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>
20 #include <asm/system.h>
21 #include <asm/pgtable.h>
22 #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]));
101 #else /* CONFIG_MMU */
102 void show_pte(struct mm_struct *mm, unsigned long addr)
104 #endif /* CONFIG_MMU */
107 * Oops. The kernel tried to access some page that wasn't present.
110 __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
111 struct pt_regs *regs)
114 * Are we prepared to handle this kernel fault?
116 if (fixup_exception(regs))
120 * No handler, we'll have to terminate things with extreme prejudice.
124 "Unable to handle kernel %s at virtual address %08lx\n",
125 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
126 "paging request", addr);
129 die("Oops", regs, fsr);
135 * Something tried to access memory that isn't in our memory map..
136 * User mode accesses just cause a SIGSEGV
139 __do_user_fault(struct task_struct *tsk, unsigned long addr,
140 unsigned int fsr, unsigned int sig, int code,
141 struct pt_regs *regs)
145 #ifdef CONFIG_DEBUG_USER
146 if (user_debug & UDBG_SEGV) {
147 printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
148 tsk->comm, sig, addr, fsr);
149 show_pte(tsk->mm, addr);
154 tsk->thread.address = addr;
155 tsk->thread.error_code = fsr;
156 tsk->thread.trap_no = 14;
160 si.si_addr = (void __user *)addr;
161 force_sig_info(sig, &si, tsk);
164 void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
166 struct task_struct *tsk = current;
167 struct mm_struct *mm = tsk->active_mm;
170 * If we are in kernel mode at this point, we
171 * have no context to handle this fault with.
174 __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
176 __do_kernel_fault(mm, addr, fsr, regs);
180 #define VM_FAULT_BADMAP 0x010000
181 #define VM_FAULT_BADACCESS 0x020000
184 __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
185 struct task_struct *tsk)
187 struct vm_area_struct *vma;
190 vma = find_vma(mm, addr);
191 fault = VM_FAULT_BADMAP;
194 if (vma->vm_start > addr)
198 * Ok, we have a good vm_area for this
199 * memory access, so we can handle it.
202 if (fsr & (1 << 11)) /* write? */
205 mask = VM_READ|VM_EXEC|VM_WRITE;
207 fault = VM_FAULT_BADACCESS;
208 if (!(vma->vm_flags & mask))
212 * If for any reason at all we couldn't handle
213 * the fault, make sure we exit gracefully rather
214 * than endlessly redo the fault.
217 fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & (1 << 11)) ? FAULT_FLAG_WRITE : 0);
218 if (unlikely(fault & VM_FAULT_ERROR)) {
219 if (fault & VM_FAULT_OOM)
221 else if (fault & VM_FAULT_SIGBUS)
225 if (fault & VM_FAULT_MAJOR)
232 if (!is_global_init(tsk))
236 * If we are out of memory for pid1, sleep for a while and retry
238 up_read(&mm->mmap_sem);
240 down_read(&mm->mmap_sem);
244 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
251 do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
253 struct task_struct *tsk;
254 struct mm_struct *mm;
255 int fault, sig, code;
257 if (notify_page_fault(regs, fsr))
264 * If we're in an interrupt or have no user
265 * context, we must not take the fault..
267 if (in_atomic() || !mm)
271 * As per x86, we may deadlock here. However, since the kernel only
272 * validly references user space from well defined areas of the code,
273 * we can bug out early if this is from code which shouldn't.
275 if (!down_read_trylock(&mm->mmap_sem)) {
276 if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
278 down_read(&mm->mmap_sem);
281 fault = __do_page_fault(mm, addr, fsr, tsk);
282 up_read(&mm->mmap_sem);
285 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
287 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
291 * If we are in kernel mode at this point, we
292 * have no context to handle this fault with.
294 if (!user_mode(regs))
297 if (fault & VM_FAULT_OOM) {
299 * We ran out of memory, or some other thing
300 * happened to us that made us unable to handle
301 * the page fault gracefully.
303 printk("VM: killing process %s\n", tsk->comm);
304 do_group_exit(SIGKILL);
307 if (fault & VM_FAULT_SIGBUS) {
309 * We had some memory, but were unable to
310 * successfully fix up this page fault.
316 * Something tried to access memory that
317 * isn't in our memory map..
320 code = fault == VM_FAULT_BADACCESS ?
321 SEGV_ACCERR : SEGV_MAPERR;
324 __do_user_fault(tsk, addr, fsr, sig, code, regs);
328 __do_kernel_fault(mm, addr, fsr, regs);
331 #else /* CONFIG_MMU */
333 do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
337 #endif /* CONFIG_MMU */
340 * First Level Translation Fault Handler
342 * We enter here because the first level page table doesn't contain
343 * a valid entry for the address.
345 * If the address is in kernel space (>= TASK_SIZE), then we are
346 * probably faulting in the vmalloc() area.
348 * If the init_task's first level page tables contains the relevant
349 * entry, we copy the it to this task. If not, we send the process
350 * a signal, fixup the exception, or oops the kernel.
352 * NOTE! We MUST NOT take any locks for this case. We may be in an
353 * interrupt or a critical region, and should only copy the information
354 * from the master page table, nothing more.
358 do_translation_fault(unsigned long addr, unsigned int fsr,
359 struct pt_regs *regs)
365 if (addr < TASK_SIZE)
366 return do_page_fault(addr, fsr, regs);
368 index = pgd_index(addr);
371 * FIXME: CP15 C1 is write only on ARMv3 architectures.
373 pgd = cpu_get_pgd() + index;
374 pgd_k = init_mm.pgd + index;
376 if (pgd_none(*pgd_k))
379 if (!pgd_present(*pgd))
380 set_pgd(pgd, *pgd_k);
382 pmd_k = pmd_offset(pgd_k, addr);
383 pmd = pmd_offset(pgd, addr);
385 if (pmd_none(*pmd_k))
388 copy_pmd(pmd, pmd_k);
392 do_bad_area(addr, fsr, regs);
395 #else /* CONFIG_MMU */
397 do_translation_fault(unsigned long addr, unsigned int fsr,
398 struct pt_regs *regs)
402 #endif /* CONFIG_MMU */
405 * Some section permission faults need to be handled gracefully.
406 * They can happen due to a __{get,put}_user during an oops.
409 do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
411 do_bad_area(addr, fsr, regs);
416 * This abort handler always returns "fault".
419 do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
424 static struct fsr_info {
425 int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
431 * The following are the standard ARMv3 and ARMv4 aborts. ARMv5
432 * defines these to be "precise" aborts.
434 { do_bad, SIGSEGV, 0, "vector exception" },
435 { do_bad, SIGILL, BUS_ADRALN, "alignment exception" },
436 { do_bad, SIGKILL, 0, "terminal exception" },
437 { do_bad, SIGILL, BUS_ADRALN, "alignment exception" },
438 { do_bad, SIGBUS, 0, "external abort on linefetch" },
439 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "section translation fault" },
440 { do_bad, SIGBUS, 0, "external abort on linefetch" },
441 { do_page_fault, SIGSEGV, SEGV_MAPERR, "page translation fault" },
442 { do_bad, SIGBUS, 0, "external abort on non-linefetch" },
443 { do_bad, SIGSEGV, SEGV_ACCERR, "section domain fault" },
444 { do_bad, SIGBUS, 0, "external abort on non-linefetch" },
445 { do_bad, SIGSEGV, SEGV_ACCERR, "page domain fault" },
446 { do_bad, SIGBUS, 0, "external abort on translation" },
447 { do_sect_fault, SIGSEGV, SEGV_ACCERR, "section permission fault" },
448 { do_bad, SIGBUS, 0, "external abort on translation" },
449 { do_page_fault, SIGSEGV, SEGV_ACCERR, "page permission fault" },
451 * The following are "imprecise" aborts, which are signalled by bit
452 * 10 of the FSR, and may not be recoverable. These are only
453 * supported if the CPU abort handler supports bit 10.
455 { do_bad, SIGBUS, 0, "unknown 16" },
456 { do_bad, SIGBUS, 0, "unknown 17" },
457 { do_bad, SIGBUS, 0, "unknown 18" },
458 { do_bad, SIGBUS, 0, "unknown 19" },
459 { do_bad, SIGBUS, 0, "lock abort" }, /* xscale */
460 { do_bad, SIGBUS, 0, "unknown 21" },
461 { do_bad, SIGBUS, BUS_OBJERR, "imprecise external abort" }, /* xscale */
462 { do_bad, SIGBUS, 0, "unknown 23" },
463 { do_bad, SIGBUS, 0, "dcache parity error" }, /* xscale */
464 { do_bad, SIGBUS, 0, "unknown 25" },
465 { do_bad, SIGBUS, 0, "unknown 26" },
466 { do_bad, SIGBUS, 0, "unknown 27" },
467 { do_bad, SIGBUS, 0, "unknown 28" },
468 { do_bad, SIGBUS, 0, "unknown 29" },
469 { do_bad, SIGBUS, 0, "unknown 30" },
470 { do_bad, SIGBUS, 0, "unknown 31" }
474 hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
475 int sig, const char *name)
477 if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) {
478 fsr_info[nr].fn = fn;
479 fsr_info[nr].sig = sig;
480 fsr_info[nr].name = name;
485 * Dispatch a data abort to the relevant handler.
487 asmlinkage void __exception
488 do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
490 const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6);
493 if (!inf->fn(addr, fsr, regs))
496 printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
497 inf->name, fsr, addr);
499 info.si_signo = inf->sig;
501 info.si_code = inf->code;
502 info.si_addr = (void __user *)addr;
503 arm_notify_die("", regs, &info, fsr, 0);
506 asmlinkage void __exception
507 do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
509 do_translation_fault(addr, 0, regs);