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