arch/x86/um/vdso/um_vdso.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
   4  *
   5  * This vDSO turns all calls into a syscall so that UML can trap them.
   6  */
   7
   8
   9 /* Disable profiling for userspace code */
  10 #define DISABLE_BRANCH_PROFILING
  11
  12 #include <linux/time.h>
  13 #include <linux/getcpu.h>
  14 #include <asm/unistd.h>
  15
  16 int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
  17 {
  18         long ret;
  19
  20         asm("syscall" : "=a" (ret) :
  21                 "0" (__NR_clock_gettime), "D" (clock), "S" (ts) : "memory");
  22
  23         return ret;
  24 }
  25 int clock_gettime(clockid_t, struct __kernel_old_timespec *)
  26         __attribute__((weak, alias("__vdso_clock_gettime")));
  27
  28 int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
  29 {
  30         long ret;
  31
  32         asm("syscall" : "=a" (ret) :
  33                 "0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory");
  34
  35         return ret;
  36 }
  37 int gettimeofday(struct __kernel_old_timeval *, struct timezone *)
  38         __attribute__((weak, alias("__vdso_gettimeofday")));
  39
  40 __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
  41 {
  42         long secs;
  43
  44         asm volatile("syscall"
  45                 : "=a" (secs)
  46                 : "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory");
  47
  48         return secs;
  49 }
  50 __kernel_old_time_t time(__kernel_old_time_t *t) __attribute__((weak, alias("__vdso_time")));
  51
  52 long
  53 __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
  54 {
  55         /*
  56          * UML does not support SMP, we can cheat here. :)
  57          */
  58
  59         if (cpu)
  60                 *cpu = 0;
  61         if (node)
  62                 *node = 0;
  63
  64         return 0;
  65 }
  66
  67 long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
  68         __attribute__((weak, alias("__vdso_getcpu")));