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 */ 36 void 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); 59 retry: 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 74 good_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 if (!user_mode(regs)) 98 goto no_context; 99 return; 100 } 101 102 /* The fault is fully completed (including releasing mmap lock) */ 103 if (fault & VM_FAULT_COMPLETED) 104 return; 105 106 /* The most common case -- we are done. */ 107 if (likely(!(fault & VM_FAULT_ERROR))) { 108 if (fault & VM_FAULT_RETRY) { 109 flags |= FAULT_FLAG_TRIED; 110 goto retry; 111 } 112 113 mmap_read_unlock(mm); 114 return; 115 } 116 117 mmap_read_unlock(mm); 118 119 /* Handle copyin/out exception cases */ 120 if (!user_mode(regs)) 121 goto no_context; 122 123 if (fault & VM_FAULT_OOM) { 124 pagefault_out_of_memory(); 125 return; 126 } 127 128 /* User-mode address is in the memory map, but we are 129 * unable to fix up the page fault. 130 */ 131 if (fault & VM_FAULT_SIGBUS) { 132 si_signo = SIGBUS; 133 si_code = BUS_ADRERR; 134 } 135 /* Address is not in the memory map */ 136 else { 137 si_signo = SIGSEGV; 138 si_code = SEGV_ACCERR; 139 } 140 force_sig_fault(si_signo, si_code, (void __user *)address); 141 return; 142 143 bad_area: 144 mmap_read_unlock(mm); 145 146 if (user_mode(regs)) { 147 force_sig_fault(SIGSEGV, si_code, (void __user *)address); 148 return; 149 } 150 /* Kernel-mode fault falls through */ 151 152 no_context: 153 fixup = search_exception_tables(pt_elr(regs)); 154 if (fixup) { 155 pt_set_elr(regs, fixup->fixup); 156 return; 157 } 158 159 /* Things are looking very, very bad now */ 160 bust_spinlocks(1); 161 printk(KERN_EMERG "Unable to handle kernel paging request at " 162 "virtual address 0x%08lx, regs %p\n", address, regs); 163 die("Bad Kernel VA", regs, SIGKILL); 164 } 165 166 167 void read_protection_fault(struct pt_regs *regs) 168 { 169 unsigned long badvadr = pt_badva(regs); 170 171 do_page_fault(badvadr, FLT_LOAD, regs); 172 } 173 174 void write_protection_fault(struct pt_regs *regs) 175 { 176 unsigned long badvadr = pt_badva(regs); 177 178 do_page_fault(badvadr, FLT_STORE, regs); 179 } 180 181 void execute_protection_fault(struct pt_regs *regs) 182 { 183 unsigned long badvadr = pt_badva(regs); 184 185 do_page_fault(badvadr, FLT_IFETCH, regs); 186 } 187