tracing, x86: fix constraint for parent variable

The constraint used for retrieving and restoring the parent function
pointer is incorrect. The parent variable is a pointer, and the
address of the pointer is modified by the asm statement and not
the pointer itself. It is incorrect to pass it in as an output
constraint since the asm will never update the pointer.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 18828aee87815704bad6571fe69d3ead9f56cd55..370bafaa43a37ed741b2e511ec1618afd3bc9684 100644 (file)
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -468,8 +468,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
         * ignore such a protection.
         */
        asm volatile(
-               "1: " _ASM_MOV " (%[parent_old]), %[old]\n"
-               "2: " _ASM_MOV " %[return_hooker], (%[parent_replaced])\n"
+               "1: " _ASM_MOV " (%[parent]), %[old]\n"
+               "2: " _ASM_MOV " %[return_hooker], (%[parent])\n"
                "   movl $0, %[faulted]\n"
 
                ".section .fixup, \"ax\"\n"
@@ -479,9 +479,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
                _ASM_EXTABLE(1b, 3b)
                _ASM_EXTABLE(2b, 3b)
 
-               : [parent_replaced] "=r" (parent), [old] "=r" (old),
-                 [faulted] "=r" (faulted)
-               : [parent_old] "0" (parent), [return_hooker] "r" (return_hooker)
+               : [old] "=r" (old), [faulted] "=r" (faulted)
+               : [parent] "r" (parent), [return_hooker] "r" (return_hooker)
                : "memory"
        );