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From: Juergen Gross <jgross@suse.com>
To: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>,
	linux-kernel@vger.kernel.org,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v2] x86/xen/64: Rearrange the SYSCALL entries
Date: Wed, 9 Aug 2017 17:39:12 +0200	[thread overview]
Message-ID: <ce774c83-70df-5188-8a24-61de00a92e8f@suse.com> (raw)
In-Reply-To: <7c88ed36805d36841ab03ec3b48b4122c4418d71.1502164668.git.luto@kernel.org>

On 08/08/17 05:59, Andy Lutomirski wrote:
> Xen's raw SYSCALL entries are much less weird than native.  Rather
> than fudging them to look like native entries, use the Xen-provided
> stack frame directly.
> 
> This lets us eliminate entry_SYSCALL_64_after_swapgs and two uses of
> the SWAPGS_UNSAFE_STACK paravirt hook.  The SYSENTER code would
> benefit from similar treatment.
> 
> This makes one change to the native code path: the compat
> instruction that clears the high 32 bits of %rax is moved slightly
> later.  I'd be surprised if this affects performance at all.
> 
> Signed-off-by: Andy Lutomirski <luto@kernel.org>

Reviewed-by: Juergen Gross <jgross@suse.com>
Tested-by: Juergen Gross <jgross@suse.com>


Thanks,

Juergen

  reply	other threads:[~2017-08-09 15:39 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-08  3:59 Andy Lutomirski
2017-08-09 15:39 ` Juergen Gross [this message]
2017-08-10 12:22 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2017-08-14  2:44 ` [PATCH v2] " Brian Gerst
2017-08-14  5:53   ` Andy Lutomirski
2017-08-14  6:42     ` Andy Lutomirski
2017-08-14  6:45     ` Andrew Cooper
2017-08-14 12:46     ` Brian Gerst

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