From: Suzuki K Poulose <suzuki.poulose@arm.com>
Date: Tue, 23 Feb 2016 10:31:39 +0000 (+0000)
Subject: arm64: Add a helper for parking CPUs in a loop
X-Git-Tag: release-20171130_firefly~4^2~100^2~1^2~2^2~24
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=45a8334205e2c8c18866f41469472a54c30a8085;p=firefly-linux-kernel-4.4.55.git

arm64: Add a helper for parking CPUs in a loop

Adds a routine which can be used to park CPUs (spinning in kernel)
when they can't be killed.

Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---

diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index 2013a4dc5124..b93eb3303131 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -78,4 +78,12 @@ extern int __cpu_disable(void);
 extern void __cpu_die(unsigned int cpu);
 extern void cpu_die(void);
 
+static inline void cpu_park_loop(void)
+{
+	for (;;) {
+		wfe();
+		wfi();
+	}
+}
+
 #endif /* ifndef __ASM_SMP_H */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index eda7d5915fbb..89413b5e1129 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -909,10 +909,7 @@ static void fail_incapable_cpu(char *cap_type,
 	/* Check if we can park ourselves */
 	if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_die)
 		cpu_ops[cpu]->cpu_die(cpu);
-	asm(
-	"1:	wfe\n"
-	"	wfi\n"
-	"	b	1b");
+	cpu_park_loop();
 }
 
 /*