LXR linux/arch/arm64/kernel/sys

   1/*
   2 * Based on arch/arm/kernel/sys_arm.c
   3 *
   4 * Copyright (C) People who wrote linux/arch/i386/kernel/sys_i386.c
   5 * Copyright (C) 1995, 1996 Russell King.
   6 * Copyright (C) 2012 ARM Ltd.
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21#include <linux/compat.h>
  22#include <linux/personality.h>
  23#include <linux/sched.h>
  24#include <linux/sched/signal.h>
  25#include <linux/slab.h>
  26#include <linux/syscalls.h>
  27#include <linux/uaccess.h>
  28
  29#include <asm/cacheflush.h>
  30#include <asm/unistd.h>
  31
  32static long
  33__do_compat_cache_op(unsigned long start, unsigned long end)
  34{
  35        long ret;
  36
  37        do {
  38                unsigned long chunk = min(PAGE_SIZE, end - start);
  39
  40                if (fatal_signal_pending(current))
  41                        return 0;
  42
  43                ret = __flush_cache_user_range(start, start + chunk);
  44                if (ret)
  45                        return ret;
  46
  47                cond_resched();
  48                start += chunk;
  49        } while (start < end);
  50
  51        return 0;
  52}
  53
  54static inline long
  55do_compat_cache_op(unsigned long start, unsigned long end, int flags)
  56{
  57        if (end < start || flags)
  58                return -EINVAL;
  59
  60        if (!access_ok(VERIFY_READ, (const void __user *)start, end - start))
  61                return -EFAULT;
  62
  63        return __do_compat_cache_op(start, end);
  64}
  65/*
  66 * Handle all unrecognised system calls.
  67 */
  68long compat_arm_syscall(struct pt_regs *regs)
  69{
  70        unsigned int no = regs->regs[7];
  71
  72        switch (no) {
  73        /*
  74         * Flush a region from virtual address 'r0' to virtual address 'r1'
  75         * _exclusive_.  There is no alignment requirement on either address;
  76         * user space does not need to know the hardware cache layout.
  77         *
  78         * r2 contains flags.  It should ALWAYS be passed as ZERO until it
  79         * is defined to be something else.  For now we ignore it, but may
  80         * the fires of hell burn in your belly if you break this rule. ;)
  81         *
  82         * (at a later date, we may want to allow this call to not flush
  83         * various aspects of the cache.  Passing '0' will guarantee that
  84         * everything necessary gets flushed to maintain consistency in
  85         * the specified region).
  86         */
  87        case __ARM_NR_compat_cacheflush:
  88                return do_compat_cache_op(regs->regs[0], regs->regs[1], regs->regs[2]);
  89
  90        case __ARM_NR_compat_set_tls:
  91                current->thread.tp_value = regs->regs[0];
  92
  93                /*
  94                 * Protect against register corruption from context switch.
  95                 * See comment in tls_thread_flush.
  96                 */
  97                barrier();
  98                write_sysreg(regs->regs[0], tpidrro_el0);
  99                return 0;
 100
 101        default:
 102                return -ENOSYS;
 103        }
 104}
 105