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

[He Zhe]

This is for
v4.19/standard/preempt-rt/base
v4.19/standard/preempt-rt/intel
v4.19/standard/preempt-rt/intel-x86

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