linux-kernel - [PATCH v2] MIPS: zboot: head.S clean up

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Date:   Wed, 30 Dec 2020 11:08:18 +0800
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     linux-mips@...r.kernel.org
Cc:     Jiaxun Yang <jiaxun.yang@...goat.com>,
        Paul Cercueil <paul@...pouillou.net>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] MIPS: zboot: head.S clean up

.cprestore is removed as we don't expect Position Independent
zboot ELF.

.noreorder is also removed and rest instructions are massaged
to improve readability.

t9 register is used for indirect jump as MIPS ABI requirement.

start label is removed as it already defined in LEAF.

Reported-by: Paul Cercueil <paul@...pouillou.net>
Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>

--
v2: Remove start label (paul)
---
 arch/mips/boot/compressed/head.S | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S
index 409cb483a9ff..977218c90bc8 100644
--- a/arch/mips/boot/compressed/head.S
+++ b/arch/mips/boot/compressed/head.S
@@ -15,8 +15,6 @@
 #include <asm/asm.h>
 #include <asm/regdef.h>
 
-	.set noreorder
-	.cprestore
 	LEAF(start)
 start:
 	/* Save boot rom start args */
@@ -35,21 +33,20 @@ start:
 	PTR_LA	a0, (.heap)	     /* heap address */
 	PTR_LA	sp, (.stack + 8192)  /* stack address */
 
-	PTR_LA	ra, 2f
-	PTR_LA	k0, decompress_kernel
-	jr	k0
-	 nop
+	PTR_LA	t9, decompress_kernel
+	jalr	t9
+
 2:
 	move	a0, s0
 	move	a1, s1
 	move	a2, s2
 	move	a3, s3
-	PTR_LI	k0, KERNEL_ENTRY
-	jr	k0
-	 nop
+	PTR_LI	t9, KERNEL_ENTRY
+	jalr	t9
+
 3:
 	b	3b
-	 nop
+
 	END(start)
 
 	.comm .heap,BOOT_HEAP_SIZE,4
-- 
2.30.0