From: Borislav Petkov <bp@alien8.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
kbuild test robot <fengguang.wu@intel.com>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: [linus:master] BUILD REGRESSION a2e5790d841658485d642196dbb0927303d6c22f
Date: Thu, 8 Feb 2018 10:46:51 +0100 [thread overview]
Message-ID: <20180208094651.GA7964@pd.tnic> (raw)
In-Reply-To: <20180208091302.GD25201@hirez.programming.kicks-ass.net>
On Thu, Feb 08, 2018 at 10:13:02AM +0100, Peter Zijlstra wrote:
> diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
> index 34d99af43994..f0d5b4a1512d 100644
> --- a/arch/x86/include/asm/bug.h
> +++ b/arch/x86/include/asm/bug.h
> @@ -12,16 +12,21 @@
> * (binutils knows about "ud1" but {en,de}codes it as 2 bytes, whereas
> * our kernel decoder thinks it takes a ModRM byte, which seems consistent
> * with various things like the Intel SDM instruction encoding rules)
> + *
> + * And now someone went and taught binutils about UD0 as taking a ModR/M too
> + * and it generates crap when disassembling the kernel. Stick a pointless 0xD6
> + * ModR/M on, which the old binutils decodes as (bad) and the new binutils sees
> + * as a valid single byte ModR/M.
> */
>
> -#define ASM_UD0 ".byte 0x0f, 0xff"
> +#define ASM_UD0 ".byte 0x0f, 0xff, 0xd6"
Yeah, we probably should say that it was SALC:
http://ref.x86asm.net/geek.html#xD6
but undefined after P4.
Not that it matters a whole lot after an UD0. And it still won't matter
if it gets redefined to some new fancy prefix.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2018-02-08 9:47 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-07 11:44 kbuild test robot
2018-02-07 18:13 ` Linus Torvalds
2018-02-07 18:35 ` Borislav Petkov
2018-02-07 18:49 ` Peter Zijlstra
2018-02-07 19:03 ` Linus Torvalds
2018-02-07 19:14 ` Peter Zijlstra
2018-02-07 19:28 ` Borislav Petkov
2018-02-07 19:43 ` Linus Torvalds
2018-02-07 20:24 ` Borislav Petkov
2018-02-08 9:13 ` Peter Zijlstra
2018-02-08 9:35 ` Peter Zijlstra
2018-02-08 9:46 ` Borislav Petkov [this message]
2018-02-08 9:47 ` David Laight
2018-02-08 10:13 ` Peter Zijlstra
2018-02-08 17:27 ` Linus Torvalds
2018-02-08 18:03 ` Peter Zijlstra
2018-02-08 18:15 ` Linus Torvalds
2018-02-08 19:44 ` Peter Zijlstra
2018-02-08 20:02 ` Linus Torvalds
2018-02-08 20:31 ` Borislav Petkov
2018-02-08 23:09 ` [PATCH 0/2] objtool fixes on top of Peter's WARN UD2 patch Josh Poimboeuf
2018-02-08 23:09 ` [PATCH 1/2] objtool: Fix seg fault in ignore_unreachable_insn() Josh Poimboeuf
2018-02-13 11:29 ` [tip:x86/pti] objtool: Fix segfault " tip-bot for Josh Poimboeuf
2018-02-15 0:26 ` tip-bot for Josh Poimboeuf
2018-02-08 23:09 ` [PATCH 2/2] x86: Annotate WARN-related UD2 as reachable Josh Poimboeuf
2018-02-13 11:30 ` [tip:x86/pti] x86/debug, objtool: Annotate WARN()-related " tip-bot for Josh Poimboeuf
2018-02-15 0:26 ` tip-bot for Josh Poimboeuf
2018-02-09 8:13 ` [PATCH 0/2] objtool fixes on top of Peter's WARN UD2 patch Peter Zijlstra
2018-02-09 8:12 ` [linus:master] BUILD REGRESSION a2e5790d841658485d642196dbb0927303d6c22f Peter Zijlstra
2018-02-13 11:30 ` [tip:x86/pti] x86/debug: Use UD2 for WARN() tip-bot for Peter Zijlstra
2018-02-15 0:27 ` tip-bot for Peter Zijlstra
2018-02-07 18:38 ` [linus:master] BUILD REGRESSION a2e5790d841658485d642196dbb0927303d6c22f Randy Dunlap
2018-02-07 19:01 ` Linus Torvalds
2018-02-07 19:06 ` Peter Zijlstra
2018-02-07 19:10 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180208094651.GA7964@pd.tnic \
--to=bp@alien8.de \
--cc=fengguang.wu@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome