Messages in this thread Patch in this message | | | Date | Tue, 18 Jul 2006 06:20:20 -0400 | From | Chuck Ebbert <> | Subject | Re: [PATCH] TIF_NOTSC and SECCOMP prctl |
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In-Reply-To: <20060714060932.GE18774@opteron.random>
On Fri, 14 Jul 2006 08:09:32 +0200, andrea@cpushare.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.
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