LXR linux/arch/arm64/kernel/sys

   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
  33static 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
  55static inline long
  56do_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(VERIFY_READ, (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 */
  69long compat_arm_syscall(struct pt_regs *regs)
  70{
  71        siginfo_t info;
  72        unsigned int no = regs->regs[7];
  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        info.si_signo = SIGILL;
 116        info.si_errno = 0;
 117        info.si_code  = ILL_ILLTRP;
 118        info.si_addr  = (void __user *)instruction_pointer(regs) -
 119                         (compat_thumb_mode(regs) ? 2 : 4);
 120
 121        arm64_notify_die("Oops - bad compat syscall(2)", regs, &info, no);
 122        return 0;
 123}
 124