[PATCH] PR32930 backends/: guard asm/perf_regs.h include

[Aaron Merey]

Hi Serhei,

On Mon, May 5, 2025 at 12:26 PM Serhei Makarov <serhei@serhei.io> wrote:
>
> asm/perf_regs.h is an arch-specific linux include, not present on
> architectures like hppa and m68k that lack perf_events support.
>
> Only one place we need to fix; others already guard the include by
> architecture, or use architecture-independent headers (e.g.
> linux/perf_events.h).
>
> * backends/libebl_PERF_FLAGS.h: Only include asm/perf_regs.h on
>   architectures where we use it.
> ---
>  backends/libebl_PERF_FLAGS.h | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/backends/libebl_PERF_FLAGS.h b/backends/libebl_PERF_FLAGS.h
> index 2ed45f0f..51c20ea6 100644
> --- a/backends/libebl_PERF_FLAGS.h
> +++ b/backends/libebl_PERF_FLAGS.h
> @@ -32,8 +32,12 @@
>  #define _LIBEBL_PERF_FLAGS_H 1
>
>  #if defined(__linux__)
> +/* XXX Need to exclude __linux__ arches without perf_regs.h. */
> +#if defined(__x86_64__) || defined(__i386__)
> +/* || defined(other_architecture)... */
>  # include <asm/perf_regs.h>
>  #endif
> +#endif
>
>  #if defined(_ASM_X86_PERF_REGS_H)
>  /* See the code in x86_initreg_sample.c for list of required regs and
> @@ -49,8 +53,8 @@
>     see the code in tools/perf/util/intel-pt.c intel_pt_add_gp_regs()
>     and note how regs are added in the same order as the perf_regs.h enum.  */
>  #else
> -/* Since asm/perf_regs.h gives the register layout for a different arch,
> -   we can't unwind x86_64 frames.  */
> +/* Since asm/perf_regs.h is absent, or gives the register layout for a
> +   different arch, we can't unwind i386 and x86_64 frames. */
>  #define PERF_FRAME_REGISTERS_I386 0
>  #define PERF_FRAME_REGISTERS_X86_64 0
>  #endif
> --
> 2.47.0
>

So if the arch is not x86_64 or i386, then PERF_FRAME_REGISTERS_* will
be 0 and this signals to the backend to skip any unwinding. LGTM.

Aaron