[linux-yocto] [PATCH] x86: lazy-preempt: use proper return label on 32bit-x86
He Zhe
zhe.he at windriver.com
Mon Mar 18 05:06:40 PDT 2019
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
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