Hi Adrian,
On Wed, Sep 04, 2019 at 10:26:13AM +0300, Adrian Hunter wrote:
[...]
> > Could you take chance to review my below replying? I'd like to get
> > your confirmation before I send out offical patch.
>
> It is not necessary to do kallsyms__parse for x86_64, so it would be better
> to check the arch before calling that.
Thanks for suggestion, will do it in the formal patch.
> However in general, having to copy and use kallsyms with perf.data if on a
> different arch does not seem very user friendly.
Agree. Seems it's more reasonable to save related info in
perf.data; TBH, I have no idea for how to do that.
> But really that is up to Arnaldo.
@Arnaldo, if possible could you take a look for below change?
If you don't think below code is the right thing and it's not a common
issue, then maybe it's more feasible to resolve this issue only for
Arm CoreSight specific.
Please let me know how about you think for this?
Thanks,
Leo Yan
> >> For your question for taking a perf.data file to a machine with a
> >> different architecture, we can firstly use command 'perf buildid-list'
> >> to print out the buildid for kallsyms, based on the dumped buildid we
> >> can find out the location for the saved kallsyms file; then we can use
> >> option '--kallsyms' to specify the offline kallsyms file and use the
> >> offline kallsyms to fixup kernel start address. The detailed commands
> >> are listed as below:
> >>
> >> root@debian:~# perf buildid-list
> >> 7b36dfca8317ef74974ebd7ee5ec0a8b35c97640 [kernel.kallsyms]
> >> 56b84aa88a1bcfe222a97a53698b92723a3977ca /usr/lib/systemd/systemd
> >> 0956b952e9cd673d48ff2cfeb1a9dbd0c853e686 /usr/lib/aarch64-linux-gnu/libm-2.28.so
> >> [...]
> >>
> >> root@debian:~# perf script --kallsyms ~/.debug/\[kernel.kallsyms\]/7b36dfca8317ef74974ebd7ee5ec0a8b35c97640/kallsyms
> >>
> >> The amended patch is as below, please review and always welcome
> >> any suggestions or comments!
> >>
> >> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> >> index 5734460fc89e..593f05cc453f 100644
> >> --- a/tools/perf/util/machine.c
> >> +++ b/tools/perf/util/machine.c
> >> @@ -2672,9 +2672,26 @@ int machine__nr_cpus_avail(struct machine *machine)
> >> return machine ? perf_env__nr_cpus_avail(machine->env) : 0;
> >> }
> >>
> >> +static int machine__fixup_kernel_start(void *arg,
> >> + const char *name __maybe_unused,
> >> + char type,
> >> + u64 start)
> >> +{
> >> + struct machine *machine = arg;
> >> +
> >> + type = toupper(type);
> >> +
> >> + /* Fixup for text, weak, data and bss sections. */
> >> + if (type == 'T' || type == 'W' || type == 'D' || type == 'B')
> >> + machine->kernel_start = min(machine->kernel_start, start);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> int machine__get_kernel_start(struct machine *machine)
> >> {
> >> struct map *map = machine__kernel_map(machine);
> >> + char filename[PATH_MAX];
> >> int err = 0;
> >>
> >> /*
> >> @@ -2696,6 +2713,22 @@ int machine__get_kernel_start(struct machine *machine)
> >> if (!err && !machine__is(machine, "x86_64"))
> >> machine->kernel_start = map->start;
> >> }
> >> +
> >> + if (symbol_conf.kallsyms_name != NULL) {
> >> + strncpy(filename, symbol_conf.kallsyms_name, PATH_MAX);
> >> + } else {
> >> + machine__get_kallsyms_filename(machine, filename, PATH_MAX);
> >> +
> >> + if (symbol__restricted_filename(filename, "/proc/kallsyms"))
> >> + goto out;
> >> + }
> >> +
> >> + if (kallsyms__parse(filename, machine, machine__fixup_kernel_start))
> >> + pr_warning("Fail to fixup kernel start address. skipping...\n");
> >> +
> >> +out:
> >> return err;
> >> }
> >>
> >>
> >> Thanks,
> >> Leo Yan
> >
>
