#endif
#include <signal.h>
+
+#ifdef HAVE_SYS_MMAN_H
#include <sys/mman.h>
+#endif
+
+/* This is deprecated on glibc but is still used by FreeBSD */
+#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
+# define MAP_ANONYMOUS MAP_ANON
+#endif
#include <pulse/xmalloc.h>
-#include <pulsecore/semaphore.h>
-#include <pulsecore/macro.h>
-#include <pulsecore/mutex.h>
#include <pulsecore/core-util.h>
+#include <pulsecore/aupdate.h>
+#include <pulsecore/atomic.h>
+#include <pulsecore/once.h>
+#include <pulsecore/mutex.h>
#include "memtrap.h"
};
static pa_memtrap *memtraps[2] = { NULL, NULL };
-static pa_atomic_t read_lock = PA_ATOMIC_INIT(0);
-static pa_static_semaphore semaphore = PA_STATIC_SEMAPHORE_INIT;
-static pa_static_mutex write_lock = PA_STATIC_MUTEX_INIT;
+static pa_aupdate *aupdate;
+static pa_static_mutex mutex = PA_STATIC_MUTEX_INIT; /* only required to serialize access to the write side */
-#define MSB (1U << (sizeof(unsigned)*8U-1))
-#define WHICH(n) (!!((n) & MSB))
-#define COUNTER(n) ((n) & ~MSB)
+static void allocate_aupdate(void) {
+ PA_ONCE_BEGIN {
+ aupdate = pa_aupdate_new();
+ } PA_ONCE_END;
+}
-pa_bool_t pa_memtrap_is_good(pa_memtrap *m) {
+bool pa_memtrap_is_good(pa_memtrap *m) {
pa_assert(m);
return !pa_atomic_load(&m->bad);
}
+#ifdef HAVE_SIGACTION
static void sigsafe_error(const char *s) {
- write(STDERR_FILENO, s, strlen(s));
+ size_t ret PA_GCC_UNUSED;
+ ret = write(STDERR_FILENO, s, strlen(s));
}
static void signal_handler(int sig, siginfo_t* si, void *data) {
- unsigned n, j;
+ unsigned j;
pa_memtrap *m;
void *r;
- /* Increase the lock counter */
- n = (unsigned) pa_atomic_inc(&read_lock);
-
- /* The uppermost bit tells us which list to look at */
- j = WHICH(n);
-
- /* When n is 0 we have about 2^31 threads running that
- * all got a sigbus at the same time, oh my! */
- pa_assert(COUNTER(n)+1 > 0);
+ j = pa_aupdate_read_begin(aupdate);
for (m = memtraps[j]; m; m = m->next[j])
if (si->si_addr >= m->start &&
pa_assert(r == m->start);
- pa_atomic_dec(&read_lock);
-
- /* Post the semaphore */
- pa_semaphore_post(pa_static_semaphore_get(&semaphore, 0));
-
+ pa_aupdate_read_end(aupdate);
return;
fail:
- pa_atomic_dec(&read_lock);
- abort();
-}
+ pa_aupdate_read_end(aupdate);
-static void memtrap_swap(unsigned n) {
-
- for (;;) {
-
- /* If the read counter is > 0 wait; if it is 0 try to swap the lists */
- if (COUNTER(n) > 0)
- pa_semaphore_wait(pa_static_semaphore_get(&semaphore, 0));
- else if (pa_atomic_cmpxchg(&read_lock, (int) n, (int) (n ^ MSB)))
- break;
-
- n = (unsigned) pa_atomic_load(&read_lock);
- }
+ sigsafe_error("Failed to handle SIGBUS.\n");
+ abort();
}
+#endif
static void memtrap_link(pa_memtrap *m, unsigned j) {
pa_assert(m);
m->prev[j] = NULL;
- m->next[j] = memtraps[j];
+
+ if ((m->next[j] = memtraps[j]))
+ m->next[j]->prev[j] = m;
+
memtraps[j] = m;
}
-static void memtrap_unlink(pa_memtrap *m, int j) {
+static void memtrap_unlink(pa_memtrap *m, unsigned j) {
pa_assert(m);
if (m->next[j])
pa_memtrap* pa_memtrap_add(const void *start, size_t size) {
pa_memtrap *m = NULL;
- pa_mutex *lock;
- unsigned n, j;
+ unsigned j;
+ pa_mutex *mx;
pa_assert(start);
pa_assert(size > 0);
- pa_assert(PA_PAGE_ALIGN_PTR(start) == start);
- pa_assert(PA_PAGE_ALIGN(size) == size);
-
- lock = pa_static_mutex_get(&write_lock, FALSE, FALSE);
- pa_mutex_lock(lock);
-
- if (!memtraps[0]) {
- struct sigaction sa;
-
- /* Before we install the signal handler, make sure the
- * semaphore is valid so that the initialization of the
- * semaphore doesn't have to happen from the signal handler */
- pa_static_semaphore_get(&semaphore, 0);
- memset(&sa, 0, sizeof(sa));
- sa.sa_sigaction = signal_handler;
- sa.sa_flags = SA_RESTART|SA_SIGINFO;
-
- pa_assert_se(sigaction(SIGBUS, &sa, NULL) == 0);
- }
-
- n = (unsigned) pa_atomic_load(&read_lock);
- j = WHICH(n);
+ start = PA_PAGE_ALIGN_PTR(start);
+ size = PA_PAGE_ALIGN(size);
m = pa_xnew(pa_memtrap, 1);
m->start = (void*) start;
m->size = size;
pa_atomic_store(&m->bad, 0);
- memtrap_link(m, !j);
- memtrap_swap(n);
+ allocate_aupdate();
+
+ mx = pa_static_mutex_get(&mutex, false, true);
+ pa_mutex_lock(mx);
+
+ j = pa_aupdate_write_begin(aupdate);
+ memtrap_link(m, j);
+ j = pa_aupdate_write_swap(aupdate);
memtrap_link(m, j);
+ pa_aupdate_write_end(aupdate);
- pa_mutex_unlock(lock);
+ pa_mutex_unlock(mx);
return m;
}
void pa_memtrap_remove(pa_memtrap *m) {
- unsigned n, j;
- pa_mutex *lock;
+ unsigned j;
+ pa_mutex *mx;
pa_assert(m);
- lock = pa_static_mutex_get(&write_lock, FALSE, FALSE);
- pa_mutex_lock(lock);
+ allocate_aupdate();
- n = (unsigned) pa_atomic_load(&read_lock);
- j = WHICH(n);
+ mx = pa_static_mutex_get(&mutex, false, true);
+ pa_mutex_lock(mx);
- memtrap_unlink(m, !j);
- memtrap_swap(n);
+ j = pa_aupdate_write_begin(aupdate);
memtrap_unlink(m, j);
+ j = pa_aupdate_write_swap(aupdate);
+ memtrap_unlink(m, j);
+ pa_aupdate_write_end(aupdate);
- pa_xfree(m);
-
- if (!memtraps[0]) {
- struct sigaction sa;
-
- memset(&sa, 0, sizeof(sa));
- sa.sa_handler = SIG_DFL;
- pa_assert_se(sigaction(SIGBUS, &sa, NULL) == 0);
- }
+ pa_mutex_unlock(mx);
- pa_mutex_unlock(lock);
+ pa_xfree(m);
}
pa_memtrap *pa_memtrap_update(pa_memtrap *m, const void *start, size_t size) {
- unsigned n, j;
- pa_mutex *lock;
+ unsigned j;
+ pa_mutex *mx;
pa_assert(m);
pa_assert(start);
pa_assert(size > 0);
- pa_assert(PA_PAGE_ALIGN_PTR(start) == start);
- pa_assert(PA_PAGE_ALIGN(size) == size);
- lock = pa_static_mutex_get(&write_lock, FALSE, FALSE);
- pa_mutex_lock(lock);
+ start = PA_PAGE_ALIGN_PTR(start);
+ size = PA_PAGE_ALIGN(size);
+
+ allocate_aupdate();
+
+ mx = pa_static_mutex_get(&mutex, false, true);
+ pa_mutex_lock(mx);
+
+ j = pa_aupdate_write_begin(aupdate);
if (m->start == start && m->size == size)
goto unlock;
- n = (unsigned) pa_atomic_load(&read_lock);
- j = WHICH(n);
-
- memtrap_unlink(m, !j);
- memtrap_swap(n);
memtrap_unlink(m, j);
+ pa_aupdate_write_swap(aupdate);
m->start = (void*) start;
m->size = size;
pa_atomic_store(&m->bad, 0);
- n = (unsigned) pa_atomic_load(&read_lock);
- j = WHICH(n);
-
- memtrap_link(m, !j);
- memtrap_swap(n);
+ pa_assert_se(pa_aupdate_write_swap(aupdate) == j);
memtrap_link(m, j);
unlock:
- pa_mutex_unlock(lock);
+ pa_aupdate_write_end(aupdate);
+
+ pa_mutex_unlock(mx);
return m;
}
+
+void pa_memtrap_install(void) {
+#ifdef HAVE_SIGACTION
+ struct sigaction sa;
+
+ allocate_aupdate();
+
+ memset(&sa, 0, sizeof(sa));
+ sa.sa_sigaction = signal_handler;
+ sa.sa_flags = SA_RESTART|SA_SIGINFO;
+
+ pa_assert_se(sigaction(SIGBUS, &sa, NULL) == 0);
+#endif
+}