Re: [Xen-devel] [PATCHv1 for-4.7] x86: show correct code in CPU state

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 03/05/16 17:15, David Vrabel wrote:
> When showing the CPU state (e.g., after a crash) the dump of code
> around RIP is incorrect.
>
> Incorrect:
>
>     Xen code around <ffff82d0801113cf> (...):
>      00 c6 c1 ee 08 48 c1 e0 <04> 03 04 f1 8b ...
>      ^^ Uninitialized         ^^ Missing 0x48
>
> Correct:
>
>     Xen code around <ffff82d0801113cf> (...):
>      c6 c1 ee 08 48 c1 e0 04 <48> 03 04 f1 8b ...
>
> When coping the bytes before RIP, the destination was off-by-one.
>
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

CC'ing Wei for release ack.

> ---
>  xen/arch/x86/traps.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
> index 8384158..0895441 100644
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -150,7 +150,7 @@ static void show_code(const struct cpu_user_regs *regs)
>                    : "=&c" (missing_before),
>                      "=&D" (tmp), "=&S" (tmp)
>                    : "0" (ARRAY_SIZE(insns_before)),
> -                    "1" (insns_before + ARRAY_SIZE(insns_before)),
> +                    "1" (insns_before + ARRAY_SIZE(insns_before) - 1),
>                      "2" (regs->rip - 1));
>      clac();
>  


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