Re: [patch 81/85] x86: fix RIP printout in early_idt_handler

From: Jike Song
Date: Thu Jan 15 2009 - 22:28:25 EST


On Fri, Jan 16, 2009 at 6:02 AM, Greg KH <gregkh@xxxxxxx> wrote:
> 2.6.27-stable review patch. If anyone has any objections, please let us know.
>
> ------------------
>
> From: Jiri Slaby <jirislaby@xxxxxxxxx>
>
> commit 7aed55d1085f71241284a30af0300feea48c36db upstream.
>
> Impact: fix debug/crash printout
>
> Since errorcode is popped out, RIP is on the top of the stack.
> Use real RIP value instead of wrong CS.
>
> Signed-off-by: Jiri Slaby <jirislaby@xxxxxxxxx>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
>
> ---
> arch/x86/kernel/head_64.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -305,7 +305,7 @@ ENTRY(early_idt_handler)
> call dump_stack
> #ifdef CONFIG_KALLSYMS
> leaq early_idt_ripmsg(%rip),%rdi
> - movq 8(%rsp),%rsi # get rip again
> + movq 0(%rsp),%rsi # get rip again
> call __print_symbol
> #endif
> #endif /* EARLY_PRINTK */

why not:

movq (%rsp), %rsi

instead? Yes, it's all the same but 0 is just unnecessary.

--
Thanks,
Jike
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