linux-kernel - Re: [PATCH] arm64: entry: Save some nops when CONFIG_ARM64_PSEUDO

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Message-ID: <784a864e-e7e5-4ce5-ec78-850b523c23b0@huawei.com>
Date:   Wed, 19 Jan 2022 17:47:09 +0800
From:   He Ying <heying24@...wei.com>
To:     Mark Rutland <mark.rutland@....com>
CC:     <catalin.marinas@....com>, <will@...nel.org>, <marcan@...can.st>,
        <maz@...nel.org>, <joey.gouly@....com>, <pcc@...gle.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: entry: Save some nops when CONFIG_ARM64_PSEUDO_NMI
 is not set


在 2022/1/19 17:35, Mark Rutland 写道:
> On Wed, Jan 19, 2022 at 02:40:58PM +0800, He Ying wrote:
>> Hi all,
>>
>> Ping. Any comments?
> The patch looks fine, but as it's the middle of the merge window people
> are busy and unlikely to look at this for the next few days.
>
> Generally it's a good idea to wait until rc1 or rc2, rebase atop that,
> and post the updated patch. Stuff like this usually gets queued around
> rc3/rc4 time.
OK. Thanks for your comment.
>
>> 锟斤拷 2022/1/12 11:24, He Ying 写锟斤拷:
>>> Arm64 pseudo-NMI feature code brings some additional nops
>>> when CONFIG_ARM64_PSEUDO_NMI is not set, which is not
>>> necessary. So add necessary ifdeffery to avoid it.
>>>
>>> Signed-off-by: He Ying <heying24@...wei.com>
> FWIW:
>
> Acked-by: Mark Rutland <mark.rutland@....com>
>
> Mark.
>
>>> ---
>>>    arch/arm64/kernel/entry.S | 4 ++++
>>>    1 file changed, 4 insertions(+)
>>>
>>> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
>>> index 2f69ae43941d..ffc32d3d909a 100644
>>> --- a/arch/arm64/kernel/entry.S
>>> +++ b/arch/arm64/kernel/entry.S
>>> @@ -300,6 +300,7 @@ alternative_else_nop_endif
>>>    	str	w21, [sp, #S_SYSCALLNO]
>>>    	.endif
>>> +#ifdef CONFIG_ARM64_PSEUDO_NMI
>>>    	/* Save pmr */
>>>    alternative_if ARM64_HAS_IRQ_PRIO_MASKING
>>>    	mrs_s	x20, SYS_ICC_PMR_EL1
>>> @@ -307,6 +308,7 @@ alternative_if ARM64_HAS_IRQ_PRIO_MASKING
>>>    	mov	x20, #GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET
>>>    	msr_s	SYS_ICC_PMR_EL1, x20
>>>    alternative_else_nop_endif
>>> +#endif
>>>    	/* Re-enable tag checking (TCO set on exception entry) */
>>>    #ifdef CONFIG_ARM64_MTE
>>> @@ -330,6 +332,7 @@ alternative_else_nop_endif
>>>    	disable_daif
>>>    	.endif
>>> +#ifdef CONFIG_ARM64_PSEUDO_NMI
>>>    	/* Restore pmr */
>>>    alternative_if ARM64_HAS_IRQ_PRIO_MASKING
>>>    	ldr	x20, [sp, #S_PMR_SAVE]
>>> @@ -339,6 +342,7 @@ alternative_if ARM64_HAS_IRQ_PRIO_MASKING
>>>    	dsb	sy				// Ensure priority change is seen by redistributor
>>>    .L__skip_pmr_sync\@:
>>>    alternative_else_nop_endif
>>> +#endif
>>>    	ldp	x21, x22, [sp, #S_PC]		// load ELR, SPSR
> .