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Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Copyright (C) 2017 SiFive
4 */
5
6#ifndef _ASM__UAPI__SYSCALLS_H
7#define _ASM__UAPI__SYSCALLS_H
8
9/*
10 * Allows the instruction cache to be flushed from userspace. Despite RISC-V
11 * having a direct 'fence.i' instruction available to userspace (which we
12 * can't trap!), that's not actually viable when running on Linux because the
13 * kernel might schedule a process on another hart. There is no way for
14 * userspace to handle this without invoking the kernel (as it doesn't know the
15 * thread->hart mappings), so we've defined a RISC-V specific system call to
16 * flush the instruction cache.
17 *
18 * __NR_riscv_flush_icache is defined to flush the instruction cache over an
19 * address range, with the flush applying to either all threads or just the
20 * caller. We don't currently do anything with the address range, that's just
21 * in there for forwards compatibility.
22 */
23#define __NR_riscv_flush_icache (__NR_arch_specific_syscall + 15)
24__SYSCALL(__NR_riscv_flush_icache, sys_riscv_flush_icache)
25
26#endif