powerpc: Add VSX context save/restore, ptrace and signal support

This patch extends the floating point save and restore code to use the
VSX load/stores when VSX is available.  This will make FP context
save/restore marginally slower on FP only code, when VSX is available,
as it has to load/store 128bits rather than just 64bits.

Mixing FP, VMX and VSX code will get constant architected state.

The signals interface is extended to enable access to VSR 0-31
doubleword 1 after discussions with tool chain maintainers.  Backward
compatibility is maintained.

The ptrace interface is also extended to allow access to VSR 0-31 full
registers.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index 942951e76586..31b9026cf1e3 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -506,6 +506,39 @@ _GLOBAL(giveup_altivec)
 
 #endif /* CONFIG_ALTIVEC */
 
+#ifdef CONFIG_VSX
+/*
+ * giveup_vsx(tsk)
+ * Disable VSX for the task given as the argument,
+ * and save the vector registers in its thread_struct.
+ * Enables the VSX for use in the kernel on return.
+ */
+_GLOBAL(giveup_vsx)
+        mfmsr   r5
+        oris    r5,r5,MSR_VSX@h
+        mtmsrd  r5                      /* enable use of VSX now */
+        isync
+
+        cmpdi   0,r3,0
+        beqlr-                          /* if no previous owner, done */
+        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:
+#ifndef CONFIG_SMP
+        li      r5,0
+        ld      r4,last_task_used_vsx@got(r2)
+        std     r5,0(r4)
+#endif /* CONFIG_SMP */
+        blr
+
+#endif /* CONFIG_VSX */
+
 /* kexec_wait(phys_cpu)
  *
  * wait for the flag to change, indicating this kernel is going away but