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authorSteven Rostedt <srostedt@redhat.com>2009-02-10 13:07:13 -0500
committerSteven Rostedt <srostedt@redhat.com>2009-02-10 13:07:13 -0500
commite3944bfac961cd7fc82f3b3143c55dc375748569 (patch)
tree26a5cd89d950ce8900e2a36dd4ca3da0d7240641 /arch/x86
parentacd895795d35d7c6405f20301a846d16998795ec (diff)
tracing, x86: fix fixup section to return to original code
Impact: fix to prevent a kernel crash on fault If for some reason the pointer to the parent function on the stack takes a fault, the fix up code will not return back to the original faulting code. This can lead to unpredictable results and perhaps even a kernel panic. A fault should not happen, but if it does, we should simply disable the tracer, warn, and continue running the kernel. It should not lead to a kernel crash. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/ftrace.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 1b43086b097a..9d549e4fe880 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -491,13 +491,15 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
491 "1: " _ASM_MOV " (%[parent_old]), %[old]\n" 491 "1: " _ASM_MOV " (%[parent_old]), %[old]\n"
492 "2: " _ASM_MOV " %[return_hooker], (%[parent_replaced])\n" 492 "2: " _ASM_MOV " %[return_hooker], (%[parent_replaced])\n"
493 " movl $0, %[faulted]\n" 493 " movl $0, %[faulted]\n"
494 "3:\n"
494 495
495 ".section .fixup, \"ax\"\n" 496 ".section .fixup, \"ax\"\n"
496 "3: movl $1, %[faulted]\n" 497 "4: movl $1, %[faulted]\n"
498 " jmp 3b\n"
497 ".previous\n" 499 ".previous\n"
498 500
499 _ASM_EXTABLE(1b, 3b) 501 _ASM_EXTABLE(1b, 4b)
500 _ASM_EXTABLE(2b, 3b) 502 _ASM_EXTABLE(2b, 4b)
501 503
502 : [parent_replaced] "=r" (parent), [old] "=r" (old), 504 : [parent_replaced] "=r" (parent), [old] "=r" (old),
503 [faulted] "=r" (faulted) 505 [faulted] "=r" (faulted)