linux-kernel - [PATCH] powerpc/irq: Modernise inline assembly in irq_soft_mask

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Date:   Tue, 20 Sep 2022 08:41:28 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/irq: Modernise inline assembly in irq_soft_mask_{set,return}

local_paca is declared as global register asm("r13"), it is therefore
garantied to always ever be r13.

It is therefore not required to opencode r13 in the assembly, use
a reference to local_paca->irq_soft_mask instead.

This also allows removing the 'memory' clobber in irq_soft_mask_set()
as GCC now knows what is being modified in memory.

Using %X modifier will give GCC a bit more flexibility on the code
generation.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/hw_irq.h | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h
index e8de249339d8..dbe037ff4474 100644
--- a/arch/powerpc/include/asm/hw_irq.h
+++ b/arch/powerpc/include/asm/hw_irq.h
@@ -115,10 +115,7 @@ static inline notrace unsigned long irq_soft_mask_return(void)
 {
 	unsigned long flags;
 
-	asm volatile(
-		"lbz %0,%1(13)"
-		: "=r" (flags)
-		: "i" (offsetof(struct paca_struct, irq_soft_mask)));
+	asm volatile("lbz%X1 %0,%1" : "=r" (flags) : "m" (local_paca->irq_soft_mask));
 
 	return flags;
 }
@@ -147,12 +144,7 @@ static inline notrace void irq_soft_mask_set(unsigned long mask)
 	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
 		WARN_ON(mask && !(mask & IRQS_DISABLED));
 
-	asm volatile(
-		"stb %0,%1(13)"
-		:
-		: "r" (mask),
-		  "i" (offsetof(struct paca_struct, irq_soft_mask))
-		: "memory");
+	asm volatile("stb%X0 %1,%0" : "=m" (local_paca->irq_soft_mask) : "r" (mask));
 }
 
 static inline notrace unsigned long irq_soft_mask_set_return(unsigned long mask)
-- 
2.37.1