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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/context_tracking.h>
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>
17#include <linux/ratelimit.h>
18#include <linux/mman.h>
19#include <linux/mm.h>
20#include <linux/smp.h>
21#include <linux/kprobes.h>
22#include <linux/perf_event.h>
23#include <linux/uaccess.h>
24
25#include <asm/branch.h>
26#include <asm/mmu_context.h>
27#include <asm/ptrace.h>
28#include <asm/highmem.h> /* For VMALLOC_END */
29#include <linux/kdebug.h>
30
31int show_unhandled_signals = 1;
32
33/*
34 * This routine handles page faults. It determines the address,
35 * and the problem, and then passes it off to one of the appropriate
36 * routines.
37 */
38static void __do_page_fault(struct pt_regs *regs, unsigned long write,
39 unsigned long address)
40{
41 struct vm_area_struct * vma = NULL;
42 struct task_struct *tsk = current;
43 struct mm_struct *mm = tsk->mm;
44 const int field = sizeof(unsigned long) * 2;
45 int si_code;
46 vm_fault_t fault;
47 unsigned int flags = FAULT_FLAG_DEFAULT;
48
49 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
50
51#if 0
52 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
53 current->comm, current->pid, field, address, write,
54 field, regs->cp0_epc);
55#endif
56
57#ifdef CONFIG_KPROBES
58 /*
59 * This is to notify the fault handler of the kprobes.
60 */
61 if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
62 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
63 return;
64#endif
65
66 si_code = SEGV_MAPERR;
67
68 /*
69 * We fault-in kernel-space virtual memory on-demand. The
70 * 'reference' page table is init_mm.pgd.
71 *
72 * NOTE! We MUST NOT take any locks for this case. We may
73 * be in an interrupt or a critical region, and should
74 * only copy the information from the master page table,
75 * nothing more.
76 */
77#ifdef CONFIG_64BIT
78# define VMALLOC_FAULT_TARGET no_context
79#else
80# define VMALLOC_FAULT_TARGET vmalloc_fault
81#endif
82
83 if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
84 goto VMALLOC_FAULT_TARGET;
85#ifdef MODULE_START
86 if (unlikely(address >= MODULE_START && address < MODULE_END))
87 goto VMALLOC_FAULT_TARGET;
88#endif
89
90 /*
91 * If we're in an interrupt or have no user
92 * context, we must not take the fault..
93 */
94 if (faulthandler_disabled() || !mm)
95 goto bad_area_nosemaphore;
96
97 if (user_mode(regs))
98 flags |= FAULT_FLAG_USER;
99
100 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
101retry:
102 mmap_read_lock(mm);
103 vma = find_vma(mm, address);
104 if (!vma)
105 goto bad_area;
106 if (vma->vm_start <= address)
107 goto good_area;
108 if (!(vma->vm_flags & VM_GROWSDOWN))
109 goto bad_area;
110 if (expand_stack(vma, address))
111 goto bad_area;
112/*
113 * Ok, we have a good vm_area for this memory access, so
114 * we can handle it..
115 */
116good_area:
117 si_code = SEGV_ACCERR;
118
119 if (write) {
120 if (!(vma->vm_flags & VM_WRITE))
121 goto bad_area;
122 flags |= FAULT_FLAG_WRITE;
123 } else {
124 if (cpu_has_rixi) {
125 if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
126#if 0
127 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
128 raw_smp_processor_id(),
129 current->comm, current->pid,
130 field, address, write,
131 field, regs->cp0_epc);
132#endif
133 goto bad_area;
134 }
135 if (!(vma->vm_flags & VM_READ) &&
136 exception_epc(regs) != address) {
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 (unlikely(!vma_is_accessible(vma)))
148 goto bad_area;
149 }
150 }
151
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 */
157 fault = handle_mm_fault(vma, address, flags, regs);
158
159 if (fault_signal_pending(fault, regs)) {
160 if (!user_mode(regs))
161 goto no_context;
162 return;
163 }
164
165 /* The fault is fully completed (including releasing mmap lock) */
166 if (fault & VM_FAULT_COMPLETED)
167 return;
168
169 if (unlikely(fault & VM_FAULT_ERROR)) {
170 if (fault & VM_FAULT_OOM)
171 goto out_of_memory;
172 else if (fault & VM_FAULT_SIGSEGV)
173 goto bad_area;
174 else if (fault & VM_FAULT_SIGBUS)
175 goto do_sigbus;
176 BUG();
177 }
178
179 if (fault & VM_FAULT_RETRY) {
180 flags |= FAULT_FLAG_TRIED;
181
182 /*
183 * No need to mmap_read_unlock(mm) as we would
184 * have already released it in __lock_page_or_retry
185 * in mm/filemap.c.
186 */
187
188 goto retry;
189 }
190
191 mmap_read_unlock(mm);
192 return;
193
194/*
195 * Something tried to access memory that isn't in our memory map..
196 * Fix it, but check if it's kernel or user first..
197 */
198bad_area:
199 mmap_read_unlock(mm);
200
201bad_area_nosemaphore:
202 /* User mode accesses just cause a SIGSEGV */
203 if (user_mode(regs)) {
204 tsk->thread.cp0_badvaddr = address;
205 tsk->thread.error_code = write;
206 if (show_unhandled_signals &&
207 unhandled_signal(tsk, SIGSEGV) &&
208 __ratelimit(&ratelimit_state)) {
209 pr_info("do_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx\n",
210 tsk->comm,
211 write ? "write access to" : "read access from",
212 field, address);
213 pr_info("epc = %0*lx in", field,
214 (unsigned long) regs->cp0_epc);
215 print_vma_addr(KERN_CONT " ", regs->cp0_epc);
216 pr_cont("\n");
217 pr_info("ra = %0*lx in", field,
218 (unsigned long) regs->regs[31]);
219 print_vma_addr(KERN_CONT " ", regs->regs[31]);
220 pr_cont("\n");
221 }
222 current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
223 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
224 return;
225 }
226
227no_context:
228 /* Are we prepared to handle this kernel fault? */
229 if (fixup_exception(regs)) {
230 current->thread.cp0_baduaddr = address;
231 return;
232 }
233
234 /*
235 * Oops. The kernel tried to access some bad page. We'll have to
236 * terminate things with extreme prejudice.
237 */
238 bust_spinlocks(1);
239
240 printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
241 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
242 raw_smp_processor_id(), field, address, field, regs->cp0_epc,
243 field, regs->regs[31]);
244 die("Oops", regs);
245
246out_of_memory:
247 /*
248 * We ran out of memory, call the OOM killer, and return the userspace
249 * (which will retry the fault, or kill us if we got oom-killed).
250 */
251 mmap_read_unlock(mm);
252 if (!user_mode(regs))
253 goto no_context;
254 pagefault_out_of_memory();
255 return;
256
257do_sigbus:
258 mmap_read_unlock(mm);
259
260 /* Kernel mode? Handle exceptions or die */
261 if (!user_mode(regs))
262 goto no_context;
263
264 /*
265 * Send a sigbus, regardless of whether we were in kernel
266 * or user mode.
267 */
268#if 0
269 printk("do_page_fault() #3: sending SIGBUS to %s for "
270 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
271 tsk->comm,
272 write ? "write access to" : "read access from",
273 field, address,
274 field, (unsigned long) regs->cp0_epc,
275 field, (unsigned long) regs->regs[31]);
276#endif
277 current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
278 tsk->thread.cp0_badvaddr = address;
279 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
280
281 return;
282#ifndef CONFIG_64BIT
283vmalloc_fault:
284 {
285 /*
286 * Synchronize this task's top level page-table
287 * with the 'reference' page table.
288 *
289 * Do _not_ use "tsk" here. We might be inside
290 * an interrupt in the middle of a task switch..
291 */
292 int offset = pgd_index(address);
293 pgd_t *pgd, *pgd_k;
294 p4d_t *p4d, *p4d_k;
295 pud_t *pud, *pud_k;
296 pmd_t *pmd, *pmd_k;
297 pte_t *pte_k;
298
299 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
300 pgd_k = init_mm.pgd + offset;
301
302 if (!pgd_present(*pgd_k))
303 goto no_context;
304 set_pgd(pgd, *pgd_k);
305
306 p4d = p4d_offset(pgd, address);
307 p4d_k = p4d_offset(pgd_k, address);
308 if (!p4d_present(*p4d_k))
309 goto no_context;
310
311 pud = pud_offset(p4d, address);
312 pud_k = pud_offset(p4d_k, address);
313 if (!pud_present(*pud_k))
314 goto no_context;
315
316 pmd = pmd_offset(pud, address);
317 pmd_k = pmd_offset(pud_k, address);
318 if (!pmd_present(*pmd_k))
319 goto no_context;
320 set_pmd(pmd, *pmd_k);
321
322 pte_k = pte_offset_kernel(pmd_k, address);
323 if (!pte_present(*pte_k))
324 goto no_context;
325 return;
326 }
327#endif
328}
329NOKPROBE_SYMBOL(__do_page_fault);
330
331asmlinkage void do_page_fault(struct pt_regs *regs,
332 unsigned long write, unsigned long address)
333{
334 enum ctx_state prev_state;
335
336 prev_state = exception_enter();
337 __do_page_fault(regs, write, address);
338 exception_exit(prev_state);
339}
340NOKPROBE_SYMBOL(do_page_fault);
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/context_tracking.h>
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>
17#include <linux/ratelimit.h>
18#include <linux/mman.h>
19#include <linux/mm.h>
20#include <linux/smp.h>
21#include <linux/kprobes.h>
22#include <linux/perf_event.h>
23#include <linux/uaccess.h>
24
25#include <asm/branch.h>
26#include <asm/mmu_context.h>
27#include <asm/ptrace.h>
28#include <asm/highmem.h> /* For VMALLOC_END */
29#include <linux/kdebug.h>
30
31int show_unhandled_signals = 1;
32
33/*
34 * This routine handles page faults. It determines the address,
35 * and the problem, and then passes it off to one of the appropriate
36 * routines.
37 */
38static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
39 unsigned long address)
40{
41 struct vm_area_struct * vma = NULL;
42 struct task_struct *tsk = current;
43 struct mm_struct *mm = tsk->mm;
44 const int field = sizeof(unsigned long) * 2;
45 int si_code;
46 vm_fault_t fault;
47 unsigned int flags = FAULT_FLAG_DEFAULT;
48
49 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
50
51#if 0
52 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
53 current->comm, current->pid, field, address, write,
54 field, regs->cp0_epc);
55#endif
56
57#ifdef CONFIG_KPROBES
58 /*
59 * This is to notify the fault handler of the kprobes.
60 */
61 if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
62 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
63 return;
64#endif
65
66 si_code = SEGV_MAPERR;
67
68 /*
69 * We fault-in kernel-space virtual memory on-demand. The
70 * 'reference' page table is init_mm.pgd.
71 *
72 * NOTE! We MUST NOT take any locks for this case. We may
73 * be in an interrupt or a critical region, and should
74 * only copy the information from the master page table,
75 * nothing more.
76 */
77#ifdef CONFIG_64BIT
78# define VMALLOC_FAULT_TARGET no_context
79#else
80# define VMALLOC_FAULT_TARGET vmalloc_fault
81#endif
82
83 if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
84 goto VMALLOC_FAULT_TARGET;
85#ifdef MODULE_START
86 if (unlikely(address >= MODULE_START && address < MODULE_END))
87 goto VMALLOC_FAULT_TARGET;
88#endif
89
90 /*
91 * If we're in an interrupt or have no user
92 * context, we must not take the fault..
93 */
94 if (faulthandler_disabled() || !mm)
95 goto bad_area_nosemaphore;
96
97 if (user_mode(regs))
98 flags |= FAULT_FLAG_USER;
99
100 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
101retry:
102 mmap_read_lock(mm);
103 vma = find_vma(mm, address);
104 if (!vma)
105 goto bad_area;
106 if (vma->vm_start <= address)
107 goto good_area;
108 if (!(vma->vm_flags & VM_GROWSDOWN))
109 goto bad_area;
110 if (expand_stack(vma, address))
111 goto bad_area;
112/*
113 * Ok, we have a good vm_area for this memory access, so
114 * we can handle it..
115 */
116good_area:
117 si_code = SEGV_ACCERR;
118
119 if (write) {
120 if (!(vma->vm_flags & VM_WRITE))
121 goto bad_area;
122 flags |= FAULT_FLAG_WRITE;
123 } else {
124 if (cpu_has_rixi) {
125 if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
126#if 0
127 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
128 raw_smp_processor_id(),
129 current->comm, current->pid,
130 field, address, write,
131 field, regs->cp0_epc);
132#endif
133 goto bad_area;
134 }
135 if (!(vma->vm_flags & VM_READ) &&
136 exception_epc(regs) != address) {
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 (unlikely(!vma_is_accessible(vma)))
148 goto bad_area;
149 }
150 }
151
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 */
157 fault = handle_mm_fault(vma, address, flags, regs);
158
159 if (fault_signal_pending(fault, regs)) {
160 if (!user_mode(regs))
161 goto no_context;
162 return;
163 }
164
165 if (unlikely(fault & VM_FAULT_ERROR)) {
166 if (fault & VM_FAULT_OOM)
167 goto out_of_memory;
168 else if (fault & VM_FAULT_SIGSEGV)
169 goto bad_area;
170 else if (fault & VM_FAULT_SIGBUS)
171 goto do_sigbus;
172 BUG();
173 }
174 if (flags & FAULT_FLAG_ALLOW_RETRY) {
175 if (fault & VM_FAULT_RETRY) {
176 flags |= FAULT_FLAG_TRIED;
177
178 /*
179 * No need to mmap_read_unlock(mm) as we would
180 * have already released it in __lock_page_or_retry
181 * in mm/filemap.c.
182 */
183
184 goto retry;
185 }
186 }
187
188 mmap_read_unlock(mm);
189 return;
190
191/*
192 * Something tried to access memory that isn't in our memory map..
193 * Fix it, but check if it's kernel or user first..
194 */
195bad_area:
196 mmap_read_unlock(mm);
197
198bad_area_nosemaphore:
199 /* User mode accesses just cause a SIGSEGV */
200 if (user_mode(regs)) {
201 tsk->thread.cp0_badvaddr = address;
202 tsk->thread.error_code = write;
203 if (show_unhandled_signals &&
204 unhandled_signal(tsk, SIGSEGV) &&
205 __ratelimit(&ratelimit_state)) {
206 pr_info("do_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx\n",
207 tsk->comm,
208 write ? "write access to" : "read access from",
209 field, address);
210 pr_info("epc = %0*lx in", field,
211 (unsigned long) regs->cp0_epc);
212 print_vma_addr(KERN_CONT " ", regs->cp0_epc);
213 pr_cont("\n");
214 pr_info("ra = %0*lx in", field,
215 (unsigned long) regs->regs[31]);
216 print_vma_addr(KERN_CONT " ", regs->regs[31]);
217 pr_cont("\n");
218 }
219 current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
220 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
221 return;
222 }
223
224no_context:
225 /* Are we prepared to handle this kernel fault? */
226 if (fixup_exception(regs)) {
227 current->thread.cp0_baduaddr = address;
228 return;
229 }
230
231 /*
232 * Oops. The kernel tried to access some bad page. We'll have to
233 * terminate things with extreme prejudice.
234 */
235 bust_spinlocks(1);
236
237 printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
238 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
239 raw_smp_processor_id(), field, address, field, regs->cp0_epc,
240 field, regs->regs[31]);
241 die("Oops", regs);
242
243out_of_memory:
244 /*
245 * We ran out of memory, call the OOM killer, and return the userspace
246 * (which will retry the fault, or kill us if we got oom-killed).
247 */
248 mmap_read_unlock(mm);
249 if (!user_mode(regs))
250 goto no_context;
251 pagefault_out_of_memory();
252 return;
253
254do_sigbus:
255 mmap_read_unlock(mm);
256
257 /* Kernel mode? Handle exceptions or die */
258 if (!user_mode(regs))
259 goto no_context;
260
261 /*
262 * Send a sigbus, regardless of whether we were in kernel
263 * or user mode.
264 */
265#if 0
266 printk("do_page_fault() #3: sending SIGBUS to %s for "
267 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
268 tsk->comm,
269 write ? "write access to" : "read access from",
270 field, address,
271 field, (unsigned long) regs->cp0_epc,
272 field, (unsigned long) regs->regs[31]);
273#endif
274 current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
275 tsk->thread.cp0_badvaddr = address;
276 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
277
278 return;
279#ifndef CONFIG_64BIT
280vmalloc_fault:
281 {
282 /*
283 * Synchronize this task's top level page-table
284 * with the 'reference' page table.
285 *
286 * Do _not_ use "tsk" here. We might be inside
287 * an interrupt in the middle of a task switch..
288 */
289 int offset = pgd_index(address);
290 pgd_t *pgd, *pgd_k;
291 p4d_t *p4d, *p4d_k;
292 pud_t *pud, *pud_k;
293 pmd_t *pmd, *pmd_k;
294 pte_t *pte_k;
295
296 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
297 pgd_k = init_mm.pgd + offset;
298
299 if (!pgd_present(*pgd_k))
300 goto no_context;
301 set_pgd(pgd, *pgd_k);
302
303 p4d = p4d_offset(pgd, address);
304 p4d_k = p4d_offset(pgd_k, address);
305 if (!p4d_present(*p4d_k))
306 goto no_context;
307
308 pud = pud_offset(p4d, address);
309 pud_k = pud_offset(p4d_k, address);
310 if (!pud_present(*pud_k))
311 goto no_context;
312
313 pmd = pmd_offset(pud, address);
314 pmd_k = pmd_offset(pud_k, address);
315 if (!pmd_present(*pmd_k))
316 goto no_context;
317 set_pmd(pmd, *pmd_k);
318
319 pte_k = pte_offset_kernel(pmd_k, address);
320 if (!pte_present(*pte_k))
321 goto no_context;
322 return;
323 }
324#endif
325}
326
327asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
328 unsigned long write, unsigned long address)
329{
330 enum ctx_state prev_state;
331
332 prev_state = exception_enter();
333 __do_page_fault(regs, write, address);
334 exception_exit(prev_state);
335}