Re: [PATCH v2 5/7] perf/amd/ibs: Enable RIP bit63 hardware filtering

[Ravi Bangoria]

Hi Ian,

>> Does the bit 63 assumption hold for guest operating systems?
> 
> Yes, this seems to be an issue, even with current swfilt approach. Let
> me inspect the code and get back.

All mainstream 64 bit OSes use the bit-63 set for kernel addresses and zero
for userspace addresses. This norm does not apply to 32 bit guests, but
those are rare, and profiling them with IBS would be even rarer. So, I'll
document this limitation in the perf-amd-ibs man page.

While looking at this, I found some issues in IBS. Below patch fixes it:

---