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

[He Zhe]

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

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
>