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);