powerpc: Restore VDSO information on critical exception om BookE

Critical exception on 64-bit booke uses user-visible SPRG3 as scratch.
Restore VDSO information in SPRG3 on exception prolog.

Use a common sprg3 field in PACA for all powerpc64 architectures.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/kvm_book3s_asm.h

@@ -74,7 +74,6 @@ struct kvmppc_host_state {
 	ulong vmhandler;
 	ulong scratch0;
 	ulong scratch1;
-	ulong sprg3;
 	u8 in_guest;
 	u8 restore_hid5;
 	u8 napping;

arch/powerpc/include/asm/paca.h

@@ -136,6 +136,7 @@ struct paca_struct {
 	u8 io_sync;			/* writel() needs spin_unlock sync */
 	u8 irq_work_pending;		/* IRQ_WORK interrupt while soft-disable */
 	u8 nap_state_lost;		/* NV GPR values lost in power7_idle */
+	u64 sprg3;			/* Saved user-visible sprg */
 
 #ifdef CONFIG_PPC_POWERNV
 	/* Pointer to OPAL machine check event structure set by the

arch/powerpc/kernel/asm-offsets.c

@@ -205,6 +205,7 @@ int main(void)
 	DEFINE(PACA_SYSTEM_TIME, offsetof(struct paca_struct, system_time));
 	DEFINE(PACA_TRAP_SAVE, offsetof(struct paca_struct, trap_save));
 	DEFINE(PACA_NAPSTATELOST, offsetof(struct paca_struct, nap_state_lost));
+	DEFINE(PACA_SPRG3, offsetof(struct paca_struct, sprg3));
 #endif /* CONFIG_PPC64 */
 
 	/* RTAS */
@@ -533,7 +534,6 @@ int main(void)
 	HSTATE_FIELD(HSTATE_VMHANDLER, vmhandler);
 	HSTATE_FIELD(HSTATE_SCRATCH0, scratch0);
 	HSTATE_FIELD(HSTATE_SCRATCH1, scratch1);
-	HSTATE_FIELD(HSTATE_SPRG3, sprg3);
 	HSTATE_FIELD(HSTATE_IN_GUEST, in_guest);
 	HSTATE_FIELD(HSTATE_RESTORE_HID5, restore_hid5);
 	HSTATE_FIELD(HSTATE_NAPPING, napping);

arch/powerpc/kernel/exceptions-64e.S

@@ -110,7 +110,9 @@
 
 #define PROLOG_STORE_RESTORE_SCRATCH_CRIT				    \
 	mfspr	r10,SPRN_SPRG_CRIT_SCRATCH;	/* get r13 */		    \
-	std	r10,PACA_EXCRIT+EX_R13(r13)
+	std	r10,PACA_EXCRIT+EX_R13(r13);				    \
+	ld	r11,PACA_SPRG3(r13);					    \
+	mtspr	SPRN_SPRG_CRIT_SCRATCH,r11;
 
 /* Variants of the "addition" argument for the prolog
  */

arch/powerpc/kernel/vdso.c

@@ -723,9 +723,7 @@ int __cpuinit vdso_getcpu_init(void)
 
 	val = (cpu & 0xfff) | ((node & 0xffff) << 16);
 	mtspr(SPRN_SPRG3, val);
-#ifdef CONFIG_KVM_BOOK3S_HANDLER
-	get_paca()->kvm_hstate.sprg3 = val;
-#endif
+	get_paca()->sprg3 = val;
 
 	put_cpu();
 

arch/powerpc/kvm/book3s_hv_rmhandlers.S

@@ -1065,7 +1065,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_206)
 	mtspr	SPRN_DABRX,r6
 
 	/* Restore SPRG3 */
-	ld	r3,HSTATE_SPRG3(r13)
+	ld	r3,PACA_SPRG3(r13)
 	mtspr	SPRN_SPRG3,r3
 
 	/*