Re: [PATCH v3 02/15] x86/entry: define _TIF_ALLWORK_MASK flags explicitly

Josh Poimboeuf
2016-12-16T22:13:51Z

On Fri, Dec 16, 2016 at 03:17:35PM +0100, Petr Mladek wrote:
> On Thu 2016-12-08 12:08:27, Josh Poimboeuf wrote:
> > The _TIF_ALLWORK_MASK macro automatically includes the least-significant
> > 16 bits of the thread_info flags, which is less than obvious and tends
> > to create confusion and surprises when reading or modifying the code.
> >
> > Define the flags explicitly.
> >
> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> > ---
> > arch/x86/include/asm/thread_info.h | 9 ++++-----
> > 1 file changed, 4 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
> > index ad6f5eb0..1fe6043 100644
> > --- a/arch/x86/include/asm/thread_info.h
> > +++ b/arch/x86/include/asm/thread_info.h
> > @@ -73,9 +73,6 @@ struct thread_info {
> > * thread information flags
> > * - these are process state flags that various assembly files
> > * may need to access
> > - * - pending work-to-be-done flags are in LSW
>
> Yup, this is not true because also some flags from the most
> significant bits are in the _TIF_ALLWORK_MASK.
>
> > - * - other flags in MSW
> > - * Warning: layout of LSW is hardcoded in entry.S
> > */
> > #define TIF_SYSCALL_TRACE 0 /* syscall trace active */
> > #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
> > @@ -133,8 +130,10 @@ struct thread_info {
> >
> > /* work to do on any return to user space */
> > #define _TIF_ALLWORK_MASK \
> > - ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT | \
> > - _TIF_NOHZ)
> > + (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \
> > + _TIF_SINGLESTEP | _TIF_NEED_RESCHED | _TIF_SYSCALL_EMU | \
> > + _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE | \
> > + _TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ)
>
> All flags are sorted by the number except for
> _TIF_SINGLESTEP and _TIF_NEED_RESCHED ;-)

You're right, I'll swap them :-)

>
> The patch does not change the existing behavior. The same
> existing flags are listed.
>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
>
> Best Regards,
> Petr

--
Josh