Re: [PATCH 07/12] perf_events: add LBR software filter support forIntel X86

[Peter Zijlstra]

On Fri, 2011-10-07 at 17:09 +0200, Andi Kleen wrote:
> > if (kernel_ip(addr) || !test_tsk_thread_flag(current, TIF_IA32))
> 
> That's not good, a 64bit process can do 32bit syscalls.
> 
> The only fully working way is to check the code segment, unfortunately
> that requires checking the LDT to be fully correct :-(

I can't really be arsed about people doing daft shit like that. The
worst that happens is that their PEBS fixup fails. Honestly if you do
crazy things like that you deserve far far worse.


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