libc/sysdeps/linux/riscv32/cache.c

   1 /* RISC-V instruction cache flushing VDSO calls
   2    Copyright (C) 2017-2020 Free Software Foundation, Inc.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation; either version 2.1 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <stdlib.h>
  19 #include <atomic.h>
  20 #include <sys/syscall.h>
  21
  22 #ifndef __NR_riscv_flush_icache
  23 #define __NR_riscv_flush_icache 259
  24 #endif
  25
  26 typedef int (*func_type) (void *, void *, unsigned long int);
  27
  28 static int
  29 __riscv_flush_icache_syscall (void *start, void *end, unsigned long int flags)
  30 {
  31   return INLINE_SYSCALL (riscv_flush_icache, 3, start, end, flags);
  32 }
  33
  34 static func_type
  35 __lookup_riscv_flush_icache (void)
  36 {
  37   /* always call the system call directly.*/
  38   return &__riscv_flush_icache_syscall;
  39 }
  40
  41 int
  42 __riscv_flush_icache (void *start, void *end, unsigned long int flags)
  43 {
  44   static volatile func_type cached_func;
  45
  46   func_type func = atomic_load_relaxed (&cached_func);
  47
  48   if (!func)
  49     {
  50       func = __lookup_riscv_flush_icache ();
  51       atomic_store_relaxed (&cached_func, func);
  52     }
  53
  54   return func (start, end, flags);
  55 }