arch/arm/include/asm/percpu.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright 2012 Calxeda, Inc.
   4  */
   5 #ifndef _ASM_ARM_PERCPU_H_
   6 #define _ASM_ARM_PERCPU_H_
   7
   8 /*
   9  * Same as asm-generic/percpu.h, except that we store the per cpu offset
  10  * in the TPIDRPRW. TPIDRPRW only exists on V6K and V7
  11  */
  12 #if defined(CONFIG_SMP) && !defined(CONFIG_CPU_V6)
  13 static inline void set_my_cpu_offset(unsigned long off)
  14 {
  15         /* Set TPIDRPRW */
  16         asm volatile("mcr p15, 0, %0, c13, c0, 4" : : "r" (off) : "memory");
  17 }
  18
  19 static inline unsigned long __my_cpu_offset(void)
  20 {
  21         unsigned long off;
  22
  23         /*
  24          * Read TPIDRPRW.
  25          * We want to allow caching the value, so avoid using volatile and
  26          * instead use a fake stack read to hazard against barrier().
  27          */
  28         asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off)
  29                 : "Q" (*(const unsigned long *)current_stack_pointer));
  30
  31         return off;
  32 }
  33 #define __my_cpu_offset __my_cpu_offset()
  34 #else
  35 #define set_my_cpu_offset(x)    do {} while(0)
  36
  37 #endif /* CONFIG_SMP */
  38
  39 #include <asm-generic/percpu.h>
  40
  41 #endif /* _ASM_ARM_PERCPU_H_ */