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powerpc: Prepare for splitting giveup_{fpu, altivec, vsx} in two

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This prepares for the decoupling of saving {fpu,altivec,vsx} registers and
marking {fpu,altivec,vsx} as being unused by a thread.

Currently giveup_{fpu,altivec,vsx}() does both however optimisations to
task switching can be made if these two operations are decoupled.
save_all() will permit the saving of registers to thread structs and leave
threads MSR with bits enabled.

This patch introduces no functional change.

Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Cyril Bur
2016-02-29 17:53:48 +11:00
committed by Michael Ellerman
parent 70fe3d980f
commit de2a20aa72
3 changed files with 45 additions and 1 deletions
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31
arch/powerpc/kernel/process.c
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@@ -444,12 +444,41 @@ void restore_math(struct pt_regs *regs)
regs->msr = msr;
}
void save_all(struct task_struct *tsk)
{
unsigned long usermsr;
if (!tsk->thread.regs)
return;
usermsr = tsk->thread.regs->msr;
if ((usermsr & msr_all_available) == 0)
return;
msr_check_and_set(msr_all_available);
if (usermsr & MSR_FP)
__giveup_fpu(tsk);
if (usermsr & MSR_VEC)
__giveup_altivec(tsk);
if (usermsr & MSR_VSX)
__giveup_vsx(tsk);
if (usermsr & MSR_SPE)
__giveup_spe(tsk);
msr_check_and_clear(msr_all_available);
}
void flush_all_to_thread(struct task_struct *tsk)
{
if (tsk->thread.regs) {
preempt_disable();
BUG_ON(tsk != current);
giveup_all(tsk);
save_all(tsk);
#ifdef CONFIG_SPE
if (tsk->thread.regs->msr & MSR_SPE)