linux-kernel - [PATCH v3 5/6] MIPS: Loongson64: SMP: Fix up play

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Message-Id: <1604387525-23400-6-git-send-email-yangtiezhu@loongson.cn>
Date:   Tue,  3 Nov 2020 15:12:04 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Huacai Chen <chenhc@...ote.com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Lu Zeng <zenglu@...ngson.cn>, Jun Yi <yijun@...ngson.cn>
Subject: [PATCH v3 5/6] MIPS: Loongson64: SMP: Fix up play_dead jump indicator

In play_dead function, the whole 64-bit PC mailbox was used as a indicator
to determine if the master core had written boot jump information.

However, after we introduced CSR mailsend, the hardware will not guarante
an atomic write for the 64-bit PC mailbox. Thus we have to use the lower
32-bit which is written at the last as the jump indicator instead.

Signed-off-by: Lu Zeng <zenglu@...ngson.cn>
Signed-off-by: Jun Yi <yijun@...ngson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---

v2: No changes
v3: Update the commit message and comment

 arch/mips/loongson64/smp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/mips/loongson64/smp.c b/arch/mips/loongson64/smp.c
index 736e98d..aa0cd72 100644
--- a/arch/mips/loongson64/smp.c
+++ b/arch/mips/loongson64/smp.c
@@ -764,9 +764,10 @@ static void loongson3_type3_play_dead(int *state_addr)
 		"1: li    %[count], 0x100             \n" /* wait for init loop */
 		"2: bnez  %[count], 2b                \n" /* limit mailbox access */
 		"   addiu %[count], -1                \n"
-		"   ld    %[initfunc], 0x20(%[base])  \n" /* get PC via mailbox */
+		"   lw    %[initfunc], 0x20(%[base])  \n" /* check lower 32-bit as jump indicator */
 		"   beqz  %[initfunc], 1b             \n"
 		"   nop                               \n"
+		"   ld    %[initfunc], 0x20(%[base])  \n" /* get PC (whole 64-bit) via mailbox */
 		"   ld    $sp, 0x28(%[base])          \n" /* get SP via mailbox */
 		"   ld    $gp, 0x30(%[base])          \n" /* get GP via mailbox */
 		"   ld    $a1, 0x38(%[base])          \n"
-- 
2.1.0