[S390] switch_to: dont restore/save access & fpu regs for kernel threads
If the previous task was a kernel thread there is no need to save the contents of the fpu and access registers since they aren't used in kernel mode. For the same reason it is not necessary to restore these registers if the next task is a kernel thread. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
parent
f861e40572
commit
fdb6d070ef
|
@ -85,14 +85,18 @@ static inline void restore_access_regs(unsigned int *acrs)
|
|||
asm volatile("lam 0,15,%0" : : "Q" (*acrs));
|
||||
}
|
||||
|
||||
#define switch_to(prev,next,last) do { \
|
||||
if (prev == next) \
|
||||
break; \
|
||||
save_fp_regs(&prev->thread.fp_regs); \
|
||||
restore_fp_regs(&next->thread.fp_regs); \
|
||||
save_access_regs(&prev->thread.acrs[0]); \
|
||||
restore_access_regs(&next->thread.acrs[0]); \
|
||||
prev = __switch_to(prev,next); \
|
||||
#define switch_to(prev,next,last) do { \
|
||||
if (prev == next) \
|
||||
break; \
|
||||
if (prev->mm) { \
|
||||
save_fp_regs(&prev->thread.fp_regs); \
|
||||
save_access_regs(&prev->thread.acrs[0]); \
|
||||
} \
|
||||
if (next->mm) { \
|
||||
restore_fp_regs(&next->thread.fp_regs); \
|
||||
restore_access_regs(&next->thread.acrs[0]); \
|
||||
} \
|
||||
prev = __switch_to(prev,next); \
|
||||
} while (0)
|
||||
|
||||
extern void account_vtime(struct task_struct *, struct task_struct *);
|
||||
|
|
Loading…
Reference in New Issue
Block a user