On x86 architecture, save/restore the 'thread_info->sysenter_return'
of tasks. This fixes crashes of threads immediately after restart.
This field is set in arch_setup_additional_pages() for thread group
leaders, and then inherited by threads. At restart, we first create
all tasks (and threads) and then restore their MMs. In particular, we
call arch_setup_additional_page() again, which may re-map the vdso
page to the saved location. However, we only do so explicitly to the
thread group leader, so the 'sysenter_return' pointers of the threads
aren't automatically adjusted.
Signed-off-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Smith <danms@xxxxxxxxxx>
---
arch/x86/include/asm/checkpoint_hdr.h | 1 +
arch/x86/kernel/checkpoint.c | 5 +++++
2 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/checkpoint_hdr.h b/arch/x86/include/asm/checkpoint_hdr.h
index 535a9c6..0505329 100644
--- a/arch/x86/include/asm/checkpoint_hdr.h
+++ b/arch/x86/include/asm/checkpoint_hdr.h
@@ -82,6 +82,7 @@ struct ckpt_hdr_header_arch {
struct ckpt_hdr_thread {
struct ckpt_hdr h;
+ __u64 sysenter_return;
__u32 thread_info_flags;
__u16 gdt_entry_tls_entries;
__u16 sizeof_tls_array;
diff --git a/arch/x86/kernel/checkpoint.c b/arch/x86/kernel/checkpoint.c
index 0258245..3fb9deb 100644
--- a/arch/x86/kernel/checkpoint.c
+++ b/arch/x86/kernel/checkpoint.c
@@ -103,6 +103,8 @@ int checkpoint_thread(struct ckpt_ctx *ctx, struct task_struct *t)
task_thread_info(t)->flags & ~CKPT_X86_TIF_UNSUPPORTED;
h->gdt_entry_tls_entries = GDT_ENTRY_TLS_ENTRIES;
h->sizeof_tls_array = tls_size;
+ h->sysenter_return = (__u64) (unsigned long)
+ task_thread_info(current)->sysenter_return;
/* For simplicity dump the entire array */
memcpy(h + 1, t->thread.tls_array, tls_size);
@@ -297,6 +299,9 @@ int restore_thread(struct ckpt_ctx *ctx)
}
}
+ task_thread_info(current)->sysenter_return =
+ (void __user *) (unsigned long) h->sysenter_return;
+
/* TODO: restore TIF flags as necessary (e.g. TIF_NOTSC) */
ret = 0;
--
1.7.0.4
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