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Date: Mon, 2 Mar 2015 09:45:02 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@kernel.org>,
        Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
        Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>, X86 ML <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] x86: do not save callee-preserved registers around
 lockdep_sys_exit_thunk
Message-ID: <20150302084502.GE5029@twins.programming.kicks-ass.net>
References: <1425083361-7252-1-git-send-email-dvlasenk@redhat.com>
 <1425083361-7252-4-git-send-email-dvlasenk@redhat.com>
 <CALCETrVTU7Ji9UOdEnBH7pjKOGLFh1+DXQCo69HGs+ZFEkPa6A@mail.gmail.com>
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On Sun, Mar 01, 2015 at 08:16:18AM -0800, Andy Lutomirski wrote:
> On Fri, Feb 27, 2015 at 4:29 PM, Denys Vlasenko <dvlasenk@redhat.com> wrote:
> > Internally, lockdep_sys_exit_thunk saves callee-clobbered registers,
> > and calls a C function, lockdep_sys_exix. Thus, callee-preserved
> > won't be mangled, there is no need to save them.
> >
> > Patch was run-tested.
> 
> Peterz, I think this was your code.

It was, I'm forever unsure on when what register are saved by which
macros/functions.

Thanks!