powerpc: Add the ability to save VSX without giving it up

This patch adds the ability to be able to save the VSX registers to the
thread struct without giving up (disabling the facility) next time the
process returns to userspace.

This patch builds on a previous optimisation for the FPU and VEC registers
in the thread copy path to avoid a possibly pointless reload of VSX state.

Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 0 insertions, 17 deletions

diff --git a/arch/powerpc/kernel/vector.S b/arch/powerpc/kernel/vector.S
index 51b0c175ea8c..1c2e7a343bf5 100644
--- a/arch/powerpc/kernel/vector.S
+++ b/arch/powerpc/kernel/vector.S
@@ -151,23 +151,6 @@ _GLOBAL(load_up_vsx)
         std     r12,_MSR(r1)
         b       fast_exception_return
 
-/*
- * __giveup_vsx(tsk)
- * Disable VSX for the task given as the argument.
- * Does NOT save vsx registers.
- */
-_GLOBAL(__giveup_vsx)
-        addi    r3,r3,THREAD            /* want THREAD of task */
-        ld      r5,PT_REGS(r3)
-        cmpdi   0,r5,0
-        beq     1f
-        ld      r4,_MSR-STACK_FRAME_OVERHEAD(r5)
-        lis     r3,MSR_VSX@h
-        andc    r4,r4,r3                /* disable VSX for previous task */
-        std     r4,_MSR-STACK_FRAME_OVERHEAD(r5)
-1:
-        blr
-
 #endif /* CONFIG_VSX */