Hi Serhei,

On Thu, Apr 9, 2026 at 4:16 PM Serhei Makarov <[email protected]> wrote:
> On Sun, Apr 5, 2026, at 8:25 PM, Aaron Merey wrote:
> >> +  /* TODO(REVIEW) The existing code in arm_initreg.c has to unpack a
> >> +     register file of 32-bit words into Dwarf_Word array, but here
> >> +     this should have happened already, probably in whatever code
> >> +     unpacks the PERF_RECORD_SAMPLE; or perf_events already provides
> >> +     an array of 64-bit regs?  */
> >
> > kernel/events/core.c:perf_output_sample_regs() looks like it
> > exclusively outputs u64 values so I don't think you need to deal with
> > unpacking 32-bit values here.
> Ok, thanks for checking. Revising the patch to use the default implementation.
>
> >> +   eh->perf_frame_regs_mask = PERF_FRAME_REGISTERS_AARCH64 | 
> >> PERF_FRAME_REGISTERS_ARM;
> >> +*/
> >
> > Seems plausible that for compat processes, perf maps arm regs onto
> > aarch64 regs but I wasn't able to verify this.
> Ok, I'll keep the comment discussing this issue but amend 
> eh->perf_frame_regs_mask
> on aarch64 as the comment suggests. I'll test a 32-bit compat binary on 
> aarch64
> tomorrow.

Ack.

Aaron

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