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/cpufeature.h>
23 #include <linux/personality.h>
24 #include <linux/sched.h>
25 #include <linux/sched/signal.h>
26 #include <linux/slab.h>
27 #include <linux/syscalls.h>
28 #include <linux/uaccess.h>
29
30 #include <asm/cacheflush.h>
31 #include <asm/system_misc.h>
32 #include <asm/tlbflush.h>
33 #include <asm/unistd.h>
34
35 static long
__do_compat_cache_op(unsigned long start,unsigned long end)36 __do_compat_cache_op(unsigned long start, unsigned long end)
37 {
38 long ret;
39
40 do {
41 unsigned long chunk = min(PAGE_SIZE, end - start);
42
43 if (fatal_signal_pending(current))
44 return 0;
45
46 if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) {
47 /*
48 * The workaround requires an inner-shareable tlbi.
49 * We pick the reserved-ASID to minimise the impact.
50 */
51 __tlbi(aside1is, __TLBI_VADDR(0, 0));
52 dsb(ish);
53 }
54
55 ret = __flush_cache_user_range(start, start + chunk);
56 if (ret)
57 return ret;
58
59 cond_resched();
60 start += chunk;
61 } while (start < end);
62
63 return 0;
64 }
65
66 static inline long
do_compat_cache_op(unsigned long start,unsigned long end,int flags)67 do_compat_cache_op(unsigned long start, unsigned long end, int flags)
68 {
69 if (end < start || flags)
70 return -EINVAL;
71
72 if (!access_ok(VERIFY_READ, (const void __user *)start, end - start))
73 return -EFAULT;
74
75 return __do_compat_cache_op(start, end);
76 }
77 /*
78 * Handle all unrecognised system calls.
79 */
compat_arm_syscall(struct pt_regs * regs,int scno)80 long compat_arm_syscall(struct pt_regs *regs, int scno)
81 {
82 siginfo_t info;
83
84 switch (scno) {
85 /*
86 * Flush a region from virtual address 'r0' to virtual address 'r1'
87 * _exclusive_. There is no alignment requirement on either address;
88 * user space does not need to know the hardware cache layout.
89 *
90 * r2 contains flags. It should ALWAYS be passed as ZERO until it
91 * is defined to be something else. For now we ignore it, but may
92 * the fires of hell burn in your belly if you break this rule. ;)
93 *
94 * (at a later date, we may want to allow this call to not flush
95 * various aspects of the cache. Passing '0' will guarantee that
96 * everything necessary gets flushed to maintain consistency in
97 * the specified region).
98 */
99 case __ARM_NR_compat_cacheflush:
100 return do_compat_cache_op(regs->regs[0], regs->regs[1], regs->regs[2]);
101
102 case __ARM_NR_compat_set_tls:
103 current->thread.uw.tp_value = regs->regs[0];
104
105 /*
106 * Protect against register corruption from context switch.
107 * See comment in tls_thread_flush.
108 */
109 barrier();
110 write_sysreg(regs->regs[0], tpidrro_el0);
111 return 0;
112
113 default:
114 /*
115 * Calls 0xf0xxx..0xf07ff are defined to return -ENOSYS
116 * if not implemented, rather than raising SIGILL. This
117 * way the calling program can gracefully determine whether
118 * a feature is supported.
119 */
120 if (scno < __ARM_NR_COMPAT_END)
121 return -ENOSYS;
122 break;
123 }
124
125 clear_siginfo(&info);
126 info.si_signo = SIGILL;
127 info.si_errno = 0;
128 info.si_code = ILL_ILLTRP;
129 info.si_addr = (void __user *)instruction_pointer(regs) -
130 (compat_thumb_mode(regs) ? 2 : 4);
131
132 arm64_notify_die("Oops - bad compat syscall(2)", regs, &info, scno);
133 return 0;
134 }
135