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References: <20240227151115.4623-1-puranjay12@gmail.com>
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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date: Mon, 11 Mar 2024 18:26:11 -0700
Message-ID: <CAADnVQLPf2-saMJxv65zqDAjc8JX-08dRUP3hbrAh=q+2xiqzg@mail.gmail.com>
Subject: Re: [PATCH bpf-next 0/1] Support kCFI + BPF on arm64
To: Puranjay Mohan <puranjay12@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, 
	Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, 
	Andrii Nakryiko <andrii@kernel.org>, Martin KaFai Lau <martin.lau@linux.dev>, 
	Eduard Zingerman <eddyz87@gmail.com>, 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>, Zi Shen Lim <zlim.lnx@gmail.com>, 
	Mark Rutland <mark.rutland@arm.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, 
	Mark Brown <broonie@kernel.org>, 
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, 
	open list <linux-kernel@vger.kernel.org>, 
	"open list:BPF [GENERAL] (Safe Dynamic Programs and Tools)" <bpf@vger.kernel.org>, Josh Poimboeuf <jpoimboe@kernel.org>
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On Tue, Feb 27, 2024 at 7:11=E2=80=AFAM Puranjay Mohan <puranjay12@gmail.co=
m> wrote:
>
> On ARM64 with CONFIG_CFI_CLANG, CFI warnings can be triggered by running
> the bpf selftests. This is because the JIT doesn't emit proper CFI prolog=
ues
> for BPF programs, callbacks, and struct_ops trampolines.
>
> Example Warning:
>
>  CFI failure at bpf_rbtree_add_impl+0x120/0x1d4 (target: bpf_prog_fb8b097=
ab47d164a_less+0x0/0x98; expected type: 0x9e4709a9)
>  WARNING: CPU: 0 PID: 1488 at bpf_rbtree_add_impl+0x120/0x1d4

..

> Running the selftests causes no CFI warnings:
> ---------------------------------------------
>
> test_progs: Summary: 454/3613 PASSED, 62 SKIPPED, 74 FAILED
> test_tag: OK (40945 tests)
> test_verifier: Summary: 789 PASSED, 0 SKIPPED, 0 FAILED

Catalin, Mark,

Could you please review and hopefully ack arm64 generic bits ?

The JIT changes largely mimic x86 changes and look correct to me.