riscv: fpu: drop SR_SD bit checking

SR_SD summarizes the dirty status of FS/VS/XS. However, the current code
structure does not fully utilize it because each extension specific code
is divided into an individual segment. So remove the SR_SD check for
now.

Signed-off-by: Andy Chiu <[email protected]>
Reviewed-by: Song Shuai <[email protected]>
Reviewed-by: Guo Ren <[email protected]>
Tested-by: Björn Töpel <[email protected]>
Tested-by: Lad Prabhakar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>

Author: AndybnACT

arch/riscv/include/asm/switch_to.h

@@ -53,8 +53,7 @@ static inline void __switch_to_fpu(struct task_struct *prev,
 	struct pt_regs *regs;
 
 	regs = task_pt_regs(prev);
-	if (unlikely(regs->status & SR_SD))
-		fstate_save(prev, regs);
+	fstate_save(prev, regs);
 	fstate_restore(next, task_pt_regs(next));
 }