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/slab.h>
  25#include <linux/syscalls.h>
  26#include <linux/uaccess.h>
  27
  28#include <asm/cacheflush.h>
  29#include <asm/unistd.h>
  30
  31static long
  32__do_compat_cache_op(unsigned long start, unsigned long end)
  33{
  34        long ret;
  35
  36        do {
  37                unsigned long chunk = min(PAGE_SIZE, end - start);
  38
  39                if (fatal_signal_pending(current))
  40                        return 0;
  41
  42                ret = __flush_cache_user_range(start, start + chunk);
  43                if (ret)
  44                        return ret;
  45
  46                cond_resched();
  47                start += chunk;
  48        } while (start < end);
  49
  50        return 0;
  51}
  52
  53static inline long
  54do_compat_cache_op(unsigned long start, unsigned long end, int flags)
  55{
  56        if (end < start || flags)
  57                return -EINVAL;
  58
  59        if (!access_ok(VERIFY_READ, start, end - start))
  60                return -EFAULT;
  61
  62        return __do_compat_cache_op(start, end);
  63}
  64/*
  65 * Handle all unrecognised system calls.
  66 */
  67long compat_arm_syscall(struct pt_regs *regs)
  68{
  69        unsigned int no = regs->regs[7];
  70
  71        switch (no) {
  72        /*
  73         * Flush a region from virtual address 'r0' to virtual address 'r1'
  74         * _exclusive_.  There is no alignment requirement on either address;
  75         * user space does not need to know the hardware cache layout.
  76         *
  77         * r2 contains flags.  It should ALWAYS be passed as ZERO until it
  78         * is defined to be something else.  For now we ignore it, but may
  79         * the fires of hell burn in your belly if you break this rule. ;)
  80         *
  81         * (at a later date, we may want to allow this call to not flush
  82         * various aspects of the cache.  Passing '0' will guarantee that
  83         * everything necessary gets flushed to maintain consistency in
  84         * the specified region).
  85         */
  86        case __ARM_NR_compat_cacheflush:
  87                return do_compat_cache_op(regs->regs[0], regs->regs[1], regs->regs[2]);
  88
  89        case __ARM_NR_compat_set_tls:
  90                current->thread.tp_value = regs->regs[0];
  91
  92                /*
  93                 * Protect against register corruption from context switch.
  94                 * See comment in tls_thread_flush.
  95                 */
  96                barrier();
  97                write_sysreg(regs->regs[0], tpidrro_el0);
  98                return 0;
  99
 100        default:
 101                return -ENOSYS;
 102        }
 103}
 104