Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * This file is subject to the terms and conditions of the GNU General Public |
| 3 | * License. See the file "COPYING" in the main directory of this archive |
| 4 | * for more details. |
| 5 | * |
| 6 | * Copyright (C) 1995 - 2000 by Ralf Baechle |
| 7 | */ |
| 8 | #include <linux/signal.h> |
| 9 | #include <linux/sched.h> |
| 10 | #include <linux/interrupt.h> |
| 11 | #include <linux/kernel.h> |
| 12 | #include <linux/errno.h> |
| 13 | #include <linux/string.h> |
| 14 | #include <linux/types.h> |
| 15 | #include <linux/ptrace.h> |
| 16 | #include <linux/mman.h> |
| 17 | #include <linux/mm.h> |
| 18 | #include <linux/smp.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 19 | #include <linux/module.h> |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 20 | #include <linux/kprobes.h> |
Deng-Cheng Zhu | 7f788d2 | 2010-10-12 19:37:21 +0800 | [diff] [blame] | 21 | #include <linux/perf_event.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 22 | |
| 23 | #include <asm/branch.h> |
| 24 | #include <asm/mmu_context.h> |
| 25 | #include <asm/system.h> |
| 26 | #include <asm/uaccess.h> |
| 27 | #include <asm/ptrace.h> |
Thiemo Seufer | 16033d6 | 2005-02-19 13:56:04 +0000 | [diff] [blame] | 28 | #include <asm/highmem.h> /* For VMALLOC_END */ |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 29 | #include <linux/kdebug.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | |
| 31 | /* |
| 32 | * This routine handles page faults. It determines the address, |
| 33 | * and the problem, and then passes it off to one of the appropriate |
| 34 | * routines. |
| 35 | */ |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 36 | asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long write, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | unsigned long address) |
| 38 | { |
| 39 | struct vm_area_struct * vma = NULL; |
| 40 | struct task_struct *tsk = current; |
| 41 | struct mm_struct *mm = tsk->mm; |
| 42 | const int field = sizeof(unsigned long) * 2; |
| 43 | siginfo_t info; |
Nick Piggin | 83c5407 | 2007-07-19 01:47:05 -0700 | [diff] [blame] | 44 | int fault; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | |
| 46 | #if 0 |
Ralf Baechle | d6f7036 | 2007-03-29 22:30:01 +0100 | [diff] [blame] | 47 | printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | current->comm, current->pid, field, address, write, |
| 49 | field, regs->cp0_epc); |
| 50 | #endif |
| 51 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 52 | #ifdef CONFIG_KPROBES |
| 53 | /* |
| 54 | * This is to notify the fault handler of the kprobes. The |
| 55 | * exception code is redundant as it is also carried in REGS, |
| 56 | * but we pass it anyhow. |
| 57 | */ |
| 58 | if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1, |
| 59 | (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP) |
| 60 | return; |
| 61 | #endif |
| 62 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | info.si_code = SEGV_MAPERR; |
| 64 | |
| 65 | /* |
| 66 | * We fault-in kernel-space virtual memory on-demand. The |
| 67 | * 'reference' page table is init_mm.pgd. |
| 68 | * |
| 69 | * NOTE! We MUST NOT take any locks for this case. We may |
| 70 | * be in an interrupt or a critical region, and should |
| 71 | * only copy the information from the master page table, |
| 72 | * nothing more. |
| 73 | */ |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 74 | #ifdef CONFIG_64BIT |
| 75 | # define VMALLOC_FAULT_TARGET no_context |
| 76 | #else |
| 77 | # define VMALLOC_FAULT_TARGET vmalloc_fault |
| 78 | #endif |
| 79 | |
Thiemo Seufer | 16033d6 | 2005-02-19 13:56:04 +0000 | [diff] [blame] | 80 | if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 81 | goto VMALLOC_FAULT_TARGET; |
Atsushi Nemoto | 656be92 | 2006-10-26 00:08:31 +0900 | [diff] [blame] | 82 | #ifdef MODULE_START |
| 83 | if (unlikely(address >= MODULE_START && address < MODULE_END)) |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 84 | goto VMALLOC_FAULT_TARGET; |
Atsushi Nemoto | 656be92 | 2006-10-26 00:08:31 +0900 | [diff] [blame] | 85 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | |
| 87 | /* |
| 88 | * If we're in an interrupt or have no user |
| 89 | * context, we must not take the fault.. |
| 90 | */ |
| 91 | if (in_atomic() || !mm) |
| 92 | goto bad_area_nosemaphore; |
| 93 | |
| 94 | down_read(&mm->mmap_sem); |
| 95 | vma = find_vma(mm, address); |
| 96 | if (!vma) |
| 97 | goto bad_area; |
| 98 | if (vma->vm_start <= address) |
| 99 | goto good_area; |
| 100 | if (!(vma->vm_flags & VM_GROWSDOWN)) |
| 101 | goto bad_area; |
| 102 | if (expand_stack(vma, address)) |
| 103 | goto bad_area; |
| 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 | if (write) { |
| 112 | if (!(vma->vm_flags & VM_WRITE)) |
| 113 | goto bad_area; |
| 114 | } else { |
David Daney | 6dd9344 | 2010-02-10 15:12:47 -0800 | [diff] [blame] | 115 | if (kernel_uses_smartmips_rixi) { |
| 116 | if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) { |
| 117 | #if 0 |
| 118 | pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n", |
| 119 | raw_smp_processor_id(), |
| 120 | current->comm, current->pid, |
| 121 | field, address, write, |
| 122 | field, regs->cp0_epc); |
| 123 | #endif |
| 124 | goto bad_area; |
| 125 | } |
| 126 | if (!(vma->vm_flags & VM_READ)) { |
| 127 | #if 0 |
| 128 | pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n", |
| 129 | raw_smp_processor_id(), |
| 130 | current->comm, current->pid, |
| 131 | field, address, write, |
| 132 | field, regs->cp0_epc); |
| 133 | #endif |
| 134 | goto bad_area; |
| 135 | } |
| 136 | } else { |
| 137 | if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) |
| 138 | goto bad_area; |
| 139 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | } |
| 141 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 142 | /* |
| 143 | * If for any reason at all we couldn't handle the fault, |
| 144 | * make sure we exit gracefully rather than endlessly redo |
| 145 | * the fault. |
| 146 | */ |
Linus Torvalds | d06063c | 2009-04-10 09:01:23 -0700 | [diff] [blame] | 147 | fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0); |
Deng-Cheng Zhu | 7f788d2 | 2010-10-12 19:37:21 +0800 | [diff] [blame] | 148 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address); |
Nick Piggin | 83c5407 | 2007-07-19 01:47:05 -0700 | [diff] [blame] | 149 | if (unlikely(fault & VM_FAULT_ERROR)) { |
| 150 | if (fault & VM_FAULT_OOM) |
| 151 | goto out_of_memory; |
| 152 | else if (fault & VM_FAULT_SIGBUS) |
| 153 | goto do_sigbus; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 154 | BUG(); |
| 155 | } |
Deng-Cheng Zhu | 7f788d2 | 2010-10-12 19:37:21 +0800 | [diff] [blame] | 156 | if (fault & VM_FAULT_MAJOR) { |
| 157 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, |
| 158 | 1, 0, regs, address); |
Nick Piggin | 83c5407 | 2007-07-19 01:47:05 -0700 | [diff] [blame] | 159 | tsk->maj_flt++; |
Deng-Cheng Zhu | 7f788d2 | 2010-10-12 19:37:21 +0800 | [diff] [blame] | 160 | } else { |
| 161 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, |
| 162 | 1, 0, regs, address); |
Nick Piggin | 83c5407 | 2007-07-19 01:47:05 -0700 | [diff] [blame] | 163 | tsk->min_flt++; |
Deng-Cheng Zhu | 7f788d2 | 2010-10-12 19:37:21 +0800 | [diff] [blame] | 164 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 165 | |
| 166 | up_read(&mm->mmap_sem); |
| 167 | return; |
| 168 | |
| 169 | /* |
| 170 | * Something tried to access memory that isn't in our memory map.. |
| 171 | * Fix it, but check if it's kernel or user first.. |
| 172 | */ |
| 173 | bad_area: |
| 174 | up_read(&mm->mmap_sem); |
| 175 | |
| 176 | bad_area_nosemaphore: |
| 177 | /* User mode accesses just cause a SIGSEGV */ |
| 178 | if (user_mode(regs)) { |
| 179 | tsk->thread.cp0_badvaddr = address; |
| 180 | tsk->thread.error_code = write; |
| 181 | #if 0 |
| 182 | printk("do_page_fault() #2: sending SIGSEGV to %s for " |
| 183 | "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", |
| 184 | tsk->comm, |
| 185 | write ? "write access to" : "read access from", |
| 186 | field, address, |
| 187 | field, (unsigned long) regs->cp0_epc, |
| 188 | field, (unsigned long) regs->regs[31]); |
| 189 | #endif |
| 190 | info.si_signo = SIGSEGV; |
| 191 | info.si_errno = 0; |
| 192 | /* info.si_code has been set above */ |
Ralf Baechle | fe00f94 | 2005-03-01 19:22:29 +0000 | [diff] [blame] | 193 | info.si_addr = (void __user *) address; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 194 | force_sig_info(SIGSEGV, &info, tsk); |
| 195 | return; |
| 196 | } |
| 197 | |
| 198 | no_context: |
| 199 | /* Are we prepared to handle this kernel fault? */ |
| 200 | if (fixup_exception(regs)) { |
| 201 | current->thread.cp0_baduaddr = address; |
| 202 | return; |
| 203 | } |
| 204 | |
| 205 | /* |
| 206 | * Oops. The kernel tried to access some bad page. We'll have to |
| 207 | * terminate things with extreme prejudice. |
| 208 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 209 | bust_spinlocks(1); |
| 210 | |
| 211 | printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " |
| 212 | "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", |
Ralf Baechle | d6f7036 | 2007-03-29 22:30:01 +0100 | [diff] [blame] | 213 | raw_smp_processor_id(), field, address, field, regs->cp0_epc, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | field, regs->regs[31]); |
| 215 | die("Oops", regs); |
| 216 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 217 | out_of_memory: |
Ralf Baechle | c7c1e38 | 2009-01-12 00:09:13 +0000 | [diff] [blame] | 218 | /* |
| 219 | * We ran out of memory, call the OOM killer, and return the userspace |
| 220 | * (which will retry the fault, or kill us if we got oom-killed). |
| 221 | */ |
Akinobu Mita | a887b4d | 2009-07-04 01:33:09 +0900 | [diff] [blame] | 222 | up_read(&mm->mmap_sem); |
Ralf Baechle | c7c1e38 | 2009-01-12 00:09:13 +0000 | [diff] [blame] | 223 | pagefault_out_of_memory(); |
| 224 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 225 | |
| 226 | do_sigbus: |
| 227 | up_read(&mm->mmap_sem); |
| 228 | |
| 229 | /* Kernel mode? Handle exceptions or die */ |
| 230 | if (!user_mode(regs)) |
| 231 | goto no_context; |
Ralf Baechle | 41c594a | 2006-04-05 09:45:45 +0100 | [diff] [blame] | 232 | else |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 233 | /* |
| 234 | * Send a sigbus, regardless of whether we were in kernel |
| 235 | * or user mode. |
| 236 | */ |
Ralf Baechle | 41c594a | 2006-04-05 09:45:45 +0100 | [diff] [blame] | 237 | #if 0 |
| 238 | printk("do_page_fault() #3: sending SIGBUS to %s for " |
| 239 | "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", |
| 240 | tsk->comm, |
| 241 | write ? "write access to" : "read access from", |
| 242 | field, address, |
| 243 | field, (unsigned long) regs->cp0_epc, |
| 244 | field, (unsigned long) regs->regs[31]); |
| 245 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 246 | tsk->thread.cp0_badvaddr = address; |
| 247 | info.si_signo = SIGBUS; |
| 248 | info.si_errno = 0; |
| 249 | info.si_code = BUS_ADRERR; |
Ralf Baechle | fe00f94 | 2005-03-01 19:22:29 +0000 | [diff] [blame] | 250 | info.si_addr = (void __user *) address; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 251 | force_sig_info(SIGBUS, &info, tsk); |
| 252 | |
| 253 | return; |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 254 | #ifndef CONFIG_64BIT |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 255 | vmalloc_fault: |
| 256 | { |
| 257 | /* |
| 258 | * Synchronize this task's top level page-table |
| 259 | * with the 'reference' page table. |
| 260 | * |
| 261 | * Do _not_ use "tsk" here. We might be inside |
| 262 | * an interrupt in the middle of a task switch.. |
| 263 | */ |
| 264 | int offset = __pgd_offset(address); |
| 265 | pgd_t *pgd, *pgd_k; |
Ralf Baechle | c6e8b58 | 2005-02-10 12:19:59 +0000 | [diff] [blame] | 266 | pud_t *pud, *pud_k; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 267 | pmd_t *pmd, *pmd_k; |
| 268 | pte_t *pte_k; |
| 269 | |
Ralf Baechle | d6f7036 | 2007-03-29 22:30:01 +0100 | [diff] [blame] | 270 | pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 271 | pgd_k = init_mm.pgd + offset; |
| 272 | |
| 273 | if (!pgd_present(*pgd_k)) |
| 274 | goto no_context; |
| 275 | set_pgd(pgd, *pgd_k); |
| 276 | |
Ralf Baechle | c6e8b58 | 2005-02-10 12:19:59 +0000 | [diff] [blame] | 277 | pud = pud_offset(pgd, address); |
| 278 | pud_k = pud_offset(pgd_k, address); |
| 279 | if (!pud_present(*pud_k)) |
| 280 | goto no_context; |
| 281 | |
| 282 | pmd = pmd_offset(pud, address); |
| 283 | pmd_k = pmd_offset(pud_k, address); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 284 | if (!pmd_present(*pmd_k)) |
| 285 | goto no_context; |
| 286 | set_pmd(pmd, *pmd_k); |
| 287 | |
| 288 | pte_k = pte_offset_kernel(pmd_k, address); |
| 289 | if (!pte_present(*pte_k)) |
| 290 | goto no_context; |
| 291 | return; |
| 292 | } |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 293 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 294 | } |