2 files changed, 15 insertions, 42 deletions

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 788295cbe4a7..19853ad8afc5 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -105,34 +105,6 @@ in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
 }
 
 /*
- * We are returning from the irq stack and go to the previous one.
- * If the previous stack is also in the irq stack, then bp in the first
- * frame of the irq stack points to the previous, interrupted one.
- * Otherwise we have another level of indirection: We first save
- * the bp of the previous stack, then we switch the stack to the irq one
- * and save a new bp that links to the previous one.
- * (See save_args())
- */
-static inline unsigned long
-fixup_bp_irq_link(unsigned long bp, unsigned long *stack,
-                  unsigned long *irq_stack, unsigned long *irq_stack_end)
-{
-#ifdef CONFIG_FRAME_POINTER
-        struct stack_frame *frame = (struct stack_frame *)bp;
-        unsigned long next;
-
-        if (!in_irq_stack(stack, irq_stack, irq_stack_end)) {
-                if (!probe_kernel_address(&frame->next_frame, next))
-                        return next;
-                else
-                        WARN_ONCE(1, "Perf: bad frame pointer = %p in "
-                                  "callchain\n", &frame->next_frame);
-        }
-#endif
-        return bp;
-}
-
-/*
  * x86-64 can have up to three kernel stacks:
  * process stack
  * interrupt stack
@@ -208,8 +180,6 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
                                  * pointer (index -1 to end) in the IRQ stack:
                                  */
                                 stack = (unsigned long *) (irq_stack_end[-1]);
-                                bp = fixup_bp_irq_link(bp, stack, irq_stack,
-                                                       irq_stack_end);
                                 irq_stack_end = NULL;
                                 ops->stack(data, "EOI");
                                 continue;
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 6131432c5afa..d656f68371a4 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -310,8 +310,11 @@ ENDPROC(native_usergs_sysret64)
         movq_cfi r10, R10-RBP
         movq_cfi r11, R11-RBP
 
-        movq_cfi rbp, 0         /* push %rbp */
-        movq %rsp, %rbp
+        /* Save rbp so that we can unwind from get_irq_regs() */
+        movq_cfi rbp, 0
+
+        /* Save previous stack value */
+        movq %rsp, %rsi
 
         leaq -RBP(%rsp),%rdi    /* arg1 for handler */
         testl $3, CS(%rdi)
@@ -327,10 +330,11 @@ ENDPROC(native_usergs_sysret64)
         jne 2f
         mov PER_CPU_VAR(irq_stack_ptr),%rsp
         EMPTY_FRAME 0
-        /*
-         * We entered an interrupt context - irqs are off:
-         */
-2:      TRACE_IRQS_OFF
+
+2:      /* Store previous stack value */
+        pushq %rsi
+        /* We entered an interrupt context - irqs are off: */
+        TRACE_IRQS_OFF
         .endm
 
 ENTRY(save_rest)
@@ -804,15 +808,14 @@ ret_from_intr:
         DISABLE_INTERRUPTS(CLBR_NONE)
         TRACE_IRQS_OFF
         decl PER_CPU_VAR(irq_count)
-        leaveq
 
-        CFI_RESTORE             rbp
+        /* Restore saved previous stack */
+        popq %rsi
+        leaq 16(%rsi), %rsp
+
         CFI_DEF_CFA_REGISTER    rsp
-        CFI_ADJUST_CFA_OFFSET   -8
+        CFI_ADJUST_CFA_OFFSET   -16
 
-        /* we did not save rbx, restore only from ARGOFFSET */
-        addq $8, %rsp
-        CFI_ADJUST_CFA_OFFSET   -8
 exit_intr:
         GET_THREAD_INFO(%rcx)
         testl $3,CS-ARGOFFSET(%rsp)