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SubjectRe: Valgrinding the kernel?
Jeff Dike wrote:
> On Fri, Jul 06, 2007 at 10:30:19AM -0700, Dan Kegel wrote:
>
>> Could you give it a shot?
>>
>
> OK, after ripping out the code that broke valgrind last time (patch
> below), I get this:
>
> ==27590== Warning: set address range perms: large range 516194304, a 0, v 0
>

Hm, wonder what that is...

> vex x86->IR: unhandled instruction bytes: 0xF3 0xAF 0x74 0x9
> ==27590== Your program just tried to execute an instruction that Valgrind
> ==27590== did not recognise. There are two possible reasons for this.
> ==27590== 1. Your program has a bug and erroneously jumped to a non-code
> ==27590== location. If you are running Memcheck and you just saw a
> ==27590== warning about a bad jump, it's probably your program's fault.
> ==27590== 2. The instruction is legitimate but Valgrind doesn't handle it,
> ==27590== i.e. it's Valgrind's fault. If you think this is the case or
> ==27590== you are not sure, please let us know.
> ==27590== Either way, Valgrind will now raise a SIGILL signal which will
> ==27590== probably kill your program.
> ==27590==
>
>
>> Maybe the problems after that will be more pedestrian.
>>
>
> Doesn't look like it.
>
> FWIW, that instruction is repz scas. In an earlier valgrind effort in
> 2002, I hit repe scas
> (http://www.goop.org/~jeremy/valgrind/76-repe-scas.patch), so maybe
> something similar is needed here.
>

The virtual CPU code has been competely rewritten since then. If its a
non-gcc generated instruction, its possible the new code
parser/generator hasn't been taught to deal with it.

>> I'm willing to focus a little effort on this.
>>
>
> I guess you'll have to fix valgrind's various bugs. See, simple :)
>

Exactly ;)

J
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