From: "Woodhouse, David" <dwmw@amazon.co.uk>
To: Tim Chen <tim.c.chen@linux.intel.com>, Andi Kleen <ak@linux.intel.com>
Cc: Paul Turner <pjt@google.com>, LKML <linux-kernel@vger.kernel.org>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linux-foundation.org>,
Dave Hansen <dave.hansen@intel.com>, <tglx@linutronix.de>,
Kees Cook <keescook@google.com>, Rik van Riel <riel@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@amacapital.net>,
Jiri Kosina <jikos@kernel.org>, <gnomes@lxorguk.ukuu.org.uk>,
<x86@kernel.org>, <bp@alien8.de>, <rga@amazon.de>
Subject: Re: [PATCH] x86/retpoline: Fill return stack buffer on vmexit
Date: Thu, 11 Jan 2018 00:04:34 +0000 [thread overview]
Message-ID: <1515629074.22302.282.camel@amazon.co.uk> (raw)
In-Reply-To: <5371f9a0-f221-af1f-641f-05e4d0991847@linux.intel.com>
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On Wed, 2018-01-10 at 15:47 -0800, Tim Chen wrote:
>
> > +
> > + asm volatile (ALTERNATIVE("",
> > + __stringify(__FILL_RETURN_BUFFER(%0, %1, _%=)),
> > + X86_FEATURE_RETPOLINE)
>
> We'll be patching in a fairly long set of instructions here. Maybe put
> the ALTERNATIVE in the assembly and use a jmp skip_\@ for the ALTERNATIVE.
Perhaps the alternatives.h header could give me a clean way of doing this:
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -177,7 +178,7 @@ static inline void vmexit_fill_RSB(void)
{
unsigned long dummy;
- asm volatile (ALTERNATIVE("",
+ asm volatile (ALTERNATIVE("jmp " alt_end_marker "f",
__stringify(__FILL_RETURN_BUFFER(%0, %1, _%=)),
X86_FEATURE_RETPOLINE)
: "=r" (dummy), ASM_CALL_CONSTRAINT : : "memory" );
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next prev parent reply other threads:[~2018-01-11 0:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-10 22:51 [PATCH] x86/retpoline: Fill return stack buffer on vmexit David Woodhouse
2018-01-10 23:22 ` David Lang
2018-01-10 23:32 ` Woodhouse, David
2018-01-10 23:47 ` Tim Chen
2018-01-11 0:04 ` Woodhouse, David [this message]
2018-01-11 8:42 ` Peter Zijlstra
2018-01-11 8:49 ` Boris Petkov
2018-01-11 9:07 ` Woodhouse, David
2018-01-11 9:32 ` Peter Zijlstra
2018-01-11 9:47 ` Borislav Petkov
2018-01-11 9:58 ` Peter Zijlstra
2018-01-11 9:58 ` Woodhouse, David
2018-01-10 23:47 ` David Woodhouse
2018-01-11 0:14 ` Tom Lendacky
2018-01-11 1:04 ` David Woodhouse
2018-01-11 1:12 ` David Woodhouse
2018-01-12 0:34 ` Tom Lendacky
2018-01-11 8:49 ` Peter Zijlstra
2018-01-11 12:10 ` Woodhouse, David
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