arch/loongarch/vdso/vgetcpu.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Fast user context implementation of getcpu()
   4  */
   5
   6 #include <asm/vdso.h>
   7 #include <linux/getcpu.h>
   8
   9 static __always_inline int read_cpu_id(void)
  10 {
  11         int cpu_id;
  12
  13         __asm__ __volatile__(
  14         "       rdtime.d $zero, %0\n"
  15         : "=r" (cpu_id)
  16         :
  17         : "memory");
  18
  19         return cpu_id;
  20 }
  21
  22 static __always_inline const struct vdso_pcpu_data *get_pcpu_data(void)
  23 {
  24         return _loongarch_data.pdata;
  25 }
  26
  27 extern
  28 int __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused);
  29 int __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused)
  30 {
  31         int cpu_id;
  32         const struct vdso_pcpu_data *data;
  33
  34         cpu_id = read_cpu_id();
  35
  36         if (cpu)
  37                 *cpu = cpu_id;
  38
  39         if (node) {
  40                 data = get_pcpu_data();
  41                 *node = data[cpu_id].node;
  42         }
  43
  44         return 0;
  45 }