2 * linux/arch/arm/mm/fault.c
4 * Copyright (C) 1995 Linus Torvalds
5 * Modifications for ARM processor (c) 1995-2004 Russell King
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 #include <linux/module.h>
12 #include <linux/signal.h>
14 #include <linux/hardirq.h>
15 #include <linux/init.h>
16 #include <linux/kprobes.h>
17 #include <linux/uaccess.h>
18 #include <linux/page-flags.h>
19 #include <linux/highmem.h>
21 #include <asm/system.h>
22 #include <asm/pgtable.h>
23 #include <asm/tlbflush.h>
29 static inline int notify_page_fault(struct pt_regs
*regs
, unsigned int fsr
)
33 if (!user_mode(regs
)) {
34 /* kprobe_running() needs smp_processor_id() */
36 if (kprobe_running() && kprobe_fault_handler(regs
, fsr
))
44 static inline int notify_page_fault(struct pt_regs
*regs
, unsigned int fsr
)
51 * This is useful to dump out the page tables associated with
54 void show_pte(struct mm_struct
*mm
, unsigned long addr
)
61 printk(KERN_ALERT
"pgd = %p\n", mm
->pgd
);
62 pgd
= pgd_offset(mm
, addr
);
63 printk(KERN_ALERT
"[%08lx] *pgd=%08lx", addr
, pgd_val(*pgd
));
77 pmd
= pmd_offset(pgd
, addr
);
78 if (PTRS_PER_PMD
!= 1)
79 printk(", *pmd=%08lx", pmd_val(*pmd
));
89 /* We must not map this if we have highmem enabled */
90 if (PageHighMem(pfn_to_page(pmd_val(*pmd
) >> PAGE_SHIFT
)))
93 pte
= pte_offset_map(pmd
, addr
);
94 printk(", *pte=%08lx", pte_val(*pte
));
95 printk(", *ppte=%08lx", pte_val(pte
[-PTRS_PER_PTE
]));
103 * Oops. The kernel tried to access some page that wasn't present.
106 __do_kernel_fault(struct mm_struct
*mm
, unsigned long addr
, unsigned int fsr
,
107 struct pt_regs
*regs
)
110 * Are we prepared to handle this kernel fault?
112 if (fixup_exception(regs
))
116 * No handler, we'll have to terminate things with extreme prejudice.
120 "Unable to handle kernel %s at virtual address %08lx\n",
121 (addr
< PAGE_SIZE
) ? "NULL pointer dereference" :
122 "paging request", addr
);
125 die("Oops", regs
, fsr
);
131 * Something tried to access memory that isn't in our memory map..
132 * User mode accesses just cause a SIGSEGV
135 __do_user_fault(struct task_struct
*tsk
, unsigned long addr
,
136 unsigned int fsr
, unsigned int sig
, int code
,
137 struct pt_regs
*regs
)
141 #ifdef CONFIG_DEBUG_USER
142 if (user_debug
& UDBG_SEGV
) {
143 printk(KERN_DEBUG
"%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
144 tsk
->comm
, sig
, addr
, fsr
);
145 show_pte(tsk
->mm
, addr
);
150 tsk
->thread
.address
= addr
;
151 tsk
->thread
.error_code
= fsr
;
152 tsk
->thread
.trap_no
= 14;
156 si
.si_addr
= (void __user
*)addr
;
157 force_sig_info(sig
, &si
, tsk
);
160 void do_bad_area(unsigned long addr
, unsigned int fsr
, struct pt_regs
*regs
)
162 struct task_struct
*tsk
= current
;
163 struct mm_struct
*mm
= tsk
->active_mm
;
166 * If we are in kernel mode at this point, we
167 * have no context to handle this fault with.
170 __do_user_fault(tsk
, addr
, fsr
, SIGSEGV
, SEGV_MAPERR
, regs
);
172 __do_kernel_fault(mm
, addr
, fsr
, regs
);
175 #define VM_FAULT_BADMAP 0x010000
176 #define VM_FAULT_BADACCESS 0x020000
179 __do_page_fault(struct mm_struct
*mm
, unsigned long addr
, unsigned int fsr
,
180 struct task_struct
*tsk
)
182 struct vm_area_struct
*vma
;
185 vma
= find_vma(mm
, addr
);
186 fault
= VM_FAULT_BADMAP
;
189 if (vma
->vm_start
> addr
)
193 * Ok, we have a good vm_area for this
194 * memory access, so we can handle it.
197 if (fsr
& (1 << 11)) /* write? */
200 mask
= VM_READ
|VM_EXEC
|VM_WRITE
;
202 fault
= VM_FAULT_BADACCESS
;
203 if (!(vma
->vm_flags
& mask
))
207 * If for any reason at all we couldn't handle
208 * the fault, make sure we exit gracefully rather
209 * than endlessly redo the fault.
212 fault
= handle_mm_fault(mm
, vma
, addr
& PAGE_MASK
, (fsr
& (1 << 11)) ? FAULT_FLAG_WRITE
: 0);
213 if (unlikely(fault
& VM_FAULT_ERROR
)) {
214 if (fault
& VM_FAULT_OOM
)
216 else if (fault
& VM_FAULT_SIGBUS
)
220 if (fault
& VM_FAULT_MAJOR
)
227 if (!is_global_init(tsk
))
231 * If we are out of memory for pid1, sleep for a while and retry
233 up_read(&mm
->mmap_sem
);
235 down_read(&mm
->mmap_sem
);
239 if (vma
->vm_flags
& VM_GROWSDOWN
&& !expand_stack(vma
, addr
))
246 do_page_fault(unsigned long addr
, unsigned int fsr
, struct pt_regs
*regs
)
248 struct task_struct
*tsk
;
249 struct mm_struct
*mm
;
250 int fault
, sig
, code
;
252 if (notify_page_fault(regs
, fsr
))
259 * If we're in an interrupt or have no user
260 * context, we must not take the fault..
262 if (in_atomic() || !mm
)
266 * As per x86, we may deadlock here. However, since the kernel only
267 * validly references user space from well defined areas of the code,
268 * we can bug out early if this is from code which shouldn't.
270 if (!down_read_trylock(&mm
->mmap_sem
)) {
271 if (!user_mode(regs
) && !search_exception_tables(regs
->ARM_pc
))
273 down_read(&mm
->mmap_sem
);
276 fault
= __do_page_fault(mm
, addr
, fsr
, tsk
);
277 up_read(&mm
->mmap_sem
);
280 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
282 if (likely(!(fault
& (VM_FAULT_ERROR
| VM_FAULT_BADMAP
| VM_FAULT_BADACCESS
))))
286 * If we are in kernel mode at this point, we
287 * have no context to handle this fault with.
289 if (!user_mode(regs
))
292 if (fault
& VM_FAULT_OOM
) {
294 * We ran out of memory, or some other thing
295 * happened to us that made us unable to handle
296 * the page fault gracefully.
298 printk("VM: killing process %s\n", tsk
->comm
);
299 do_group_exit(SIGKILL
);
302 if (fault
& VM_FAULT_SIGBUS
) {
304 * We had some memory, but were unable to
305 * successfully fix up this page fault.
311 * Something tried to access memory that
312 * isn't in our memory map..
315 code
= fault
== VM_FAULT_BADACCESS
?
316 SEGV_ACCERR
: SEGV_MAPERR
;
319 __do_user_fault(tsk
, addr
, fsr
, sig
, code
, regs
);
323 __do_kernel_fault(mm
, addr
, fsr
, regs
);
328 * First Level Translation Fault Handler
330 * We enter here because the first level page table doesn't contain
331 * a valid entry for the address.
333 * If the address is in kernel space (>= TASK_SIZE), then we are
334 * probably faulting in the vmalloc() area.
336 * If the init_task's first level page tables contains the relevant
337 * entry, we copy the it to this task. If not, we send the process
338 * a signal, fixup the exception, or oops the kernel.
340 * NOTE! We MUST NOT take any locks for this case. We may be in an
341 * interrupt or a critical region, and should only copy the information
342 * from the master page table, nothing more.
345 do_translation_fault(unsigned long addr
, unsigned int fsr
,
346 struct pt_regs
*regs
)
352 if (addr
< TASK_SIZE
)
353 return do_page_fault(addr
, fsr
, regs
);
355 index
= pgd_index(addr
);
358 * FIXME: CP15 C1 is write only on ARMv3 architectures.
360 pgd
= cpu_get_pgd() + index
;
361 pgd_k
= init_mm
.pgd
+ index
;
363 if (pgd_none(*pgd_k
))
366 if (!pgd_present(*pgd
))
367 set_pgd(pgd
, *pgd_k
);
369 pmd_k
= pmd_offset(pgd_k
, addr
);
370 pmd
= pmd_offset(pgd
, addr
);
372 if (pmd_none(*pmd_k
))
375 copy_pmd(pmd
, pmd_k
);
379 do_bad_area(addr
, fsr
, regs
);
384 * Some section permission faults need to be handled gracefully.
385 * They can happen due to a __{get,put}_user during an oops.
388 do_sect_fault(unsigned long addr
, unsigned int fsr
, struct pt_regs
*regs
)
390 do_bad_area(addr
, fsr
, regs
);
395 * This abort handler always returns "fault".
398 do_bad(unsigned long addr
, unsigned int fsr
, struct pt_regs
*regs
)
403 static struct fsr_info
{
404 int (*fn
)(unsigned long addr
, unsigned int fsr
, struct pt_regs
*regs
);
410 * The following are the standard ARMv3 and ARMv4 aborts. ARMv5
411 * defines these to be "precise" aborts.
413 { do_bad
, SIGSEGV
, 0, "vector exception" },
414 { do_bad
, SIGILL
, BUS_ADRALN
, "alignment exception" },
415 { do_bad
, SIGKILL
, 0, "terminal exception" },
416 { do_bad
, SIGILL
, BUS_ADRALN
, "alignment exception" },
417 { do_bad
, SIGBUS
, 0, "external abort on linefetch" },
418 { do_translation_fault
, SIGSEGV
, SEGV_MAPERR
, "section translation fault" },
419 { do_bad
, SIGBUS
, 0, "external abort on linefetch" },
420 { do_page_fault
, SIGSEGV
, SEGV_MAPERR
, "page translation fault" },
421 { do_bad
, SIGBUS
, 0, "external abort on non-linefetch" },
422 { do_bad
, SIGSEGV
, SEGV_ACCERR
, "section domain fault" },
423 { do_bad
, SIGBUS
, 0, "external abort on non-linefetch" },
424 { do_bad
, SIGSEGV
, SEGV_ACCERR
, "page domain fault" },
425 { do_bad
, SIGBUS
, 0, "external abort on translation" },
426 { do_sect_fault
, SIGSEGV
, SEGV_ACCERR
, "section permission fault" },
427 { do_bad
, SIGBUS
, 0, "external abort on translation" },
428 { do_page_fault
, SIGSEGV
, SEGV_ACCERR
, "page permission fault" },
430 * The following are "imprecise" aborts, which are signalled by bit
431 * 10 of the FSR, and may not be recoverable. These are only
432 * supported if the CPU abort handler supports bit 10.
434 { do_bad
, SIGBUS
, 0, "unknown 16" },
435 { do_bad
, SIGBUS
, 0, "unknown 17" },
436 { do_bad
, SIGBUS
, 0, "unknown 18" },
437 { do_bad
, SIGBUS
, 0, "unknown 19" },
438 { do_bad
, SIGBUS
, 0, "lock abort" }, /* xscale */
439 { do_bad
, SIGBUS
, 0, "unknown 21" },
440 { do_bad
, SIGBUS
, BUS_OBJERR
, "imprecise external abort" }, /* xscale */
441 { do_bad
, SIGBUS
, 0, "unknown 23" },
442 { do_bad
, SIGBUS
, 0, "dcache parity error" }, /* xscale */
443 { do_bad
, SIGBUS
, 0, "unknown 25" },
444 { do_bad
, SIGBUS
, 0, "unknown 26" },
445 { do_bad
, SIGBUS
, 0, "unknown 27" },
446 { do_bad
, SIGBUS
, 0, "unknown 28" },
447 { do_bad
, SIGBUS
, 0, "unknown 29" },
448 { do_bad
, SIGBUS
, 0, "unknown 30" },
449 { do_bad
, SIGBUS
, 0, "unknown 31" }
453 hook_fault_code(int nr
, int (*fn
)(unsigned long, unsigned int, struct pt_regs
*),
454 int sig
, const char *name
)
456 if (nr
>= 0 && nr
< ARRAY_SIZE(fsr_info
)) {
457 fsr_info
[nr
].fn
= fn
;
458 fsr_info
[nr
].sig
= sig
;
459 fsr_info
[nr
].name
= name
;
464 * Dispatch a data abort to the relevant handler.
466 asmlinkage
void __exception
467 do_DataAbort(unsigned long addr
, unsigned int fsr
, struct pt_regs
*regs
)
469 const struct fsr_info
*inf
= fsr_info
+ (fsr
& 15) + ((fsr
& (1 << 10)) >> 6);
472 if (!inf
->fn(addr
, fsr
, regs
))
475 printk(KERN_ALERT
"Unhandled fault: %s (0x%03x) at 0x%08lx\n",
476 inf
->name
, fsr
, addr
);
478 info
.si_signo
= inf
->sig
;
480 info
.si_code
= inf
->code
;
481 info
.si_addr
= (void __user
*)addr
;
482 arm_notify_die("", regs
, &info
, fsr
, 0);
485 asmlinkage
void __exception
486 do_PrefetchAbort(unsigned long addr
, struct pt_regs
*regs
)
488 do_translation_fault(addr
, 0, regs
);