[linux-yocto] [PATCH] x86: lazy-preempt: use proper return label on 32bit-x86

[Bruce Ashfield]

On Tue, Mar 19, 2019 at 1:18 AM He Zhe <zhe.he at windriver.com> wrote:
>
>
>
> On 3/19/19 11:42 AM, Bruce Ashfield wrote:
> > On Mon, Mar 18, 2019 at 8:06 AM He Zhe <zhe.he at windriver.com> wrote:
> >> This is for
> >> v4.19/standard/preempt-rt/base
> >> v4.19/standard/preempt-rt/intel
> >> v4.19/standard/preempt-rt/intel-x86
> > Is this also part of an -rt stable/dev update ? It should be, but I
> > didn't have time to look today.
>
> Yes, this is part of v4.19.25-rt16
> https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/log/?h=linux-4.19.y-rt
>
> I was thinking before your regular merge, this might be worth a cherry pick.
>

If I don't have my update out by the end of the week, I'll do the cherry pick.

Bruce

> Zhe
>
> >
> > The reason I ask, is that I should do a refresh of -rt on 4.19, and if
> > this is part of the latest -rt updates, I'd rather pick them all up
> > versus cherry picking just a single change.
> >
> > Bruce
> >
> >> Zhe
> >>
> >> On 3/18/19 8:04 PM, zhe.he at windriver.com wrote:
> >>> From: Sebastian Andrzej Siewior <bigeasy at linutronix.de>
> >>>
> >>> The lazy-preempt uses the wrong return label in case preemption isn't
> >>> possible. This results crash while returning to the kernel.
> >>>
> >>> Use the correct return label if preemption isn' possible.
> >>>
> >>> Reported-by: Andri Yngvason <andri at yngvason.is>
> >>> Signed-off-by: Sebastian Andrzej Siewior <bigeasy at linutronix.de>
> >>>
> >>> commit 2c85fda444207949be4ad5e38a49ee8b4e5171cb upstream
> >>>
> >>> Fix x86 32bit boot failure and hang.
> >>>
> >>> Signed-off-by: He Zhe <zhe.he at windriver.com>
> >>> ---
> >>>  arch/x86/entry/entry_32.S | 8 ++++----
> >>>  1 file changed, 4 insertions(+), 4 deletions(-)
> >>>
> >>> diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
> >>> index 0169c25..e6f61c8 100644
> >>> --- a/arch/x86/entry/entry_32.S
> >>> +++ b/arch/x86/entry/entry_32.S
> >>> @@ -773,15 +773,15 @@ ENTRY(resume_kernel)
> >>>
> >>>       # atleast preempt count == 0 ?
> >>>       cmpl $_PREEMPT_ENABLED,PER_CPU_VAR(__preempt_count)
> >>> -     jne restore_all
> >>> +     jne     restore_all_kernel
> >>>
> >>>       movl    PER_CPU_VAR(current_task), %ebp
> >>>       cmpl    $0,TASK_TI_preempt_lazy_count(%ebp)     # non-zero preempt_lazy_count ?
> >>> -     jnz     restore_all
> >>> +     jnz     restore_all_kernel
> >>>
> >>>       testl   $_TIF_NEED_RESCHED_LAZY, TASK_TI_flags(%ebp)
> >>> -     jz      restore_all
> >>> -     test_int_off:
> >>> +     jz      restore_all_kernel
> >>> +test_int_off:
> >>>  #endif
> >>>       testl   $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off (exception path) ?
> >>>       jz      restore_all_kernel
> >
>


-- 
- Thou shalt not follow the NULL pointer, for chaos and madness await
thee at its end
- "Use the force Harry" - Gandalf, Star Trek II