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Subject[PATCH] riscv: vector: Check SR_SD before saving vstate
Date
The SD bit summarizes the dirty states of FS, VS, or XS fields,
providing a "fast check" before saving fstate or vstate.

Let __switch_to_vector() check SD bit as __switch_to_fpu() does.

Fixes: 3a2df6323def ("riscv: Add task switch support for vector")
Signed-off-by: Song Shuai <songshuaishuai@tinylab.org>
---
arch/riscv/include/asm/vector.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/vector.h b/arch/riscv/include/asm/vector.h
index 87aaef656257..d30fa56f67c6 100644
--- a/arch/riscv/include/asm/vector.h
+++ b/arch/riscv/include/asm/vector.h
@@ -190,7 +190,8 @@ static inline void __switch_to_vector(struct task_struct *prev,
struct pt_regs *regs;

regs = task_pt_regs(prev);
- riscv_v_vstate_save(prev, regs);
+ if (unlikely(regs->status & SR_SD))
+ riscv_v_vstate_save(prev, regs);
riscv_v_vstate_restore(next, task_pt_regs(next));
}

--
2.20.1

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