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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/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>
19#include <linux/module.h>
20#include <linux/kprobes.h>
21#include <linux/perf_event.h>
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>
28#include <asm/highmem.h> /* For VMALLOC_END */
29#include <linux/kdebug.h>
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 */
36asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long write,
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;
44 int fault;
45
46#if 0
47 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
48 current->comm, current->pid, field, address, write,
49 field, regs->cp0_epc);
50#endif
51
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
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 */
74#ifdef CONFIG_64BIT
75# define VMALLOC_FAULT_TARGET no_context
76#else
77# define VMALLOC_FAULT_TARGET vmalloc_fault
78#endif
79
80 if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
81 goto VMALLOC_FAULT_TARGET;
82#ifdef MODULE_START
83 if (unlikely(address >= MODULE_START && address < MODULE_END))
84 goto VMALLOC_FAULT_TARGET;
85#endif
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 */
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 {
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 }
140 }
141
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 */
147 fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
148 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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;
154 BUG();
155 }
156 if (fault & VM_FAULT_MAJOR) {
157 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
158 tsk->maj_flt++;
159 } else {
160 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
161 tsk->min_flt++;
162 }
163
164 up_read(&mm->mmap_sem);
165 return;
166
167/*
168 * Something tried to access memory that isn't in our memory map..
169 * Fix it, but check if it's kernel or user first..
170 */
171bad_area:
172 up_read(&mm->mmap_sem);
173
174bad_area_nosemaphore:
175 /* User mode accesses just cause a SIGSEGV */
176 if (user_mode(regs)) {
177 tsk->thread.cp0_badvaddr = address;
178 tsk->thread.error_code = write;
179#if 0
180 printk("do_page_fault() #2: sending SIGSEGV to %s for "
181 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
182 tsk->comm,
183 write ? "write access to" : "read access from",
184 field, address,
185 field, (unsigned long) regs->cp0_epc,
186 field, (unsigned long) regs->regs[31]);
187#endif
188 info.si_signo = SIGSEGV;
189 info.si_errno = 0;
190 /* info.si_code has been set above */
191 info.si_addr = (void __user *) address;
192 force_sig_info(SIGSEGV, &info, tsk);
193 return;
194 }
195
196no_context:
197 /* Are we prepared to handle this kernel fault? */
198 if (fixup_exception(regs)) {
199 current->thread.cp0_baduaddr = address;
200 return;
201 }
202
203 /*
204 * Oops. The kernel tried to access some bad page. We'll have to
205 * terminate things with extreme prejudice.
206 */
207 bust_spinlocks(1);
208
209 printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
210 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
211 raw_smp_processor_id(), field, address, field, regs->cp0_epc,
212 field, regs->regs[31]);
213 die("Oops", regs);
214
215out_of_memory:
216 /*
217 * We ran out of memory, call the OOM killer, and return the userspace
218 * (which will retry the fault, or kill us if we got oom-killed).
219 */
220 up_read(&mm->mmap_sem);
221 pagefault_out_of_memory();
222 return;
223
224do_sigbus:
225 up_read(&mm->mmap_sem);
226
227 /* Kernel mode? Handle exceptions or die */
228 if (!user_mode(regs))
229 goto no_context;
230 else
231 /*
232 * Send a sigbus, regardless of whether we were in kernel
233 * or user mode.
234 */
235#if 0
236 printk("do_page_fault() #3: sending SIGBUS to %s for "
237 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
238 tsk->comm,
239 write ? "write access to" : "read access from",
240 field, address,
241 field, (unsigned long) regs->cp0_epc,
242 field, (unsigned long) regs->regs[31]);
243#endif
244 tsk->thread.cp0_badvaddr = address;
245 info.si_signo = SIGBUS;
246 info.si_errno = 0;
247 info.si_code = BUS_ADRERR;
248 info.si_addr = (void __user *) address;
249 force_sig_info(SIGBUS, &info, tsk);
250
251 return;
252#ifndef CONFIG_64BIT
253vmalloc_fault:
254 {
255 /*
256 * Synchronize this task's top level page-table
257 * with the 'reference' page table.
258 *
259 * Do _not_ use "tsk" here. We might be inside
260 * an interrupt in the middle of a task switch..
261 */
262 int offset = __pgd_offset(address);
263 pgd_t *pgd, *pgd_k;
264 pud_t *pud, *pud_k;
265 pmd_t *pmd, *pmd_k;
266 pte_t *pte_k;
267
268 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
269 pgd_k = init_mm.pgd + offset;
270
271 if (!pgd_present(*pgd_k))
272 goto no_context;
273 set_pgd(pgd, *pgd_k);
274
275 pud = pud_offset(pgd, address);
276 pud_k = pud_offset(pgd_k, address);
277 if (!pud_present(*pud_k))
278 goto no_context;
279
280 pmd = pmd_offset(pud, address);
281 pmd_k = pmd_offset(pud_k, address);
282 if (!pmd_present(*pmd_k))
283 goto no_context;
284 set_pmd(pmd, *pmd_k);
285
286 pte_k = pte_offset_kernel(pmd_k, address);
287 if (!pte_present(*pte_k))
288 goto no_context;
289 return;
290 }
291#endif
292}
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}