From: Peter Zijlstra <peterz@infradead.org>
To: Joao Moreira <joao@overdrivepizza.com>
Cc: x86@kernel.org, hjl.tools@gmail.com, jpoimboe@redhat.com,
andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org,
ndesaulniers@google.com, keescook@chromium.org,
samitolvanen@google.com, mark.rutland@arm.com,
alyssa.milburn@intel.com
Subject: Re: [PATCH 24/29] x86/text-patching: Make text_gen_insn() IBT aware
Date: Thu, 24 Feb 2022 10:10:12 +0100 [thread overview]
Message-ID: <YhdLdMiVgeYOGP/H@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <5c77889ca6b988b0dff65136264bd1fb@overdrivepizza.com>
On Wed, Feb 23, 2022 at 05:18:04PM -0800, Joao Moreira wrote:
> > +#ifdef CONFIG_X86_IBT
> > + if (is_endbr(dest))
> > + dest += 4;
> > +#endif
>
> Hi, FWIIW I saw this snippet trigger a bug in the jump_label infra where the
> target displacement would not fit in a JMP8 operand.
Bah, I was afraid of seening that :/
> For these cases perhaps we can verify if the displacement fits the operand
> and, if not, simply ignore and lose the decode cycle which may not be a huge
> problem and remains semantically correct. Seems more sensible than padding
> jump tables with nops. In the meantime I'll investigate clang's behavior and
> if it is really a bug, I'll work on a patch.
Urgh, trouble is, we're going to be re-writing a bunch of ENDBR to be
UD1 0x0(%eax),%eax, and you really don't want to try and execute those.
next prev parent reply other threads:[~2022-02-24 9:10 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-18 16:49 [PATCH 00/29] x86: Kernel IBT Peter Zijlstra
2022-02-18 16:49 ` [PATCH 01/29] static_call: Avoid building empty .static_call_sites Peter Zijlstra
2022-02-18 16:49 ` [PATCH 02/29] x86/module: Fix the paravirt vs alternative order Peter Zijlstra
2022-02-18 20:28 ` Josh Poimboeuf
2022-02-18 21:22 ` Peter Zijlstra
2022-02-18 23:28 ` Josh Poimboeuf
2022-02-18 16:49 ` [PATCH 03/29] objtool: Add --dry-run Peter Zijlstra
2022-02-18 16:49 ` [PATCH 04/29] x86/livepatch: Validate __fentry__ location Peter Zijlstra
2022-02-18 21:08 ` Josh Poimboeuf
2022-02-23 10:09 ` Peter Zijlstra
2022-02-23 10:21 ` Miroslav Benes
2022-02-23 10:57 ` Peter Zijlstra
2022-02-23 12:41 ` Steven Rostedt
2022-02-23 14:05 ` Peter Zijlstra
2022-02-23 14:16 ` Steven Rostedt
2022-02-23 14:23 ` Steven Rostedt
2022-02-23 14:33 ` Steven Rostedt
2022-02-23 14:49 ` Peter Zijlstra
2022-02-23 15:54 ` Peter Zijlstra
2022-02-18 16:49 ` [PATCH 05/29] x86: Base IBT bits Peter Zijlstra
2022-02-18 20:49 ` Andrew Cooper
2022-02-18 21:11 ` David Laight
2022-02-18 21:24 ` Andrew Cooper
2022-02-18 22:37 ` David Laight
2022-02-18 21:26 ` Peter Zijlstra
2022-02-18 21:14 ` Josh Poimboeuf
2022-02-18 21:21 ` Peter Zijlstra
2022-02-18 22:12 ` Joao Moreira
2022-02-19 1:07 ` Edgecombe, Rick P
2022-02-18 16:49 ` [PATCH 06/29] x86/ibt: Add ANNOTATE_NOENDBR Peter Zijlstra
2022-02-18 16:49 ` [PATCH 07/29] x86/entry: Sprinkle ENDBR dust Peter Zijlstra
2022-02-19 0:23 ` Josh Poimboeuf
2022-02-19 23:08 ` Peter Zijlstra
2022-02-19 0:36 ` Josh Poimboeuf
2022-02-18 16:49 ` [PATCH 08/29] x86/linkage: Add ENDBR to SYM_FUNC_START*() Peter Zijlstra
2022-02-18 16:49 ` [PATCH 09/29] x86/ibt,paravirt: Sprinkle ENDBR Peter Zijlstra
2022-02-18 16:49 ` [PATCH 10/29] x86/bpf: Add ENDBR instructions to prologue Peter Zijlstra
2022-02-18 16:49 ` [PATCH 11/29] x86/ibt,crypto: Add ENDBR for the jump-table entries Peter Zijlstra
2022-02-18 16:49 ` [PATCH 12/29] x86/ibt,kvm: Add ENDBR to fastops Peter Zijlstra
2022-02-18 16:49 ` [PATCH 13/29] x86/ibt,ftrace: Add ENDBR to samples/ftrace Peter Zijlstra
2022-02-18 16:49 ` [PATCH 14/29] x86/ibt: Add IBT feature, MSR and #CP handling Peter Zijlstra
2022-02-18 19:31 ` Andrew Cooper
2022-02-18 21:15 ` Peter Zijlstra
2022-02-19 1:20 ` Edgecombe, Rick P
2022-02-19 1:21 ` Josh Poimboeuf
2022-02-19 9:24 ` Peter Zijlstra
2022-02-21 8:24 ` Kees Cook
2022-02-22 4:38 ` Edgecombe, Rick P
2022-02-22 9:32 ` Peter Zijlstra
2022-02-18 16:49 ` [PATCH 15/29] x86: Disable IBT around firmware Peter Zijlstra
2022-02-21 8:27 ` Kees Cook
2022-02-21 10:06 ` Peter Zijlstra
2022-02-21 13:22 ` Peter Zijlstra
2022-02-21 15:54 ` Kees Cook
2022-02-21 16:10 ` Peter Zijlstra
2022-02-18 16:49 ` [PATCH 16/29] x86/bugs: Disable Retpoline when IBT Peter Zijlstra
2022-02-19 2:15 ` Josh Poimboeuf
2022-02-22 15:00 ` Peter Zijlstra
2022-02-25 0:19 ` Josh Poimboeuf
2022-02-18 16:49 ` [PATCH 17/29] x86/ibt: Annotate text references Peter Zijlstra
2022-02-19 5:22 ` Josh Poimboeuf
2022-02-19 9:39 ` Peter Zijlstra
2022-02-18 16:49 ` [PATCH 18/29] x86/ibt,ftrace: Annotate ftrace code patching Peter Zijlstra
2022-02-18 16:49 ` [PATCH 19/29] x86/ibt,xen: Annotate away warnings Peter Zijlstra
2022-02-18 20:24 ` Andrew Cooper
2022-02-18 21:05 ` Peter Zijlstra
2022-02-18 23:07 ` Andrew Cooper
2022-02-21 14:20 ` Peter Zijlstra
2022-02-18 16:49 ` [PATCH 20/29] x86/ibt,sev: Annotations Peter Zijlstra
2022-02-18 16:49 ` [PATCH 21/29] objtool: Rename --duplicate to --lto Peter Zijlstra
2022-02-26 19:42 ` Josh Poimboeuf
2022-02-26 21:48 ` Josh Poimboeuf
2022-02-28 11:05 ` Peter Zijlstra
2022-02-28 18:32 ` Josh Poimboeuf
2022-02-28 20:09 ` Peter Zijlstra
2022-02-28 20:18 ` Josh Poimboeuf
2022-03-01 14:19 ` Miroslav Benes
2022-02-18 16:49 ` [PATCH 22/29] Kbuild: Prepare !CLANG whole module objtool Peter Zijlstra
2022-02-18 16:49 ` [PATCH 23/29] objtool: Read the NOENDBR annotation Peter Zijlstra
2022-02-18 16:49 ` [PATCH 24/29] x86/text-patching: Make text_gen_insn() IBT aware Peter Zijlstra
2022-02-24 1:18 ` Joao Moreira
2022-02-24 9:10 ` Peter Zijlstra [this message]
2022-02-18 16:49 ` [PATCH 25/29] x86/ibt: Dont generate ENDBR in .discard.text Peter Zijlstra
2022-02-18 16:49 ` [PATCH 26/29] objtool: Add IBT validation / fixups Peter Zijlstra
2022-02-18 16:49 ` [PATCH 27/29] x86/ibt: Finish --ibt-fix-direct on module loading Peter Zijlstra
2022-02-18 16:49 ` [PATCH 28/29] x86/ibt: Ensure module init/exit points have references Peter Zijlstra
2022-02-18 16:49 ` [PATCH 29/29] x86/alternative: Use .ibt_endbr_sites to seal indirect calls Peter Zijlstra
2022-02-19 1:29 ` [PATCH 00/29] x86: Kernel IBT Edgecombe, Rick P
2022-02-19 9:58 ` Peter Zijlstra
2022-02-19 16:00 ` Andrew Cooper
2022-02-21 8:42 ` Kees Cook
2022-02-21 9:24 ` Peter Zijlstra
2022-02-23 7:26 ` Kees Cook
2022-02-24 16:47 ` Mike Rapoport
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