From: Tim Chen <tim.c.chen@linux.intel.com>
To: David Woodhouse <dwmw@amazon.co.uk>, 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: Wed, 10 Jan 2018 15:47:35 -0800 [thread overview]
Message-ID: <5371f9a0-f221-af1f-641f-05e4d0991847@linux.intel.com> (raw)
In-Reply-To: <1515624682-3556-1-git-send-email-dwmw@amazon.co.uk>
On 01/10/2018 02:51 PM, David Woodhouse wrote:
> + */
> +#define __FILL_RETURN_BUFFER(reg, sp, uniq) \
> + mov $(NUM_BRANCHES_TO_FILL/2), reg; \
> + .align 16; \
> +.Ldo_call1_ ## uniq: \
> + call .Ldo_call2_ ## uniq; \
> +.Ltrap1_ ## uniq: \
> + pause; \
> + jmp .Ltrap1_ ## uniq; \
> + .align 16; \
> +.Ldo_call2_ ## uniq: \
> + call .Ldo_loop_ ## uniq; \
> +.Ltrap2_ ## uniq: \
> + pause; \
> + jmp .Ltrap2_ ## uniq; \
> + .align 16; \
> +.Ldo_loop_ ## uniq: \
> + dec reg; \
> + jnz .Ldo_call1_ ## uniq; \
> + add $(BITS_PER_LONG/8)*NUM_BRANCHES_TO_FILL, sp;
> +
> #ifdef __ASSEMBLY__
>
> +
> + 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.
Thanks.
Tim
next prev parent reply other threads:[~2018-01-10 23:47 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-10 22:51 David Woodhouse
2018-01-10 23:22 ` David Lang
2018-01-10 23:32 ` Woodhouse, David
2018-01-10 23:47 ` Tim Chen [this message]
2018-01-11 0:04 ` Woodhouse, David
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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