Re: [PATCH 3/5] perf util: Introduce architecture specific errno/name mapping

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Thu, Jan 18, 2018 at 11:07:33AM +0100, Jiri Olsa escreveu:
> On Tue, Jan 16, 2018 at 10:46:29AM +0100, Hendrik Brueckner wrote:
> 
> SNIP
> 
> > index 12dec6e..90ce14f 100644
> > --- a/tools/perf/Makefile.config
> > +++ b/tools/perf/Makefile.config
> > @@ -249,7 +249,7 @@ INC_FLAGS += -I$(srctree)/tools/arch/$(SRCARCH)/include/uapi
> >  INC_FLAGS += -I$(srctree)/tools/arch/$(SRCARCH)/include/
> >  INC_FLAGS += -I$(srctree)/tools/arch/$(SRCARCH)/
> >  
> > -# $(obj-perf)      for generated common-cmds.h
> > +# $(obj-perf)      for generated common-cmds.h and errno-names.c
> >  # $(obj-perf)/util for generated bison/flex headers
> >  ifneq ($(OUTPUT),)
> >  INC_FLAGS += -I$(obj-perf)/util
> > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> > index 9fdefd7..332b4b4 100644
> > --- a/tools/perf/Makefile.perf
> > +++ b/tools/perf/Makefile.perf
> > @@ -518,6 +518,9 @@ $(OUTPUT)common-cmds.h: util/generate-cmdlist.sh command-list.txt
> >  $(OUTPUT)common-cmds.h: $(wildcard Documentation/perf-*.txt)
> >  	$(QUIET_GEN). util/generate-cmdlist.sh > $@+ && mv $@+ $@
> >  
> > +$(OUTPUT)util/errno-names.c: util/generate-errno-names.sh
> > +	$(QUIET_GEN). util/generate-errno-names.sh "$(CC)" "$(srctree)/tools" > $@+ && mv $@+ $@
> 
> so this generates errno-names.c with following code:
> 
> const char *arch_errno_to_name(const char *arch, int err)
> {
>         if (!strcmp(arch, "alpha"))
>                 return errno_to_name__alpha(err);
>         if (!strcmp(arch, "arm"))
>                 return errno_to_name__arm(err);
>         if (!strcmp(arch, "arm64"))
>                 return errno_to_name__arm64(err);
> 
> 
> is there a reason why we want all archs compiled in?
> I'd think we just need the arch perf is built in

think about:

On an arm64 system:

	perf trace record -a sleep 1

scp that to an x86_64 system and do:

	perf trace -i perf.data

But doing that strcmp per call seems excessive, perhaps we could have
something like:

	trace->arch = arch_syscalls__init(arch_name);

	char *s = arch_syscalls__strerrno(trace->arch, err);

Have to look at the code to find the right naming according to what we
already have.

- Arnaldo
- Arnaldo