1 files changed, 70 insertions, 0 deletions
diff --git a/arch/arm/include/asm/percpu.h b/arch/arm/include/asm/percpu.h
new file mode 100644
index 000000000..7545c87c2
--- /dev/null
+++ b/arch/arm/include/asm/percpu.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2012 Calxeda, Inc.
+ */
+#ifndef _ASM_ARM_PERCPU_H_
+#define _ASM_ARM_PERCPU_H_
+
+#include <asm/insn.h>
+
+register unsigned long current_stack_pointer asm ("sp");
+
+/*
+ * Same as asm-generic/percpu.h, except that we store the per cpu offset
+ * in the TPIDRPRW. TPIDRPRW only exists on V6K and V7
+ */
+#ifdef CONFIG_SMP
+static inline void set_my_cpu_offset(unsigned long off)
+{
+	extern unsigned int smp_on_up;
+
+	if (IS_ENABLED(CONFIG_CPU_V6) && !smp_on_up)
+		return;
+
+	/* Set TPIDRPRW */
+	asm volatile("mcr p15, 0, %0, c13, c0, 4" : : "r" (off) : "memory");
+}
+
+static __always_inline unsigned long __my_cpu_offset(void)
+{
+	unsigned long off;
+
+	/*
+	 * Read TPIDRPRW.
+	 * We want to allow caching the value, so avoid using volatile and
+	 * instead use a fake stack read to hazard against barrier().
+	 */
+	asm("0:	mrc p15, 0, %0, c13, c0, 4			\n\t"
+#ifdef CONFIG_CPU_V6
+	    "1:							\n\t"
+	    "	.subsection 1					\n\t"
+#if defined(CONFIG_ARM_HAS_GROUP_RELOCS) && \
+    !(defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS))
+	    "2: " LOAD_SYM_ARMV6(%0, __per_cpu_offset) "	\n\t"
+	    "	b	1b					\n\t"
+#else
+	    "2: ldr	%0, 3f					\n\t"
+	    "	ldr	%0, [%0]				\n\t"
+	    "	b	1b					\n\t"
+	    "3:	.long	__per_cpu_offset			\n\t"
+#endif
+	    "	.previous					\n\t"
+	    "	.pushsection \".alt.smp.init\", \"a\"		\n\t"
+	    "	.long	0b - .					\n\t"
+	    "	b	. + (2b - 0b)				\n\t"
+	    "	.popsection					\n\t"
+#endif
+	     : "=r" (off)
+	     : "Q" (*(const unsigned long *)current_stack_pointer));
+
+	return off;
+}
+#define __my_cpu_offset __my_cpu_offset()
+#else
+#define set_my_cpu_offset(x)	do {} while(0)
+
+#endif /* CONFIG_SMP */
+
+#include <asm-generic/percpu.h>
+
+#endif /* _ASM_ARM_PERCPU_H_ */