arch/riscv/kernel/sys_riscv.c

   1 /*
   2  * Copyright (C) 2012 Regents of the University of California
   3  * Copyright (C) 2014 Darius Rad <darius@bluespec.com>
   4  * Copyright (C) 2017 SiFive
   5  *
   6  *   This program is free software; you can redistribute it and/or
   7  *   modify it under the terms of the GNU General Public License
   8  *   as published by the Free Software Foundation, version 2.
   9  *
  10  *   This program is distributed in the hope that it will be useful,
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *   GNU General Public License for more details.
  14  */
  15
  16 #include <linux/syscalls.h>
  17 #include <asm/unistd.h>
  18 #include <asm/cacheflush.h>
  19 #include <asm-generic/mman-common.h>
  20
  21 static long riscv_sys_mmap(unsigned long addr, unsigned long len,
  22                            unsigned long prot, unsigned long flags,
  23                            unsigned long fd, off_t offset,
  24                            unsigned long page_shift_offset)
  25 {
  26         if (unlikely(offset & (~PAGE_MASK >> page_shift_offset)))
  27                 return -EINVAL;
  28
  29         if ((prot & PROT_WRITE) && (prot & PROT_EXEC))
  30                 if (unlikely(!(prot & PROT_READ)))
  31                         return -EINVAL;
  32
  33         return ksys_mmap_pgoff(addr, len, prot, flags, fd,
  34                                offset >> (PAGE_SHIFT - page_shift_offset));
  35 }
  36
  37 #ifdef CONFIG_64BIT
  38 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
  39         unsigned long, prot, unsigned long, flags,
  40         unsigned long, fd, off_t, offset)
  41 {
  42         return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 0);
  43 }
  44 #else
  45 SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
  46         unsigned long, prot, unsigned long, flags,
  47         unsigned long, fd, off_t, offset)
  48 {
  49         /*
  50          * Note that the shift for mmap2 is constant (12),
  51          * regardless of PAGE_SIZE
  52          */
  53         return riscv_sys_mmap(addr, len, prot, flags, fd, offset, 12);
  54 }
  55 #endif /* !CONFIG_64BIT */
  56
  57 /*
  58  * Allows the instruction cache to be flushed from userspace.  Despite RISC-V
  59  * having a direct 'fence.i' instruction available to userspace (which we
  60  * can't trap!), that's not actually viable when running on Linux because the
  61  * kernel might schedule a process on another hart.  There is no way for
  62  * userspace to handle this without invoking the kernel (as it doesn't know the
  63  * thread->hart mappings), so we've defined a RISC-V specific system call to
  64  * flush the instruction cache.
  65  *
  66  * sys_riscv_flush_icache() is defined to flush the instruction cache over an
  67  * address range, with the flush applying to either all threads or just the
  68  * caller.  We don't currently do anything with the address range, that's just
  69  * in there for forwards compatibility.
  70  */
  71 SYSCALL_DEFINE3(riscv_flush_icache, uintptr_t, start, uintptr_t, end,
  72         uintptr_t, flags)
  73 {
  74         /* Check the reserved flags. */
  75         if (unlikely(flags & ~SYS_RISCV_FLUSH_ICACHE_ALL))
  76                 return -EINVAL;
  77
  78         flush_icache_mm(current->mm, flags & SYS_RISCV_FLUSH_ICACHE_LOCAL);
  79
  80         return 0;
  81 }