Re: [PATCH] tracing: ring-buffer: allowlist clang-generated symbols

On Wed, 17 Jun 2026 14:26:36 +0100
Vincent Donnefort <[email protected]> wrote:

> On Tue, Jun 16, 2026 at 06:42:03PM +0200, Arnd Bergmann wrote:
> > From: Arnd Bergmann <[email protected]>
> > 
> > In randconfig build testing using clang-22, I came across two
> > sets of extra symbols in the ring buffer code that may get
> > inserted by the compiler:
> > 
> > Unexpected symbols in kernel/trace/simple_ring_buffer.o:
> >          U memset
> > 
> > Unexpected symbols in kernel/trace/simple_ring_buffer.o:
> >                  U llvm_gcda_emit_arcs
> >                  U llvm_gcda_emit_function
> >                  U llvm_gcda_end_file
> >                  U llvm_gcda_start_file
> >                  U llvm_gcda_summary_info
> >                  U llvm_gcov_init
> > 
> > Add all of these to the allowlist.
> > 
> > Signed-off-by: Arnd Bergmann <[email protected]>
> > ---
> >  kernel/trace/Makefile | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> > index f934ff586bd4..aa8564fb8ff4 100644
> > --- a/kernel/trace/Makefile
> > +++ b/kernel/trace/Makefile
> > @@ -146,6 +146,7 @@ KASAN_SANITIZE_undefsyms_base.o := y  
> 
> Would "GCOV_PROFILE_undefsyms_base.o := y" work?

Arnd?

-- Steve

> 
> >  
> >  UNDEFINED_ALLOWLIST = __asan __gcov __kasan __kcsan __hwasan __sancov __sanitizer __tsan __ubsan __msan \
> >  		      __aeabi_unwind_cpp __s390_indirect_jump __x86_indirect_thunk simple_ring_buffer \
> > +		      memset llvm_gcda llvm_gcov \
> >  		      $(shell $(NM) -u $(obj)/undefsyms_base.o 2>/dev/null | awk '{print $$2}')
> >  
> >  quiet_cmd_check_undefined = NM      $<
> > -- 
> > 2.39.5
> >