linux-kernel - [PATCH] MIPS: Fix IRQ tracing when call handle

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Date:   Mon, 25 May 2020 11:31:23 +0800
From:   YuanJunQing <yuanjunqing66@....com>
To:     tsbogend@...ha.franken.de
Cc:     paulburton@...nel.org, chenhc@...ote.com,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        liulichao@...ngson.cn, YuanJunQing <yuanjunqing66@....com>
Subject: [PATCH] MIPS: Fix IRQ tracing when call handle_fpe()

 Register "a1" is unsaved in this function,
 when CONFIG_TRACE_IRQFLAGS is enabled,
 the TRACE_IRQS_OFF macro will call trace_hardirqs_off(),
 and this may change register "a1".
 The variment of register "a1" may send SIGFPE signal
 to task when call do_fpe(),and this may kill the task.

Signed-off-by: YuanJunQing <yuanjunqing66@....com>
---
 arch/mips/kernel/genex.S | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index 8236fb291e3f..956a76429773 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -480,16 +480,18 @@ NESTED(nmi_handler, PT_SIZE, sp)
 	/* gas fails to assemble cfc1 for some archs (octeon).*/ \
 	.set	mips1
 	SET_HARDFLOAT
-	cfc1	a1, fcr31
+	cfc1	s0, fcr31
 	.set	pop
 	CLI
 	TRACE_IRQS_OFF
+	move    a1,s0
 	.endm
 
 	.macro	__build_clear_msa_fpe
-	_cfcmsa	a1, MSA_CSR
+	_cfcmsa	s0, MSA_CSR
 	CLI
 	TRACE_IRQS_OFF
+	move    a1,s0
 	.endm
 
 	.macro	__build_clear_ade
-- 
2.17.1