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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Mon, 4 Dec 2023 08:28:21 -0800
Message-ID: <CAKwvOd=ZgoeXQAZZoLNYmd0OyuHktsnxLtcKzH4MEoDkPXnqyA@mail.gmail.com>
Subject: Re: [PATCH 2/2] x86/cfi,bpf: Fix BPF JIT call
To:     Sami Tolvanen <samitolvanen@google.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        paul.walmsley@sifive.com, palmer@dabbelt.com,
        aou@eecs.berkeley.edu, tglx@linutronix.de, mingo@redhat.com,
        bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
        hpa@zytor.com, davem@davemloft.net, dsahern@kernel.org,
        ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
        martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev,
        john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com,
        haoluo@google.com, jolsa@kernel.org, Arnd Bergmann <arnd@arndb.de>,
        keescook@chromium.org, nathan@kernel.org,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, bpf@vger.kernel.org,
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On Fri, Dec 1, 2023 at 3:54=E2=80=AFPM Sami Tolvanen <samitolvanen@google.c=
om> wrote:
>
> On Wed, Nov 22, 2023 at 3:15=E2=80=AFAM Peter Zijlstra <peterz@infradead.=
org> wrote:
> >
> > So the kCFI thing is 'new' but readily inspected by objdump or godbolt:
> >
> >   https://godbolt.org/z/sGe18z3ca
> >
> > (@Sami, that .Ltmp15 thing, I don't see that in the kernel, what
> > compiler flag makes that go away?)
>
> Hmm, that looks like that's what we emit to .kcfi_traps. I suppose
> Godbolt just doesn't show the section directives?

Filter > [uncheck] Directives

>
> https://github.com/llvm/llvm-project/blob/main/llvm/test/CodeGen/X86/kcfi=
.ll#L30
>
> Sami


--=20
Thanks,
~Nick Desaulniers