1 files changed, 40 insertions, 9 deletions

diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index 82c6d7f1fd73..b9389d72b2f7 100644
--- a/arch/x86/kernel/unwind_frame.c
+++ b/arch/x86/kernel/unwind_frame.c
@@ -104,6 +104,11 @@ static inline unsigned long *last_frame(struct unwind_state *state)
         return (unsigned long *)task_pt_regs(state->task) - 2;
 }
 
+static bool is_last_frame(struct unwind_state *state)
+{
+        return state->bp == last_frame(state);
+}
+
 #ifdef CONFIG_X86_32
 #define GCC_REALIGN_WORDS 3
 #else
@@ -115,16 +120,15 @@ static inline unsigned long *last_aligned_frame(struct unwind_state *state)
         return last_frame(state) - GCC_REALIGN_WORDS;
 }
 
-static bool is_last_task_frame(struct unwind_state *state)
+static bool is_last_aligned_frame(struct unwind_state *state)
 {
         unsigned long *last_bp = last_frame(state);
         unsigned long *aligned_bp = last_aligned_frame(state);
 
         /*
-         * 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 in the prologue of a function
-         * called by head/entry code.  Examples:
+         * GCC can occasionally decide to realign the stack pointer and change
+         * the offset of the stack frame in the prologue of a function called
+         * by head/entry code.  Examples:
          *
          * <start_secondary>:
          *      push   %edi
@@ -141,11 +145,38 @@ static bool is_last_task_frame(struct unwind_state *state)
          *      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.
+         * After aligning the stack, it pushes a duplicate copy of the return
+         * address before pushing the frame pointer.
+         */
+        return (state->bp == aligned_bp && *(aligned_bp + 1) == *(last_bp + 1));
+}
+
+static bool is_last_ftrace_frame(struct unwind_state *state)
+{
+        unsigned long *last_bp = last_frame(state);
+        unsigned long *last_ftrace_bp = last_bp - 3;
+
+        /*
+         * When unwinding from an ftrace handler of a function called by entry
+         * code, the stack layout of the last frame is:
+         *
+         *   bp
+         *   parent ret addr
+         *   bp
+         *   function ret addr
+         *   parent ret addr
+         *   pt_regs
+         *   -----------------
          */
-        return (state->bp == last_bp ||
-                (state->bp == aligned_bp && *(aligned_bp+1) == *(last_bp+1)));
+        return (state->bp == last_ftrace_bp &&
+                *state->bp == *(state->bp + 2) &&
+                *(state->bp + 1) == *(state->bp + 4));
+}
+
+static bool is_last_task_frame(struct unwind_state *state)
+{
+        return is_last_frame(state) || is_last_aligned_frame(state) ||
+               is_last_ftrace_frame(state);
 }
 
 /*