mirror of
https://github.com/checkpoint-restore/criu.git
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vdso/ia32: separate compat vdso helper
As helper unmaps 64-bit vDSO blob, it can call only raw syscalls. Also by that reason it's code should be not instrumented with GCOV/ASAN. Disable instrumentation by separating it into new object and filtering gcov/asan cflags. Fixes: #290 @avagin, it rarely reproduces, I failed to reproduce even once (with gcov, on the same env00 test, with the same linux-next) please, reopen #290 if you'll spot it afterward. Reported-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com> Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
This commit is contained in:
Dmitry Safonov
Andrei Vagin
parent
164e048a8a
commit
f2504723c9
4 changed files with 81 additions and 65 deletions
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@ -86,7 +86,9 @@ ifeq ($(VDSO),y)
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obj-y += pie-util-vdso.o
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obj-y += vdso.o
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obj-y += pie-util-vdso-elf32.o
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CFLAGS_pie-util-vdso-elf32.o += -DCONFIG_VDSO_32
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CFLAGS_pie-util-vdso-elf32.o += -DCONFIG_VDSO_32
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obj-$(CONFIG_COMPAT) += vdso-compat.o
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CFLAGS_REMOVE_vdso-compat.o += $(CFLAGS-ASAN) $(CFLAGS-GCOV)
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endif
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PROTOBUF_GEN := scripts/protobuf-gen.sh
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@ -18,6 +18,11 @@ extern int vdso_init(void);
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extern int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
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struct vm_area_list *vma_area_list);
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#ifdef CONFIG_COMPAT
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void compat_vdso_helper(struct vdso_symtable *native, int pipe_fd,
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int err_fd, void *vdso_buf, size_t buf_size);
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#endif
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#else /* CONFIG_VDSO */
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#define vdso_init() (0)
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71
criu/vdso-compat.c
Normal file
71
criu/vdso-compat.c
Normal file
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@ -0,0 +1,71 @@
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#include <sys/syscall.h>
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#include <signal.h>
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#include <string.h>
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#include <unistd.h>
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#include "types.h"
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#include "parasite-syscall.h"
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#include "parasite.h"
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#include "vdso.h"
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static void exit_on(int ret, int err_fd, char *reason)
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{
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if (ret) {
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syscall(__NR_write, err_fd, reason, strlen(reason));
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syscall(__NR_exit, ret);
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}
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}
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/*
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* Because of restrictions of ARCH_MAP_VDSO_* API, new vDSO blob
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* can be mapped only if there is no vDSO blob present for a process.
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* This is a helper process, it unmaps 64-bit vDSO and maps 32-bit vDSO.
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* Then it copies vDSO blob to shared with CRIU mapping.
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*
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* The purpose is to fill compat vdso's symtable (vdso_compat_rt).
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* It's an optimization to fill symtable only once at CRIU restore
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* for all restored tasks.
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*
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* @native - 64-bit vDSO blob (for easy unmap)
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* @pipe_fd - to get size of compat blob from /proc/.../maps
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* @err_fd - to print error messages
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* @vdso_buf, buf_size - shared with CRIU buffer
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*
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* WARN: This helper shouldn't call pr_err() or any syscall with
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* Glibc's wrapper function - it may very likely blow up.
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*/
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void compat_vdso_helper(struct vdso_symtable *native, int pipe_fd,
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int err_fd, void *vdso_buf, size_t buf_size)
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{
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size_t vma_size;
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void *vdso_addr;
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long vdso_size;
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long ret;
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vma_size = native->vma_end - native->vma_start;
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ret = syscall(__NR_munmap, native->vma_start, vma_size);
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exit_on(ret, err_fd, "Error: Failed to unmap native vdso\n");
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vma_size = native->vvar_end - native->vvar_start;
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ret = syscall(__NR_munmap, native->vvar_start, vma_size);
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exit_on(ret, err_fd, "Error: Failed to unmap native vvar\n");
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ret = syscall(__NR_arch_prctl, ARCH_MAP_VDSO_32, native->vma_start);
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if (ret < 0)
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exit_on(ret, err_fd, "Error: ARCH_MAP_VDSO failed\n");
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vdso_size = ret;
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if (vdso_size > buf_size)
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exit_on(-1, err_fd, "Error: Compatible vdso's size is bigger than reserved buf\n");
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/* Stop so CRIU could parse smaps to find 32-bit vdso's size */
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ret = syscall(__NR_kill, syscall(__NR_getpid), SIGSTOP);
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exit_on(ret, err_fd, "Error: Can't stop myself with SIGSTOP (having a good time)\n");
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ret = syscall(__NR_read, pipe_fd, &vdso_addr, sizeof(void *));
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if (ret != sizeof(void *))
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exit_on(-1, err_fd, "Error: Can't read size of mmaped vdso from pipe\n");
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memcpy(vdso_buf, vdso_addr, vdso_size);
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syscall(__NR_exit, 0);
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}
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66
criu/vdso.c
66
criu/vdso.c
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@ -330,68 +330,6 @@ static int vdso_fill_self_symtable(struct vdso_symtable *s)
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}
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#ifdef CONFIG_COMPAT
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static void exit_on(int ret, int err_fd, char *reason)
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{
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if (ret) {
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syscall(__NR_write, err_fd, reason, strlen(reason));
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syscall(__NR_exit, ret);
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}
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}
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/*
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* Because of restrictions of ARCH_MAP_VDSO_* API, new vDSO blob
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* can be mapped only if there is no vDSO blob present for a process.
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* This is a helper process, it unmaps 64-bit vDSO and maps 32-bit vDSO.
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* Then it copies vDSO blob to shared with CRIU mapping.
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*
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* The purpose is to fill compat vdso's symtable (vdso_compat_rt).
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* It's an optimization to fill symtable only once at CRIU restore
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* for all restored tasks.
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*
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* @native - 64-bit vDSO blob (for easy unmap)
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* @pipe_fd - to get size of compat blob from /proc/.../maps
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* @err_fd - to print error messages
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* @vdso_buf, buf_size - shared with CRIU buffer
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*
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* WARN: This helper shouldn't call pr_err() or any syscall with
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* Glibc's wrapper function - it may very likely blow up.
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*/
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static void compat_vdso_helper(struct vdso_symtable *native, int pipe_fd,
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int err_fd, void *vdso_buf, size_t buf_size)
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{
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size_t vma_size;
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void *vdso_addr;
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long vdso_size;
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long ret;
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vma_size = native->vma_end - native->vma_start;
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ret = syscall(__NR_munmap, native->vma_start, vma_size);
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exit_on(ret, err_fd, "Error: Failed to unmap native vdso\n");
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vma_size = native->vvar_end - native->vvar_start;
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ret = syscall(__NR_munmap, native->vvar_start, vma_size);
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exit_on(ret, err_fd, "Error: Failed to unmap native vvar\n");
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ret = syscall(__NR_arch_prctl, ARCH_MAP_VDSO_32, native->vma_start);
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if (ret < 0)
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exit_on(ret, err_fd, "Error: ARCH_MAP_VDSO failed\n");
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vdso_size = ret;
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if (vdso_size > buf_size)
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exit_on(-1, err_fd, "Error: Compatible vdso's size is bigger than reserved buf\n");
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/* Stop so CRIU could parse smaps to find 32-bit vdso's size */
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ret = syscall(__NR_kill, syscall(__NR_getpid), SIGSTOP);
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exit_on(ret, err_fd, "Error: Can't stop myself with SIGSTOP (having a good time)\n");
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ret = syscall(__NR_read, pipe_fd, &vdso_addr, sizeof(void *));
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if (ret != sizeof(void *))
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exit_on(-1, err_fd, "Error: Can't read size of mmaped vdso from pipe\n");
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memcpy(vdso_buf, vdso_addr, vdso_size);
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syscall(__NR_exit, 0);
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}
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static int vdso_mmap_compat(struct vdso_symtable *native,
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struct vdso_symtable *compat, void *vdso_buf, size_t buf_size)
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{
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@ -503,13 +441,13 @@ out_unmap:
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return ret;
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}
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#else
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#else /* CONFIG_COMPAT */
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static int vdso_fill_compat_symtable(struct vdso_symtable *native,
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struct vdso_symtable *compat)
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{
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return 0;
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}
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#endif
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#endif /* CONFIG_COMPAT */
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int vdso_init(void)
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{
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