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/slab.h>
  25 #include <linux/syscalls.h>
  26 #include <linux/uaccess.h>
  27
  28 #include <asm/cacheflush.h>
  29 #include <asm/unistd.h>
  30
  31 static 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
  53 static inline long
  54 do_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  */
  67 long 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 }