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
6 * Copyright (C) 1995 - 2000 by Ralf Baechle
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>
19 #include <linux/smp.h>
20 #include <linux/module.h>
21 #include <linux/kprobes.h>
22 #include <linux/perf_event.h>
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>
32 * This routine handles page faults. It determines the address,
33 * and the problem, and then passes it off to one of the appropriate
36 static void __kprobes
__do_page_fault(struct pt_regs
*regs
, unsigned long write
,
37 unsigned long address
)
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;
45 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
|
46 (write
? FAULT_FLAG_WRITE
: 0);
49 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
50 current
->comm
, current
->pid
, field
, address
, write
,
51 field
, regs
->cp0_epc
);
56 * This is to notify the fault handler of the kprobes. The
57 * exception code is redundant as it is also carried in REGS,
58 * but we pass it anyhow.
60 if (notify_die(DIE_PAGE_FAULT
, "page fault", regs
, -1,
61 (regs
->cp0_cause
>> 2) & 0x1f, SIGSEGV
) == NOTIFY_STOP
)
65 info
.si_code
= SEGV_MAPERR
;
68 * We fault-in kernel-space virtual memory on-demand. The
69 * 'reference' page table is init_mm.pgd.
71 * NOTE! We MUST NOT take any locks for this case. We may
72 * be in an interrupt or a critical region, and should
73 * only copy the information from the master page table,
77 # define VMALLOC_FAULT_TARGET no_context
79 # define VMALLOC_FAULT_TARGET vmalloc_fault
82 if (unlikely(address
>= VMALLOC_START
&& address
<= VMALLOC_END
))
83 goto VMALLOC_FAULT_TARGET
;
85 if (unlikely(address
>= MODULE_START
&& address
< MODULE_END
))
86 goto VMALLOC_FAULT_TARGET
;
90 * If we're in an interrupt or have no user
91 * context, we must not take the fault..
93 if (in_atomic() || !mm
)
94 goto bad_area_nosemaphore
;
97 down_read(&mm
->mmap_sem
);
98 vma
= find_vma(mm
, address
);
101 if (vma
->vm_start
<= address
)
103 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
105 if (expand_stack(vma
, address
))
108 * Ok, we have a good vm_area for this memory access, so
112 info
.si_code
= SEGV_ACCERR
;
115 if (!(vma
->vm_flags
& VM_WRITE
))
119 if (address
== regs
->cp0_epc
&& !(vma
->vm_flags
& VM_EXEC
)) {
121 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
122 raw_smp_processor_id(),
123 current
->comm
, current
->pid
,
124 field
, address
, write
,
125 field
, regs
->cp0_epc
);
129 if (!(vma
->vm_flags
& VM_READ
)) {
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
);
140 if (!(vma
->vm_flags
& (VM_READ
| VM_WRITE
| VM_EXEC
)))
146 * If for any reason at all we couldn't handle the fault,
147 * make sure we exit gracefully rather than endlessly redo
150 fault
= handle_mm_fault(mm
, vma
, address
, flags
);
152 if ((fault
& VM_FAULT_RETRY
) && fatal_signal_pending(current
))
155 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS
, 1, regs
, address
);
156 if (unlikely(fault
& VM_FAULT_ERROR
)) {
157 if (fault
& VM_FAULT_OOM
)
159 else if (fault
& VM_FAULT_SIGBUS
)
163 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
164 if (fault
& VM_FAULT_MAJOR
) {
165 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ
, 1,
169 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN
, 1,
173 if (fault
& VM_FAULT_RETRY
) {
174 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
175 flags
|= FAULT_FLAG_TRIED
;
178 * No need to up_read(&mm->mmap_sem) as we would
179 * have already released it in __lock_page_or_retry
187 up_read(&mm
->mmap_sem
);
191 * Something tried to access memory that isn't in our memory map..
192 * Fix it, but check if it's kernel or user first..
195 up_read(&mm
->mmap_sem
);
197 bad_area_nosemaphore
:
198 /* User mode accesses just cause a SIGSEGV */
199 if (user_mode(regs
)) {
200 tsk
->thread
.cp0_badvaddr
= address
;
201 tsk
->thread
.error_code
= write
;
203 printk("do_page_fault() #2: sending SIGSEGV to %s for "
204 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
206 write
? "write access to" : "read access from",
208 field
, (unsigned long) regs
->cp0_epc
,
209 field
, (unsigned long) regs
->regs
[31]);
211 info
.si_signo
= SIGSEGV
;
213 /* info.si_code has been set above */
214 info
.si_addr
= (void __user
*) address
;
215 force_sig_info(SIGSEGV
, &info
, tsk
);
220 /* Are we prepared to handle this kernel fault? */
221 if (fixup_exception(regs
)) {
222 current
->thread
.cp0_baduaddr
= address
;
227 * Oops. The kernel tried to access some bad page. We'll have to
228 * terminate things with extreme prejudice.
232 printk(KERN_ALERT
"CPU %d Unable to handle kernel paging request at "
233 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
234 raw_smp_processor_id(), field
, address
, field
, regs
->cp0_epc
,
235 field
, regs
->regs
[31]);
240 * We ran out of memory, call the OOM killer, and return the userspace
241 * (which will retry the fault, or kill us if we got oom-killed).
243 up_read(&mm
->mmap_sem
);
244 pagefault_out_of_memory();
248 up_read(&mm
->mmap_sem
);
250 /* Kernel mode? Handle exceptions or die */
251 if (!user_mode(regs
))
255 * Send a sigbus, regardless of whether we were in kernel
259 printk("do_page_fault() #3: sending SIGBUS to %s for "
260 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
262 write
? "write access to" : "read access from",
264 field
, (unsigned long) regs
->cp0_epc
,
265 field
, (unsigned long) regs
->regs
[31]);
267 tsk
->thread
.cp0_badvaddr
= address
;
268 info
.si_signo
= SIGBUS
;
270 info
.si_code
= BUS_ADRERR
;
271 info
.si_addr
= (void __user
*) address
;
272 force_sig_info(SIGBUS
, &info
, tsk
);
279 * Synchronize this task's top level page-table
280 * with the 'reference' page table.
282 * Do _not_ use "tsk" here. We might be inside
283 * an interrupt in the middle of a task switch..
285 int offset
= __pgd_offset(address
);
291 pgd
= (pgd_t
*) pgd_current
[raw_smp_processor_id()] + offset
;
292 pgd_k
= init_mm
.pgd
+ offset
;
294 if (!pgd_present(*pgd_k
))
296 set_pgd(pgd
, *pgd_k
);
298 pud
= pud_offset(pgd
, address
);
299 pud_k
= pud_offset(pgd_k
, address
);
300 if (!pud_present(*pud_k
))
303 pmd
= pmd_offset(pud
, address
);
304 pmd_k
= pmd_offset(pud_k
, address
);
305 if (!pmd_present(*pmd_k
))
307 set_pmd(pmd
, *pmd_k
);
309 pte_k
= pte_offset_kernel(pmd_k
, address
);
310 if (!pte_present(*pte_k
))
317 asmlinkage
void __kprobes
do_page_fault(struct pt_regs
*regs
,
318 unsigned long write
, unsigned long address
)
320 enum ctx_state prev_state
;
322 prev_state
= exception_enter();
323 __do_page_fault(regs
, write
, address
);
324 exception_exit(prev_state
);