From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Alexei Starovoitov <ast@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Kairui Song <kasong@redhat.com>, Song Liu <songliubraving@fb.com>,
lkml <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>
Subject: Re: Getting empty callchain from perf_callchain_kernel()
Date: Wed, 22 May 2019 12:45:17 -0500 [thread overview]
Message-ID: <20190522174517.pbdopvookggen3d7@treble> (raw)
In-Reply-To: <ab047883-69f6-1175-153f-5ad9462c6389@fb.com>
On Wed, May 22, 2019 at 02:49:07PM +0000, Alexei Starovoitov wrote:
> The one that is broken is prog_tests/stacktrace_map.c
> There we attach bpf to standard tracepoint where
> kernel suppose to collect pt_regs before calling into bpf.
> And that's what bpf_get_stackid_tp() is doing.
> It passes pt_regs (that was collected before any bpf)
> into bpf_get_stackid() which calls get_perf_callchain().
> Same thing with kprobes, uprobes.
Is it trying to unwind through ___bpf_prog_run()?
If so, that would at least explain why ORC isn't working. Objtool
currently ignores that function because it can't follow the jump table.
--
Josh
next prev parent reply other threads:[~2019-05-22 17:45 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-16 23:51 Getting empty callchain from perf_callchain_kernel() Song Liu
2019-05-17 7:46 ` Peter Zijlstra
2019-05-17 8:10 ` Peter Zijlstra
2019-05-17 8:15 ` Kairui Song
2019-05-17 8:32 ` Kairui Song
2019-05-17 16:22 ` Song Liu
2019-05-17 9:10 ` Peter Zijlstra
2019-05-17 18:40 ` Song Liu
2019-05-17 21:06 ` Alexei Starovoitov
2019-05-17 21:48 ` Song Liu
2019-05-19 18:07 ` Kairui Song
2019-05-20 17:22 ` Song Liu
2019-05-22 13:51 ` Peter Zijlstra
2019-05-19 18:06 ` Kairui Song
2019-05-20 17:16 ` Song Liu
2019-05-20 17:19 ` Song Liu
2019-05-22 14:02 ` Peter Zijlstra
2019-05-22 14:49 ` Alexei Starovoitov
2019-05-22 17:45 ` Josh Poimboeuf [this message]
2019-05-22 23:46 ` Josh Poimboeuf
2019-05-23 6:48 ` Kairui Song
2019-05-23 8:27 ` Song Liu
2019-05-23 9:11 ` Kairui Song
2019-05-23 13:32 ` Josh Poimboeuf
2019-05-23 14:50 ` Kairui Song
2019-05-23 15:24 ` Josh Poimboeuf
2019-05-23 16:41 ` Kairui Song
2019-05-23 17:27 ` Josh Poimboeuf
2019-05-24 2:20 ` Kairui Song
2019-05-24 23:23 ` Josh Poimboeuf
2019-05-27 11:57 ` Kairui Song
2019-06-06 16:04 ` Song Liu
2019-06-06 23:58 ` Josh Poimboeuf
2019-06-11 21:03 ` Josh Poimboeuf
2019-05-24 8:53 ` Peter Zijlstra
2019-05-24 13:05 ` Josh Poimboeuf
2019-06-12 3:05 ` Josh Poimboeuf
2019-06-12 8:54 ` Peter Zijlstra
2019-06-12 14:50 ` Josh Poimboeuf
2019-06-13 20:26 ` Josh Poimboeuf
2019-06-12 13:10 ` Steven Rostedt
2019-06-12 14:26 ` Josh Poimboeuf
2019-05-22 18:07 ` Josh Poimboeuf
2019-05-22 21:55 ` Alexei Starovoitov
2019-05-17 16:32 ` Song Liu
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