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authorPaul Mackerras <paulus@samba.org>2013-09-10 20:21:10 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-10-11 17:26:50 +1100
commit18461960cbf50bf345ef0667d45d5f64de8fb893 (patch)
tree58947fe30598814684f7e33424675e204316e8ef /arch/powerpc/kernel/vector.S
parentde79f7b9f6f92ec1bd6f61fa1f20de60728a5b5e (diff)
downloadlinux-next-18461960cbf50bf345ef0667d45d5f64de8fb893.tar.gz
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>
Diffstat (limited to 'arch/powerpc/kernel/vector.S')
-rw-r--r--arch/powerpc/kernel/vector.S29
1 files changed, 27 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/vector.S b/arch/powerpc/kernel/vector.S
index a48df870b696..eacda4eea2d7 100644
--- a/arch/powerpc/kernel/vector.S
+++ b/arch/powerpc/kernel/vector.S
@@ -37,6 +37,28 @@ _GLOBAL(do_load_up_transact_altivec)
#endif
/*
+ * Load state from memory into VMX registers including VSCR.
+ * Assumes the caller has enabled VMX in the MSR.
+ */
+_GLOBAL(load_vr_state)
+ li r4,VRSTATE_VSCR
+ lvx vr0,r4,r3
+ mtvscr vr0
+ REST_32VRS(0,r4,r3)
+ blr
+
+/*
+ * Store VMX state into memory, including VSCR.
+ * Assumes the caller has enabled VMX in the MSR.
+ */
+_GLOBAL(store_vr_state)
+ SAVE_32VRS(0, r4, r3)
+ mfvscr vr0
+ li r4, VRSTATE_VSCR
+ stvx vr0, r4, r3
+ blr
+
+/*
* Disable VMX for the task which had it previously,
* and save its vector registers in its thread_struct.
* Enables the VMX for use in the kernel on return.
@@ -144,9 +166,12 @@ _GLOBAL(giveup_altivec)
PPC_LCMPI 0,r3,0
beqlr /* if no previous owner, done */
addi r3,r3,THREAD /* want THREAD of task */
- addi r7,r3,THREAD_VRSTATE
+ PPC_LL r7,THREAD_VRSAVEAREA(r3)
PPC_LL r5,PT_REGS(r3)
- PPC_LCMPI 0,r5,0
+ PPC_LCMPI 0,r7,0
+ bne 2f
+ addi r7,r3,THREAD_VRSTATE
+2: PPC_LCMPI 0,r5,0
SAVE_32VRS(0,r4,r7)
mfvscr vr0
li r4,VRSTATE_VSCR