arch/um/sys-x86/vdso/um_vdso.c

   1 /*
   2  * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This vDSO turns all calls into a syscall so that UML can trap them.
   9  */
  10
  11
  12 /* Disable profiling for userspace code */
  13 #define DISABLE_BRANCH_PROFILING
  14
  15 #include <linux/time.h>
  16 #include <linux/getcpu.h>
  17 #include <asm/unistd.h>
  18
  19 int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
  20 {
  21         long ret;
  22
  23         asm("syscall" : "=a" (ret) :
  24                 "0" (__NR_clock_gettime), "D" (clock), "S" (ts) : "memory");
  25
  26         return ret;
  27 }
  28 int clock_gettime(clockid_t, struct timespec *)
  29         __attribute__((weak, alias("__vdso_clock_gettime")));
  30
  31 int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
  32 {
  33         long ret;
  34
  35         asm("syscall" : "=a" (ret) :
  36                 "0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory");
  37
  38         return ret;
  39 }
  40 int gettimeofday(struct timeval *, struct timezone *)
  41         __attribute__((weak, alias("__vdso_gettimeofday")));
  42
  43 time_t __vdso_time(time_t *t)
  44 {
  45         long secs;
  46
  47         asm volatile("syscall"
  48                 : "=a" (secs)
  49                 : "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory");
  50
  51         return secs;
  52 }
  53 int time(time_t *t) __attribute__((weak, alias("__vdso_time")));
  54
  55 long
  56 __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
  57 {
  58         /*
  59          * UML does not support SMP, we can cheat here. :)
  60          */
  61
  62         if (cpu)
  63                 *cpu = 0;
  64         if (node)
  65                 *node = 0;
  66
  67         return 0;
  68 }
  69
  70 long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
  71         __attribute__((weak, alias("__vdso_getcpu")));