Re: [RFC PATCH 2/2] sparc64: Support PERF_SAMPLE_REGS_USER and PERF_SAMPLE_STACK_USER

[Stian Halseth <stian@itx.no>]

[-- Attachment #1: Type: text/plain, Size: 921 bytes --]


On Tue, 2026-09-22 at 14:18 +0000, sashiko-bot@kernel.org wrote:
> 
> [Severity: Medium]
> Since HAVE_PERF_USER_STACK_DUMP is selected in Kconfig, shouldn't
> there also
> be an override for perf_user_stack_pointer() here to account for
> STACK_BIAS
> on 64-bit tasks?

Nothing to override. perf_user_stack_pointer() is a plain macro in
kernel/events/internal.h. Also, I don't think we should, as long as
every consumer takes the sampled stack pointer register as the base.

sparc-aware consumers add the 2047 when they interpret the stack. Like
for example ptrace data. It would make sparc the only arch where dump
doesn't begin at the SP register.

> 
> [Severity: Medium]
> Will this unconditionally truncate 64-bit kernel registers for 32-bit
> compat
> tasks?
Yes, will correct that.
Next version truncates only when user_mode(regs), the same test arm64
makes with compat_user_mode().



[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 228 bytes --]