Vineet Gupta | fbd7053 | 2013-01-18 15:12:20 +0530 | [diff] [blame] | 1 | /* Page Fault Handling for ARC (TLB Miss / ProtV) |
| 2 | * |
| 3 | * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License version 2 as |
| 7 | * published by the Free Software Foundation. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/signal.h> |
| 11 | #include <linux/interrupt.h> |
| 12 | #include <linux/sched.h> |
| 13 | #include <linux/errno.h> |
| 14 | #include <linux/ptrace.h> |
Vineet Gupta | fbd7053 | 2013-01-18 15:12:20 +0530 | [diff] [blame] | 15 | #include <linux/uaccess.h> |
| 16 | #include <linux/kdebug.h> |
| 17 | #include <asm/pgalloc.h> |
Vineet Gupta | da1677b | 2013-05-14 13:28:17 +0530 | [diff] [blame] | 18 | #include <asm/mmu.h> |
Vineet Gupta | fbd7053 | 2013-01-18 15:12:20 +0530 | [diff] [blame] | 19 | |
| 20 | static int handle_vmalloc_fault(struct mm_struct *mm, unsigned long address) |
| 21 | { |
| 22 | /* |
| 23 | * Synchronize this task's top level page-table |
| 24 | * with the 'reference' page table. |
| 25 | */ |
| 26 | pgd_t *pgd, *pgd_k; |
| 27 | pud_t *pud, *pud_k; |
| 28 | pmd_t *pmd, *pmd_k; |
| 29 | |
| 30 | pgd = pgd_offset_fast(mm, address); |
| 31 | pgd_k = pgd_offset_k(address); |
| 32 | |
| 33 | if (!pgd_present(*pgd_k)) |
| 34 | goto bad_area; |
| 35 | |
| 36 | pud = pud_offset(pgd, address); |
| 37 | pud_k = pud_offset(pgd_k, address); |
| 38 | if (!pud_present(*pud_k)) |
| 39 | goto bad_area; |
| 40 | |
| 41 | pmd = pmd_offset(pud, address); |
| 42 | pmd_k = pmd_offset(pud_k, address); |
| 43 | if (!pmd_present(*pmd_k)) |
| 44 | goto bad_area; |
| 45 | |
| 46 | set_pmd(pmd, *pmd_k); |
| 47 | |
| 48 | /* XXX: create the TLB entry here */ |
| 49 | return 0; |
| 50 | |
| 51 | bad_area: |
| 52 | return 1; |
| 53 | } |
| 54 | |
Vineet Gupta | 38a9ff6 | 2013-06-12 15:13:40 +0530 | [diff] [blame^] | 55 | void do_page_fault(struct pt_regs *regs, unsigned long address) |
Vineet Gupta | fbd7053 | 2013-01-18 15:12:20 +0530 | [diff] [blame] | 56 | { |
| 57 | struct vm_area_struct *vma = NULL; |
| 58 | struct task_struct *tsk = current; |
| 59 | struct mm_struct *mm = tsk->mm; |
| 60 | siginfo_t info; |
| 61 | int fault, ret; |
Vineet Gupta | 38a9ff6 | 2013-06-12 15:13:40 +0530 | [diff] [blame^] | 62 | int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ |
Vineet Gupta | fbd7053 | 2013-01-18 15:12:20 +0530 | [diff] [blame] | 63 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE | |
| 64 | (write ? FAULT_FLAG_WRITE : 0); |
| 65 | |
| 66 | /* |
| 67 | * We fault-in kernel-space virtual memory on-demand. The |
| 68 | * 'reference' page table is init_mm.pgd. |
| 69 | * |
| 70 | * NOTE! We MUST NOT take any locks for this case. We may |
| 71 | * be in an interrupt or a critical region, and should |
| 72 | * only copy the information from the master page table, |
| 73 | * nothing more. |
| 74 | */ |
| 75 | if (address >= VMALLOC_START && address <= VMALLOC_END) { |
| 76 | ret = handle_vmalloc_fault(mm, address); |
| 77 | if (unlikely(ret)) |
| 78 | goto bad_area_nosemaphore; |
| 79 | else |
| 80 | return; |
| 81 | } |
| 82 | |
| 83 | info.si_code = SEGV_MAPERR; |
| 84 | |
| 85 | /* |
| 86 | * If we're in an interrupt or have no user |
| 87 | * context, we must not take the fault.. |
| 88 | */ |
| 89 | if (in_atomic() || !mm) |
| 90 | goto no_context; |
| 91 | |
| 92 | retry: |
| 93 | down_read(&mm->mmap_sem); |
| 94 | vma = find_vma(mm, address); |
| 95 | if (!vma) |
| 96 | goto bad_area; |
| 97 | if (vma->vm_start <= address) |
| 98 | goto good_area; |
| 99 | if (!(vma->vm_flags & VM_GROWSDOWN)) |
| 100 | goto bad_area; |
| 101 | if (expand_stack(vma, address)) |
| 102 | goto bad_area; |
| 103 | |
| 104 | /* |
| 105 | * Ok, we have a good vm_area for this memory access, so |
| 106 | * we can handle it.. |
| 107 | */ |
| 108 | good_area: |
| 109 | info.si_code = SEGV_ACCERR; |
| 110 | |
| 111 | /* Handle protection violation, execute on heap or stack */ |
| 112 | |
Vineet Gupta | 38a9ff6 | 2013-06-12 15:13:40 +0530 | [diff] [blame^] | 113 | if ((regs->ecr_vec == ECR_V_PROTV) && |
| 114 | (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) |
Vineet Gupta | fbd7053 | 2013-01-18 15:12:20 +0530 | [diff] [blame] | 115 | goto bad_area; |
| 116 | |
| 117 | if (write) { |
| 118 | if (!(vma->vm_flags & VM_WRITE)) |
| 119 | goto bad_area; |
| 120 | } else { |
| 121 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) |
| 122 | goto bad_area; |
| 123 | } |
| 124 | |
| 125 | survive: |
| 126 | /* |
| 127 | * If for any reason at all we couldn't handle the fault, |
| 128 | * make sure we exit gracefully rather than endlessly redo |
| 129 | * the fault. |
| 130 | */ |
| 131 | fault = handle_mm_fault(mm, vma, address, flags); |
| 132 | |
| 133 | /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */ |
| 134 | if (unlikely(fatal_signal_pending(current))) { |
| 135 | if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY)) |
| 136 | up_read(&mm->mmap_sem); |
| 137 | if (user_mode(regs)) |
| 138 | return; |
| 139 | } |
| 140 | |
| 141 | if (likely(!(fault & VM_FAULT_ERROR))) { |
| 142 | if (flags & FAULT_FLAG_ALLOW_RETRY) { |
| 143 | /* To avoid updating stats twice for retry case */ |
| 144 | if (fault & VM_FAULT_MAJOR) |
| 145 | tsk->maj_flt++; |
| 146 | else |
| 147 | tsk->min_flt++; |
| 148 | |
| 149 | if (fault & VM_FAULT_RETRY) { |
| 150 | flags &= ~FAULT_FLAG_ALLOW_RETRY; |
| 151 | flags |= FAULT_FLAG_TRIED; |
| 152 | goto retry; |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | /* Fault Handled Gracefully */ |
| 157 | up_read(&mm->mmap_sem); |
| 158 | return; |
| 159 | } |
| 160 | |
| 161 | /* TBD: switch to pagefault_out_of_memory() */ |
| 162 | if (fault & VM_FAULT_OOM) |
| 163 | goto out_of_memory; |
| 164 | else if (fault & VM_FAULT_SIGBUS) |
| 165 | goto do_sigbus; |
| 166 | |
| 167 | /* no man's land */ |
| 168 | BUG(); |
| 169 | |
| 170 | /* |
| 171 | * Something tried to access memory that isn't in our memory map.. |
| 172 | * Fix it, but check if it's kernel or user first.. |
| 173 | */ |
| 174 | bad_area: |
| 175 | up_read(&mm->mmap_sem); |
| 176 | |
| 177 | bad_area_nosemaphore: |
| 178 | /* User mode accesses just cause a SIGSEGV */ |
| 179 | if (user_mode(regs)) { |
| 180 | tsk->thread.fault_address = address; |
Vineet Gupta | fbd7053 | 2013-01-18 15:12:20 +0530 | [diff] [blame] | 181 | info.si_signo = SIGSEGV; |
| 182 | info.si_errno = 0; |
| 183 | /* info.si_code has been set above */ |
| 184 | info.si_addr = (void __user *)address; |
| 185 | force_sig_info(SIGSEGV, &info, tsk); |
| 186 | return; |
| 187 | } |
| 188 | |
| 189 | no_context: |
| 190 | /* Are we prepared to handle this kernel fault? |
| 191 | * |
| 192 | * (The kernel has valid exception-points in the source |
| 193 | * when it acesses user-memory. When it fails in one |
| 194 | * of those points, we find it in a table and do a jump |
| 195 | * to some fixup code that loads an appropriate error |
| 196 | * code) |
| 197 | */ |
| 198 | if (fixup_exception(regs)) |
| 199 | return; |
| 200 | |
Vineet Gupta | 38a9ff6 | 2013-06-12 15:13:40 +0530 | [diff] [blame^] | 201 | die("Oops", regs, address); |
Vineet Gupta | fbd7053 | 2013-01-18 15:12:20 +0530 | [diff] [blame] | 202 | |
| 203 | out_of_memory: |
| 204 | if (is_global_init(tsk)) { |
| 205 | yield(); |
| 206 | goto survive; |
| 207 | } |
| 208 | up_read(&mm->mmap_sem); |
| 209 | |
| 210 | if (user_mode(regs)) |
| 211 | do_group_exit(SIGKILL); /* This will never return */ |
| 212 | |
| 213 | goto no_context; |
| 214 | |
| 215 | do_sigbus: |
| 216 | up_read(&mm->mmap_sem); |
| 217 | |
| 218 | if (!user_mode(regs)) |
| 219 | goto no_context; |
| 220 | |
| 221 | tsk->thread.fault_address = address; |
Vineet Gupta | fbd7053 | 2013-01-18 15:12:20 +0530 | [diff] [blame] | 222 | info.si_signo = SIGBUS; |
| 223 | info.si_errno = 0; |
| 224 | info.si_code = BUS_ADRERR; |
| 225 | info.si_addr = (void __user *)address; |
| 226 | force_sig_info(SIGBUS, &info, tsk); |
| 227 | } |