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| author | Steven Rostedt <srostedt@redhat.com> | 2009-02-10 18:07:13 (GMT) |
|---|---|---|
| committer | Steven Rostedt <srostedt@redhat.com> | 2009-02-10 18:07:13 (GMT) |
| commit | e3944bfac961cd7fc82f3b3143c55dc375748569 (patch) | |
| tree | 26a5cd89d950ce8900e2a36dd4ca3da0d7240641 /arch/x86 | |
| parent | acd895795d35d7c6405f20301a846d16998795ec (diff) | |
| download | linux-e3944bfac961cd7fc82f3b3143c55dc375748569.tar.xz | |
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.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 1b43086..9d549e4 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) "1: " _ASM_MOV " (%[parent_old]), %[old]\n" "2: " _ASM_MOV " %[return_hooker], (%[parent_replaced])\n" " movl $0, %[faulted]\n" + "3:\n" ".section .fixup, \"ax\"\n" - "3: movl $1, %[faulted]\n" + "4: movl $1, %[faulted]\n" + " jmp 3b\n" ".previous\n" - _ASM_EXTABLE(1b, 3b) - _ASM_EXTABLE(2b, 3b) + _ASM_EXTABLE(1b, 4b) + _ASM_EXTABLE(2b, 4b) : [parent_replaced] "=r" (parent), [old] "=r" (old), [faulted] "=r" (faulted) |