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

Petr Mladek
2016-12-16T14:17:35Z

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 ;-)

The patch does not change the existing behavior. The same
existing flags are listed.

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr