ARM: Put target PC for PSCI CPU_ON on per-CPU stack

Use a per-CPU variable for saving the target PC during CPU_ON
operations. This allows us to run this service independently on targets
that have more than 2 cores and also core-local power control.

CC: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Tested-by: Ian Campbell <ijc@hellion.org.uk>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/cpu/armv7/psci.S

@@ -17,6 +17,7 @@
 
 #include <config.h>
 #include <linux/linkage.h>
+#include <asm/macro.h>
 #include <asm/psci.h>
 
 	.pushsection ._secure.text, "ax"
@@ -202,6 +203,7 @@ ENTRY(psci_get_cpu_stack_top)
 	add	r5, r5, #0x2000			@ Skip two pages
 	lsr	r5, r5, #12			@ Align to start of page
 	lsl	r5, r5, #12
+	sub	r5, r5, #4			@ reserve 1 word for target PC
 	sub	r0, r5, r0			@ here's our stack!
 
 	bx	lr
@@ -212,13 +214,10 @@ ENTRY(psci_cpu_entry)
 
 	bl	_nonsec_init
 
-	adr	r0, _psci_target_pc
-	ldr	r0, [r0]
+	bl	psci_get_cpu_id			@ CPU ID => r0
+	bl	psci_get_cpu_stack_top		@ stack top => r0
+	ldr	r0, [r0]			@ target PC at stack top
 	b	_do_nonsec_entry
 ENDPROC(psci_cpu_entry)
 
-.globl _psci_target_pc
-_psci_target_pc:
-	.word	0
-
 	.popsection

arch/arm/cpu/armv7/sunxi/psci.S

@@ -139,8 +139,11 @@ out:	mcr	p15, 0, r7, c1, c1, 0
 	@ r2 = target PC
 .globl	psci_cpu_on
 psci_cpu_on:
-	ldr	r0, =_psci_target_pc
-	str	r2, [r0]
+	push	{lr}
+
+	mov	r0, r1
+	bl	psci_get_cpu_stack_top	@ get stack top of target CPU
+	str	r2, [r0]		@ store target PC at stack top
 	dsb
 
 	movw	r0, #(SUN7I_CPUCFG_BASE & 0xffff)
@@ -195,7 +198,7 @@ psci_cpu_on:
 	str	r6, [r0, #0x1e4]
 
 	mov	r0, #ARM_PSCI_RET_SUCCESS	@ Return PSCI_RET_SUCCESS
-	mov	pc, lr
+	pop	{pc}
 
 .globl	psci_cpu_off
 psci_cpu_off: