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 | */ |
Ralf Baechle | c3fc5cd | 2013-05-29 01:07:19 +0200 | [diff] [blame] | 8 | #include <linux/context_tracking.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 9 | #include <linux/signal.h> |
| 10 | #include <linux/sched.h> |
| 11 | #include <linux/interrupt.h> |
| 12 | #include <linux/kernel.h> |
| 13 | #include <linux/errno.h> |
| 14 | #include <linux/string.h> |
| 15 | #include <linux/types.h> |
| 16 | #include <linux/ptrace.h> |
Markos Chandras | d79d853 | 2015-01-21 10:54:46 +0000 | [diff] [blame] | 17 | #include <linux/ratelimit.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 18 | #include <linux/mman.h> |
| 19 | #include <linux/mm.h> |
| 20 | #include <linux/smp.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | #include <linux/module.h> |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 22 | #include <linux/kprobes.h> |
Deng-Cheng Zhu | 7f788d2 | 2010-10-12 19:37:21 +0800 | [diff] [blame] | 23 | #include <linux/perf_event.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | |
| 25 | #include <asm/branch.h> |
| 26 | #include <asm/mmu_context.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | #include <asm/uaccess.h> |
| 28 | #include <asm/ptrace.h> |
Thiemo Seufer | 16033d6 | 2005-02-19 13:56:04 +0000 | [diff] [blame] | 29 | #include <asm/highmem.h> /* For VMALLOC_END */ |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 30 | #include <linux/kdebug.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | |
Markos Chandras | d79d853 | 2015-01-21 10:54:46 +0000 | [diff] [blame] | 32 | int show_unhandled_signals = 1; |
| 33 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 34 | /* |
| 35 | * This routine handles page faults. It determines the address, |
| 36 | * and the problem, and then passes it off to one of the appropriate |
| 37 | * routines. |
| 38 | */ |
Ralf Baechle | c3fc5cd | 2013-05-29 01:07:19 +0200 | [diff] [blame] | 39 | static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write, |
| 40 | unsigned long address) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | { |
| 42 | struct vm_area_struct * vma = NULL; |
| 43 | struct task_struct *tsk = current; |
| 44 | struct mm_struct *mm = tsk->mm; |
| 45 | const int field = sizeof(unsigned long) * 2; |
| 46 | siginfo_t info; |
Nick Piggin | 83c5407 | 2007-07-19 01:47:05 -0700 | [diff] [blame] | 47 | int fault; |
Johannes Weiner | 759496b | 2013-09-12 15:13:39 -0700 | [diff] [blame] | 48 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 49 | |
Markos Chandras | d79d853 | 2015-01-21 10:54:46 +0000 | [diff] [blame] | 50 | static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); |
| 51 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | #if 0 |
Ralf Baechle | d6f7036 | 2007-03-29 22:30:01 +0100 | [diff] [blame] | 53 | 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] | 54 | current->comm, current->pid, field, address, write, |
| 55 | field, regs->cp0_epc); |
| 56 | #endif |
| 57 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 58 | #ifdef CONFIG_KPROBES |
| 59 | /* |
Ralf Baechle | 7034228 | 2013-01-22 12:59:30 +0100 | [diff] [blame] | 60 | * This is to notify the fault handler of the kprobes. The |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 61 | * exception code is redundant as it is also carried in REGS, |
| 62 | * but we pass it anyhow. |
| 63 | */ |
| 64 | if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1, |
| 65 | (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP) |
| 66 | return; |
| 67 | #endif |
| 68 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 69 | info.si_code = SEGV_MAPERR; |
| 70 | |
| 71 | /* |
| 72 | * We fault-in kernel-space virtual memory on-demand. The |
| 73 | * 'reference' page table is init_mm.pgd. |
| 74 | * |
| 75 | * NOTE! We MUST NOT take any locks for this case. We may |
| 76 | * be in an interrupt or a critical region, and should |
| 77 | * only copy the information from the master page table, |
| 78 | * nothing more. |
| 79 | */ |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 80 | #ifdef CONFIG_64BIT |
| 81 | # define VMALLOC_FAULT_TARGET no_context |
| 82 | #else |
| 83 | # define VMALLOC_FAULT_TARGET vmalloc_fault |
| 84 | #endif |
| 85 | |
Thiemo Seufer | 16033d6 | 2005-02-19 13:56:04 +0000 | [diff] [blame] | 86 | if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 87 | goto VMALLOC_FAULT_TARGET; |
Atsushi Nemoto | 656be92 | 2006-10-26 00:08:31 +0900 | [diff] [blame] | 88 | #ifdef MODULE_START |
| 89 | if (unlikely(address >= MODULE_START && address < MODULE_END)) |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 90 | goto VMALLOC_FAULT_TARGET; |
Atsushi Nemoto | 656be92 | 2006-10-26 00:08:31 +0900 | [diff] [blame] | 91 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | |
| 93 | /* |
| 94 | * If we're in an interrupt or have no user |
| 95 | * context, we must not take the fault.. |
| 96 | */ |
| 97 | if (in_atomic() || !mm) |
| 98 | goto bad_area_nosemaphore; |
| 99 | |
Johannes Weiner | 759496b | 2013-09-12 15:13:39 -0700 | [diff] [blame] | 100 | if (user_mode(regs)) |
| 101 | flags |= FAULT_FLAG_USER; |
Kautuk Consul | 43ca495 | 2011-12-23 16:52:42 +0530 | [diff] [blame] | 102 | retry: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | down_read(&mm->mmap_sem); |
| 104 | vma = find_vma(mm, address); |
| 105 | if (!vma) |
| 106 | goto bad_area; |
| 107 | if (vma->vm_start <= address) |
| 108 | goto good_area; |
| 109 | if (!(vma->vm_flags & VM_GROWSDOWN)) |
| 110 | goto bad_area; |
| 111 | if (expand_stack(vma, address)) |
| 112 | goto bad_area; |
| 113 | /* |
| 114 | * Ok, we have a good vm_area for this memory access, so |
| 115 | * we can handle it.. |
| 116 | */ |
| 117 | good_area: |
| 118 | info.si_code = SEGV_ACCERR; |
| 119 | |
| 120 | if (write) { |
| 121 | if (!(vma->vm_flags & VM_WRITE)) |
| 122 | goto bad_area; |
Johannes Weiner | 759496b | 2013-09-12 15:13:39 -0700 | [diff] [blame] | 123 | flags |= FAULT_FLAG_WRITE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 124 | } else { |
Steven J. Hill | 05857c6 | 2012-09-13 16:51:46 -0500 | [diff] [blame] | 125 | if (cpu_has_rixi) { |
David Daney | 6dd9344 | 2010-02-10 15:12:47 -0800 | [diff] [blame] | 126 | if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) { |
| 127 | #if 0 |
| 128 | pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI 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 | if (!(vma->vm_flags & VM_READ)) { |
| 137 | #if 0 |
| 138 | pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n", |
| 139 | raw_smp_processor_id(), |
| 140 | current->comm, current->pid, |
| 141 | field, address, write, |
| 142 | field, regs->cp0_epc); |
| 143 | #endif |
| 144 | goto bad_area; |
| 145 | } |
| 146 | } else { |
| 147 | if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) |
| 148 | goto bad_area; |
| 149 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 150 | } |
| 151 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 152 | /* |
| 153 | * If for any reason at all we couldn't handle the fault, |
| 154 | * make sure we exit gracefully rather than endlessly redo |
| 155 | * the fault. |
| 156 | */ |
Kautuk Consul | 43ca495 | 2011-12-23 16:52:42 +0530 | [diff] [blame] | 157 | fault = handle_mm_fault(mm, vma, address, flags); |
| 158 | |
| 159 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) |
| 160 | return; |
| 161 | |
Peter Zijlstra | a8b0ca1 | 2011-06-27 14:41:57 +0200 | [diff] [blame] | 162 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
Nick Piggin | 83c5407 | 2007-07-19 01:47:05 -0700 | [diff] [blame] | 163 | if (unlikely(fault & VM_FAULT_ERROR)) { |
| 164 | if (fault & VM_FAULT_OOM) |
| 165 | goto out_of_memory; |
Linus Torvalds | 33692f2 | 2015-01-29 10:51:32 -0800 | [diff] [blame] | 166 | else if (fault & VM_FAULT_SIGSEGV) |
| 167 | goto bad_area; |
Nick Piggin | 83c5407 | 2007-07-19 01:47:05 -0700 | [diff] [blame] | 168 | else if (fault & VM_FAULT_SIGBUS) |
| 169 | goto do_sigbus; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 170 | BUG(); |
| 171 | } |
Kautuk Consul | 43ca495 | 2011-12-23 16:52:42 +0530 | [diff] [blame] | 172 | if (flags & FAULT_FLAG_ALLOW_RETRY) { |
| 173 | if (fault & VM_FAULT_MAJOR) { |
| 174 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, |
| 175 | regs, address); |
| 176 | tsk->maj_flt++; |
| 177 | } else { |
| 178 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, |
| 179 | regs, address); |
| 180 | tsk->min_flt++; |
| 181 | } |
| 182 | if (fault & VM_FAULT_RETRY) { |
| 183 | flags &= ~FAULT_FLAG_ALLOW_RETRY; |
Shaohua Li | 45cac65 | 2012-10-08 16:32:19 -0700 | [diff] [blame] | 184 | flags |= FAULT_FLAG_TRIED; |
Kautuk Consul | 43ca495 | 2011-12-23 16:52:42 +0530 | [diff] [blame] | 185 | |
| 186 | /* |
| 187 | * No need to up_read(&mm->mmap_sem) as we would |
| 188 | * have already released it in __lock_page_or_retry |
| 189 | * in mm/filemap.c. |
| 190 | */ |
| 191 | |
| 192 | goto retry; |
| 193 | } |
Deng-Cheng Zhu | 7f788d2 | 2010-10-12 19:37:21 +0800 | [diff] [blame] | 194 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 195 | |
| 196 | up_read(&mm->mmap_sem); |
| 197 | return; |
| 198 | |
| 199 | /* |
| 200 | * Something tried to access memory that isn't in our memory map.. |
| 201 | * Fix it, but check if it's kernel or user first.. |
| 202 | */ |
| 203 | bad_area: |
| 204 | up_read(&mm->mmap_sem); |
| 205 | |
| 206 | bad_area_nosemaphore: |
| 207 | /* User mode accesses just cause a SIGSEGV */ |
| 208 | if (user_mode(regs)) { |
| 209 | tsk->thread.cp0_badvaddr = address; |
| 210 | tsk->thread.error_code = write; |
Markos Chandras | d79d853 | 2015-01-21 10:54:46 +0000 | [diff] [blame] | 211 | if (show_unhandled_signals && |
| 212 | unhandled_signal(tsk, SIGSEGV) && |
| 213 | __ratelimit(&ratelimit_state)) { |
| 214 | pr_info("\ndo_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx", |
| 215 | tsk->comm, |
| 216 | write ? "write access to" : "read access from", |
| 217 | field, address); |
| 218 | pr_info("epc = %0*lx in", field, |
| 219 | (unsigned long) regs->cp0_epc); |
| 220 | print_vma_addr(" ", regs->cp0_epc); |
| 221 | pr_info("ra = %0*lx in", field, |
| 222 | (unsigned long) regs->regs[31]); |
| 223 | print_vma_addr(" ", regs->regs[31]); |
| 224 | pr_info("\n"); |
| 225 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 226 | info.si_signo = SIGSEGV; |
| 227 | info.si_errno = 0; |
| 228 | /* info.si_code has been set above */ |
Ralf Baechle | fe00f94 | 2005-03-01 19:22:29 +0000 | [diff] [blame] | 229 | info.si_addr = (void __user *) address; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 230 | force_sig_info(SIGSEGV, &info, tsk); |
| 231 | return; |
| 232 | } |
| 233 | |
| 234 | no_context: |
Ralf Baechle | 7034228 | 2013-01-22 12:59:30 +0100 | [diff] [blame] | 235 | /* Are we prepared to handle this kernel fault? */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 236 | if (fixup_exception(regs)) { |
| 237 | current->thread.cp0_baduaddr = address; |
| 238 | return; |
| 239 | } |
| 240 | |
| 241 | /* |
| 242 | * Oops. The kernel tried to access some bad page. We'll have to |
| 243 | * terminate things with extreme prejudice. |
| 244 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 245 | bust_spinlocks(1); |
| 246 | |
| 247 | printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " |
| 248 | "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", |
Ralf Baechle | d6f7036 | 2007-03-29 22:30:01 +0100 | [diff] [blame] | 249 | raw_smp_processor_id(), field, address, field, regs->cp0_epc, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 250 | field, regs->regs[31]); |
| 251 | die("Oops", regs); |
| 252 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 253 | out_of_memory: |
Ralf Baechle | c7c1e38 | 2009-01-12 00:09:13 +0000 | [diff] [blame] | 254 | /* |
| 255 | * We ran out of memory, call the OOM killer, and return the userspace |
| 256 | * (which will retry the fault, or kill us if we got oom-killed). |
| 257 | */ |
Akinobu Mita | a887b4d | 2009-07-04 01:33:09 +0900 | [diff] [blame] | 258 | up_read(&mm->mmap_sem); |
Johannes Weiner | 8713410 | 2013-09-12 15:13:38 -0700 | [diff] [blame] | 259 | if (!user_mode(regs)) |
| 260 | goto no_context; |
Ralf Baechle | c7c1e38 | 2009-01-12 00:09:13 +0000 | [diff] [blame] | 261 | pagefault_out_of_memory(); |
| 262 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 263 | |
| 264 | do_sigbus: |
| 265 | up_read(&mm->mmap_sem); |
| 266 | |
| 267 | /* Kernel mode? Handle exceptions or die */ |
| 268 | if (!user_mode(regs)) |
| 269 | goto no_context; |
Ralf Baechle | 41c594a | 2006-04-05 09:45:45 +0100 | [diff] [blame] | 270 | else |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 271 | /* |
| 272 | * Send a sigbus, regardless of whether we were in kernel |
| 273 | * or user mode. |
| 274 | */ |
Ralf Baechle | 41c594a | 2006-04-05 09:45:45 +0100 | [diff] [blame] | 275 | #if 0 |
| 276 | printk("do_page_fault() #3: sending SIGBUS to %s for " |
| 277 | "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", |
| 278 | tsk->comm, |
| 279 | write ? "write access to" : "read access from", |
| 280 | field, address, |
| 281 | field, (unsigned long) regs->cp0_epc, |
| 282 | field, (unsigned long) regs->regs[31]); |
| 283 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 284 | tsk->thread.cp0_badvaddr = address; |
| 285 | info.si_signo = SIGBUS; |
| 286 | info.si_errno = 0; |
| 287 | info.si_code = BUS_ADRERR; |
Ralf Baechle | fe00f94 | 2005-03-01 19:22:29 +0000 | [diff] [blame] | 288 | info.si_addr = (void __user *) address; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 289 | force_sig_info(SIGBUS, &info, tsk); |
| 290 | |
| 291 | return; |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 292 | #ifndef CONFIG_64BIT |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 293 | vmalloc_fault: |
| 294 | { |
| 295 | /* |
| 296 | * Synchronize this task's top level page-table |
| 297 | * with the 'reference' page table. |
| 298 | * |
| 299 | * Do _not_ use "tsk" here. We might be inside |
| 300 | * an interrupt in the middle of a task switch.. |
| 301 | */ |
| 302 | int offset = __pgd_offset(address); |
| 303 | pgd_t *pgd, *pgd_k; |
Ralf Baechle | c6e8b58 | 2005-02-10 12:19:59 +0000 | [diff] [blame] | 304 | pud_t *pud, *pud_k; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 305 | pmd_t *pmd, *pmd_k; |
| 306 | pte_t *pte_k; |
| 307 | |
Ralf Baechle | d6f7036 | 2007-03-29 22:30:01 +0100 | [diff] [blame] | 308 | pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 309 | pgd_k = init_mm.pgd + offset; |
| 310 | |
| 311 | if (!pgd_present(*pgd_k)) |
| 312 | goto no_context; |
| 313 | set_pgd(pgd, *pgd_k); |
| 314 | |
Ralf Baechle | c6e8b58 | 2005-02-10 12:19:59 +0000 | [diff] [blame] | 315 | pud = pud_offset(pgd, address); |
| 316 | pud_k = pud_offset(pgd_k, address); |
| 317 | if (!pud_present(*pud_k)) |
| 318 | goto no_context; |
| 319 | |
| 320 | pmd = pmd_offset(pud, address); |
| 321 | pmd_k = pmd_offset(pud_k, address); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 322 | if (!pmd_present(*pmd_k)) |
| 323 | goto no_context; |
| 324 | set_pmd(pmd, *pmd_k); |
| 325 | |
| 326 | pte_k = pte_offset_kernel(pmd_k, address); |
| 327 | if (!pte_present(*pte_k)) |
| 328 | goto no_context; |
| 329 | return; |
| 330 | } |
David Daney | 2ca2ebf | 2009-09-02 15:47:34 -0700 | [diff] [blame] | 331 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 332 | } |
Ralf Baechle | c3fc5cd | 2013-05-29 01:07:19 +0200 | [diff] [blame] | 333 | |
| 334 | asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, |
| 335 | unsigned long write, unsigned long address) |
| 336 | { |
| 337 | enum ctx_state prev_state; |
| 338 | |
| 339 | prev_state = exception_enter(); |
| 340 | __do_page_fault(regs, write, address); |
| 341 | exception_exit(prev_state); |
| 342 | } |