LXR linux/arch/hexagon/mm/vm

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Memory fault handling for Hexagon
   4 *
   5 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   6 */
   7
   8/*
   9 * Page fault handling for the Hexagon Virtual Machine.
  10 * Can also be called by a native port emulating the HVM
  11 * execptions.
  12 */
  13
  14#include <asm/pgtable.h>
  15#include <asm/traps.h>
  16#include <linux/uaccess.h>
  17#include <linux/mm.h>
  18#include <linux/sched/signal.h>
  19#include <linux/signal.h>
  20#include <linux/extable.h>
  21#include <linux/hardirq.h>
  22
  23/*
  24 * Decode of hardware exception sends us to one of several
  25 * entry points.  At each, we generate canonical arguments
  26 * for handling by the abstract memory management code.
  27 */
  28#define FLT_IFETCH     -1
  29#define FLT_LOAD        0
  30#define FLT_STORE       1
  31
  32
  33/*
  34 * Canonical page fault handler
  35 */
  36void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
  37{
  38        struct vm_area_struct *vma;
  39        struct mm_struct *mm = current->mm;
  40        int si_signo;
  41        int si_code = SEGV_MAPERR;
  42        vm_fault_t fault;
  43        const struct exception_table_entry *fixup;
  44        unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
  45
  46        /*
  47         * If we're in an interrupt or have no user context,
  48         * then must not take the fault.
  49         */
  50        if (unlikely(in_interrupt() || !mm))
  51                goto no_context;
  52
  53        local_irq_enable();
  54
  55        if (user_mode(regs))
  56                flags |= FAULT_FLAG_USER;
  57retry:
  58        down_read(&mm->mmap_sem);
  59        vma = find_vma(mm, address);
  60        if (!vma)
  61                goto bad_area;
  62
  63        if (vma->vm_start <= address)
  64                goto good_area;
  65
  66        if (!(vma->vm_flags & VM_GROWSDOWN))
  67                goto bad_area;
  68
  69        if (expand_stack(vma, address))
  70                goto bad_area;
  71
  72good_area:
  73        /* Address space is OK.  Now check access rights. */
  74        si_code = SEGV_ACCERR;
  75
  76        switch (cause) {
  77        case FLT_IFETCH:
  78                if (!(vma->vm_flags & VM_EXEC))
  79                        goto bad_area;
  80                break;
  81        case FLT_LOAD:
  82                if (!(vma->vm_flags & VM_READ))
  83                        goto bad_area;
  84                break;
  85        case FLT_STORE:
  86                if (!(vma->vm_flags & VM_WRITE))
  87                        goto bad_area;
  88                flags |= FAULT_FLAG_WRITE;
  89                break;
  90        }
  91
  92        fault = handle_mm_fault(vma, address, flags);
  93
  94        if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
  95                return;
  96
  97        /* The most common case -- we are done. */
  98        if (likely(!(fault & VM_FAULT_ERROR))) {
  99                if (flags & FAULT_FLAG_ALLOW_RETRY) {
 100                        if (fault & VM_FAULT_MAJOR)
 101                                current->maj_flt++;
 102                        else
 103                                current->min_flt++;
 104                        if (fault & VM_FAULT_RETRY) {
 105                                flags &= ~FAULT_FLAG_ALLOW_RETRY;
 106                                flags |= FAULT_FLAG_TRIED;
 107                                goto retry;
 108                        }
 109                }
 110
 111                up_read(&mm->mmap_sem);
 112                return;
 113        }
 114
 115        up_read(&mm->mmap_sem);
 116
 117        /* Handle copyin/out exception cases */
 118        if (!user_mode(regs))
 119                goto no_context;
 120
 121        if (fault & VM_FAULT_OOM) {
 122                pagefault_out_of_memory();
 123                return;
 124        }
 125
 126        /* User-mode address is in the memory map, but we are
 127         * unable to fix up the page fault.
 128         */
 129        if (fault & VM_FAULT_SIGBUS) {
 130                si_signo = SIGBUS;
 131                si_code = BUS_ADRERR;
 132        }
 133        /* Address is not in the memory map */
 134        else {
 135                si_signo = SIGSEGV;
 136                si_code  = SEGV_ACCERR;
 137        }
 138        force_sig_fault(si_signo, si_code, (void __user *)address);
 139        return;
 140
 141bad_area:
 142        up_read(&mm->mmap_sem);
 143
 144        if (user_mode(regs)) {
 145                force_sig_fault(SIGSEGV, si_code, (void __user *)address);
 146                return;
 147        }
 148        /* Kernel-mode fault falls through */
 149
 150no_context:
 151        fixup = search_exception_tables(pt_elr(regs));
 152        if (fixup) {
 153                pt_set_elr(regs, fixup->fixup);
 154                return;
 155        }
 156
 157        /* Things are looking very, very bad now */
 158        bust_spinlocks(1);
 159        printk(KERN_EMERG "Unable to handle kernel paging request at "
 160                "virtual address 0x%08lx, regs %p\n", address, regs);
 161        die("Bad Kernel VA", regs, SIGKILL);
 162}
 163
 164
 165void read_protection_fault(struct pt_regs *regs)
 166{
 167        unsigned long badvadr = pt_badva(regs);
 168
 169        do_page_fault(badvadr, FLT_LOAD, regs);
 170}
 171
 172void write_protection_fault(struct pt_regs *regs)
 173{
 174        unsigned long badvadr = pt_badva(regs);
 175
 176        do_page_fault(badvadr, FLT_STORE, regs);
 177}
 178
 179void execute_protection_fault(struct pt_regs *regs)
 180{
 181        unsigned long badvadr = pt_badva(regs);
 182
 183        do_page_fault(badvadr, FLT_IFETCH, regs);
 184}
 185