linux-kernel - [PATCH v2] LoongArch: Clean useless vcsr in loongarch

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Date:   Mon,  4 Jul 2022 23:36:12 +0800
From:   Qi Hu <huqi@...ngson.cn>
To:     Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>
Cc:     loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH v2] LoongArch: Clean useless vcsr in loongarch_fpu.

The `vcsr` is not used anymore. Remove this member from `loongarch_fpu`.

>From 3A5000(LoongArch), `vcsr` is removed in hardware. FP and LSX/LASX
both use `fcsr` as their csr.

Particularly, fcsr from $r16 to $r31 are reserved for LSX/LASX, and
using the registers in this area will cause SXD/ASXD if LSX/LASX is
not enabled.

Signed-off-by: Qi Hu <huqi@...ngson.cn>
---
V2:
- Add more details in the commit message.
---
 arch/loongarch/include/asm/fpregdef.h  |  1 -
 arch/loongarch/include/asm/processor.h |  2 --
 arch/loongarch/kernel/asm-offsets.c    |  1 -
 arch/loongarch/kernel/fpu.S            | 10 ----------
 4 files changed, 14 deletions(-)

diff --git a/arch/loongarch/include/asm/fpregdef.h b/arch/loongarch/include/asm/fpregdef.h
index adb16e4b4..b6be52783 100644
--- a/arch/loongarch/include/asm/fpregdef.h
+++ b/arch/loongarch/include/asm/fpregdef.h
@@ -48,6 +48,5 @@
 #define fcsr1	$r1
 #define fcsr2	$r2
 #define fcsr3	$r3
-#define vcsr16	$r16
 
 #endif /* _ASM_FPREGDEF_H */
diff --git a/arch/loongarch/include/asm/processor.h b/arch/loongarch/include/asm/processor.h
index 1d63c934b..57ec45aa0 100644
--- a/arch/loongarch/include/asm/processor.h
+++ b/arch/loongarch/include/asm/processor.h
@@ -80,7 +80,6 @@ BUILD_FPR_ACCESS(64)
 
 struct loongarch_fpu {
 	unsigned int	fcsr;
-	unsigned int	vcsr;
 	uint64_t	fcc;	/* 8x8 */
 	union fpureg	fpr[NUM_FPU_REGS];
 };
@@ -161,7 +160,6 @@ struct thread_struct {
 	 */							\
 	.fpu			= {				\
 		.fcsr		= 0,				\
-		.vcsr		= 0,				\
 		.fcc		= 0,				\
 		.fpr		= {{{0,},},},			\
 	},							\
diff --git a/arch/loongarch/kernel/asm-offsets.c b/arch/loongarch/kernel/asm-offsets.c
index bfb65eb28..20cd9e16a 100644
--- a/arch/loongarch/kernel/asm-offsets.c
+++ b/arch/loongarch/kernel/asm-offsets.c
@@ -166,7 +166,6 @@ void output_thread_fpu_defines(void)
 
 	OFFSET(THREAD_FCSR, loongarch_fpu, fcsr);
 	OFFSET(THREAD_FCC,  loongarch_fpu, fcc);
-	OFFSET(THREAD_VCSR, loongarch_fpu, vcsr);
 	BLANK();
 }
 
diff --git a/arch/loongarch/kernel/fpu.S b/arch/loongarch/kernel/fpu.S
index 75c6ce068..a631a7137 100644
--- a/arch/loongarch/kernel/fpu.S
+++ b/arch/loongarch/kernel/fpu.S
@@ -146,16 +146,6 @@
 	movgr2fcsr	fcsr0, \tmp0
 	.endm
 
-	.macro sc_save_vcsr base, tmp0
-	movfcsr2gr	\tmp0, vcsr16
-	EX	st.w \tmp0, \base, 0
-	.endm
-
-	.macro sc_restore_vcsr base, tmp0
-	EX	ld.w \tmp0, \base, 0
-	movgr2fcsr	vcsr16, \tmp0
-	.endm
-
 /*
  * Save a thread's fp context.
  */
-- 
2.36.1