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

   1 /* RISC-V instruction cache flushing VDSO calls
   2    Copyright (C) 2017-2019 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    <http://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
  30 typedef int (*func_type) (void *, void *, unsigned long int);
  31
  32 static int
  33 __riscv_flush_icache_syscall (void *start, void *end, unsigned long int flags)
  34 {
  35   return INLINE_SYSCALL (riscv_flush_icache, 3, start, end, flags);
  36 }
  37
  38 static func_type
  39 __lookup_riscv_flush_icache (void)
  40 {
  41   PREPARE_VERSION_KNOWN (linux_version, LINUX_4_15);
  42
  43   func_type func = _dl_vdso_vsym ("__vdso_flush_icache", &linux_version);
  44
  45   /* If there is no vDSO entry then call the system call directly.  All Linux
  46      versions provide the vDSO entry, but QEMU's user-mode emulation doesn't
  47      provide a vDSO.  */
  48   if (!func)
  49     func = &__riscv_flush_icache_syscall;
  50
  51   return func;
  52 }
  53
  54 #ifdef SHARED
  55
  56 # define INIT_ARCH()
  57 libc_ifunc (__riscv_flush_icache, __lookup_riscv_flush_icache ())
  58
  59 #else
  60
  61 int
  62 __riscv_flush_icache (void *start, void *end, unsigned long int flags)
  63 {
  64   static volatile func_type cached_func;
  65
  66   func_type func = atomic_load_relaxed (&cached_func);
  67
  68   if (!func)
  69     {
  70       func = __lookup_riscv_flush_icache ();
  71       atomic_store_relaxed (&cached_func, func);
  72     }
  73
  74   return func (start, end, flags);
  75 }
  76
  77 #endif