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

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Date:   Tue, 11 Jan 2022 22:24:10 -0500
From:   He Ying <heying24@...wei.com>
To:     <catalin.marinas@....com>, <will@...nel.org>,
        <mark.rutland@....com>, <marcan@...can.st>, <maz@...nel.org>,
        <joey.gouly@....com>, <pcc@...gle.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <heying24@...wei.com>
Subject: [PATCH] arm64: entry: Save some nops when CONFIG_ARM64_PSEUDO_NMI is not set

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>
---
 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
 
-- 
2.17.1