Messages in this thread | | | Date | Wed, 16 Nov 2011 11:05:49 +0530 | Subject | Crash when memset of shared mapped memory in ARM | From | naveen yadav <> |
| |
Hi All,
I am running below Test program on ARM cortex a9/a8 on kernel version 2.6.35.14 as well as on 3.0.
Please find the test case where:
1. Create shared memory object using shm_open(If we use normal open then no problem only problem with shm_open)
2. ftruncate to given size
3. memory map the shared object to given memory address ( I haved tested without MAP_SHARED, MAP_FIXED as well, problem exist)
4. Memset the shared memory (got page fault when accessing the second page)
Observation: Only observed in ARM ( i.e not present in MIPS and X86)
#undef NDEBUG #define _GNU_SOURCE #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <sys/ipc.h> #include <sys/shm.h> #include <errno.h> #include <pthread.h> #include <string.h> #include <signal.h> #include <fcntl.h> #include <sys/types.h> #include <sys/mman.h>
enum { SHM_INIT, SHM_GET };
enum { PARENT, CHILD };
#define FIXED_MMAP_ADDR 0x20000000 #define MMAP_SIZE 0x10000
static int shmid; static char shm_name[100]; static int sleep_period = 100000; void * shmem_init(int flag) { int start = FIXED_MMAP_ADDR; int memory_size = MMAP_SIZE; int mode = 0666; void *addr; int ret; sprintf(shm_name, "/shmem_1234"); shmid = shm_open (shm_name, O_RDWR | O_EXCL | O_CREAT | O_TRUNC, mode); if (shmid < 0) { if (errno == EEXIST) { printf ("shm_open: %s\n", strerror(errno)); shmid = shm_open (shm_name, O_RDWR, mode);
} else { printf("failed to shm_open, err=%s\n", strerror(errno)); return NULL; } } ret = fcntl (shmid, F_SETFD, FD_CLOEXEC); if (ret < 0) { printf("fcntl: %s\n", strerror(errno)); return NULL; } ret = ftruncate (shmid, memory_size); if (ret < 0) { printf("ftruncate: %s\n", strerror(errno)); return NULL; } addr = mmap ((void *)start, memory_size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, shmid, 0); if (addr == MAP_FAILED) { printf ("mmap: %s\n", strerror(errno)); close (shmid); shm_unlink (shm_name); return NULL; } if (flag == SHM_INIT){ printf ("mmap: addr %p\n", addr); /* memset on arm creates a unhandled page fault, works fine on mips */ memset(addr, 0, memory_size); } return (void *)addr; }
pthread_mutex_t * shmem_mutex_init(int flag) { pthread_mutex_t * pmutex = (pthread_mutex_t *)shmem_init(flag); #if 0 pthread_mutexattr_t attr; if (flag == SHM_INIT) { pthread_mutexattr_init (&attr); pthread_mutexattr_setpshared (&attr, PTHREAD_PROCESS_SHARED); pthread_mutexattr_setprotocol (&attr, PTHREAD_PRIO_INHERIT); pthread_mutexattr_setrobust_np (&attr, PTHREAD_MUTEX_STALLED_NP); pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_ERRORCHECK); if (pthread_mutex_init (pmutex, &attr) != 0) { printf("Init mutex failed, err=%s\n", strerror(errno)); pthread_mutexattr_destroy (&attr); return NULL; } } #endif return pmutex; }
void long_running_task(int flag) { static int counter = 0; if (flag == PARENT) usleep(5*sleep_period); else usleep(3*sleep_period); counter = (counter + 1) % 100; printf("%d: completed %d computing\n", getpid(), counter); }
void sig_handler(int signum) { close(shmid); shm_unlink(shm_name); exit(0); }
int main(int argc, char *argv[]) { pthread_mutex_t *mutex_parent, *mutex_child; // signal(SIGUSR1, sig_handler); // if (fork()) { /* parent process */ if ((mutex_parent = shmem_mutex_init(SHM_INIT)) == NULL) { printf("failed to get the shmem_mutex\n"); exit(-1); } #if 0 while (1) { printf("%d: try to hold the lock\n", getpid()); pthread_mutex_lock(mutex_parent); printf("%d: got the lock\n", getpid()); long_running_task(PARENT); pthread_mutex_unlock(mutex_parent); printf("%d: released the lock\n", getpid()); } #endif // } else { #if 0 /* child process */ usleep(sleep_period); if ((mutex_child = shmem_mutex_init(SHM_GET)) == NULL) { printf("failed to get the shmem_mutex\n"); exit(-1); } while (1) { printf("%d: try to hold the lock\n", getpid()); pthread_mutex_lock(mutex_child); printf("%d: got the lock\n", getpid()); long_running_task(CHILD); pthread_mutex_unlock(mutex_child); printf("%d: released the lock\n", getpid()); } #endif // } return 0; }
| |