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		asm ("msr tpidrro_el0, %0" : : "r" (regs->regs[0]));
 98		return 0;
 99
100	default:
101		return -ENOSYS;
102	}
103}