arch/x86/include/asm/vsyscall.h

   1 #ifndef _ASM_X86_VSYSCALL_H
   2 #define _ASM_X86_VSYSCALL_H
   3
   4 #include <linux/seqlock.h>
   5 #include <uapi/asm/vsyscall.h>
   6
   7 #define VGETCPU_RDTSCP  1
   8 #define VGETCPU_LSL     2
   9
  10 /* kernel space (writeable) */
  11 extern int vgetcpu_mode;
  12 extern struct timezone sys_tz;
  13
  14 #include <asm/vvar.h>
  15
  16 extern void map_vsyscall(void);
  17
  18 /*
  19  * Called on instruction fetch fault in vsyscall page.
  20  * Returns true if handled.
  21  */
  22 extern bool emulate_vsyscall(struct pt_regs *regs, unsigned long address);
  23
  24 #ifdef CONFIG_X86_64
  25
  26 #define VGETCPU_CPU_MASK 0xfff
  27
  28 static inline unsigned int __getcpu(void)
  29 {
  30         unsigned int p;
  31
  32         if (VVAR(vgetcpu_mode) == VGETCPU_RDTSCP) {
  33                 /* Load per CPU data from RDTSCP */
  34                 native_read_tscp(&p);
  35         } else {
  36                 /* Load per CPU data from GDT */
  37                 asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
  38         }
  39
  40         return p;
  41 }
  42 #endif /* CONFIG_X86_64 */
  43
  44 #endif /* _ASM_X86_VSYSCALL_H */