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/traps.h>
  15#include <linux/uaccess.h>
  16#include <linux/mm.h>
  17#include <linux/sched/signal.h>
  18#include <linux/signal.h>
  19#include <linux/extable.h>
  20#include <linux/hardirq.h>
  21#include <linux/perf_event.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_DEFAULT;
  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;
  57
  58        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
  59retry:
  60        mmap_read_lock(mm);
  61        vma = find_vma(mm, address);
  62        if (!vma)
  63                goto bad_area;
  64
  65        if (vma->vm_start <= address)
  66                goto good_area;
  67
  68        if (!(vma->vm_flags & VM_GROWSDOWN))
  69                goto bad_area;
  70
  71        if (expand_stack(vma, address))
  72                goto bad_area;
  73
  74good_area:
  75        /* Address space is OK.  Now check access rights. */
  76        si_code = SEGV_ACCERR;
  77
  78        switch (cause) {
  79        case FLT_IFETCH:
  80                if (!(vma->vm_flags & VM_EXEC))
  81                        goto bad_area;
  82                break;
  83        case FLT_LOAD:
  84                if (!(vma->vm_flags & VM_READ))
  85                        goto bad_area;
  86                break;
  87        case FLT_STORE:
  88                if (!(vma->vm_flags & VM_WRITE))
  89                        goto bad_area;
  90                flags |= FAULT_FLAG_WRITE;
  91                break;
  92        }
  93
  94        fault = handle_mm_fault(vma, address, flags, regs);
  95
  96        if (fault_signal_pending(fault, regs))
  97                return;
  98
  99        /* The most common case -- we are done. */
 100        if (likely(!(fault & VM_FAULT_ERROR))) {
 101                if (flags & FAULT_FLAG_ALLOW_RETRY) {
 102                        if (fault & VM_FAULT_RETRY) {
 103                                flags |= FAULT_FLAG_TRIED;
 104                                goto retry;
 105                        }
 106                }
 107
 108                mmap_read_unlock(mm);
 109                return;
 110        }
 111
 112        mmap_read_unlock(mm);
 113
 114        /* Handle copyin/out exception cases */
 115        if (!user_mode(regs))
 116                goto no_context;
 117
 118        if (fault & VM_FAULT_OOM) {
 119                pagefault_out_of_memory();
 120                return;
 121        }
 122
 123        /* User-mode address is in the memory map, but we are
 124         * unable to fix up the page fault.
 125         */
 126        if (fault & VM_FAULT_SIGBUS) {
 127                si_signo = SIGBUS;
 128                si_code = BUS_ADRERR;
 129        }
 130        /* Address is not in the memory map */
 131        else {
 132                si_signo = SIGSEGV;
 133                si_code  = SEGV_ACCERR;
 134        }
 135        force_sig_fault(si_signo, si_code, (void __user *)address);
 136        return;
 137
 138bad_area:
 139        mmap_read_unlock(mm);
 140
 141        if (user_mode(regs)) {
 142                force_sig_fault(SIGSEGV, si_code, (void __user *)address);
 143                return;
 144        }
 145        /* Kernel-mode fault falls through */
 146
 147no_context:
 148        fixup = search_exception_tables(pt_elr(regs));
 149        if (fixup) {
 150                pt_set_elr(regs, fixup->fixup);
 151                return;
 152        }
 153
 154        /* Things are looking very, very bad now */
 155        bust_spinlocks(1);
 156        printk(KERN_EMERG "Unable to handle kernel paging request at "
 157                "virtual address 0x%08lx, regs %p\n", address, regs);
 158        die("Bad Kernel VA", regs, SIGKILL);
 159}
 160
 161
 162void read_protection_fault(struct pt_regs *regs)
 163{
 164        unsigned long badvadr = pt_badva(regs);
 165
 166        do_page_fault(badvadr, FLT_LOAD, regs);
 167}
 168
 169void write_protection_fault(struct pt_regs *regs)
 170{
 171        unsigned long badvadr = pt_badva(regs);
 172
 173        do_page_fault(badvadr, FLT_STORE, regs);
 174}
 175
 176void execute_protection_fault(struct pt_regs *regs)
 177{
 178        unsigned long badvadr = pt_badva(regs);
 179
 180        do_page_fault(badvadr, FLT_IFETCH, regs);
 181}
 182