Re: [RFC][PATCH 07/11] perf: Provide PERF_SAMPLE_REGS

David Miller
2010-03-03T17:55:37Z

From: Stephane Eranian <eranian@google.com>
Date: Wed, 3 Mar 2010 09:49:33 -0800

> On Wed, Mar 3, 2010 at 9:39 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>> On Wed, 2010-03-03 at 09:30 -0800, Stephane Eranian wrote:
>>> This assumes struct pt_regs is somehow exported to userland.
>>> Is that the case?
>>
>> I seems to have understood they were, and asm/ptrace.h seems to agree
>> with that, it has !__KERNEL__ definitions for struct pt_regs.
>>
> Seems to be the case, indeed.

BTW, how are you going to cope with compat systems?

If I build 'perf' on a sparc64 kernel build, it's going to get the
64-bit pt_regs. So I can't then use that binary on a sparc box
running a 32-bit kernel.

And vice versa.

And more generally aren't we supposed to be able to eventually analyze
perf dumps on any platform not just the one 'perf' was built under?

We'll need to do something about the encoding of pt_regs, therefore.