Messages in this thread | | | Date | Tue, 17 Apr 2012 00:09:25 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 1/1] i387: ptrace breaks the lazy-fpu-restore logic |
| |
Damn, I forgot to add
Cc: <stable@vger.kernel.org> # 3.3
On 04/16, Oleg Nesterov wrote: > Starting from 7e16838d "i387: support lazy restore of FPU state" > we assume that fpu_owner_task doesn't need restore_fpu_checking() > on the context switch, its FPU state should match what we already > have in the FPU on this CPU. > > However, debugger can change the tracee's FPU state, in this case > we should reset fpu.last_cpu to ensure fpu_lazy_restore() can't > return true. > > Change init_fpu() to do this, it is called by user_regset->set() > methods. > > Reported-by: Jan Kratochvil <jan.kratochvil@redhat.com> > Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Oleg Nesterov <oleg@redhat.com> > --- > arch/x86/kernel/i387.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c > index 7734bcb..2d6e649 100644 > --- a/arch/x86/kernel/i387.c > +++ b/arch/x86/kernel/i387.c > @@ -235,6 +235,7 @@ int init_fpu(struct task_struct *tsk) > if (tsk_used_math(tsk)) { > if (HAVE_HWFP && tsk == current) > unlazy_fpu(tsk); > + tsk->thread.fpu.last_cpu = ~0; > return 0; > } > > -- > 1.5.5.1 >
| |