LXR linux/arch/arm64/kernel/sys

   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
  24static 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 = caches_clean_inval_user_pou(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((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, int scno)
  70{
  71        unsigned long 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 = instruction_pointer(regs) - (compat_thumb_mode(regs) ? 2 : 4);
 115
 116        arm64_notify_die("Oops - bad compat syscall(2)", regs,
 117                         SIGILL, ILL_ILLTRP, addr, scno);
 118        return 0;
 119}
 120