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From:   Chen Zhongjin <chenzhongjin@huawei.com>
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Subject: [PATCH -next 4/7] riscv: syscall: Don't clobber s0 when syscall
Date:   Tue, 20 Sep 2022 23:11:59 +0800
Message-ID: <20220920151202.180057-5-chenzhongjin@huawei.com>
In-Reply-To: <20220920151202.180057-1-chenzhongjin@huawei.com>
References: <20220920151202.180057-1-chenzhongjin@huawei.com>
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syscall uses s0 to load address of sys_call_table.

Since now we uses s0 to save pt_regs for unwinding, clobber
s0 can make unwinder treat s0 as pt_regs address. Use s1 for
this job.

Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
---
 arch/riscv/kernel/entry.S | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index ecb15c7430b4..a3b14a649782 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -205,33 +205,33 @@ handle_syscall:
 check_syscall_nr:
 	/* Check to make sure we don't jump to a bogus syscall number. */
 	li t0, __NR_syscalls
-	la s0, sys_ni_syscall
+	la s1, sys_ni_syscall
 	/*
 	 * Syscall number held in a7.
 	 * If syscall number is above allowed value, redirect to ni_syscall.
 	 */
 	bgeu a7, t0, 3f
 #ifdef CONFIG_COMPAT
-	REG_L s0, PT_STATUS(sp)
-	srli s0, s0, SR_UXL_SHIFT
-	andi s0, s0, (SR_UXL >> SR_UXL_SHIFT)
+	REG_L s1, PT_STATUS(sp)
+	srli s1, s1, SR_UXL_SHIFT
+	andi s1, s1, (SR_UXL >> SR_UXL_SHIFT)
 	li t0, (SR_UXL_32 >> SR_UXL_SHIFT)
-	sub t0, s0, t0
+	sub t0, s1, t0
 	bnez t0, 1f
 
 	/* Call compat_syscall */
-	la s0, compat_sys_call_table
+	la s1, compat_sys_call_table
 	j 2f
 1:
 #endif
 	/* Call syscall */
-	la s0, sys_call_table
+	la s1, sys_call_table
 2:
 	slli t0, a7, RISCV_LGPTR
-	add s0, s0, t0
-	REG_L s0, 0(s0)
+	add s1, s1, t0
+	REG_L s1, 0(s1)
 3:
-	jalr s0
+	jalr s1
 
 ret_from_syscall:
 	/* Set user a0 to kernel a0 */
-- 
2.17.1