sysdeps/unix/sysv/linux/riscv/flush-icache.c

   1 /* RISC-V instruction cache flushing VDSO calls
   2    Copyright (C) 2017-2020 Free Software Foundation, Inc.
   3
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public License as
   8    published by the Free Software Foundation; either version 2.1 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <dl-vdso.h>
  21 #include <stdlib.h>
  22 #include <atomic.h>
  23 #include <sys/cachectl.h>
  24 #if __has_include (<asm/syscalls.h>)
  25 # include <asm/syscalls.h>
  26 #else
  27 # include <asm/unistd.h>
  28 #endif
  29 #include <sys/syscall.h>
  30
  31 typedef int (*func_type) (void *, void *, unsigned long int);
  32
  33 static int
  34 __riscv_flush_icache_syscall (void *start, void *end, unsigned long int flags)
  35 {
  36   return INLINE_SYSCALL (riscv_flush_icache, 3, start, end, flags);
  37 }
  38
  39 static func_type
  40 __lookup_riscv_flush_icache (void)
  41 {
  42   func_type func = dl_vdso_vsym ("__vdso_flush_icache");
  43
  44   /* If there is no vDSO entry then call the system call directly.  All Linux
  45      versions provide the vDSO entry, but QEMU's user-mode emulation doesn't
  46      provide a vDSO.  */
  47   if (!func)
  48     func = &__riscv_flush_icache_syscall;
  49
  50   return func;
  51 }
  52
  53 #ifdef SHARED
  54
  55 # define INIT_ARCH()
  56 libc_ifunc (__riscv_flush_icache, __lookup_riscv_flush_icache ())
  57
  58 #else
  59
  60 int
  61 __riscv_flush_icache (void *start, void *end, unsigned long int flags)
  62 {
  63   static volatile func_type cached_func;
  64
  65   func_type func = atomic_load_relaxed (&cached_func);
  66
  67   if (!func)
  68     {
  69       func = __lookup_riscv_flush_icache ();
  70       atomic_store_relaxed (&cached_func, func);
  71     }
  72
  73   return func (start, end, flags);
  74 }
  75
  76 #endif