blob: 137ee76a0045c2cc51629a07bbaf1deb382a1451 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/module.h>
David Daneyc1bf2072010-08-03 11:22:20 -070020#include <linux/kprobes.h>
Deng-Cheng Zhu7f788d22010-10-12 19:37:21 +080021#include <linux/perf_event.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022
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 Seufer16033d62005-02-19 13:56:04 +000028#include <asm/highmem.h> /* For VMALLOC_END */
David Daneyc1bf2072010-08-03 11:22:20 -070029#include <linux/kdebug.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
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 Daneyc1bf2072010-08-03 11:22:20 -070036asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long write,
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 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 Piggin83c54072007-07-19 01:47:05 -070044 int fault;
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46#if 0
Ralf Baechled6f70362007-03-29 22:30:01 +010047 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
Linus Torvalds1da177e2005-04-16 15:20:36 -070048 current->comm, current->pid, field, address, write,
49 field, regs->cp0_epc);
50#endif
51
David Daneyc1bf2072010-08-03 11:22:20 -070052#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 Torvalds1da177e2005-04-16 15:20:36 -070063 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 Daney2ca2ebf2009-09-02 15:47:34 -070074#ifdef CONFIG_64BIT
75# define VMALLOC_FAULT_TARGET no_context
76#else
77# define VMALLOC_FAULT_TARGET vmalloc_fault
78#endif
79
Thiemo Seufer16033d62005-02-19 13:56:04 +000080 if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
David Daney2ca2ebf2009-09-02 15:47:34 -070081 goto VMALLOC_FAULT_TARGET;
Atsushi Nemoto656be922006-10-26 00:08:31 +090082#ifdef MODULE_START
83 if (unlikely(address >= MODULE_START && address < MODULE_END))
David Daney2ca2ebf2009-09-02 15:47:34 -070084 goto VMALLOC_FAULT_TARGET;
Atsushi Nemoto656be922006-10-26 00:08:31 +090085#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
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 */
108good_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 Daney6dd93442010-02-10 15:12:47 -0800115 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 Torvalds1da177e2005-04-16 15:20:36 -0700140 }
141
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 /*
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 Torvaldsd06063c2009-04-10 09:01:23 -0700147 fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
Deng-Cheng Zhu7f788d22010-10-12 19:37:21 +0800148 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
Nick Piggin83c54072007-07-19 01:47:05 -0700149 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 Torvalds1da177e2005-04-16 15:20:36 -0700154 BUG();
155 }
Deng-Cheng Zhu7f788d22010-10-12 19:37:21 +0800156 if (fault & VM_FAULT_MAJOR) {
157 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
158 1, 0, regs, address);
Nick Piggin83c54072007-07-19 01:47:05 -0700159 tsk->maj_flt++;
Deng-Cheng Zhu7f788d22010-10-12 19:37:21 +0800160 } else {
161 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
162 1, 0, regs, address);
Nick Piggin83c54072007-07-19 01:47:05 -0700163 tsk->min_flt++;
Deng-Cheng Zhu7f788d22010-10-12 19:37:21 +0800164 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
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 */
173bad_area:
174 up_read(&mm->mmap_sem);
175
176bad_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 Baechlefe00f942005-03-01 19:22:29 +0000193 info.si_addr = (void __user *) address;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 force_sig_info(SIGSEGV, &info, tsk);
195 return;
196 }
197
198no_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 Torvalds1da177e2005-04-16 15:20:36 -0700209 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 Baechled6f70362007-03-29 22:30:01 +0100213 raw_smp_processor_id(), field, address, field, regs->cp0_epc,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 field, regs->regs[31]);
215 die("Oops", regs);
216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217out_of_memory:
Ralf Baechlec7c1e382009-01-12 00:09:13 +0000218 /*
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 Mitaa887b4d2009-07-04 01:33:09 +0900222 up_read(&mm->mmap_sem);
Ralf Baechlec7c1e382009-01-12 00:09:13 +0000223 pagefault_out_of_memory();
224 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225
226do_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 Baechle41c594a2006-04-05 09:45:45 +0100232 else
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 /*
234 * Send a sigbus, regardless of whether we were in kernel
235 * or user mode.
236 */
Ralf Baechle41c594a2006-04-05 09:45:45 +0100237#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 Torvalds1da177e2005-04-16 15:20:36 -0700246 tsk->thread.cp0_badvaddr = address;
247 info.si_signo = SIGBUS;
248 info.si_errno = 0;
249 info.si_code = BUS_ADRERR;
Ralf Baechlefe00f942005-03-01 19:22:29 +0000250 info.si_addr = (void __user *) address;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 force_sig_info(SIGBUS, &info, tsk);
252
253 return;
David Daney2ca2ebf2009-09-02 15:47:34 -0700254#ifndef CONFIG_64BIT
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255vmalloc_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 Baechlec6e8b582005-02-10 12:19:59 +0000266 pud_t *pud, *pud_k;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 pmd_t *pmd, *pmd_k;
268 pte_t *pte_k;
269
Ralf Baechled6f70362007-03-29 22:30:01 +0100270 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 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 Baechlec6e8b582005-02-10 12:19:59 +0000277 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 Torvalds1da177e2005-04-16 15:20:36 -0700284 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 Daney2ca2ebf2009-09-02 15:47:34 -0700293#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294}