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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 <asm/traps.h>
30#include <linux/kdebug.h>
31
32int show_unhandled_signals = 1;
33
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 */
39static void __do_page_fault(struct pt_regs *regs, unsigned long write,
40 unsigned long address)
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 int si_code;
47 vm_fault_t fault;
48 unsigned int flags = FAULT_FLAG_DEFAULT;
49
50 static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
51
52#if 0
53 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
54 current->comm, current->pid, field, address, write,
55 field, regs->cp0_epc);
56#endif
57
58#ifdef CONFIG_KPROBES
59 /*
60 * This is to notify the fault handler of the kprobes.
61 */
62 if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
63 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
64 return;
65#endif
66
67 si_code = SEGV_MAPERR;
68
69 /*
70 * We fault-in kernel-space virtual memory on-demand. The
71 * 'reference' page table is init_mm.pgd.
72 *
73 * NOTE! We MUST NOT take any locks for this case. We may
74 * be in an interrupt or a critical region, and should
75 * only copy the information from the master page table,
76 * nothing more.
77 */
78#ifdef CONFIG_64BIT
79# define VMALLOC_FAULT_TARGET no_context
80#else
81# define VMALLOC_FAULT_TARGET vmalloc_fault
82#endif
83
84 if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
85 goto VMALLOC_FAULT_TARGET;
86#ifdef MODULE_START
87 if (unlikely(address >= MODULE_START && address < MODULE_END))
88 goto VMALLOC_FAULT_TARGET;
89#endif
90
91 /*
92 * If we're in an interrupt or have no user
93 * context, we must not take the fault..
94 */
95 if (faulthandler_disabled() || !mm)
96 goto bad_area_nosemaphore;
97
98 if (user_mode(regs))
99 flags |= FAULT_FLAG_USER;
100
101 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
102retry:
103 vma = lock_mm_and_find_vma(mm, address, regs);
104 if (!vma)
105 goto bad_area_nosemaphore;
106/*
107 * Ok, we have a good vm_area for this memory access, so
108 * we can handle it..
109 */
110 si_code = SEGV_ACCERR;
111
112 if (write) {
113 if (!(vma->vm_flags & VM_WRITE))
114 goto bad_area;
115 flags |= FAULT_FLAG_WRITE;
116 } else {
117 if (cpu_has_rixi) {
118 if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
119#if 0
120 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
121 raw_smp_processor_id(),
122 current->comm, current->pid,
123 field, address, write,
124 field, regs->cp0_epc);
125#endif
126 goto bad_area;
127 }
128 if (!(vma->vm_flags & VM_READ) &&
129 exception_epc(regs) != address) {
130#if 0
131 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n",
132 raw_smp_processor_id(),
133 current->comm, current->pid,
134 field, address, write,
135 field, regs->cp0_epc);
136#endif
137 goto bad_area;
138 }
139 } else {
140 if (unlikely(!vma_is_accessible(vma)))
141 goto bad_area;
142 }
143 }
144
145 /*
146 * If for any reason at all we couldn't handle the fault,
147 * make sure we exit gracefully rather than endlessly redo
148 * the fault.
149 */
150 fault = handle_mm_fault(vma, address, flags, regs);
151
152 if (fault_signal_pending(fault, regs)) {
153 if (!user_mode(regs))
154 goto no_context;
155 return;
156 }
157
158 /* The fault is fully completed (including releasing mmap lock) */
159 if (fault & VM_FAULT_COMPLETED)
160 return;
161
162 if (unlikely(fault & VM_FAULT_ERROR)) {
163 if (fault & VM_FAULT_OOM)
164 goto out_of_memory;
165 else if (fault & VM_FAULT_SIGSEGV)
166 goto bad_area;
167 else if (fault & VM_FAULT_SIGBUS)
168 goto do_sigbus;
169 BUG();
170 }
171
172 if (fault & VM_FAULT_RETRY) {
173 flags |= FAULT_FLAG_TRIED;
174
175 /*
176 * No need to mmap_read_unlock(mm) as we would
177 * have already released it in __lock_page_or_retry
178 * in mm/filemap.c.
179 */
180
181 goto retry;
182 }
183
184 mmap_read_unlock(mm);
185 return;
186
187/*
188 * Something tried to access memory that isn't in our memory map..
189 * Fix it, but check if it's kernel or user first..
190 */
191bad_area:
192 mmap_read_unlock(mm);
193
194bad_area_nosemaphore:
195 /* User mode accesses just cause a SIGSEGV */
196 if (user_mode(regs)) {
197 tsk->thread.cp0_badvaddr = address;
198 tsk->thread.error_code = write;
199 if (show_unhandled_signals &&
200 unhandled_signal(tsk, SIGSEGV) &&
201 __ratelimit(&ratelimit_state)) {
202 pr_info("do_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx\n",
203 tsk->comm,
204 write ? "write access to" : "read access from",
205 field, address);
206 pr_info("epc = %0*lx in", field,
207 (unsigned long) regs->cp0_epc);
208 print_vma_addr(KERN_CONT " ", regs->cp0_epc);
209 pr_cont("\n");
210 pr_info("ra = %0*lx in", field,
211 (unsigned long) regs->regs[31]);
212 print_vma_addr(KERN_CONT " ", regs->regs[31]);
213 pr_cont("\n");
214 }
215 current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
216 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
217 return;
218 }
219
220no_context:
221 /* Are we prepared to handle this kernel fault? */
222 if (fixup_exception(regs)) {
223 current->thread.cp0_baduaddr = address;
224 return;
225 }
226
227 /*
228 * Oops. The kernel tried to access some bad page. We'll have to
229 * terminate things with extreme prejudice.
230 */
231 bust_spinlocks(1);
232
233 printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
234 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
235 raw_smp_processor_id(), field, address, field, regs->cp0_epc,
236 field, regs->regs[31]);
237 die("Oops", regs);
238
239out_of_memory:
240 /*
241 * We ran out of memory, call the OOM killer, and return the userspace
242 * (which will retry the fault, or kill us if we got oom-killed).
243 */
244 mmap_read_unlock(mm);
245 if (!user_mode(regs))
246 goto no_context;
247 pagefault_out_of_memory();
248 return;
249
250do_sigbus:
251 mmap_read_unlock(mm);
252
253 /* Kernel mode? Handle exceptions or die */
254 if (!user_mode(regs))
255 goto no_context;
256
257 /*
258 * Send a sigbus, regardless of whether we were in kernel
259 * or user mode.
260 */
261#if 0
262 printk("do_page_fault() #3: sending SIGBUS to %s for "
263 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
264 tsk->comm,
265 write ? "write access to" : "read access from",
266 field, address,
267 field, (unsigned long) regs->cp0_epc,
268 field, (unsigned long) regs->regs[31]);
269#endif
270 current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
271 tsk->thread.cp0_badvaddr = address;
272 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
273
274 return;
275#ifndef CONFIG_64BIT
276vmalloc_fault:
277 {
278 /*
279 * Synchronize this task's top level page-table
280 * with the 'reference' page table.
281 *
282 * Do _not_ use "tsk" here. We might be inside
283 * an interrupt in the middle of a task switch..
284 */
285 int offset = pgd_index(address);
286 pgd_t *pgd, *pgd_k;
287 p4d_t *p4d, *p4d_k;
288 pud_t *pud, *pud_k;
289 pmd_t *pmd, *pmd_k;
290 pte_t *pte_k;
291
292 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
293 pgd_k = init_mm.pgd + offset;
294
295 if (!pgd_present(*pgd_k))
296 goto no_context;
297 set_pgd(pgd, *pgd_k);
298
299 p4d = p4d_offset(pgd, address);
300 p4d_k = p4d_offset(pgd_k, address);
301 if (!p4d_present(*p4d_k))
302 goto no_context;
303
304 pud = pud_offset(p4d, address);
305 pud_k = pud_offset(p4d_k, address);
306 if (!pud_present(*pud_k))
307 goto no_context;
308
309 pmd = pmd_offset(pud, address);
310 pmd_k = pmd_offset(pud_k, address);
311 if (!pmd_present(*pmd_k))
312 goto no_context;
313 set_pmd(pmd, *pmd_k);
314
315 pte_k = pte_offset_kernel(pmd_k, address);
316 if (!pte_present(*pte_k))
317 goto no_context;
318 return;
319 }
320#endif
321}
322NOKPROBE_SYMBOL(__do_page_fault);
323
324asmlinkage void do_page_fault(struct pt_regs *regs,
325 unsigned long write, unsigned long address)
326{
327 enum ctx_state prev_state;
328
329 prev_state = exception_enter();
330 __do_page_fault(regs, write, address);
331 exception_exit(prev_state);
332}
333NOKPROBE_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 return;
161
162 if (unlikely(fault & VM_FAULT_ERROR)) {
163 if (fault & VM_FAULT_OOM)
164 goto out_of_memory;
165 else if (fault & VM_FAULT_SIGSEGV)
166 goto bad_area;
167 else if (fault & VM_FAULT_SIGBUS)
168 goto do_sigbus;
169 BUG();
170 }
171 if (flags & FAULT_FLAG_ALLOW_RETRY) {
172 if (fault & VM_FAULT_RETRY) {
173 flags |= FAULT_FLAG_TRIED;
174
175 /*
176 * No need to mmap_read_unlock(mm) as we would
177 * have already released it in __lock_page_or_retry
178 * in mm/filemap.c.
179 */
180
181 goto retry;
182 }
183 }
184
185 mmap_read_unlock(mm);
186 return;
187
188/*
189 * Something tried to access memory that isn't in our memory map..
190 * Fix it, but check if it's kernel or user first..
191 */
192bad_area:
193 mmap_read_unlock(mm);
194
195bad_area_nosemaphore:
196 /* User mode accesses just cause a SIGSEGV */
197 if (user_mode(regs)) {
198 tsk->thread.cp0_badvaddr = address;
199 tsk->thread.error_code = write;
200 if (show_unhandled_signals &&
201 unhandled_signal(tsk, SIGSEGV) &&
202 __ratelimit(&ratelimit_state)) {
203 pr_info("do_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx\n",
204 tsk->comm,
205 write ? "write access to" : "read access from",
206 field, address);
207 pr_info("epc = %0*lx in", field,
208 (unsigned long) regs->cp0_epc);
209 print_vma_addr(KERN_CONT " ", regs->cp0_epc);
210 pr_cont("\n");
211 pr_info("ra = %0*lx in", field,
212 (unsigned long) regs->regs[31]);
213 print_vma_addr(KERN_CONT " ", regs->regs[31]);
214 pr_cont("\n");
215 }
216 current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
217 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
218 return;
219 }
220
221no_context:
222 /* Are we prepared to handle this kernel fault? */
223 if (fixup_exception(regs)) {
224 current->thread.cp0_baduaddr = address;
225 return;
226 }
227
228 /*
229 * Oops. The kernel tried to access some bad page. We'll have to
230 * terminate things with extreme prejudice.
231 */
232 bust_spinlocks(1);
233
234 printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
235 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
236 raw_smp_processor_id(), field, address, field, regs->cp0_epc,
237 field, regs->regs[31]);
238 die("Oops", regs);
239
240out_of_memory:
241 /*
242 * We ran out of memory, call the OOM killer, and return the userspace
243 * (which will retry the fault, or kill us if we got oom-killed).
244 */
245 mmap_read_unlock(mm);
246 if (!user_mode(regs))
247 goto no_context;
248 pagefault_out_of_memory();
249 return;
250
251do_sigbus:
252 mmap_read_unlock(mm);
253
254 /* Kernel mode? Handle exceptions or die */
255 if (!user_mode(regs))
256 goto no_context;
257
258 /*
259 * Send a sigbus, regardless of whether we were in kernel
260 * or user mode.
261 */
262#if 0
263 printk("do_page_fault() #3: sending SIGBUS to %s for "
264 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
265 tsk->comm,
266 write ? "write access to" : "read access from",
267 field, address,
268 field, (unsigned long) regs->cp0_epc,
269 field, (unsigned long) regs->regs[31]);
270#endif
271 current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
272 tsk->thread.cp0_badvaddr = address;
273 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
274
275 return;
276#ifndef CONFIG_64BIT
277vmalloc_fault:
278 {
279 /*
280 * Synchronize this task's top level page-table
281 * with the 'reference' page table.
282 *
283 * Do _not_ use "tsk" here. We might be inside
284 * an interrupt in the middle of a task switch..
285 */
286 int offset = pgd_index(address);
287 pgd_t *pgd, *pgd_k;
288 p4d_t *p4d, *p4d_k;
289 pud_t *pud, *pud_k;
290 pmd_t *pmd, *pmd_k;
291 pte_t *pte_k;
292
293 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
294 pgd_k = init_mm.pgd + offset;
295
296 if (!pgd_present(*pgd_k))
297 goto no_context;
298 set_pgd(pgd, *pgd_k);
299
300 p4d = p4d_offset(pgd, address);
301 p4d_k = p4d_offset(pgd_k, address);
302 if (!p4d_present(*p4d_k))
303 goto no_context;
304
305 pud = pud_offset(p4d, address);
306 pud_k = pud_offset(p4d_k, address);
307 if (!pud_present(*pud_k))
308 goto no_context;
309
310 pmd = pmd_offset(pud, address);
311 pmd_k = pmd_offset(pud_k, address);
312 if (!pmd_present(*pmd_k))
313 goto no_context;
314 set_pmd(pmd, *pmd_k);
315
316 pte_k = pte_offset_kernel(pmd_k, address);
317 if (!pte_present(*pte_k))
318 goto no_context;
319 return;
320 }
321#endif
322}
323
324asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
325 unsigned long write, unsigned long address)
326{
327 enum ctx_state prev_state;
328
329 prev_state = exception_enter();
330 __do_page_fault(regs, write, address);
331 exception_exit(prev_state);
332}