[PATCH] arm64: perf: fix syscalltbl path base

[Arnd Bergmann]

On Mon, Dec 15, 2025, at 17:49, Leo Yan wrote:
> On Mon, Dec 15, 2025 at 01:22:04PM +0100, Arnd Bergmann wrote:
> As discussed in [1], I would prefer to drop these headers, but Ian
> noted that this could break builds with older toolchains.

I didn't find the reference to breaking, do you just mean it
would break when falling back to a header provided by the
toolchain's own asm/unistd.h, or a problem with the modern
generated version that is solved by using the old asm-generic
file?

> Generating the headers dynamically would avoid maintaining duplicated
> copies under tools/ and no need for periodic syncs.  However, this is a
> quite big effort, not just perf, we need to update makefiles to the path
> of the installed headers.  I'd like to hear opinions from tools
> (perf/bpf/selftest) maintainers before proceeding.

I see that we do ship the sources for generating headers on
most architectures in tools/perf/arch/*/entry/syscalls/syscall*.tbl,
the only exceptions being mips-o32, mips-n32 and x86.

I would also point out that s390 no longer needs a custom script
as of 6.19, since the last incompatibility between the s390 format
and the x86 format of the tbl files got resolved with the removal
of the s390 compat mode.

>> or we just stick with
>> the old asm-generic/unistd.h copy and use that on arm64 as well.
>
> I will proceed this way for now.  From a maintenance view, it is a
> pragmatic solution that only requires reverting a few patches and does
> not introduce any new code.

Note that if we ever need to update the
tools/include/uapi/asm-generic/unistd.h file for new syscalls,
that will get harder in the future once we remove the
kernel's own include/uapi/asm-generic/unistd.h. I'm sorry
I never sent that fix after the previous cleanup that introduced
the common script.

     Arnd