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Message-ID: <20160524122630.GQ8897@kernel.org> Date: Tue, 24 May 2016 09:26:30 -0300 From: Arnaldo Carvalho de Melo <acme@...nel.org> To: Wang Nan <wangnan0@...wei.com> Cc: pi3orama@....com, linux-kernel@...r.kernel.org, Arnaldo Carvalho de Melo <acme@...hat.com>, Zefan Li <lizefan@...wei.com> Subject: Re: [PATCH 2/2] perf record: Fix crash when kptr is restricted 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): sorry, hadn't seen this one, applying. :-) - Arnaldo > # 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 <wangnan0@...wei.com> > Cc: Arnaldo Carvalho de Melo <acme@...hat.com> > Cc: Zefan Li <lizefan@...wei.com> > Cc: pi3orama@....com > --- > 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
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