On Tue, 10 Jan 2017, Josh Poimboeuf wrote:
> On Tue, Jan 10, 2017 at 11:14:51AM +0100, Miroslav Benes wrote:
> > On Mon, 9 Jan 2017, Josh Poimboeuf wrote:
> > > Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
> > > ---
> > > arch/x86/include/asm/stacktrace.h | 5 +----
> > > arch/x86/include/asm/switch_to.h | 10 +++++++++-
> > > 2 files changed, 10 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/arch/x86/include/asm/stacktrace.h
> > > b/arch/x86/include/asm/stacktrace.h
> > > index 20ce3db..2e41c50 100644
> > > --- a/arch/x86/include/asm/stacktrace.h
> > > +++ b/arch/x86/include/asm/stacktrace.h
> > > @@ -52,16 +52,13 @@ static inline bool on_stack(struct stack_info *info,
> > > void *addr, size_t len)
> > > static inline unsigned long *
> > > get_frame_pointer(struct task_struct *task, struct pt_regs *regs)
> > > {
> > > - struct inactive_task_frame *frame;
> > > -
> > > if (regs)
> > > return (unsigned long *)regs->bp;
> > >
> > > if (task == current)
> > > return __builtin_frame_address(0);
> > >
> > > - frame = (struct inactive_task_frame *)task->thread.sp;
> > > - return (unsigned long *)READ_ONCE_NOCHECK(frame->bp);
> > > + return &((struct inactive_task_frame *)task->thread.sp)->bp;
> >
> > You effectively remove one of the changes from the previous patch -
> > READ_ONCE_NOCHECK. Is it intentional?
>
> Yes, notice that it's no longer reading the value of bp on the stack.
> It's instead getting a pointer to it. Since there's no longer a stack
> access, READ_ONCE_NOCHECK is no longer needed.
Oh, of course. Sorry for the noise.
Miroslav
