Re: [PATCH v4 5/6] perf arm_spe: Decode Arm N1 IMPDEF events

On Tue, Apr 14, 2026 at 03:52:02PM +0000, [email protected] wrote:
> Sashiko AI review found 1 potential issue(s):
> - [Low] The relative include path `#include "../../arm64/include/asm/cputype.h"` is invalid and relies on accidental directory traversal through a compiler `-I` flag.
> --
> 
> commit 7fc153524fe60dc6d6f08fd73b7ea3f46e904e39
> Author: James Clark <[email protected]>
> 
> perf arm_spe: Decode Arm N1 IMPDEF events
> 
> This commit adds a framework to decode the N1 IMPDEF event for Arm SPE, 
> which isn't covered by the common list. It also increases the packet 
> description buffer size to accommodate more strings without falling back 
> to a hex dump.
> 
> Link: https://developer.arm.com/documentation/100616/0401/Statistical-Profiling-Extension/implementation-defined-features-of-SPE
> 
> > diff --git a/tools/perf/util/arm-spe-decoder/Build b/tools/perf/util/arm-spe-decoder/Build
> > index ab500e0efe244..97a298d1e2791 100644
> > --- a/tools/perf/util/arm-spe-decoder/Build
> > +++ b/tools/perf/util/arm-spe-decoder/Build
> > @@ -1 +1,3 @@
> >  perf-util-y += arm-spe-pkt-decoder.o arm-spe-decoder.o
> > +
> > +CFLAGS_arm-spe-pkt-decoder.o += -I$(srctree)/tools/arch/arm64/include/ -I$(OUTPUT)arch/arm64/include/generated/
> 
> [ ... ]
> 
> > diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
> > index 67ca356100e53..b74f887a48f2a 100644
> > --- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
> > +++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
> > @@ -15,6 +15,8 @@
> >  
> >  #include "arm-spe-pkt-decoder.h"
> >  
> > +#include "../../arm64/include/asm/cputype.h"
> 
> Is this relative include path correct?
> 
> It looks like this file is located in tools/perf/util/arm-spe-decoder/, so
> the relative path resolves to tools/perf/arm64/include/asm/cputype.h,
> which doesn't exist.
> 
> It seems this only compiles because the newly added -I flag in the Build
> file causes the preprocessor to resolve the include relative to
> tools/arch/arm64/include/. The path then inadvertently evaluates back to the
> correct file by traversing backwards out of the include directory and diving
> back in.
> 
> Could this be made less brittle by relying directly on the include flag,
> using #include <asm/cputype.h> instead?

This is just a possible improvement and not strictly a problem as the -I
is structured today, so lets not postpone processing this patchset
because of this, this can be considered some other time.

- Arnaldo