From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Kees Cook <keescook@chromium.org>
Subject: Re: Remaining randconfig objtool warnings, linux-next-20200428
Date: Wed, 29 Apr 2020 00:33:27 +0200 [thread overview]
Message-ID: <20200428223327.GC16027@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200428220353.uepo455bj76sym4k@treble>
On Tue, Apr 28, 2020 at 05:03:53PM -0500, Josh Poimboeuf wrote:
> On Tue, Apr 28, 2020 at 11:55:54PM +0200, Peter Zijlstra wrote:
> > binutils.git/gas/configure/tc-i386.c:i386_generate_nops
> >
> > When there's too many NOPs (as here) it generates a JMP across the NOPS.
> > It makes some sort of sense, at some point executing NOPs is going to be
> > more expensive than a branch.. But shees..
>
> Urgh. Even if I tell it specifically to pad with NOPs, it still does
> this "trick". I have no idea how to deal with this in objtool.
This is horrible... but it _might_ just work.
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 0e9504fabe52..545f50f5de56 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -599,7 +599,18 @@ SYM_CODE_END(common_spurious)
_ASM_NOKPROBE(common_spurious)
/* common_interrupt is a hotpath. Align it */
+SYM_FUNC_START_LOCAL_NOALIGN(__ignore_me)
.p2align CONFIG_X86_L1_CACHE_SHIFT
+SYM_FUNC_END(__ignore_me)
+
+.pushsection .discard.func_stack_frame_non_standard
+ .align 8
+ .type __func_stack_frame_non_standard___ignore_me, @object
+ .size __func_stack_frame_non_standard___ignore_me, 8
+__func_stack_frame_non_standard___ignore_me:
+ .quad __ignore_me
+.popsection
+
SYM_CODE_START_LOCAL(common_interrupt)
addq $-0x80, (%rsp) /* Adjust vector to [-256, -1] range */
call interrupt_entry
next prev parent reply other threads:[~2020-04-28 22:33 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-28 14:49 Remaining randconfig objtool warnings, linux-next-20200428 Arnd Bergmann
2020-04-28 16:10 ` Josh Poimboeuf
2020-04-28 19:11 ` Kees Cook
2020-04-28 20:19 ` Arnd Bergmann
2020-04-28 20:38 ` Josh Poimboeuf
2020-04-28 21:55 ` Peter Zijlstra
2020-04-28 22:03 ` Josh Poimboeuf
2020-04-28 22:33 ` Peter Zijlstra [this message]
2020-04-28 22:48 ` Josh Poimboeuf
2020-04-28 23:08 ` Josh Poimboeuf
2020-04-29 18:55 ` Josh Poimboeuf
2020-04-29 22:46 ` Arnd Bergmann
2020-04-29 23:01 ` Josh Poimboeuf
2020-04-29 23:11 ` Josh Poimboeuf
2020-04-29 23:28 ` Josh Poimboeuf
2020-04-30 13:41 ` Arnd Bergmann
2020-04-30 14:33 ` Josh Poimboeuf
2020-04-30 19:46 ` Josh Poimboeuf
2020-04-30 20:59 ` Arnd Bergmann
2020-04-30 21:10 ` Josh Poimboeuf
2020-04-30 21:08 ` Josh Poimboeuf
2020-04-30 23:02 ` Josh Poimboeuf
2020-04-29 19:18 ` Josh Poimboeuf
2020-05-01 12:23 ` Peter Zijlstra
2020-04-30 14:05 ` Arnd Bergmann
2020-05-01 0:28 ` Josh Poimboeuf
2020-05-01 11:41 ` Arnd Bergmann
2020-05-01 17:16 ` Peter Zijlstra
2020-05-01 12:27 ` Peter Zijlstra
2020-05-01 1:07 ` Josh Poimboeuf
2020-05-01 11:18 ` Arnd Bergmann
2020-05-01 12:33 ` Peter Zijlstra
2020-05-01 13:08 ` Arnd Bergmann
2020-05-01 15:49 ` Josh Poimboeuf
2020-05-01 17:21 ` Arnd Bergmann
2020-05-01 17:26 ` Peter Zijlstra
2020-05-01 17:50 ` Josh Poimboeuf
2020-05-01 19:47 ` Arnd Bergmann
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