1 /* RISC-V instruction cache flushing VDSO calls
2 Copyright (C) 2017-2021 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
__riscv_flush_icache_syscall(void * start,void * end,unsigned long int flags)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
__lookup_riscv_flush_icache(void)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
77