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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

  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 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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