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 <[email protected]> Signed-off-by: Dan Smith <[email protected]> --- 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 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
