linux-kernel - [PATCH] powerpc/32s: Fix assembler warning about r0

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Date:   Thu,  6 Aug 2020 06:01:42 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/32s: Fix assembler warning about r0

The assembler says:
  arch/powerpc/kernel/head_32.S:1095: Warning: invalid register expression

It's objecting to the use of r0 as the RA argument. That's because
when RA = 0 the literal value 0 is used, rather than the content of
r0, making the use of r0 in the source potentially confusing.

Fix it to use a literal 0, the generated code is identical.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/head_32.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index f3ab94d73936..5624db0e09a1 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -1092,7 +1092,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
 	 */
 	lis	r5, abatron_pteptrs@h
 	ori	r5, r5, abatron_pteptrs@l
-	stw	r5, 0xf0(r0)	/* This much match your Abatron config */
+	stw	r5, 0xf0(0)	/* This much match your Abatron config */
 	lis	r6, swapper_pg_dir@h
 	ori	r6, r6, swapper_pg_dir@l
 	tophys(r5, r5)
-- 
2.25.0