Date: Thu, 23 Apr 2015 12:44:02 +0200
From: Borislav Petkov <bp@alien8.de>
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>, Brian Gerst <brgerst@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>, Oleg Nesterov <oleg@redhat.com>,
        Ingo Molnar <mingo@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>, Will Drewry <wad@chromium.org>,
        =?utf-8?B?RnLDqWTDqXJpYw==?= Weisbecker <fweisbec@gmail.com>,
        Alexei Starovoitov <ast@plumgrid.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        "linux-tip-commits@vger.kernel.org" 
	<linux-tip-commits@vger.kernel.org>
Subject: Re: [tip:x86/vdso] x86/vdso32/syscall.S: Do not load __USER32_DS to
 %ss
Message-ID: <20150423104401.GF28327@pd.tnic>
References: <63da6d778f69fd0f1345d9287f6764d58be519fa.1427482099.git.luto@kernel.org>
 <tip-e7d6eefaaa443130079d73cd05039d90b3db7a4a@git.kernel.org>
 <CAMzpN2gD2kfKaXSYsXjZo=bLQYLk3A-sU_8qizfkp5paRuaePQ@mail.gmail.com>
 <CALCETrVH6STDwEuLY3gFaNevtjvtOZ7Ox3e10ZhtmitCJnJUKQ@mail.gmail.com>
 <5538C1C5.7010408@redhat.com>
 <20150423101840.GC28327@pd.tnic>
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On Thu, Apr 23, 2015 at 12:26:43PM +0200, Denys Vlasenko wrote:
> Yes. It loads *selector*. AMD docs say that selector is loaded as you say,
> but *cached descriptor* of SS (which is a different entity) is not modified.
> 
> If *cached descriptor* is invalid, in 32-bit mode stack ops
> will fail. (In 64-bit mode, CPU doesn't do those checks).

So how can that happen with wine? Something's changing the cached
descriptor and only the write to %ss reloads it with the correct value?

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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