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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/mman.h>
18#include <linux/mm.h>
19#include <linux/smp.h>
20#include <linux/module.h>
21#include <linux/kprobes.h>
22#include <linux/perf_event.h>
23
24#include <asm/branch.h>
25#include <asm/mmu_context.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 */
36static 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 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
46
47#if 0
48 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
49 current->comm, current->pid, field, address, write,
50 field, regs->cp0_epc);
51#endif
52
53#ifdef CONFIG_KPROBES
54 /*
55 * This is to notify the fault handler of the kprobes. The
56 * exception code is redundant as it is also carried in REGS,
57 * but we pass it anyhow.
58 */
59 if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
60 (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP)
61 return;
62#endif
63
64 info.si_code = SEGV_MAPERR;
65
66 /*
67 * We fault-in kernel-space virtual memory on-demand. The
68 * 'reference' page table is init_mm.pgd.
69 *
70 * NOTE! We MUST NOT take any locks for this case. We may
71 * be in an interrupt or a critical region, and should
72 * only copy the information from the master page table,
73 * nothing more.
74 */
75#ifdef CONFIG_64BIT
76# define VMALLOC_FAULT_TARGET no_context
77#else
78# define VMALLOC_FAULT_TARGET vmalloc_fault
79#endif
80
81 if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
82 goto VMALLOC_FAULT_TARGET;
83#ifdef MODULE_START
84 if (unlikely(address >= MODULE_START && address < MODULE_END))
85 goto VMALLOC_FAULT_TARGET;
86#endif
87
88 /*
89 * If we're in an interrupt or have no user
90 * context, we must not take the fault..
91 */
92 if (in_atomic() || !mm)
93 goto bad_area_nosemaphore;
94
95 if (user_mode(regs))
96 flags |= FAULT_FLAG_USER;
97retry:
98 down_read(&mm->mmap_sem);
99 vma = find_vma(mm, address);
100 if (!vma)
101 goto bad_area;
102 if (vma->vm_start <= address)
103 goto good_area;
104 if (!(vma->vm_flags & VM_GROWSDOWN))
105 goto bad_area;
106 if (expand_stack(vma, address))
107 goto bad_area;
108/*
109 * Ok, we have a good vm_area for this memory access, so
110 * we can handle it..
111 */
112good_area:
113 info.si_code = SEGV_ACCERR;
114
115 if (write) {
116 if (!(vma->vm_flags & VM_WRITE))
117 goto bad_area;
118 flags |= FAULT_FLAG_WRITE;
119 } else {
120 if (cpu_has_rixi) {
121 if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
122#if 0
123 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
124 raw_smp_processor_id(),
125 current->comm, current->pid,
126 field, address, write,
127 field, regs->cp0_epc);
128#endif
129 goto bad_area;
130 }
131 if (!(vma->vm_flags & VM_READ)) {
132#if 0
133 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n",
134 raw_smp_processor_id(),
135 current->comm, current->pid,
136 field, address, write,
137 field, regs->cp0_epc);
138#endif
139 goto bad_area;
140 }
141 } else {
142 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
143 goto bad_area;
144 }
145 }
146
147 /*
148 * If for any reason at all we couldn't handle the fault,
149 * make sure we exit gracefully rather than endlessly redo
150 * the fault.
151 */
152 fault = handle_mm_fault(mm, vma, address, flags);
153
154 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
155 return;
156
157 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
158 if (unlikely(fault & VM_FAULT_ERROR)) {
159 if (fault & VM_FAULT_OOM)
160 goto out_of_memory;
161 else if (fault & VM_FAULT_SIGBUS)
162 goto do_sigbus;
163 BUG();
164 }
165 if (flags & FAULT_FLAG_ALLOW_RETRY) {
166 if (fault & VM_FAULT_MAJOR) {
167 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
168 regs, address);
169 tsk->maj_flt++;
170 } else {
171 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
172 regs, address);
173 tsk->min_flt++;
174 }
175 if (fault & VM_FAULT_RETRY) {
176 flags &= ~FAULT_FLAG_ALLOW_RETRY;
177 flags |= FAULT_FLAG_TRIED;
178
179 /*
180 * No need to up_read(&mm->mmap_sem) as we would
181 * have already released it in __lock_page_or_retry
182 * in mm/filemap.c.
183 */
184
185 goto retry;
186 }
187 }
188
189 up_read(&mm->mmap_sem);
190 return;
191
192/*
193 * Something tried to access memory that isn't in our memory map..
194 * Fix it, but check if it's kernel or user first..
195 */
196bad_area:
197 up_read(&mm->mmap_sem);
198
199bad_area_nosemaphore:
200 /* User mode accesses just cause a SIGSEGV */
201 if (user_mode(regs)) {
202 tsk->thread.cp0_badvaddr = address;
203 tsk->thread.error_code = write;
204#if 0
205 printk("do_page_fault() #2: sending SIGSEGV to %s for "
206 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
207 tsk->comm,
208 write ? "write access to" : "read access from",
209 field, address,
210 field, (unsigned long) regs->cp0_epc,
211 field, (unsigned long) regs->regs[31]);
212#endif
213 info.si_signo = SIGSEGV;
214 info.si_errno = 0;
215 /* info.si_code has been set above */
216 info.si_addr = (void __user *) address;
217 force_sig_info(SIGSEGV, &info, tsk);
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 up_read(&mm->mmap_sem);
246 if (!user_mode(regs))
247 goto no_context;
248 pagefault_out_of_memory();
249 return;
250
251do_sigbus:
252 up_read(&mm->mmap_sem);
253
254 /* Kernel mode? Handle exceptions or die */
255 if (!user_mode(regs))
256 goto no_context;
257 else
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 tsk->thread.cp0_badvaddr = address;
272 info.si_signo = SIGBUS;
273 info.si_errno = 0;
274 info.si_code = BUS_ADRERR;
275 info.si_addr = (void __user *) address;
276 force_sig_info(SIGBUS, &info, tsk);
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_offset(address);
290 pgd_t *pgd, *pgd_k;
291 pud_t *pud, *pud_k;
292 pmd_t *pmd, *pmd_k;
293 pte_t *pte_k;
294
295 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
296 pgd_k = init_mm.pgd + offset;
297
298 if (!pgd_present(*pgd_k))
299 goto no_context;
300 set_pgd(pgd, *pgd_k);
301
302 pud = pud_offset(pgd, address);
303 pud_k = pud_offset(pgd_k, address);
304 if (!pud_present(*pud_k))
305 goto no_context;
306
307 pmd = pmd_offset(pud, address);
308 pmd_k = pmd_offset(pud_k, address);
309 if (!pmd_present(*pmd_k))
310 goto no_context;
311 set_pmd(pmd, *pmd_k);
312
313 pte_k = pte_offset_kernel(pmd_k, address);
314 if (!pte_present(*pte_k))
315 goto no_context;
316 return;
317 }
318#endif
319}
320
321asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
322 unsigned long write, unsigned long address)
323{
324 enum ctx_state prev_state;
325
326 prev_state = exception_enter();
327 __do_page_fault(regs, write, address);
328 exception_exit(prev_state);
329}