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Date: Mon, 27 Jan 2014 18:39:31 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Anvin <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        the arch/x86 maintainers <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] de-asmify the x86-64 system call slowpath
Message-ID: <20140127173931.GB32450@redhat.com>
References: <CA+55aFzNxTtvNX7zqBELHs489e5mEx1sM=i=red=aQAGviXrNw@mail.gmail.com> <20140127102759.GY11314@laptop.programming.kicks-ass.net> <20140127113627.GC10323@ZenIV.linux.org.uk>
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On 01/27, Al Viro wrote:
>
> BTW, there's an additional pile of obfuscation:
> /* work to do on interrupt/exception return */
> #define _TIF_WORK_MASK                                                  \
>         (0x0000FFFF &                                                   \
>          ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|                       \
>            _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU))
>
> /* work to do on any return to user space */
> #define _TIF_ALLWORK_MASK                                               \
>         ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT |       \
>         _TIF_NOHZ)

Heh, yes ;)

> Why is _TIF_UPROBE *not* a part
> of _TIF_DO_NOTIFY_MASK, for example?

Yes, please see another email. That is why uprobe_deny_signal()
sets TIF_NOTIFY_RESUME along with TIF_UPROBE.

Oleg.