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优化主线程获取栈顶/栈底耗时较大的问题 #42

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优化主线程获取栈顶/栈底耗时较大的问题 #42

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142 changes: 50 additions & 92 deletions library/src/main/unwind32/ptrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ b * limitations under the License.
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <inttypes.h>

#include "ptrace-arch.h"
#include "libudf_unwind_p.h"
Expand Down Expand Up @@ -105,111 +106,68 @@ static pid_t ubrd_pid;

static int ubrd_get_main_thread_stack(pid_t pid)
{
char c, line[1024];
int i = 0, j = 0, fd = -1;
void* lib = NULL;
int (*close_fptr)(int) = NULL; //use func ptr to avoid open/close rehook deadlock
int (*open_fptr)(const char *, int, ...) = NULL;

lib = dlopen("libc.so", RTLD_NOW|RTLD_GLOBAL);
if (lib == NULL) {
LIBUDF_LOG("Could not open libc.so: %s\n", dlerror());
return -1;
}

close_fptr = (int (*)(int))dlsym(lib, "close");
open_fptr = (int (*)(const char *, int, ...))dlsym(lib, "open");
if (!close_fptr || !open_fptr) {
LIBUDF_LOG("invalid open/close: %s\n", dlerror());
dlclose(lib);
return -1;
}

char line[1024];
snprintf(line, sizeof(line), "/proc/self/task/%d/maps", pid);

fd = open_fptr(line, O_RDONLY);
FILE* fd = fopen(line, "r");
if (fd < 0) {
LIBUDF_LOG("/proc/%d/task/%d/maps open fail\n", pid, pid);
dlclose(lib);
return -1;
}

while (1) {
if (!read(fd, &c, 1)) break;
if (c == '\n') {
line[i] = '\0';
if (strncmp((const char *)&line[i-7], "[stack]", 7) == 0) {
const char* stack_start;
LIBUDF_LOG("stack:%s\n", line);
#if defined(__LP64__)
//64bit main stack format
//7ff1bf1000-7ff1c12000 rw-p 00000000 00:00 0 [stack]
line[9] = '0';
line[10] = 'x';
line[21] = '\0'; //line[11~20] stack start
stack_start = (const char*)&line[9];
#else
//32bit main stack format
//becd7000-becf8000 rw-p 00000000 00:00 0 [stack]
line[7] = '0';
line[8] = 'x';
line[17] = '\0'; //line[9~16] 32bit main thread stack start
stack_start = (const char*)&line[7];
#endif
_main_thread_stack_start = strtoul(stack_start, (char **)NULL, 16);
_main_thread_stack_size = 8 * 1024 * 1024; //bypass RLIMIT check for simple handling
LIBUDF_LOG("[LCH_DEBUG]main_thread_stack_start:%p, main_thread_stack_size:%p\n",
while (fgets(line, sizeof(line), fd)) {
if (strstr(line, "[stack]") != NULL) {
LIBUDF_LOG("stack:%s\n", line);
const char* stack_start;
#if defined(__LP64__)
//64bit main stack format
//7ff1bf1000-7ff1c12000 rw-p 00000000 00:00 0 [stack]
line[9] = '0';
line[10] = 'x';
line[21] = '\0'; //line[11~20] stack start
stack_start = (const char*)&line[9];
#else
//32bit main stack format
//becd7000-becf8000 rw-p 00000000 00:00 0 [stack]
line[7] = '0';
line[8] = 'x';
line[17] = '\0'; //line[9~16] 32bit main thread stack start
stack_start = (const char*)&line[7];
#endif
_main_thread_stack_start = strtoul(stack_start, (char **)NULL, 16);
_main_thread_stack_size = 8 * 1024 * 1024; //bypass RLIMIT check for simple handling
LIBUDF_LOG("[LCH_DEBUG]main_thread_stack_start:%p, main_thread_stack_size:%p\n",
(void *)_main_thread_stack_start, (void *)_main_thread_stack_size);
close_fptr(fd);
dlclose(lib);
return 0;
}
else {
i = 0;
}
}
else {
line[i++] = c;
fclose(fd);
return 0;
}
}
close_fptr(fd);

// stack is 28th parameter from /proc/self/stat
fd = open_fptr("/proc/self/stat", O_RDONLY);
if (fd < 0) {
LIBUDF_LOG("/proc/self/stat open fail\n");
dlclose(lib);
return -1;
}
fclose(fd);

i = j = 0;
line[0] = '\0';
while (1) {
if (!read(fd, &c, 1)) break;
if (c == ' ') {
j++;
if (j == 28) {
line[i] = '\0';
break;
}
}
else if (j == 27) {
line[i++] = c;
}
}
// stack is 28th parameter from /proc/self/stat
fd = fopen("/proc/self/stat", "re");
if (fd == NULL) {
LIBUDF_LOG("/proc/self/stat open fail\n");
return -1;
}

if (line[0] != '\0') {
_main_thread_stack_start = strtoul(line, (char **)NULL, 10);
_main_thread_stack_size = 8 * 1024 * 1024; // bypass RLIMIT check for simple handling
LIBUDF_LOG("[LCH_DEBUG]main_thread_stack_start:%p, main_thread_stack_size:%p\n",
(void *)_main_thread_stack_start, (void *)_main_thread_stack_size);
close_fptr(fd);
dlclose(lib);
return 0;
}
if (fgets(line, sizeof(line), fd)) {
const char *end_of_comm = strrchr((const char *)line, (int)')');
size_t stack_start = 0;
if (1 == sscanf(end_of_comm + 1,
" %*c %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u %*u %*u %*d %*d %*d %*d %*d %*d %*u %*u "
"%*d %*u %*u %*u %" SCNuPTR,
&stack_start)) {
_main_thread_stack_start = stack_start;
_main_thread_stack_size = 8 * 1024 * 1024; // bypass RLIMIT check for simple handling
LIBUDF_LOG("[LCH_DEBUG]main_thread_stack_start:%p, main_thread_stack_size:%p\n",
(void *)_main_thread_stack_start, (void *)_main_thread_stack_size);
fclose(fd);
return 0;
}
}

close_fptr(fd);
dlclose(lib);
fclose(fd);
return -1;
}

Expand Down