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/***
This file is part of PulseAudio.
Copyright 2009 Lennart Poettering
PulseAudio is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
PulseAudio is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
***/
#ifdef HAVE_CONFIG_H
#include <config.h>
#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/core-util.h>
#include <pulsecore/aupdate.h>
#include <pulsecore/atomic.h>
#include <pulsecore/once.h>
#include <pulsecore/mutex.h>
#include "memtrap.h"
struct pa_memtrap {
void *start;
size_t size;
pa_atomic_t bad;
pa_memtrap *next[2], *prev[2];
};
static pa_memtrap *memtraps[2] = { NULL, NULL };
static pa_aupdate *aupdate;
static pa_static_mutex mutex = PA_STATIC_MUTEX_INIT; /* only required to serialize access to the write side */
static void allocate_aupdate(void) {
PA_ONCE_BEGIN {
aupdate = pa_aupdate_new();
} PA_ONCE_END;
}
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) {
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 j;
pa_memtrap *m;
void *r;
j = pa_aupdate_read_begin(aupdate);
for (m = memtraps[j]; m; m = m->next[j])
if (si->si_addr >= m->start &&
(uint8_t*) si->si_addr < (uint8_t*) m->start + m->size)
break;
if (!m)
goto fail;
pa_atomic_store(&m->bad, 1);
/* Remap anonymous memory into the bad segment */
if ((r = mmap(m->start, m->size, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_FIXED|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
sigsafe_error("mmap() failed.\n");
goto fail;
}
pa_assert(r == m->start);
pa_aupdate_read_end(aupdate);
return;
fail:
pa_aupdate_read_end(aupdate);
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;
if ((m->next[j] = memtraps[j]))
m->next[j]->prev[j] = m;
memtraps[j] = m;
}
static void memtrap_unlink(pa_memtrap *m, unsigned j) {
pa_assert(m);
if (m->next[j])
m->next[j]->prev[j] = m->prev[j];
if (m->prev[j])
m->prev[j]->next[j] = m->next[j];
else
memtraps[j] = m->next[j];
}
pa_memtrap* pa_memtrap_add(const void *start, size_t size) {
pa_memtrap *m = NULL;
unsigned j;
pa_mutex *mx;
pa_assert(start);
pa_assert(size > 0);
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);
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(mx);
return m;
}
void pa_memtrap_remove(pa_memtrap *m) {
unsigned j;
pa_mutex *mx;
pa_assert(m);
allocate_aupdate();
mx = pa_static_mutex_get(&mutex, false, true);
pa_mutex_lock(mx);
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_mutex_unlock(mx);
pa_xfree(m);
}
pa_memtrap *pa_memtrap_update(pa_memtrap *m, const void *start, size_t size) {
unsigned j;
pa_mutex *mx;
pa_assert(m);
pa_assert(start);
pa_assert(size > 0);
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;
memtrap_unlink(m, j);
pa_aupdate_write_swap(aupdate);
m->start = (void*) start;
m->size = size;
pa_atomic_store(&m->bad, 0);
pa_assert_se(pa_aupdate_write_swap(aupdate) == j);
memtrap_link(m, j);
unlock:
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);
#ifdef __FreeBSD_kernel__
pa_assert_se(sigaction(SIGSEGV, &sa, NULL) == 0);
#endif
#endif
}
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