From: Borislav Petkov <bp@alien8.de>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
x86@kernel.org, llvm@lists.linux.dev,
linux-sparse@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel test robot <lkp@intel.com>,
Nathan Chancellor <nathan@kernel.org>
Subject: Re: [PATCH] objtool: prefer memory clobber & %= to volatile & __COUNTER__
Date: Wed, 19 Jan 2022 11:01:21 +0100 [thread overview]
Message-ID: <YefhcXouSQwETTvl@zn.tnic> (raw)
In-Reply-To: <20220119000327.oapghqad4lebnsra@treble>
On Tue, Jan 18, 2022 at 04:03:27PM -0800, Josh Poimboeuf wrote:
> If one of the '__bug_table' asm snippets isn't immediately followed by
> the .L[un]reachable asm, then yeah, it's the same issue.
Found one.
AFAICT, that's the WARN_ON_ONCE(1) catch-all in the default: label of
the switch-case in nf_hook(). That thing is followed by other gunk and
no *reachable label near it.
Damn - that was too good to be true. Gotta love those compilers. :-P
# ./include/linux/netfilter.h:252: WARN_ON_ONCE(1);
#APP
# 252 "./include/linux/netfilter.h" 1
1: .byte 0x0f, 0x0b
.pushsection __bug_table,"aw"
2: .long 1b - 2b # bug_entry::bug_addr
.long .LC5 - 2b # bug_entry::file #
.word 252 # bug_entry::line #
.word 2307 # bug_entry::flags #
.org 2b+12 #
.popsection
# 0 "" 2
#NO_APP
.p2align 4,,3
jmp .L344 #
.L265:
# ./include/linux/netfilter.h:229: hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]);
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-01-19 10:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-14 1:05 [PATCH] objtool: prefer memory clobber & %= to volatile & __COUNTER__ Nick Desaulniers
2022-01-14 21:58 ` Nathan Chancellor
2022-01-16 13:32 ` Borislav Petkov
2022-01-18 19:22 ` Josh Poimboeuf
2022-01-18 23:01 ` Josh Poimboeuf
2022-01-18 23:33 ` Borislav Petkov
2022-01-19 0:03 ` Josh Poimboeuf
2022-01-19 10:01 ` Borislav Petkov [this message]
2022-01-24 23:26 ` Nick Desaulniers
2022-01-24 23:38 ` Nick Desaulniers
2022-01-25 18:49 ` Borislav Petkov
2022-01-25 23:31 ` Segher Boessenkool
2022-01-26 0:59 ` Nick Desaulniers
2022-01-26 2:12 ` Nick Desaulniers
2022-01-26 11:13 ` Segher Boessenkool
2022-01-31 20:45 ` Nick Desaulniers
2022-01-31 22:13 ` Segher Boessenkool
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