powerpc/64: Move set_soft_enabled() and rename

Move set_soft_enabled() from powerpc/kernel/irq.c to asm/hw_irq.c, to
encourage updates to paca->soft_enabled done via these access
function. Add "memory" clobber to hint compiler since
paca->soft_enabled memory is the target here.

Renaming it as soft_enabled_set() will make namespaces works better as
prefix than a postfix when new soft_enabled manipulation functions are
introduced.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/hw_irq.h

@@ -49,6 +49,21 @@ extern void unknown_exception(struct pt_regs *regs);
 #ifdef CONFIG_PPC64
 #include <asm/paca.h>
 
+/*
+ * The "memory" clobber acts as both a compiler barrier
+ * for the critical section and as a clobber because
+ * we changed paca->soft_enabled
+ */
+static inline notrace void soft_enabled_set(unsigned long enable)
+{
+	asm volatile(
+		"stb %0,%1(13)"
+		:
+		: "r" (enable),
+		  "i" (offsetof(struct paca_struct, soft_enabled))
+		: "memory");
+}
+
 static inline unsigned long arch_local_save_flags(void)
 {
 	unsigned long flags;
@@ -63,12 +78,7 @@ static inline unsigned long arch_local_save_flags(void)
 
 static inline void arch_local_irq_disable(void)
 {
-	asm volatile(
-		"stb %0,%1(13)"
-		:
-		: "r" (IRQS_DISABLED),
-		  "i" (offsetof(struct paca_struct, soft_enabled))
-		: "memory");
+	soft_enabled_set(IRQS_DISABLED);
 }
 
 extern void arch_local_irq_restore(unsigned long);

arch/powerpc/include/asm/kvm_ppc.h

@@ -873,7 +873,7 @@ static inline void kvmppc_fix_ee_before_entry(void)
 
 	/* Only need to enable IRQs by hard enabling them after this */
 	local_paca->irq_happened = 0;
-	local_paca->soft_enabled = IRQS_ENABLED;
+	soft_enabled_set(IRQS_ENABLED);
 #endif
 }
 

arch/powerpc/kernel/irq.c

@@ -107,12 +107,6 @@ static inline notrace unsigned long get_irq_happened(void)
 	return happened;
 }
 
-static inline notrace void set_soft_enabled(unsigned long enable)
-{
-	__asm__ __volatile__("stb %0,%1(13)"
-	: : "r" (enable), "i" (offsetof(struct paca_struct, soft_enabled)));
-}
-
 static inline notrace int decrementer_check_overflow(void)
 {
  	u64 now = get_tb_or_rtc();
@@ -231,7 +225,7 @@ notrace void arch_local_irq_restore(unsigned long en)
 	unsigned int replay;
 
 	/* Write the new soft-enabled value */
-	set_soft_enabled(en);
+	soft_enabled_set(en);
 	if (en == IRQS_DISABLED)
 		return;
 	/*
@@ -277,7 +271,7 @@ notrace void arch_local_irq_restore(unsigned long en)
 	}
 #endif /* CONFIG_TRACE_IRQFLAGS */
 
-	set_soft_enabled(IRQS_DISABLED);
+	soft_enabled_set(IRQS_DISABLED);
 	trace_hardirqs_off();
 
 	/*
@@ -289,7 +283,7 @@ notrace void arch_local_irq_restore(unsigned long en)
 
 	/* We can soft-enable now */
 	trace_hardirqs_on();
-	set_soft_enabled(IRQS_ENABLED);
+	soft_enabled_set(IRQS_ENABLED);
 
 	/*
 	 * And replay if we have to. This will return with interrupts
@@ -364,7 +358,7 @@ bool prep_irq_for_idle(void)
 	 * of entering the low power state.
 	 */
 	local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
-	local_paca->soft_enabled = IRQS_ENABLED;
+	soft_enabled_set(IRQS_ENABLED);
 
 	/* Tell the caller to enter the low power state */
 	return true;

arch/powerpc/kernel/setup_64.c

@@ -189,7 +189,7 @@ static void __init fixup_boot_paca(void)
 	/* Allow percpu accesses to work until we setup percpu data */
 	get_paca()->data_offset = 0;
 	/* Mark interrupts disabled in PACA */
-	get_paca()->soft_enabled = IRQS_DISABLED;
+	soft_enabled_set(IRQS_DISABLED);
 }
 
 static void __init configure_exceptions(void)
@@ -352,7 +352,7 @@ void __init early_setup(unsigned long dt_ptr)
 void early_setup_secondary(void)
 {
 	/* Mark interrupts disabled in PACA */
-	get_paca()->soft_enabled = 0;
+	soft_enabled_set(IRQS_DISABLED);
 
 	/* Initialize the hash table or TLB handling */
 	early_init_mmu_secondary();

arch/powerpc/kernel/time.c

@@ -253,15 +253,15 @@ void accumulate_stolen_time(void)
 	 * needs to reflect that so various debug stuff doesn't
 	 * complain
 	 */
-	local_paca->soft_enabled = IRQS_DISABLED;
+	soft_enabled_set(IRQS_DISABLED);
 
 	sst = scan_dispatch_log(acct->starttime_user);
 	ust = scan_dispatch_log(acct->starttime);
 	acct->stime -= sst;
 	acct->utime -= ust;
 	acct->steal_time += ust + sst;
 
-	local_paca->soft_enabled = save_soft_enabled;
+	soft_enabled_set(save_soft_enabled);
 }
 
 static inline u64 calculate_stolen_time(u64 stop_tb)