arch/arm64/kernel/sys_compat.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Based on arch/arm/kernel/sys_arm.c
   4  *
   5  * Copyright (C) People who wrote linux/arch/i386/kernel/sys_i386.c
   6  * Copyright (C) 1995, 1996 Russell King.
   7  * Copyright (C) 2012 ARM Ltd.
   8  */
   9
  10 #include <linux/compat.h>
  11 #include <linux/cpufeature.h>
  12 #include <linux/personality.h>
  13 #include <linux/sched.h>
  14 #include <linux/sched/signal.h>
  15 #include <linux/slab.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/uaccess.h>
  18
  19 #include <asm/cacheflush.h>
  20 #include <asm/system_misc.h>
  21 #include <asm/tlbflush.h>
  22 #include <asm/unistd.h>
  23
  24 static long
  25 __do_compat_cache_op(unsigned long start, unsigned long end)
  26 {
  27         long ret;
  28
  29         do {
  30                 unsigned long chunk = min(PAGE_SIZE, end - start);
  31
  32                 if (fatal_signal_pending(current))
  33                         return 0;
  34
  35                 if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) {
  36                         /*
  37                          * The workaround requires an inner-shareable tlbi.
  38                          * We pick the reserved-ASID to minimise the impact.
  39                          */
  40                         __tlbi(aside1is, __TLBI_VADDR(0, 0));
  41                         dsb(ish);
  42                 }
  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, int scno)
  70 {
  71         void __user *addr;
  72
  73         switch (scno) {
  74         /*
  75          * Flush a region from virtual address 'r0' to virtual address 'r1'
  76          * _exclusive_.  There is no alignment requirement on either address;
  77          * user space does not need to know the hardware cache layout.
  78          *
  79          * r2 contains flags.  It should ALWAYS be passed as ZERO until it
  80          * is defined to be something else.  For now we ignore it, but may
  81          * the fires of hell burn in your belly if you break this rule. ;)
  82          *
  83          * (at a later date, we may want to allow this call to not flush
  84          * various aspects of the cache.  Passing '0' will guarantee that
  85          * everything necessary gets flushed to maintain consistency in
  86          * the specified region).
  87          */
  88         case __ARM_NR_compat_cacheflush:
  89                 return do_compat_cache_op(regs->regs[0], regs->regs[1], regs->regs[2]);
  90
  91         case __ARM_NR_compat_set_tls:
  92                 current->thread.uw.tp_value = regs->regs[0];
  93
  94                 /*
  95                  * Protect against register corruption from context switch.
  96                  * See comment in tls_thread_flush.
  97                  */
  98                 barrier();
  99                 write_sysreg(regs->regs[0], tpidrro_el0);
 100                 return 0;
 101
 102         default:
 103                 /*
 104                  * Calls 0xf0xxx..0xf07ff are defined to return -ENOSYS
 105                  * if not implemented, rather than raising SIGILL. This
 106                  * way the calling program can gracefully determine whether
 107                  * a feature is supported.
 108                  */
 109                 if (scno < __ARM_NR_COMPAT_END)
 110                         return -ENOSYS;
 111                 break;
 112         }
 113
 114         addr  = (void __user *)instruction_pointer(regs) -
 115                 (compat_thumb_mode(regs) ? 2 : 4);
 116
 117         arm64_notify_die("Oops - bad compat syscall(2)", regs,
 118                          SIGILL, ILL_ILLTRP, addr, scno);
 119         return 0;
 120 }