There is currently no way to open(O_RDONLY) and mmap(PROT_READ) when creating a memory region from a file. This functionality is needed since the underlying host file may not allow writing. Add a bool readonly argument to memory_region_init_ram_from_file() and the APIs it calls. Extend memory_region_init_ram_from_file() rather than introducing a memory_region_init_rom_from_file() API so that callers can easily make a choice between read/write and read-only at runtime without calling different APIs. No new RAMBlock flag is introduced for read-only because it's unclear whether RAMBlocks need to know that they are read-only. Pass a bool readonly argument instead. Both of these design decisions can be changed in the future. It just seemed like the simplest approach to me. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Igor Mammedov <imammedo@redhat.com> Reviewed-by: Liam Merwick <liam.merwick@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Message-Id: <20210104171320.575838-2-stefanha@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
869 lines
22 KiB
C
869 lines
22 KiB
C
/*
|
|
* os-posix-lib.c
|
|
*
|
|
* Copyright (c) 2003-2008 Fabrice Bellard
|
|
* Copyright (c) 2010 Red Hat, Inc.
|
|
*
|
|
* QEMU library functions on POSIX which are shared between QEMU and
|
|
* the QEMU tools.
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
* of this software and associated documentation files (the "Software"), to deal
|
|
* in the Software without restriction, including without limitation the rights
|
|
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
* copies of the Software, and to permit persons to whom the Software is
|
|
* furnished to do so, subject to the following conditions:
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|
*
|
|
* The above copyright notice and this permission notice shall be included in
|
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* all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
|
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
* THE SOFTWARE.
|
|
*/
|
|
|
|
#include "qemu/osdep.h"
|
|
#include <termios.h>
|
|
|
|
#include <glib/gprintf.h>
|
|
|
|
#include "qemu-common.h"
|
|
#include "sysemu/sysemu.h"
|
|
#include "trace.h"
|
|
#include "qapi/error.h"
|
|
#include "qemu/sockets.h"
|
|
#include "qemu/thread.h"
|
|
#include <libgen.h>
|
|
#include "qemu/cutils.h"
|
|
#include "qemu/compiler.h"
|
|
|
|
#ifdef CONFIG_LINUX
|
|
#include <sys/syscall.h>
|
|
#endif
|
|
|
|
#ifdef __FreeBSD__
|
|
#include <sys/sysctl.h>
|
|
#include <sys/user.h>
|
|
#include <sys/thr.h>
|
|
#include <libutil.h>
|
|
#endif
|
|
|
|
#ifdef __NetBSD__
|
|
#include <sys/sysctl.h>
|
|
#include <lwp.h>
|
|
#endif
|
|
|
|
#ifdef __APPLE__
|
|
#include <mach-o/dyld.h>
|
|
#endif
|
|
|
|
#ifdef __HAIKU__
|
|
#include <kernel/image.h>
|
|
#endif
|
|
|
|
#include "qemu/mmap-alloc.h"
|
|
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
#include "qemu/error-report.h"
|
|
#endif
|
|
|
|
#define MAX_MEM_PREALLOC_THREAD_COUNT 16
|
|
|
|
struct MemsetThread {
|
|
char *addr;
|
|
size_t numpages;
|
|
size_t hpagesize;
|
|
QemuThread pgthread;
|
|
sigjmp_buf env;
|
|
};
|
|
typedef struct MemsetThread MemsetThread;
|
|
|
|
static MemsetThread *memset_thread;
|
|
static int memset_num_threads;
|
|
static bool memset_thread_failed;
|
|
|
|
static QemuMutex page_mutex;
|
|
static QemuCond page_cond;
|
|
static bool threads_created_flag;
|
|
|
|
int qemu_get_thread_id(void)
|
|
{
|
|
#if defined(__linux__)
|
|
return syscall(SYS_gettid);
|
|
#elif defined(__FreeBSD__)
|
|
/* thread id is up to INT_MAX */
|
|
long tid;
|
|
thr_self(&tid);
|
|
return (int)tid;
|
|
#elif defined(__NetBSD__)
|
|
return _lwp_self();
|
|
#elif defined(__OpenBSD__)
|
|
return getthrid();
|
|
#else
|
|
return getpid();
|
|
#endif
|
|
}
|
|
|
|
int qemu_daemon(int nochdir, int noclose)
|
|
{
|
|
return daemon(nochdir, noclose);
|
|
}
|
|
|
|
bool qemu_write_pidfile(const char *path, Error **errp)
|
|
{
|
|
int fd;
|
|
char pidstr[32];
|
|
|
|
while (1) {
|
|
struct stat a, b;
|
|
struct flock lock = {
|
|
.l_type = F_WRLCK,
|
|
.l_whence = SEEK_SET,
|
|
.l_len = 0,
|
|
};
|
|
|
|
fd = qemu_open_old(path, O_CREAT | O_WRONLY, S_IRUSR | S_IWUSR);
|
|
if (fd == -1) {
|
|
error_setg_errno(errp, errno, "Cannot open pid file");
|
|
return false;
|
|
}
|
|
|
|
if (fstat(fd, &b) < 0) {
|
|
error_setg_errno(errp, errno, "Cannot stat file");
|
|
goto fail_close;
|
|
}
|
|
|
|
if (fcntl(fd, F_SETLK, &lock)) {
|
|
error_setg_errno(errp, errno, "Cannot lock pid file");
|
|
goto fail_close;
|
|
}
|
|
|
|
/*
|
|
* Now make sure the path we locked is the same one that now
|
|
* exists on the filesystem.
|
|
*/
|
|
if (stat(path, &a) < 0) {
|
|
/*
|
|
* PID file disappeared, someone else must be racing with
|
|
* us, so try again.
|
|
*/
|
|
close(fd);
|
|
continue;
|
|
}
|
|
|
|
if (a.st_ino == b.st_ino) {
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* PID file was recreated, someone else must be racing with
|
|
* us, so try again.
|
|
*/
|
|
close(fd);
|
|
}
|
|
|
|
if (ftruncate(fd, 0) < 0) {
|
|
error_setg_errno(errp, errno, "Failed to truncate pid file");
|
|
goto fail_unlink;
|
|
}
|
|
|
|
snprintf(pidstr, sizeof(pidstr), FMT_pid "\n", getpid());
|
|
if (write(fd, pidstr, strlen(pidstr)) != strlen(pidstr)) {
|
|
error_setg(errp, "Failed to write pid file");
|
|
goto fail_unlink;
|
|
}
|
|
|
|
return true;
|
|
|
|
fail_unlink:
|
|
unlink(path);
|
|
fail_close:
|
|
close(fd);
|
|
return false;
|
|
}
|
|
|
|
void *qemu_oom_check(void *ptr)
|
|
{
|
|
if (ptr == NULL) {
|
|
fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
|
|
abort();
|
|
}
|
|
return ptr;
|
|
}
|
|
|
|
void *qemu_try_memalign(size_t alignment, size_t size)
|
|
{
|
|
void *ptr;
|
|
|
|
if (alignment < sizeof(void*)) {
|
|
alignment = sizeof(void*);
|
|
} else {
|
|
g_assert(is_power_of_2(alignment));
|
|
}
|
|
|
|
#if defined(CONFIG_POSIX_MEMALIGN)
|
|
int ret;
|
|
ret = posix_memalign(&ptr, alignment, size);
|
|
if (ret != 0) {
|
|
errno = ret;
|
|
ptr = NULL;
|
|
}
|
|
#elif defined(CONFIG_BSD)
|
|
ptr = valloc(size);
|
|
#else
|
|
ptr = memalign(alignment, size);
|
|
#endif
|
|
trace_qemu_memalign(alignment, size, ptr);
|
|
return ptr;
|
|
}
|
|
|
|
void *qemu_memalign(size_t alignment, size_t size)
|
|
{
|
|
return qemu_oom_check(qemu_try_memalign(alignment, size));
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|
}
|
|
|
|
/* alloc shared memory pages */
|
|
void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared)
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|
{
|
|
size_t align = QEMU_VMALLOC_ALIGN;
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|
void *ptr = qemu_ram_mmap(-1, size, align, false, shared, false);
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|
|
|
if (ptr == MAP_FAILED) {
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|
return NULL;
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|
}
|
|
|
|
if (alignment) {
|
|
*alignment = align;
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|
}
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|
|
|
trace_qemu_anon_ram_alloc(size, ptr);
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|
return ptr;
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|
}
|
|
|
|
void qemu_vfree(void *ptr)
|
|
{
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|
trace_qemu_vfree(ptr);
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|
free(ptr);
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|
}
|
|
|
|
void qemu_anon_ram_free(void *ptr, size_t size)
|
|
{
|
|
trace_qemu_anon_ram_free(ptr, size);
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qemu_ram_munmap(-1, ptr, size);
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|
}
|
|
|
|
void qemu_set_block(int fd)
|
|
{
|
|
int f;
|
|
f = fcntl(fd, F_GETFL);
|
|
assert(f != -1);
|
|
f = fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
|
|
assert(f != -1);
|
|
}
|
|
|
|
int qemu_try_set_nonblock(int fd)
|
|
{
|
|
int f;
|
|
f = fcntl(fd, F_GETFL);
|
|
if (f == -1) {
|
|
return -errno;
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|
}
|
|
if (fcntl(fd, F_SETFL, f | O_NONBLOCK) == -1) {
|
|
#ifdef __OpenBSD__
|
|
/*
|
|
* Previous to OpenBSD 6.3, fcntl(F_SETFL) is not permitted on
|
|
* memory devices and sets errno to ENODEV.
|
|
* It's OK if we fail to set O_NONBLOCK on devices like /dev/null,
|
|
* because they will never block anyway.
|
|
*/
|
|
if (errno == ENODEV) {
|
|
return 0;
|
|
}
|
|
#endif
|
|
return -errno;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void qemu_set_nonblock(int fd)
|
|
{
|
|
int f;
|
|
f = qemu_try_set_nonblock(fd);
|
|
assert(f == 0);
|
|
}
|
|
|
|
int socket_set_fast_reuse(int fd)
|
|
{
|
|
int val = 1, ret;
|
|
|
|
ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
|
|
(const char *)&val, sizeof(val));
|
|
|
|
assert(ret == 0);
|
|
|
|
return ret;
|
|
}
|
|
|
|
void qemu_set_cloexec(int fd)
|
|
{
|
|
int f;
|
|
f = fcntl(fd, F_GETFD);
|
|
assert(f != -1);
|
|
f = fcntl(fd, F_SETFD, f | FD_CLOEXEC);
|
|
assert(f != -1);
|
|
}
|
|
|
|
/*
|
|
* Creates a pipe with FD_CLOEXEC set on both file descriptors
|
|
*/
|
|
int qemu_pipe(int pipefd[2])
|
|
{
|
|
int ret;
|
|
|
|
#ifdef CONFIG_PIPE2
|
|
ret = pipe2(pipefd, O_CLOEXEC);
|
|
if (ret != -1 || errno != ENOSYS) {
|
|
return ret;
|
|
}
|
|
#endif
|
|
ret = pipe(pipefd);
|
|
if (ret == 0) {
|
|
qemu_set_cloexec(pipefd[0]);
|
|
qemu_set_cloexec(pipefd[1]);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
char *
|
|
qemu_get_local_state_pathname(const char *relative_pathname)
|
|
{
|
|
g_autofree char *dir = g_strdup_printf("%s/%s",
|
|
CONFIG_QEMU_LOCALSTATEDIR,
|
|
relative_pathname);
|
|
return get_relocated_path(dir);
|
|
}
|
|
|
|
void qemu_set_tty_echo(int fd, bool echo)
|
|
{
|
|
struct termios tty;
|
|
|
|
tcgetattr(fd, &tty);
|
|
|
|
if (echo) {
|
|
tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
|
|
} else {
|
|
tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
|
|
}
|
|
|
|
tcsetattr(fd, TCSANOW, &tty);
|
|
}
|
|
|
|
static const char *exec_dir;
|
|
|
|
void qemu_init_exec_dir(const char *argv0)
|
|
{
|
|
char *p = NULL;
|
|
char buf[PATH_MAX];
|
|
|
|
if (exec_dir) {
|
|
return;
|
|
}
|
|
|
|
#if defined(__linux__)
|
|
{
|
|
int len;
|
|
len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
|
|
if (len > 0) {
|
|
buf[len] = 0;
|
|
p = buf;
|
|
}
|
|
}
|
|
#elif defined(__FreeBSD__) \
|
|
|| (defined(__NetBSD__) && defined(KERN_PROC_PATHNAME))
|
|
{
|
|
#if defined(__FreeBSD__)
|
|
static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
|
|
#else
|
|
static int mib[4] = {CTL_KERN, KERN_PROC_ARGS, -1, KERN_PROC_PATHNAME};
|
|
#endif
|
|
size_t len = sizeof(buf) - 1;
|
|
|
|
*buf = '\0';
|
|
if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
|
|
*buf) {
|
|
buf[sizeof(buf) - 1] = '\0';
|
|
p = buf;
|
|
}
|
|
}
|
|
#elif defined(__APPLE__)
|
|
{
|
|
char fpath[PATH_MAX];
|
|
uint32_t len = sizeof(fpath);
|
|
if (_NSGetExecutablePath(fpath, &len) == 0) {
|
|
p = realpath(fpath, buf);
|
|
if (!p) {
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
#elif defined(__HAIKU__)
|
|
{
|
|
image_info ii;
|
|
int32_t c = 0;
|
|
|
|
*buf = '\0';
|
|
while (get_next_image_info(0, &c, &ii) == B_OK) {
|
|
if (ii.type == B_APP_IMAGE) {
|
|
strncpy(buf, ii.name, sizeof(buf));
|
|
buf[sizeof(buf) - 1] = 0;
|
|
p = buf;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
/* If we don't have any way of figuring out the actual executable
|
|
location then try argv[0]. */
|
|
if (!p && argv0) {
|
|
p = realpath(argv0, buf);
|
|
}
|
|
if (p) {
|
|
exec_dir = g_path_get_dirname(p);
|
|
} else {
|
|
exec_dir = CONFIG_BINDIR;
|
|
}
|
|
}
|
|
|
|
const char *qemu_get_exec_dir(void)
|
|
{
|
|
return exec_dir;
|
|
}
|
|
|
|
static void sigbus_handler(int signal)
|
|
{
|
|
int i;
|
|
if (memset_thread) {
|
|
for (i = 0; i < memset_num_threads; i++) {
|
|
if (qemu_thread_is_self(&memset_thread[i].pgthread)) {
|
|
siglongjmp(memset_thread[i].env, 1);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
static void *do_touch_pages(void *arg)
|
|
{
|
|
MemsetThread *memset_args = (MemsetThread *)arg;
|
|
sigset_t set, oldset;
|
|
|
|
/*
|
|
* On Linux, the page faults from the loop below can cause mmap_sem
|
|
* contention with allocation of the thread stacks. Do not start
|
|
* clearing until all threads have been created.
|
|
*/
|
|
qemu_mutex_lock(&page_mutex);
|
|
while(!threads_created_flag){
|
|
qemu_cond_wait(&page_cond, &page_mutex);
|
|
}
|
|
qemu_mutex_unlock(&page_mutex);
|
|
|
|
/* unblock SIGBUS */
|
|
sigemptyset(&set);
|
|
sigaddset(&set, SIGBUS);
|
|
pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
|
|
|
|
if (sigsetjmp(memset_args->env, 1)) {
|
|
memset_thread_failed = true;
|
|
} else {
|
|
char *addr = memset_args->addr;
|
|
size_t numpages = memset_args->numpages;
|
|
size_t hpagesize = memset_args->hpagesize;
|
|
size_t i;
|
|
for (i = 0; i < numpages; i++) {
|
|
/*
|
|
* Read & write back the same value, so we don't
|
|
* corrupt existing user/app data that might be
|
|
* stored.
|
|
*
|
|
* 'volatile' to stop compiler optimizing this away
|
|
* to a no-op
|
|
*
|
|
* TODO: get a better solution from kernel so we
|
|
* don't need to write at all so we don't cause
|
|
* wear on the storage backing the region...
|
|
*/
|
|
*(volatile char *)addr = *addr;
|
|
addr += hpagesize;
|
|
}
|
|
}
|
|
pthread_sigmask(SIG_SETMASK, &oldset, NULL);
|
|
return NULL;
|
|
}
|
|
|
|
static inline int get_memset_num_threads(int smp_cpus)
|
|
{
|
|
long host_procs = sysconf(_SC_NPROCESSORS_ONLN);
|
|
int ret = 1;
|
|
|
|
if (host_procs > 0) {
|
|
ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus);
|
|
}
|
|
/* In case sysconf() fails, we fall back to single threaded */
|
|
return ret;
|
|
}
|
|
|
|
static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
|
|
int smp_cpus)
|
|
{
|
|
static gsize initialized = 0;
|
|
size_t numpages_per_thread, leftover;
|
|
char *addr = area;
|
|
int i = 0;
|
|
|
|
if (g_once_init_enter(&initialized)) {
|
|
qemu_mutex_init(&page_mutex);
|
|
qemu_cond_init(&page_cond);
|
|
g_once_init_leave(&initialized, 1);
|
|
}
|
|
|
|
memset_thread_failed = false;
|
|
threads_created_flag = false;
|
|
memset_num_threads = get_memset_num_threads(smp_cpus);
|
|
memset_thread = g_new0(MemsetThread, memset_num_threads);
|
|
numpages_per_thread = numpages / memset_num_threads;
|
|
leftover = numpages % memset_num_threads;
|
|
for (i = 0; i < memset_num_threads; i++) {
|
|
memset_thread[i].addr = addr;
|
|
memset_thread[i].numpages = numpages_per_thread + (i < leftover);
|
|
memset_thread[i].hpagesize = hpagesize;
|
|
qemu_thread_create(&memset_thread[i].pgthread, "touch_pages",
|
|
do_touch_pages, &memset_thread[i],
|
|
QEMU_THREAD_JOINABLE);
|
|
addr += memset_thread[i].numpages * hpagesize;
|
|
}
|
|
|
|
qemu_mutex_lock(&page_mutex);
|
|
threads_created_flag = true;
|
|
qemu_cond_broadcast(&page_cond);
|
|
qemu_mutex_unlock(&page_mutex);
|
|
|
|
for (i = 0; i < memset_num_threads; i++) {
|
|
qemu_thread_join(&memset_thread[i].pgthread);
|
|
}
|
|
g_free(memset_thread);
|
|
memset_thread = NULL;
|
|
|
|
return memset_thread_failed;
|
|
}
|
|
|
|
void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
|
|
Error **errp)
|
|
{
|
|
int ret;
|
|
struct sigaction act, oldact;
|
|
size_t hpagesize = qemu_fd_getpagesize(fd);
|
|
size_t numpages = DIV_ROUND_UP(memory, hpagesize);
|
|
|
|
memset(&act, 0, sizeof(act));
|
|
act.sa_handler = &sigbus_handler;
|
|
act.sa_flags = 0;
|
|
|
|
ret = sigaction(SIGBUS, &act, &oldact);
|
|
if (ret) {
|
|
error_setg_errno(errp, errno,
|
|
"os_mem_prealloc: failed to install signal handler");
|
|
return;
|
|
}
|
|
|
|
/* touch pages simultaneously */
|
|
if (touch_all_pages(area, hpagesize, numpages, smp_cpus)) {
|
|
error_setg(errp, "os_mem_prealloc: Insufficient free host memory "
|
|
"pages available to allocate guest RAM");
|
|
}
|
|
|
|
ret = sigaction(SIGBUS, &oldact, NULL);
|
|
if (ret) {
|
|
/* Terminate QEMU since it can't recover from error */
|
|
perror("os_mem_prealloc: failed to reinstall signal handler");
|
|
exit(1);
|
|
}
|
|
}
|
|
|
|
char *qemu_get_pid_name(pid_t pid)
|
|
{
|
|
char *name = NULL;
|
|
|
|
#if defined(__FreeBSD__)
|
|
/* BSDs don't have /proc, but they provide a nice substitute */
|
|
struct kinfo_proc *proc = kinfo_getproc(pid);
|
|
|
|
if (proc) {
|
|
name = g_strdup(proc->ki_comm);
|
|
free(proc);
|
|
}
|
|
#else
|
|
/* Assume a system with reasonable procfs */
|
|
char *pid_path;
|
|
size_t len;
|
|
|
|
pid_path = g_strdup_printf("/proc/%d/cmdline", pid);
|
|
g_file_get_contents(pid_path, &name, &len, NULL);
|
|
g_free(pid_path);
|
|
#endif
|
|
|
|
return name;
|
|
}
|
|
|
|
|
|
pid_t qemu_fork(Error **errp)
|
|
{
|
|
sigset_t oldmask, newmask;
|
|
struct sigaction sig_action;
|
|
int saved_errno;
|
|
pid_t pid;
|
|
|
|
/*
|
|
* Need to block signals now, so that child process can safely
|
|
* kill off caller's signal handlers without a race.
|
|
*/
|
|
sigfillset(&newmask);
|
|
if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) != 0) {
|
|
error_setg_errno(errp, errno,
|
|
"cannot block signals");
|
|
return -1;
|
|
}
|
|
|
|
pid = fork();
|
|
saved_errno = errno;
|
|
|
|
if (pid < 0) {
|
|
/* attempt to restore signal mask, but ignore failure, to
|
|
* avoid obscuring the fork failure */
|
|
(void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
|
|
error_setg_errno(errp, saved_errno,
|
|
"cannot fork child process");
|
|
errno = saved_errno;
|
|
return -1;
|
|
} else if (pid) {
|
|
/* parent process */
|
|
|
|
/* Restore our original signal mask now that the child is
|
|
* safely running. Only documented failures are EFAULT (not
|
|
* possible, since we are using just-grabbed mask) or EINVAL
|
|
* (not possible, since we are using correct arguments). */
|
|
(void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
|
|
} else {
|
|
/* child process */
|
|
size_t i;
|
|
|
|
/* Clear out all signal handlers from parent so nothing
|
|
* unexpected can happen in our child once we unblock
|
|
* signals */
|
|
sig_action.sa_handler = SIG_DFL;
|
|
sig_action.sa_flags = 0;
|
|
sigemptyset(&sig_action.sa_mask);
|
|
|
|
for (i = 1; i < NSIG; i++) {
|
|
/* Only possible errors are EFAULT or EINVAL The former
|
|
* won't happen, the latter we expect, so no need to check
|
|
* return value */
|
|
(void)sigaction(i, &sig_action, NULL);
|
|
}
|
|
|
|
/* Unmask all signals in child, since we've no idea what the
|
|
* caller's done with their signal mask and don't want to
|
|
* propagate that to children */
|
|
sigemptyset(&newmask);
|
|
if (pthread_sigmask(SIG_SETMASK, &newmask, NULL) != 0) {
|
|
Error *local_err = NULL;
|
|
error_setg_errno(&local_err, errno,
|
|
"cannot unblock signals");
|
|
error_report_err(local_err);
|
|
_exit(1);
|
|
}
|
|
}
|
|
return pid;
|
|
}
|
|
|
|
void *qemu_alloc_stack(size_t *sz)
|
|
{
|
|
void *ptr, *guardpage;
|
|
int flags;
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
void *ptr2;
|
|
#endif
|
|
size_t pagesz = qemu_real_host_page_size;
|
|
#ifdef _SC_THREAD_STACK_MIN
|
|
/* avoid stacks smaller than _SC_THREAD_STACK_MIN */
|
|
long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN);
|
|
*sz = MAX(MAX(min_stack_sz, 0), *sz);
|
|
#endif
|
|
/* adjust stack size to a multiple of the page size */
|
|
*sz = ROUND_UP(*sz, pagesz);
|
|
/* allocate one extra page for the guard page */
|
|
*sz += pagesz;
|
|
|
|
flags = MAP_PRIVATE | MAP_ANONYMOUS;
|
|
#if defined(MAP_STACK) && defined(__OpenBSD__)
|
|
/* Only enable MAP_STACK on OpenBSD. Other OS's such as
|
|
* Linux/FreeBSD/NetBSD have a flag with the same name
|
|
* but have differing functionality. OpenBSD will SEGV
|
|
* if it spots execution with a stack pointer pointing
|
|
* at memory that was not allocated with MAP_STACK.
|
|
*/
|
|
flags |= MAP_STACK;
|
|
#endif
|
|
|
|
ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE, flags, -1, 0);
|
|
if (ptr == MAP_FAILED) {
|
|
perror("failed to allocate memory for stack");
|
|
abort();
|
|
}
|
|
|
|
#if defined(HOST_IA64)
|
|
/* separate register stack */
|
|
guardpage = ptr + (((*sz - pagesz) / 2) & ~pagesz);
|
|
#elif defined(HOST_HPPA)
|
|
/* stack grows up */
|
|
guardpage = ptr + *sz - pagesz;
|
|
#else
|
|
/* stack grows down */
|
|
guardpage = ptr;
|
|
#endif
|
|
if (mprotect(guardpage, pagesz, PROT_NONE) != 0) {
|
|
perror("failed to set up stack guard page");
|
|
abort();
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
for (ptr2 = ptr + pagesz; ptr2 < ptr + *sz; ptr2 += sizeof(uint32_t)) {
|
|
*(uint32_t *)ptr2 = 0xdeadbeaf;
|
|
}
|
|
#endif
|
|
|
|
return ptr;
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
static __thread unsigned int max_stack_usage;
|
|
#endif
|
|
|
|
void qemu_free_stack(void *stack, size_t sz)
|
|
{
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
unsigned int usage;
|
|
void *ptr;
|
|
|
|
for (ptr = stack + qemu_real_host_page_size; ptr < stack + sz;
|
|
ptr += sizeof(uint32_t)) {
|
|
if (*(uint32_t *)ptr != 0xdeadbeaf) {
|
|
break;
|
|
}
|
|
}
|
|
usage = sz - (uintptr_t) (ptr - stack);
|
|
if (usage > max_stack_usage) {
|
|
error_report("thread %d max stack usage increased from %u to %u",
|
|
qemu_get_thread_id(), max_stack_usage, usage);
|
|
max_stack_usage = usage;
|
|
}
|
|
#endif
|
|
|
|
munmap(stack, sz);
|
|
}
|
|
|
|
/*
|
|
* Disable CFI checks.
|
|
* We are going to call a signal hander directly. Such handler may or may not
|
|
* have been defined in our binary, so there's no guarantee that the pointer
|
|
* used to set the handler is a cfi-valid pointer. Since the handlers are
|
|
* stored in kernel memory, changing the handler to an attacker-defined
|
|
* function requires being able to call a sigaction() syscall,
|
|
* which is not as easy as overwriting a pointer in memory.
|
|
*/
|
|
QEMU_DISABLE_CFI
|
|
void sigaction_invoke(struct sigaction *action,
|
|
struct qemu_signalfd_siginfo *info)
|
|
{
|
|
siginfo_t si = {};
|
|
si.si_signo = info->ssi_signo;
|
|
si.si_errno = info->ssi_errno;
|
|
si.si_code = info->ssi_code;
|
|
|
|
/* Convert the minimal set of fields defined by POSIX.
|
|
* Positive si_code values are reserved for kernel-generated
|
|
* signals, where the valid siginfo fields are determined by
|
|
* the signal number. But according to POSIX, it is unspecified
|
|
* whether SI_USER and SI_QUEUE have values less than or equal to
|
|
* zero.
|
|
*/
|
|
if (info->ssi_code == SI_USER || info->ssi_code == SI_QUEUE ||
|
|
info->ssi_code <= 0) {
|
|
/* SIGTERM, etc. */
|
|
si.si_pid = info->ssi_pid;
|
|
si.si_uid = info->ssi_uid;
|
|
} else if (info->ssi_signo == SIGILL || info->ssi_signo == SIGFPE ||
|
|
info->ssi_signo == SIGSEGV || info->ssi_signo == SIGBUS) {
|
|
si.si_addr = (void *)(uintptr_t)info->ssi_addr;
|
|
} else if (info->ssi_signo == SIGCHLD) {
|
|
si.si_pid = info->ssi_pid;
|
|
si.si_status = info->ssi_status;
|
|
si.si_uid = info->ssi_uid;
|
|
}
|
|
action->sa_sigaction(info->ssi_signo, &si, NULL);
|
|
}
|
|
|
|
#ifndef HOST_NAME_MAX
|
|
# ifdef _POSIX_HOST_NAME_MAX
|
|
# define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
|
|
# else
|
|
# define HOST_NAME_MAX 255
|
|
# endif
|
|
#endif
|
|
|
|
char *qemu_get_host_name(Error **errp)
|
|
{
|
|
long len = -1;
|
|
g_autofree char *hostname = NULL;
|
|
|
|
#ifdef _SC_HOST_NAME_MAX
|
|
len = sysconf(_SC_HOST_NAME_MAX);
|
|
#endif /* _SC_HOST_NAME_MAX */
|
|
|
|
if (len < 0) {
|
|
len = HOST_NAME_MAX;
|
|
}
|
|
|
|
/* Unfortunately, gethostname() below does not guarantee a
|
|
* NULL terminated string. Therefore, allocate one byte more
|
|
* to be sure. */
|
|
hostname = g_new0(char, len + 1);
|
|
|
|
if (gethostname(hostname, len) < 0) {
|
|
error_setg_errno(errp, errno,
|
|
"cannot get hostname");
|
|
return NULL;
|
|
}
|
|
|
|
return g_steal_pointer(&hostname);
|
|
}
|
|
|
|
size_t qemu_get_host_physmem(void)
|
|
{
|
|
#ifdef _SC_PHYS_PAGES
|
|
long pages = sysconf(_SC_PHYS_PAGES);
|
|
if (pages > 0) {
|
|
if (pages > SIZE_MAX / qemu_real_host_page_size) {
|
|
return SIZE_MAX;
|
|
} else {
|
|
return pages * qemu_real_host_page_size;
|
|
}
|
|
}
|
|
#endif
|
|
return 0;
|
|
}
|