (uintptr_t)value; char* symbol = demangle_symbol_name(buf); if (!symbol) { symbol = strdup(buf); -- cgit v1.1