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