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