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-rw-r--r--arch/x86/kernel/unwind_frame.c36
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)));
}
/*