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From: Ingo Molnar <mingo@kernel.org>
To: "Joan Bruguera Micó" <joanbrugueram@gmail.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Uros Bizjak <ubizjak@gmail.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH 2/2] x86/bpf: Fix IP for relocating call depth accounting
Date: Thu, 21 Mar 2024 10:05:08 +0100	[thread overview]
Message-ID: <Zfv4RGwe5+h0zNI5@gmail.com> (raw)
In-Reply-To: <20240316232104.368561-3-joanbrugueram@gmail.com>


* Joan Bruguera Micó <joanbrugueram@gmail.com> wrote:

> The recently introduced support for %rip-relative relocations in the
> call thunk template assumes that the code is being patched in-place,
> so the destination of the relocation matches the address of the code.
> This is not true for the call depth accounting emitted by the BPF JIT,
> so the calculated address is wrong and usually causes a page fault.
> 
> Pass the destination IP when the BPF JIT emits call depth accounting.
> 
> Fixes: 17bce3b2ae2d ("x86/callthunks: Handle %rip-relative relocations in call thunk template")
> Signed-off-by: Joan Bruguera Micó <joanbrugueram@gmail.com>
> ---
>  arch/x86/include/asm/alternative.h |  4 ++--
>  arch/x86/kernel/callthunks.c       |  4 ++--

For the generic x86 changes - I guess you want to push this upstream via 
the networking tree:

  Acked-by: Ingo Molnar <mingo@kernel.org>

Thanks,

	Ingo

      parent reply	other threads:[~2024-03-21  9:05 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-16 23:21 [PATCH 0/2] x86/bpf: Fixes for the BPF JIT with retbleed=stuff Joan Bruguera Micó
2024-03-16 23:21 ` [PATCH 1/2] x86/bpf: Fix IP after emitting call depth accounting Joan Bruguera Micó
2024-03-16 23:21 ` [PATCH 2/2] x86/bpf: Fix IP for relocating " Joan Bruguera Micó
2024-03-18  7:12   ` Uros Bizjak
2024-03-21  9:05   ` Ingo Molnar [this message]

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