linux-kernel - Re: [PATCH 0/9] x86/bpf: unwinder fixes

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Message-ID: <F836C59D-3C80-4D45-9BB8-34FF893A22EB@fb.com>
Date:   Thu, 13 Jun 2019 19:00:23 +0000
From:   Song Liu <songliubraving@...com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
CC:     "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        "Daniel Borkmann" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "Peter Zijlstra" <peterz@...radead.org>,
        Kairui Song <kasong@...hat.com>
Subject: Re: [PATCH 0/9] x86/bpf: unwinder fixes



> On Jun 13, 2019, at 6:20 AM, Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> 
> The following commit
> 
>  d15d356887e7 ("perf/x86: Make perf callchains work without CONFIG_FRAME_POINTER")
> 
> was a step in the right direction, but it triggered some BPF selftest
> failures.  That commit exposed the fact that we currently can't unwind
> through BPF code.
> 
> - Patch 1 (originally from Song Liu) fixes a bug in the above commit
>  (regs->ip getting skipped in the stack trace).
> 
> - Patch 2 fixes non-JIT BPF for the ORC unwinder.
> 
> - Patches 3-5 are preparatory improvements for patch 6.
> 
> - Patch 6 fixes JIT BPF for the FP unwinder.
> 
> - Patch 7 fixes JIT BPF for the ORC unwinder (building on patch 6).
> 
> - Patches 8-9 are some readability cleanups.

These work well in my tests. Thanks!

Tested-by: Song Liu <songliubraving@...com>

> 
> 
> Josh Poimboeuf (8):
>  objtool: Fix ORC unwinding in non-JIT BPF generated code
>  x86/bpf: Move epilogue generation to a dedicated function
>  x86/bpf: Simplify prologue generation
>  x86/bpf: Support SIB byte generation
>  x86/bpf: Fix JIT frame pointer usage
>  x86/unwind/orc: Fall back to using frame pointers for generated code
>  x86/bpf: Convert asm comments to AT&T syntax
>  x86/bpf: Convert MOV function/macro argument ordering to AT&T syntax
> 
> Song Liu (1):
>  perf/x86: Always store regs->ip in perf_callchain_kernel()
> 
> arch/x86/events/core.c       |  10 +-
> arch/x86/kernel/unwind_orc.c |  26 ++-
> arch/x86/net/bpf_jit_comp.c  | 355 ++++++++++++++++++++---------------
> kernel/bpf/core.c            |   5 +-
> tools/objtool/check.c        |  16 +-
> 5 files changed, 246 insertions(+), 166 deletions(-)
> 
> -- 
> 2.20.1
>