linux-kernel - Re: [PATCH 1/2] bpf: Add bpf_has_frame

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Message-ID: <6l5jgeoajy7jtkpfpk7iaglmauyempa4uctbvn32syrmgvqqej@ls7qvu2nqpir>
Date: Tue, 2 Dec 2025 15:10:15 -0800
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org, live-patching@...r.kernel.org, 
	bpf@...r.kernel.org, Andrey Grodzovsky <andrey.grodzovsky@...wdstrike.com>, 
	Petr Mladek <pmladek@...e.com>, Song Liu <song@...nel.org>, 
	Raja Khan <raja.khan@...wdstrike.com>, Miroslav Benes <mbenes@...e.cz>, 
	Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH 1/2] bpf: Add bpf_has_frame_pointer()

On Tue, Dec 02, 2025 at 10:19:18AM -0800, Josh Poimboeuf wrote:
> @@ -3299,6 +3304,8 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
>  	}
>  	EMIT1(0x55);		 /* push rbp */
>  	EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */
> +	im->ksym.fp_start = prog - (u8 *)rw_image;

CI is reporting NULL pointer deref here, @im can be NULL.  Will fix.

-- 
Josh