linux-kernel - Process context of perf sample from interrupt handler

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Message-ID: <CALe4XzZsRBQZNjAPEGZfOHYO0fP6qL3y0jGNhBZ57q2XGV8VFA@mail.gmail.com>
Date:   Wed, 4 Oct 2017 09:54:16 -0400
From:   Probir Roy <proy.cse@...il.com>
To:     linux-kernel@...r.kernel.org
Subject: Process context of perf sample from interrupt handler

Hi,

I'm writing a Linux kernel module that uses debug-register to sample
Linux kernel using perf interface "register_wide_hw_breakpoint". I am
interested to get the "callchain" of the process context at the sample
handler. For this I have set PERF_SAMPLE_CALLCHAIN as a sample type.

One issue is that the associated instruction pointer(IP) and
callchain(perf_callchain) of the samples belongs to nmi context rather
than process context. How can I collect the information associated
with process context rather than nmi context? Previously, I have done
sampling from user-space which gave me correct callchain. But I cannot
make it work from kernel space. Any help would be appreciated.

Regards,
Probir