[CRIU] [PATCH 2/2] vdso/ia32: separate compat vdso helper
Dmitry Safonov
dsafonov at virtuozzo.com
Tue Apr 18 10:04:09 PDT 2017
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 at openvz.org>
Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
---
criu/Makefile.crtools | 4 ++-
criu/include/vdso.h | 5 ++++
criu/vdso-compat.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++
criu/vdso.c | 66 ++---------------------------------------------
4 files changed, 81 insertions(+), 65 deletions(-)
create mode 100644 criu/vdso-compat.c
diff --git a/criu/Makefile.crtools b/criu/Makefile.crtools
index e98837f1340d..03756ae294fe 100644
--- a/criu/Makefile.crtools
+++ b/criu/Makefile.crtools
@@ -91,7 +91,9 @@ ifeq ($(VDSO),y)
obj-y += pie-util-vdso.o
obj-y += vdso.o
obj-y += pie-util-vdso-elf32.o
-CFLAGS_pie-util-vdso-elf32.o += -DCONFIG_VDSO_32
+CFLAGS_pie-util-vdso-elf32.o += -DCONFIG_VDSO_32
+obj-$(CONFIG_COMPAT) += vdso-compat.o
+CFLAGS_REMOVE_vdso-compat.o += $(CFLAGS-ASAN) $(CFLAGS-GCOV)
endif
PROTOBUF_GEN := scripts/protobuf-gen.sh
diff --git a/criu/include/vdso.h b/criu/include/vdso.h
index 9b6010c03d64..e118ed7f33f6 100644
--- a/criu/include/vdso.h
+++ b/criu/include/vdso.h
@@ -18,6 +18,11 @@ extern int vdso_init(void);
extern int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
struct vm_area_list *vma_area_list);
+#ifdef CONFIG_COMPAT
+void compat_vdso_helper(struct vdso_symtable *native, int pipe_fd,
+ int err_fd, void *vdso_buf, size_t buf_size);
+#endif
+
#else /* CONFIG_VDSO */
#define vdso_init() (0)
diff --git a/criu/vdso-compat.c b/criu/vdso-compat.c
new file mode 100644
index 000000000000..7669eb3df5d4
--- /dev/null
+++ b/criu/vdso-compat.c
@@ -0,0 +1,71 @@
+#include <sys/syscall.h>
+#include <signal.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "types.h"
+#include "parasite-syscall.h"
+#include "parasite.h"
+#include "vdso.h"
+
+static void exit_on(int ret, int err_fd, char *reason)
+{
+ if (ret) {
+ syscall(__NR_write, err_fd, reason, strlen(reason));
+ syscall(__NR_exit, ret);
+ }
+}
+/*
+ * Because of restrictions of ARCH_MAP_VDSO_* API, new vDSO blob
+ * can be mapped only if there is no vDSO blob present for a process.
+ * This is a helper process, it unmaps 64-bit vDSO and maps 32-bit vDSO.
+ * Then it copies vDSO blob to shared with CRIU mapping.
+ *
+ * The purpose is to fill compat vdso's symtable (vdso_compat_rt).
+ * It's an optimization to fill symtable only once at CRIU restore
+ * for all restored tasks.
+ *
+ * @native - 64-bit vDSO blob (for easy unmap)
+ * @pipe_fd - to get size of compat blob from /proc/.../maps
+ * @err_fd - to print error messages
+ * @vdso_buf, buf_size - shared with CRIU buffer
+ *
+ * WARN: This helper shouldn't call pr_err() or any syscall with
+ * Glibc's wrapper function - it may very likely blow up.
+ */
+void compat_vdso_helper(struct vdso_symtable *native, int pipe_fd,
+ int err_fd, void *vdso_buf, size_t buf_size)
+{
+ size_t vma_size;
+ void *vdso_addr;
+ long vdso_size;
+ long ret;
+
+ vma_size = native->vma_end - native->vma_start;
+ ret = syscall(__NR_munmap, native->vma_start, vma_size);
+ exit_on(ret, err_fd, "Error: Failed to unmap native vdso\n");
+
+ vma_size = native->vvar_end - native->vvar_start;
+ ret = syscall(__NR_munmap, native->vvar_start, vma_size);
+ exit_on(ret, err_fd, "Error: Failed to unmap native vvar\n");
+
+ ret = syscall(__NR_arch_prctl, ARCH_MAP_VDSO_32, native->vma_start);
+ if (ret < 0)
+ exit_on(ret, err_fd, "Error: ARCH_MAP_VDSO failed\n");
+
+ vdso_size = ret;
+ if (vdso_size > buf_size)
+ exit_on(-1, err_fd, "Error: Compatible vdso's size is bigger than reserved buf\n");
+
+ /* Stop so CRIU could parse smaps to find 32-bit vdso's size */
+ ret = syscall(__NR_kill, syscall(__NR_getpid), SIGSTOP);
+ exit_on(ret, err_fd, "Error: Can't stop myself with SIGSTOP (having a good time)\n");
+
+ ret = syscall(__NR_read, pipe_fd, &vdso_addr, sizeof(void *));
+ if (ret != sizeof(void *))
+ exit_on(-1, err_fd, "Error: Can't read size of mmaped vdso from pipe\n");
+
+ memcpy(vdso_buf, vdso_addr, vdso_size);
+
+ syscall(__NR_exit, 0);
+}
diff --git a/criu/vdso.c b/criu/vdso.c
index 770853514619..8bc7b5d3b951 100644
--- a/criu/vdso.c
+++ b/criu/vdso.c
@@ -330,68 +330,6 @@ static int vdso_fill_self_symtable(struct vdso_symtable *s)
}
#ifdef CONFIG_COMPAT
-static void exit_on(int ret, int err_fd, char *reason)
-{
- if (ret) {
- syscall(__NR_write, err_fd, reason, strlen(reason));
- syscall(__NR_exit, ret);
- }
-}
-/*
- * Because of restrictions of ARCH_MAP_VDSO_* API, new vDSO blob
- * can be mapped only if there is no vDSO blob present for a process.
- * This is a helper process, it unmaps 64-bit vDSO and maps 32-bit vDSO.
- * Then it copies vDSO blob to shared with CRIU mapping.
- *
- * The purpose is to fill compat vdso's symtable (vdso_compat_rt).
- * It's an optimization to fill symtable only once at CRIU restore
- * for all restored tasks.
- *
- * @native - 64-bit vDSO blob (for easy unmap)
- * @pipe_fd - to get size of compat blob from /proc/.../maps
- * @err_fd - to print error messages
- * @vdso_buf, buf_size - shared with CRIU buffer
- *
- * WARN: This helper shouldn't call pr_err() or any syscall with
- * Glibc's wrapper function - it may very likely blow up.
- */
-static void compat_vdso_helper(struct vdso_symtable *native, int pipe_fd,
- int err_fd, void *vdso_buf, size_t buf_size)
-{
- size_t vma_size;
- void *vdso_addr;
- long vdso_size;
- long ret;
-
- vma_size = native->vma_end - native->vma_start;
- ret = syscall(__NR_munmap, native->vma_start, vma_size);
- exit_on(ret, err_fd, "Error: Failed to unmap native vdso\n");
-
- vma_size = native->vvar_end - native->vvar_start;
- ret = syscall(__NR_munmap, native->vvar_start, vma_size);
- exit_on(ret, err_fd, "Error: Failed to unmap native vvar\n");
-
- ret = syscall(__NR_arch_prctl, ARCH_MAP_VDSO_32, native->vma_start);
- if (ret < 0)
- exit_on(ret, err_fd, "Error: ARCH_MAP_VDSO failed\n");
-
- vdso_size = ret;
- if (vdso_size > buf_size)
- exit_on(-1, err_fd, "Error: Compatible vdso's size is bigger than reserved buf\n");
-
- /* Stop so CRIU could parse smaps to find 32-bit vdso's size */
- ret = syscall(__NR_kill, syscall(__NR_getpid), SIGSTOP);
- exit_on(ret, err_fd, "Error: Can't stop myself with SIGSTOP (having a good time)\n");
-
- ret = syscall(__NR_read, pipe_fd, &vdso_addr, sizeof(void *));
- if (ret != sizeof(void *))
- exit_on(-1, err_fd, "Error: Can't read size of mmaped vdso from pipe\n");
-
- memcpy(vdso_buf, vdso_addr, vdso_size);
-
- syscall(__NR_exit, 0);
-}
-
static int vdso_mmap_compat(struct vdso_symtable *native,
struct vdso_symtable *compat, void *vdso_buf, size_t buf_size)
{
@@ -503,13 +441,13 @@ out_unmap:
return ret;
}
-#else
+#else /* CONFIG_COMPAT */
static int vdso_fill_compat_symtable(struct vdso_symtable *native,
struct vdso_symtable *compat)
{
return 0;
}
-#endif
+#endif /* CONFIG_COMPAT */
int vdso_init(void)
{
--
2.12.2
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