From: Peter Zijlstra <peterz@infradead.org>
To: Song Liu <songliubraving@fb.com>
Cc: Song Liu <song@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Luis Chamberlain <mcgrof@kernel.org>,
"Torvalds, Linus" <torvalds@linux-foundation.org>,
"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 2/5] x86/alternative: introduce text_poke_set
Date: Thu, 19 May 2022 09:38:24 +0200 [thread overview]
Message-ID: <20220519073824.GA2578@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <A4019486-85F3-4900-8073-6879608706B1@fb.com>
On Wed, May 18, 2022 at 06:34:18PM +0000, Song Liu wrote:
>
>
> > On May 18, 2022, at 10:09 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Sun, May 15, 2022 at 10:40:48PM -0700, Song Liu wrote:
> >> Introduce a memset like API for text_poke. This will be used to fill the
> >> unused RX memory with illegal instructions.
> >
> > FWIW, you're going to use it to set INT3 (0xCC), that's not an illegal
> > instruction. INTO (0xCE) would be an illegal instruction (in 64bit
> > mode).
>
> Hmm… we have been using INT3 as illegal/invalid/special instructions in
> the JIT. I guess they are equally good for this job?
INT3 is right, it's just not illegal. Terminology is everything :-)
INT3 is the breakpoint instruction, it raises #BP, an illegal
instruction would raise #UD. Different exception vectors and such.
next prev parent reply other threads:[~2022-05-19 7:39 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-16 5:40 [PATCH bpf-next 0/5] bpf_prog_pack followup Song Liu
2022-05-16 5:40 ` [PATCH bpf-next 1/5] bpf: fill new bpf_prog_pack with illegal instructions Song Liu
2022-05-16 5:40 ` [PATCH bpf-next 2/5] x86/alternative: introduce text_poke_set Song Liu
2022-05-17 19:16 ` Edgecombe, Rick P
2022-05-17 21:09 ` Song Liu
2022-05-18 6:58 ` Song Liu
2022-05-18 7:45 ` Peter Zijlstra
2022-05-18 15:32 ` Song Liu
2022-05-18 17:09 ` Peter Zijlstra
2022-05-18 18:34 ` Song Liu
2022-05-19 7:38 ` Peter Zijlstra [this message]
2022-05-16 5:40 ` [PATCH bpf-next 3/5] bpf: introduce bpf_arch_text_invalidate for bpf_prog_pack Song Liu
2022-05-16 5:40 ` [PATCH bpf-next 5/5] bpf: use module_alloc_huge " Song Liu
2022-05-17 19:15 ` Edgecombe, Rick P
2022-05-17 21:08 ` Song Liu
2022-05-17 23:58 ` Edgecombe, Rick P
2022-05-18 6:25 ` Song Liu
2022-05-18 6:34 ` Song Liu
2022-05-18 16:49 ` Edgecombe, Rick P
2022-05-18 18:31 ` Song Liu
2022-05-19 6:42 ` Song Liu
2022-05-19 16:56 ` Edgecombe, Rick P
2022-05-19 18:25 ` Song Liu
[not found] ` <20220516054051.114490-5-song@kernel.org>
2022-05-18 6:28 ` [PATCH bpf-next 4/5] module: introduce module_alloc_huge Song Liu
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