Em Tue, May 24, 2016 at 09:21:28AM +0000, Wang Nan escreveu:
> Before this patch, a simple 'perf record' could fail if kptr_restrict
> is set to 1 (for normal user) or 2 (for root):
>
> # perf record ls
> WARNING: Kernel address maps (/proc/{kallsyms,modules}) are restricted,
> check /proc/sys/kernel/kptr_restrict.
>
> Samples in kernel functions may not be resolved if a suitable vmlinux
> file is not found in the buildid cache or in the vmlinux path.
>
> Samples in kernel modules won't be resolved at all.
>
> If some relocation was applied (e.g. kexec) symbols may be misresolved
> even with a suitable vmlinux or kallsyms file.
>
> Segmentation fault (core dumped)
>
> This patch skips perf_event__synthesize_kernel_mmap() when kptr is not
> available.
>
> Signed-off-by: Wang Nan <[email protected]>
Thanks, applied and added a:
Fixes: 45e90056904b ("perf machine: Do not bail out if not managing to read ref
reloc symbol")
But I'll investigate a bit more later, as the patch fixes the problem,
but I think probably it'd be better to check what is not being set up
in the ref reloc symbol stuff not bailed out by the patch above.
- Arnaldo
> Cc: Arnaldo Carvalho de Melo <[email protected]>
> Cc: Zefan Li <[email protected]>
> Cc: [email protected]
> ---
> tools/perf/util/event.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index f6fcc68..9b141f1 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -673,6 +673,8 @@ int perf_event__synthesize_kernel_mmap(struct perf_tool
> *tool,
> int err;
> union perf_event *event;
>
> + if (symbol_conf.kptr_restrict)
> + return -1;
> if (map == NULL)
> return -1;
>
> --
> 1.8.3.4
