* Andy Lutomirski <l...@amacapital.net> [2014-11-13 14:31:21]:
> x86 call do_notify_resume on paranoid returns if TIF_UPROBE is set
> but not on non-paranoid returns. I suspect that this is a mistake
> and that the code only works because int3 is paranoid.
>
> Setting _TIF_NOTIFY_RESUME in the uprobe code was probably a
> workaround for the x86 bug. With that bug fixed, we can remove
> _TIF_NOTIFY_RESUME from the uprobes code.
>
> Cc: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
> Reported-by: Oleg Nesterov <o...@redhat.com>
> Signed-off-by: Andy Lutomirski <l...@amacapital.net>
> ---
> arch/x86/include/asm/thread_info.h | 2 +-
> kernel/events/uprobes.c | 1 -
> 2 files changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/thread_info.h
> b/arch/x86/include/asm/thread_info.h
> index 854053889d4d..547e344a6dc6 100644
> --- a/arch/x86/include/asm/thread_info.h
> +++ b/arch/x86/include/asm/thread_info.h
> @@ -141,7 +141,7 @@ struct thread_info {
> /* Only used for 64 bit */
> #define _TIF_DO_NOTIFY_MASK \
> (_TIF_SIGPENDING | _TIF_MCE_NOTIFY | _TIF_NOTIFY_RESUME | \
> - _TIF_USER_RETURN_NOTIFY)
> + _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE)
The comment above says only for 64 bit. So would this still work for
i386?
>
> /* flags to check in __switch_to() */
> #define _TIF_WORK_CTXSW
> \
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 1d0af8a2c646..ed8f2cde34c5 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1640,7 +1640,6 @@ bool uprobe_deny_signal(void)
> if (__fatal_signal_pending(t) ||
> arch_uprobe_xol_was_trapped(t)) {
> utask->state = UTASK_SSTEP_TRAPPED;
> set_tsk_thread_flag(t, TIF_UPROBE);
> - set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
> }
> }
>
> --
> 1.9.3
>
--
Thanks and Regards
Srikar Dronamraju
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