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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date: Fri, 15 Dec 2023 16:53:48 -0800
Message-ID: <CAADnVQJoEkdjyCEJRPASjBw1QGsKYrF33QdMGc1RZa9b88bAEA@mail.gmail.com>
Subject: Re: [PATCH v3 0/7] x86/cfi,bpf: Fix CFI vs eBPF
To: Peter Zijlstra <peterz@infradead.org>, Ilya Leoshkevich <iii@linux.ibm.com>, 
	Martin KaFai Lau <martin.lau@kernel.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, 
	Albert Ou <aou@eecs.berkeley.edu>, Thomas Gleixner <tglx@linutronix.de>, 
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, 
	Dave Hansen <dave.hansen@linux.intel.com>, X86 ML <x86@kernel.org>, 
	"H. Peter Anvin" <hpa@zytor.com>, "David S. Miller" <davem@davemloft.net>, David Ahern <dsahern@kernel.org>, 
	Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>, 
	Martin KaFai Lau <martin.lau@linux.dev>, Song Liu <song@kernel.org>, 
	Yonghong Song <yonghong.song@linux.dev>, John Fastabend <john.fastabend@gmail.com>, 
	KP Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>, 
	Jiri Olsa <jolsa@kernel.org>, Arnd Bergmann <arnd@arndb.de>, 
	Sami Tolvanen <samitolvanen@google.com>, Kees Cook <keescook@chromium.org>, 
	Nathan Chancellor <nathan@kernel.org>, Nick Desaulniers <ndesaulniers@google.com>, 
	linux-riscv <linux-riscv@lists.infradead.org>, LKML <linux-kernel@vger.kernel.org>, 
	Network Development <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>, 
	linux-arch <linux-arch@vger.kernel.org>, clang-built-linux <llvm@lists.linux.dev>, 
	Josh Poimboeuf <jpoimboe@kernel.org>, Joao Moreira <joao@overdrivepizza.com>, 
	Mark Rutland <mark.rutland@arm.com>
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On Fri, Dec 15, 2023 at 1:33=E2=80=AFAM Peter Zijlstra <peterz@infradead.or=
g> wrote:
>
> Hi!
>
> What started with the simple observation that bpf_dispatcher_*_func() was
> broken for calling CFI functions with a __nocfi calling context for FineI=
BT
> ended up with a complete BPF wide CFI fixup.
>
> With these changes on the BPF selftest suite passes without crashing -- t=
here's
> still a few failures, but Alexei has graciously offered to look into thos=
e.
>
> (Alexei, I have presumed your SoB on the very last patch, please update
> as you see fit)
>
> Changes since v2 are numerous but include:
>  - cfi_get_offset() -- as a means to communicate the offset (ast)
>  - 5 new patches fixing various BPF internals to be CFI clean

Looks great to me. Pushed to bpf-next.

There is a failure on s390 that I temporarily denylisted
with an extra patch.
And sent a proposed fix:
https://lore.kernel.org/bpf/20231216004549.78355-1-alexei.starovoitov@gmail=
.com/

Ilya,
please take a look.

> Note: it *might* be possible to merge the
> bpf_bpf_tcp_ca.c:unsupported_ops[] thing into the CFI stubs, as is
> get_info will have a NULL stub, unlike the others.

That's a good idea. Will clean up unsupported_ops.
Either myself or Martin will follow up.