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Date: Tue, 18 Jul 2006 06:20:20 -0400 From: Chuck Ebbert <76306.1226@...puserve.com> To: "andrea@...share.com" <andrea@...share.com> Cc: "bruce@...rew.cmu.edu" <bruce@...rew.cmu.edu>, linux-kernel <linux-kernel@...r.kernel.org>, Alan Cox <alan@...rguk.ukuu.org.uk>, Arjan van de Ven <arjan@...radead.org>, Adrian Bunk <bunk@...sta.de>, Lee Revell <rlrevell@...-job.com>, Linus Torvalds <torvalds@...l.org>, Ingo Molnar <mingo@...e.hu> Subject: Re: [PATCH] TIF_NOTSC and SECCOMP prctl In-Reply-To: <20060714060932.GE18774@...eron.random> On Fri, 14 Jul 2006 08:09:32 +0200, andrea@...share.com wrote: > The below patch seems to work, I ported all my client code on top of > prctl already. (it's a bit more painful to autodetect a kernel with > CONFIG_SECCOMP turned off but I already adapted to it) AFAIC the /proc method of controlling seccomp is so ugly it should just go, but what about backwards compatibility? I have a couple of questions: +void disable_TSC(void) +{ + if (!test_and_set_thread_flag(TIF_NOTSC)) + /* + * Must flip the CPU state synchronously with + * TIF_NOTSC in the current running context. + */ + hard_disable_TSC(); +} This gets called from sys_prctl(). Do you need to worry about preemption between the test_and_set and TSC disable? --- a/include/asm-i386/processor.h Thu Jul 13 03:03:35 2006 +0700 +++ b/include/asm-i386/processor.h Fri Jul 14 07:47:57 2006 +0200 @@ -256,6 +256,10 @@ static inline void clear_in_cr4 (unsigne cr4 &= ~mask; write_cr4(cr4); } + +extern void hard_disable_TSC(void); +extern void disable_TSC(void); +extern void hard_enable_TSC(void); Maybe these should be inline? They're really small and that way you don't need #ifdef around the code for them. > Reviews are welcome (then I will move into x86-64, all other archs > supporting seccomp should require no changes despite the API > change). Thanks. For x86_64 you need this: ftp://ftp.firstfloor.org/pub/ak/x86_64/quilt-current/patches/tif-flags-for-debug-regs-and-io-bitmap-in-ctxsw But I don't think Andi plans on pushing it for 2.6.18. -- Chuck - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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