arch/arm64/kernel/sys_compat.c

   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/system_misc.h>
  31 #include <asm/unistd.h>
  32
  33 static long
  34 __do_compat_cache_op(unsigned long start, unsigned long end)
  35 {
  36         long ret;
  37
  38         do {
  39                 unsigned long chunk = min(PAGE_SIZE, end - start);
  40
  41                 if (fatal_signal_pending(current))
  42                         return 0;
  43
  44                 ret = __flush_cache_user_range(start, start + chunk);
  45                 if (ret)
  46                         return ret;
  47
  48                 cond_resched();
  49                 start += chunk;
  50         } while (start < end);
  51
  52         return 0;
  53 }
  54
  55 static inline long
  56 do_compat_cache_op(unsigned long start, unsigned long end, int flags)
  57 {
  58         if (end < start || flags)
  59                 return -EINVAL;
  60
  61         if (!access_ok((const void __user *)start, end - start))
  62                 return -EFAULT;
  63
  64         return __do_compat_cache_op(start, end);
  65 }
  66 /*
  67  * Handle all unrecognised system calls.
  68  */
  69 long compat_arm_syscall(struct pt_regs *regs)
  70 {
  71         unsigned int no = regs->regs[7];
  72         void __user *addr;
  73
  74         switch (no) {
  75         /*
  76          * Flush a region from virtual address 'r0' to virtual address 'r1'
  77          * _exclusive_.  There is no alignment requirement on either address;
  78          * user space does not need to know the hardware cache layout.
  79          *
  80          * r2 contains flags.  It should ALWAYS be passed as ZERO until it
  81          * is defined to be something else.  For now we ignore it, but may
  82          * the fires of hell burn in your belly if you break this rule. ;)
  83          *
  84          * (at a later date, we may want to allow this call to not flush
  85          * various aspects of the cache.  Passing '0' will guarantee that
  86          * everything necessary gets flushed to maintain consistency in
  87          * the specified region).
  88          */
  89         case __ARM_NR_compat_cacheflush:
  90                 return do_compat_cache_op(regs->regs[0], regs->regs[1], regs->regs[2]);
  91
  92         case __ARM_NR_compat_set_tls:
  93                 current->thread.uw.tp_value = regs->regs[0];
  94
  95                 /*
  96                  * Protect against register corruption from context switch.
  97                  * See comment in tls_thread_flush.
  98                  */
  99                 barrier();
 100                 write_sysreg(regs->regs[0], tpidrro_el0);
 101                 return 0;
 102
 103         default:
 104                 /*
 105                  * Calls 9f00xx..9f07ff are defined to return -ENOSYS
 106                  * if not implemented, rather than raising SIGILL. This
 107                  * way the calling program can gracefully determine whether
 108                  * a feature is supported.
 109                  */
 110                 if ((no & 0xffff) <= 0x7ff)
 111                         return -ENOSYS;
 112                 break;
 113         }
 114
 115         addr  = (void __user *)instruction_pointer(regs) -
 116                 (compat_thumb_mode(regs) ? 2 : 4);
 117
 118         arm64_notify_die("Oops - bad compat syscall(2)", regs,
 119                          SIGILL, ILL_ILLTRP, addr, no);
 120         return 0;
 121 }