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}
104