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 inline void
  32 do_compat_cache_op(unsigned long start, unsigned long end, int flags)
  33 {
  34         struct mm_struct *mm = current->active_mm;
  35         struct vm_area_struct *vma;
  36
  37         if (end < start || flags)
  38                 return;
  39
  40         down_read(&mm->mmap_sem);
  41         vma = find_vma(mm, start);
  42         if (vma && vma->vm_start < end) {
  43                 if (start < vma->vm_start)
  44                         start = vma->vm_start;
  45                 if (end > vma->vm_end)
  46                         end = vma->vm_end;
  47                 up_read(&mm->mmap_sem);
  48                 __flush_cache_user_range(start & PAGE_MASK, PAGE_ALIGN(end));
  49                 return;
  50         }
  51         up_read(&mm->mmap_sem);
  52 }
  53
  54 /*
  55  * Handle all unrecognised system calls.
  56  */
  57 long compat_arm_syscall(struct pt_regs *regs)
  58 {
  59         unsigned int no = regs->regs[7];
  60
  61         switch (no) {
  62         /*
  63          * Flush a region from virtual address 'r0' to virtual address 'r1'
  64          * _exclusive_.  There is no alignment requirement on either address;
  65          * user space does not need to know the hardware cache layout.
  66          *
  67          * r2 contains flags.  It should ALWAYS be passed as ZERO until it
  68          * is defined to be something else.  For now we ignore it, but may
  69          * the fires of hell burn in your belly if you break this rule. ;)
  70          *
  71          * (at a later date, we may want to allow this call to not flush
  72          * various aspects of the cache.  Passing '0' will guarantee that
  73          * everything necessary gets flushed to maintain consistency in
  74          * the specified region).
  75          */
  76         case __ARM_NR_compat_cacheflush:
  77                 do_compat_cache_op(regs->regs[0], regs->regs[1], regs->regs[2]);
  78                 return 0;
  79
  80         case __ARM_NR_compat_set_tls:
  81                 current->thread.tp_value = regs->regs[0];
  82                 asm ("msr tpidrro_el0, %0" : : "r" (regs->regs[0]));
  83                 return 0;
  84
  85         default:
  86                 return -ENOSYS;
  87         }
  88 }