1  /* RISC-V instruction cache flushing VDSO calls
       2     Copyright (C) 2017-2023 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