[ARM64,v4.4,V3,15/44] arm64: Add a helper for parking CPUs in a loop

Message ID a990b94f1fa5ec079a180d333e3d0005e2e7f5ed.1567077734.git.viresh.kumar@linaro.org
State New
Headers show
Series
  • V4.4 backport of arm64 Spectre patches
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Commit Message

Viresh Kumar Aug. 29, 2019, 11:34 a.m.
From: Suzuki K Poulose <suzuki.poulose@arm.com>


Commit c4bc34d20273db698c51951a1951dba0a722e162 upstream.

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>

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

---
 arch/arm64/include/asm/smp.h   | 8 ++++++++
 arch/arm64/kernel/cpufeature.c | 5 +----
 2 files changed, 9 insertions(+), 4 deletions(-)

-- 
2.21.0.rc0.269.g1a574e7a288b

Patch

diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index d9c3d6a6100a..53b53a9b3e5a 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -69,4 +69,12 @@  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 b7f01bf47988..4adf18307568 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -868,10 +868,7 @@  void cpu_die_early(void)
 	/* 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();
 }
 
 /*