powerpc: Provide for giveup_fpu/altivec to save state in alternate location

This provides a facility which is intended for use by KVM, where the
contents of the FP/VSX and VMX (Altivec) registers can be saved away
to somewhere other than the thread_struct when kernel code wants to
use floating point or VMX instructions.  This is done by providing a
pointer in the thread_struct to indicate where the state should be
saved to.  The giveup_fpu() and giveup_altivec() functions test these
pointers and save state to the indicated location if they are non-NULL.
Note that the MSR_FP/VEC bits in task->thread.regs->msr are still used
to indicate whether the CPU register state is live, even when an
alternate save location is being used.

This also provides load_fp_state() and load_vr_state() functions, which
load up FP/VSX and VMX state from memory into the CPU registers, and
corresponding store_fp_state() and store_vr_state() functions, which
store FP/VSX and VMX state into memory from the CPU registers.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index 21646dbe1bb3..56a4bec1b11a 100644
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -98,9 +98,13 @@ EXPORT_SYMBOL(start_thread);
 
 #ifdef CONFIG_PPC_FPU
 EXPORT_SYMBOL(giveup_fpu);
+EXPORT_SYMBOL(load_fp_state);
+EXPORT_SYMBOL(store_fp_state);
 #endif
 #ifdef CONFIG_ALTIVEC
 EXPORT_SYMBOL(giveup_altivec);
+EXPORT_SYMBOL(load_vr_state);
+EXPORT_SYMBOL(store_vr_state);
 #endif /* CONFIG_ALTIVEC */
 #ifdef CONFIG_VSX
 EXPORT_SYMBOL(giveup_vsx);