[PATCH] perf syscalltbl: Add syscalltbl__id_at_idx() with no syscall table support

[Ian Rogers]

On Tue, Sep 24, 2024 at 8:26 AM Charlie Jenkins <charlie at rivosinc.com> wrote:
>
> On Fri, Aug 30, 2024 at 09:30:50PM -0700, Charlie Jenkins wrote:
> > When HAVE_SYSCALL_TABLE_SUPPORT is not defined, neither is
> > syscalltbl__id_at_idx(). However, this function is expected to be
> > defined when HAVE_BPF_SKEL is defined.
> >
> > Return -1 from syscalltbl__id_at_idx() to match the other functions when
> > HAVE_SYSCALL_TABLE_SUPPORT is not defined.
> >
> > Without this, compiling perf on riscv when libtraceevents, libelf, and
> > clang are available will cause the functions trying to call
> > syscalltbl__id_at_idx() to be compiled. This results in the following
> > error:
> >
> > /usr/bin/ld: perf-in.o: in function `.L0 ':
> > builtin-trace.c:(.text+0x60b14): undefined reference to `syscalltbl__id_at_idx'
> > /usr/bin/ld: builtin-trace.c:(.text+0x60c6c): undefined reference to `syscalltbl__id_at_idx'
> > /usr/bin/ld: perf-in.o: in function `.L2564':
> > builtin-trace.c:(.text+0x60cb6): undefined reference to `syscalltbl__id_at_idx'
> > collect2: error: ld returned 1 exit status
> > make[2]: *** [Makefile.perf:793: perf] Error 1
> > make[1]: *** [Makefile.perf:290: sub-make] Error 2
> > make: *** [Makefile:70: all] Error 2
> > make: Leaving directory '/src/linux-6.11-rc5/tools/perf'
> >
> > This patch resolves this issue for all architectures which do not define
> > HAVE_SYSCALL_TABLE_SUPPORT.
> >
> > $ ./perf trace -e syscalls:sys_enter_mmap --max-events=1 ls
> > 0.000 ls/287 syscalls:sys_enter_mmap(__syscall_nr: 222, len: 9939, prot: READ, flags: PRIVATE, fd: 3)
> >
> > Signed-off-by: Charlie Jenkins <charlie at rivosinc.com>
> > Reported-by: David Abdurachmanov <davidlt at rivosinc.com>
> > Suggested-by: David Abdurachmanov <davidlt at rivosinc.com>
> > Fixes: 7a2fb5619cc1 ("perf trace: Fix iteration of syscall ids in syscalltbl->entries")
> > ---
> >  tools/perf/util/syscalltbl.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/tools/perf/util/syscalltbl.c b/tools/perf/util/syscalltbl.c
> > index 0dd26b991b3f..12654460428f 100644
> > --- a/tools/perf/util/syscalltbl.c
> > +++ b/tools/perf/util/syscalltbl.c
> > @@ -188,4 +188,9 @@ int syscalltbl__strglobmatch_first(struct syscalltbl *tbl, const char *syscall_g
> >  {
> >       return syscalltbl__strglobmatch_next(tbl, syscall_glob, idx);
> >  }
> > +
> > +int syscalltbl__id_at_idx(struct syscalltbl *tbl __always_unused, int idx __always_unused)
> > +{
> > +     return -1;
> > +}
> >  #endif /* HAVE_SYSCALL_TABLE_SUPPORT */
> >
> > ---
> > base-commit: 985bf40edf4343dcb04c33f58b40b4a85c1776d4
> > change-id: 20240830-perf_syscalltbl_fix-4f586221795e
> > --
> > - Charlie
> >
>
> Can this please be picked up? Compilation on riscv (along with any of
> the other architectures that don't have syscall table support) is
> broken. The long term solution is to add support for the syscall table
> on riscv. I will send out a patch for that, but in the meantime it would
> be great to have this in the tree.

I thought something had been done:
https://lore.kernel.org/lkml/739001a4-4df1-4dec-a141-926c78c5c07e@kernel.org/
Not sure what's happened.

Thanks,
Ian