sys_riscv.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * Copyright (C) 2012 Regents of the University of California
 4 * Copyright (C) 2014 Darius Rad <darius@bluespec.com>
 5 * Copyright (C) 2017 SiFive
 6 */
 7
 8#include <linux/syscalls.h>
 9#include <asm/cacheflush.h>
10
11static long riscv_sys_mmap(unsigned long addr, unsigned long len,
12			   unsigned long prot, unsigned long flags,
13			   unsigned long fd, unsigned long offset,
14			   unsigned long page_shift_offset)
15{
16	if (unlikely(offset & (~PAGE_MASK >> page_shift_offset)))
17		return -EINVAL;
18
19	return ksys_mmap_pgoff(addr, len, prot, flags, fd,
20			       offset >> (PAGE_SHIFT - page_shift_offset));
21}
22
23#ifdef CONFIG_64BIT
24SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
25	unsigned long, prot, unsigned long, flags,
26	unsigned long, fd, unsigned long, offset)
27{
28	return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 0);
29}
30#endif
31
32#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
33SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
34	unsigned long, prot, unsigned long, flags,
35	unsigned long, fd, unsigned long, offset)
36{
37	/*
38	 * Note that the shift for mmap2 is constant (12),
39	 * regardless of PAGE_SIZE
40	 */
41	return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 12);
42}
43#endif
44
45/*
46 * Allows the instruction cache to be flushed from userspace.  Despite RISC-V
47 * having a direct 'fence.i' instruction available to userspace (which we
48 * can't trap!), that's not actually viable when running on Linux because the
49 * kernel might schedule a process on another hart.  There is no way for
50 * userspace to handle this without invoking the kernel (as it doesn't know the
51 * thread->hart mappings), so we've defined a RISC-V specific system call to
52 * flush the instruction cache.
53 *
54 * sys_riscv_flush_icache() is defined to flush the instruction cache over an
55 * address range, with the flush applying to either all threads or just the
56 * caller.  We don't currently do anything with the address range, that's just
57 * in there for forwards compatibility.
58 */
59SYSCALL_DEFINE3(riscv_flush_icache, uintptr_t, start, uintptr_t, end,
60	uintptr_t, flags)
61{
62	/* Check the reserved flags. */
63	if (unlikely(flags & ~SYS_RISCV_FLUSH_ICACHE_ALL))
64		return -EINVAL;
65
66	flush_icache_mm(current->mm, flags & SYS_RISCV_FLUSH_ICACHE_LOCAL);
67
68	return 0;
69}
70
71/* Not defined using SYSCALL_DEFINE0 to avoid error injection */
72asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *__unused)
73{
74	return -ENOSYS;
75}