1 files changed, 30 insertions, 6 deletions

diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index 478d15dbaee4..08339262b666 100644
--- a/arch/x86/kernel/unwind_frame.c
+++ b/arch/x86/kernel/unwind_frame.c
@@ -82,19 +82,43 @@ static size_t regs_size(struct pt_regs *regs)
         return sizeof(*regs);
 }
 
+#ifdef CONFIG_X86_32
+#define GCC_REALIGN_WORDS 3
+#else
+#define GCC_REALIGN_WORDS 1
+#endif
+
 static bool is_last_task_frame(struct unwind_state *state)
 {
-        unsigned long bp = (unsigned long)state->bp;
-        unsigned long regs = (unsigned long)task_pt_regs(state->task);
+        unsigned long *last_bp = (unsigned long *)task_pt_regs(state->task) - 2;
+        unsigned long *aligned_bp = last_bp - GCC_REALIGN_WORDS;
 
         /*
          * We have to check for the last task frame at two different locations
          * because gcc can occasionally decide to realign the stack pointer and
-         * change the offset of the stack frame by a word in the prologue of a
-         * function called by head/entry code.
+         * change the offset of the stack frame in the prologue of a function
+         * called by head/entry code.  Examples:
+         *
+         * <start_secondary>:
+         *      push   %edi
+         *      lea    0x8(%esp),%edi
+         *      and    $0xfffffff8,%esp
+         *      pushl  -0x4(%edi)
+         *      push   %ebp
+         *      mov    %esp,%ebp
+         *
+         * <x86_64_start_kernel>:
+         *      lea    0x8(%rsp),%r10
+         *      and    $0xfffffffffffffff0,%rsp
+         *      pushq  -0x8(%r10)
+         *      push   %rbp
+         *      mov    %rsp,%rbp
+         *
+         * Note that after aligning the stack, it pushes a duplicate copy of
+         * the return address before pushing the frame pointer.
          */
-        return bp == regs - FRAME_HEADER_SIZE ||
-               bp == regs - FRAME_HEADER_SIZE - sizeof(long);
+        return (state->bp == last_bp ||
+                (state->bp == aligned_bp && *(aligned_bp+1) == *(last_bp+1)));
 }
 
 /*