When using a memory-backend object with prealloc turned on, QEMU will memset() the first byte in every memory page to zero. While this might have been acceptable for memory backends associated with RAM, this corrupts application data for NVDIMMs. Instead of setting every page to zero, read the current byte value and then just write that same value back, so we are not corrupting the original data. Directly write the value instead of memset()ing it, since there's no benefit to memset for a single byte write. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Message-id: 20170303113255.28262-1-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
717 lines
18 KiB
C
717 lines
18 KiB
C
/*
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* os-posix-lib.c
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*
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* Copyright (c) 2003-2008 Fabrice Bellard
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* Copyright (c) 2010 Red Hat, Inc.
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*
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* QEMU library functions on POSIX which are shared between QEMU and
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* the QEMU tools.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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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.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu/osdep.h"
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#include <termios.h>
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#include <glib/gprintf.h>
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#include "sysemu/sysemu.h"
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#include "trace.h"
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#include "qapi/error.h"
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#include "qemu/sockets.h"
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#include <libgen.h>
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#include <sys/signal.h>
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#include "qemu/cutils.h"
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#ifdef CONFIG_LINUX
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#include <sys/syscall.h>
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#endif
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#ifdef __FreeBSD__
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#include <sys/sysctl.h>
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#include <sys/user.h>
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#include <libutil.h>
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#endif
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#include "qemu/mmap-alloc.h"
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#ifdef CONFIG_DEBUG_STACK_USAGE
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#include "qemu/error-report.h"
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#endif
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#define MAX_MEM_PREALLOC_THREAD_COUNT (MIN(sysconf(_SC_NPROCESSORS_ONLN), 16))
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struct MemsetThread {
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char *addr;
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uint64_t numpages;
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uint64_t hpagesize;
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QemuThread pgthread;
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sigjmp_buf env;
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};
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typedef struct MemsetThread MemsetThread;
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static MemsetThread *memset_thread;
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static int memset_num_threads;
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static bool memset_thread_failed;
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int qemu_get_thread_id(void)
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{
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#if defined(__linux__)
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return syscall(SYS_gettid);
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#else
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return getpid();
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#endif
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}
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int qemu_daemon(int nochdir, int noclose)
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{
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return daemon(nochdir, noclose);
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}
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void *qemu_oom_check(void *ptr)
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{
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if (ptr == NULL) {
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fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
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abort();
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}
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return ptr;
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}
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void *qemu_try_memalign(size_t alignment, size_t size)
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{
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void *ptr;
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if (alignment < sizeof(void*)) {
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alignment = sizeof(void*);
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}
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#if defined(_POSIX_C_SOURCE) && !defined(__sun__)
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int ret;
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ret = posix_memalign(&ptr, alignment, size);
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if (ret != 0) {
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errno = ret;
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ptr = NULL;
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}
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#elif defined(CONFIG_BSD)
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ptr = valloc(size);
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#else
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ptr = memalign(alignment, size);
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#endif
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trace_qemu_memalign(alignment, size, ptr);
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return ptr;
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}
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void *qemu_memalign(size_t alignment, size_t size)
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{
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return qemu_oom_check(qemu_try_memalign(alignment, size));
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}
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/* alloc shared memory pages */
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void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment)
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{
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size_t align = QEMU_VMALLOC_ALIGN;
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void *ptr = qemu_ram_mmap(-1, size, align, false);
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if (ptr == MAP_FAILED) {
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return NULL;
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}
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if (alignment) {
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*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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}
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void qemu_vfree(void *ptr)
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{
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trace_qemu_vfree(ptr);
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free(ptr);
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}
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void qemu_anon_ram_free(void *ptr, size_t size)
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{
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trace_qemu_anon_ram_free(ptr, size);
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qemu_ram_munmap(ptr, size);
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}
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void qemu_set_block(int fd)
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{
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int f;
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f = fcntl(fd, F_GETFL);
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fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
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}
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void qemu_set_nonblock(int fd)
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{
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int f;
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f = fcntl(fd, F_GETFL);
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fcntl(fd, F_SETFL, f | O_NONBLOCK);
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}
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int socket_set_fast_reuse(int fd)
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{
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int val = 1, ret;
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ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
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(const char *)&val, sizeof(val));
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assert(ret == 0);
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return ret;
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}
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void qemu_set_cloexec(int fd)
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{
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int f;
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f = fcntl(fd, F_GETFD);
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fcntl(fd, F_SETFD, f | FD_CLOEXEC);
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}
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/*
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* Creates a pipe with FD_CLOEXEC set on both file descriptors
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*/
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int qemu_pipe(int pipefd[2])
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{
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int ret;
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#ifdef CONFIG_PIPE2
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ret = pipe2(pipefd, O_CLOEXEC);
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if (ret != -1 || errno != ENOSYS) {
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return ret;
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}
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#endif
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ret = pipe(pipefd);
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if (ret == 0) {
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qemu_set_cloexec(pipefd[0]);
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qemu_set_cloexec(pipefd[1]);
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}
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return ret;
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}
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int qemu_utimens(const char *path, const struct timespec *times)
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{
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struct timeval tv[2], tv_now;
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struct stat st;
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int i;
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#ifdef CONFIG_UTIMENSAT
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int ret;
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ret = utimensat(AT_FDCWD, path, times, AT_SYMLINK_NOFOLLOW);
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if (ret != -1 || errno != ENOSYS) {
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return ret;
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}
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#endif
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/* Fallback: use utimes() instead of utimensat() */
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/* happy if special cases */
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if (times[0].tv_nsec == UTIME_OMIT && times[1].tv_nsec == UTIME_OMIT) {
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return 0;
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}
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if (times[0].tv_nsec == UTIME_NOW && times[1].tv_nsec == UTIME_NOW) {
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return utimes(path, NULL);
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}
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/* prepare for hard cases */
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if (times[0].tv_nsec == UTIME_NOW || times[1].tv_nsec == UTIME_NOW) {
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gettimeofday(&tv_now, NULL);
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}
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if (times[0].tv_nsec == UTIME_OMIT || times[1].tv_nsec == UTIME_OMIT) {
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stat(path, &st);
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}
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for (i = 0; i < 2; i++) {
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if (times[i].tv_nsec == UTIME_NOW) {
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tv[i].tv_sec = tv_now.tv_sec;
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tv[i].tv_usec = tv_now.tv_usec;
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} else if (times[i].tv_nsec == UTIME_OMIT) {
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tv[i].tv_sec = (i == 0) ? st.st_atime : st.st_mtime;
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tv[i].tv_usec = 0;
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} else {
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tv[i].tv_sec = times[i].tv_sec;
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tv[i].tv_usec = times[i].tv_nsec / 1000;
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}
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}
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return utimes(path, &tv[0]);
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}
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char *
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qemu_get_local_state_pathname(const char *relative_pathname)
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{
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return g_strdup_printf("%s/%s", CONFIG_QEMU_LOCALSTATEDIR,
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relative_pathname);
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}
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void qemu_set_tty_echo(int fd, bool echo)
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{
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struct termios tty;
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tcgetattr(fd, &tty);
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if (echo) {
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tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
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} else {
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tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
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}
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tcsetattr(fd, TCSANOW, &tty);
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}
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static char exec_dir[PATH_MAX];
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void qemu_init_exec_dir(const char *argv0)
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{
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char *dir;
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char *p = NULL;
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char buf[PATH_MAX];
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assert(!exec_dir[0]);
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#if defined(__linux__)
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{
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int len;
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len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
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if (len > 0) {
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buf[len] = 0;
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p = buf;
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}
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}
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#elif defined(__FreeBSD__)
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{
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static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
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size_t len = sizeof(buf) - 1;
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*buf = '\0';
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if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
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*buf) {
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buf[sizeof(buf) - 1] = '\0';
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p = buf;
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}
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}
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#endif
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/* If we don't have any way of figuring out the actual executable
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location then try argv[0]. */
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if (!p) {
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if (!argv0) {
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return;
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}
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p = realpath(argv0, buf);
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if (!p) {
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return;
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}
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}
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dir = g_path_get_dirname(p);
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pstrcpy(exec_dir, sizeof(exec_dir), dir);
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g_free(dir);
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}
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char *qemu_get_exec_dir(void)
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{
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return g_strdup(exec_dir);
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}
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static void sigbus_handler(int signal)
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{
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int i;
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if (memset_thread) {
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for (i = 0; i < memset_num_threads; i++) {
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if (qemu_thread_is_self(&memset_thread[i].pgthread)) {
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siglongjmp(memset_thread[i].env, 1);
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}
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}
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}
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}
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static void *do_touch_pages(void *arg)
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{
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MemsetThread *memset_args = (MemsetThread *)arg;
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char *addr = memset_args->addr;
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uint64_t numpages = memset_args->numpages;
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uint64_t hpagesize = memset_args->hpagesize;
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sigset_t set, oldset;
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int i = 0;
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/* unblock SIGBUS */
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sigemptyset(&set);
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sigaddset(&set, SIGBUS);
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pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
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if (sigsetjmp(memset_args->env, 1)) {
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memset_thread_failed = true;
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} else {
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for (i = 0; i < numpages; i++) {
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/*
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* Read & write back the same value, so we don't
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* corrupt existing user/app data that might be
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* stored.
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*
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* 'volatile' to stop compiler optimizing this away
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* to a no-op
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*
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* TODO: get a better solution from kernel so we
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* don't need to write at all so we don't cause
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* wear on the storage backing the region...
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*/
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*(volatile char *)addr = *addr;
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addr += hpagesize;
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}
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}
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pthread_sigmask(SIG_SETMASK, &oldset, NULL);
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return NULL;
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}
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static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
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int smp_cpus)
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{
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uint64_t numpages_per_thread, size_per_thread;
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char *addr = area;
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int i = 0;
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memset_thread_failed = false;
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memset_num_threads = MIN(smp_cpus, MAX_MEM_PREALLOC_THREAD_COUNT);
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memset_thread = g_new0(MemsetThread, memset_num_threads);
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numpages_per_thread = (numpages / memset_num_threads);
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size_per_thread = (hpagesize * numpages_per_thread);
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for (i = 0; i < memset_num_threads; i++) {
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memset_thread[i].addr = addr;
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memset_thread[i].numpages = (i == (memset_num_threads - 1)) ?
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numpages : numpages_per_thread;
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memset_thread[i].hpagesize = hpagesize;
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qemu_thread_create(&memset_thread[i].pgthread, "touch_pages",
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do_touch_pages, &memset_thread[i],
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QEMU_THREAD_JOINABLE);
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addr += size_per_thread;
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numpages -= numpages_per_thread;
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}
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for (i = 0; i < memset_num_threads; i++) {
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qemu_thread_join(&memset_thread[i].pgthread);
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}
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g_free(memset_thread);
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memset_thread = NULL;
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return memset_thread_failed;
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}
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void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
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Error **errp)
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{
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int ret;
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struct sigaction act, oldact;
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size_t hpagesize = qemu_fd_getpagesize(fd);
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size_t numpages = DIV_ROUND_UP(memory, hpagesize);
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memset(&act, 0, sizeof(act));
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act.sa_handler = &sigbus_handler;
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act.sa_flags = 0;
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ret = sigaction(SIGBUS, &act, &oldact);
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if (ret) {
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error_setg_errno(errp, errno,
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"os_mem_prealloc: failed to install signal handler");
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return;
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}
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/* touch pages simultaneously */
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if (touch_all_pages(area, hpagesize, numpages, smp_cpus)) {
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error_setg(errp, "os_mem_prealloc: Insufficient free host memory "
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"pages available to allocate guest RAM\n");
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}
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ret = sigaction(SIGBUS, &oldact, NULL);
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if (ret) {
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/* Terminate QEMU since it can't recover from error */
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perror("os_mem_prealloc: failed to reinstall signal handler");
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exit(1);
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}
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}
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static struct termios oldtty;
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static void term_exit(void)
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{
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tcsetattr(0, TCSANOW, &oldtty);
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}
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static void term_init(void)
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{
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struct termios tty;
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tcgetattr(0, &tty);
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oldtty = tty;
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tty.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP
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|INLCR|IGNCR|ICRNL|IXON);
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tty.c_oflag |= OPOST;
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tty.c_lflag &= ~(ECHO|ECHONL|ICANON|IEXTEN);
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tty.c_cflag &= ~(CSIZE|PARENB);
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tty.c_cflag |= CS8;
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tty.c_cc[VMIN] = 1;
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tty.c_cc[VTIME] = 0;
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tcsetattr(0, TCSANOW, &tty);
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atexit(term_exit);
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}
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int qemu_read_password(char *buf, int buf_size)
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{
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uint8_t ch;
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int i, ret;
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printf("password: ");
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fflush(stdout);
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term_init();
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i = 0;
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for (;;) {
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ret = read(0, &ch, 1);
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if (ret == -1) {
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if (errno == EAGAIN || errno == EINTR) {
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continue;
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} else {
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break;
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}
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} else if (ret == 0) {
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ret = -1;
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break;
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} else {
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if (ch == '\r' ||
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ch == '\n') {
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ret = 0;
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break;
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}
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if (i < (buf_size - 1)) {
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buf[i++] = ch;
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}
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}
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}
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term_exit();
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buf[i] = '\0';
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printf("\n");
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return ret;
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}
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char *qemu_get_pid_name(pid_t pid)
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{
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char *name = NULL;
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#if defined(__FreeBSD__)
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/* BSDs don't have /proc, but they provide a nice substitute */
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struct kinfo_proc *proc = kinfo_getproc(pid);
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if (proc) {
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name = g_strdup(proc->ki_comm);
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free(proc);
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}
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#else
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/* Assume a system with reasonable procfs */
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char *pid_path;
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size_t len;
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pid_path = g_strdup_printf("/proc/%d/cmdline", pid);
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|
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;
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE
|
|
void *ptr2;
|
|
#endif
|
|
size_t pagesz = getpagesize();
|
|
#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;
|
|
|
|
ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
if (ptr == MAP_FAILED) {
|
|
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) {
|
|
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 + getpagesize(); 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);
|
|
}
|
|
|
|
void sigaction_invoke(struct sigaction *action,
|
|
struct qemu_signalfd_siginfo *info)
|
|
{
|
|
siginfo_t si = { 0 };
|
|
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;
|
|
} else if (info->ssi_signo == SIGIO) {
|
|
si.si_band = info->ssi_band;
|
|
}
|
|
action->sa_sigaction(info->ssi_signo, &si, NULL);
|
|
}
|