From: Cyril Bur <cyrilbur@gmail.com>
To: Michael Neuling <mikey@neuling.org>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH V2 4/8] powerpc: Explicitly disable math features when copying thread
Date: Fri, 15 Jan 2016 16:54:16 +1100 [thread overview]
Message-ID: <20160115165416.2f7328ae@camb691> (raw)
In-Reply-To: <1452836542.25634.33.camel@neuling.org>
On Fri, 15 Jan 2016 16:42:22 +1100
Michael Neuling <mikey@neuling.org> wrote:
> On Fri, 2016-01-15 at 16:04 +1100, Cyril Bur wrote:
> > With threads leaving the math bits enabled in their saved MSR to indicate
> > that the hardware is hot and a restore is not needed, children need to turn
> > it off as when they do get scheduled, there's no way their registers could
> > have been hot.
>
> Is this a bug in the current code?
>
You're very consistent:
https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-November/136469.html
;)
> Mikey
>
> > Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
> > ---
> > arch/powerpc/kernel/process.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/powerpc/kernel/process.c
> > b/arch/powerpc/kernel/process.c
> > index dccc87e..e0c3d2d 100644
> > --- a/arch/powerpc/kernel/process.c
> > +++ b/arch/powerpc/kernel/process.c
> > @@ -1307,6 +1307,7 @@ int copy_thread(unsigned long clone_flags,
> > unsigned long usp,
> >
> > f = ret_from_fork;
> > }
> > + childregs->msr &= ~(MSR_FP|MSR_VEC|MSR_VSX);
> > sp -= STACK_FRAME_OVERHEAD;
> >
> > /*
next prev parent reply other threads:[~2016-01-15 5:54 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-15 5:04 [PATCH V2 0/8] FP/VEC/VSX switching optimisations Cyril Bur
2016-01-15 5:04 ` [PATCH V2 1/8] selftests/powerpc: Test the preservation of FPU and VMX regs across syscall Cyril Bur
2016-01-15 5:04 ` [PATCH V2 2/8] selftests/powerpc: Test preservation of FPU and VMX regs across preemption Cyril Bur
2016-01-15 5:04 ` [PATCH V2 3/8] selftests/powerpc: Test FPU and VMX regs in signal ucontext Cyril Bur
2016-01-15 5:04 ` [PATCH V2 4/8] powerpc: Explicitly disable math features when copying thread Cyril Bur
2016-01-15 5:42 ` Michael Neuling
2016-01-15 5:54 ` Cyril Bur [this message]
2016-01-15 6:04 ` Michael Neuling
2016-01-15 5:04 ` [PATCH V2 5/8] powerpc: Restore FPU/VEC/VSX if previously used Cyril Bur
2016-01-15 6:02 ` Michael Neuling
2016-01-18 2:05 ` Cyril Bur
2016-01-15 5:04 ` [PATCH V2 6/8] powerpc: Add the ability to save FPU without giving it up Cyril Bur
2016-01-15 6:08 ` Michael Neuling
2016-01-15 7:38 ` Denis Kirjanov
2016-01-15 7:42 ` Denis Kirjanov
2016-01-15 5:04 ` [PATCH V2 7/8] powerpc: Add the ability to save Altivec " Cyril Bur
2016-01-15 5:04 ` [PATCH V2 8/8] powerpc: Add the ability to save VSX " Cyril Bur
2016-01-15 6:25 ` Michael Neuling
2016-01-18 2:10 ` Cyril Bur
2016-01-18 4:29 ` Michael Neuling
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