2 * Page fault handler for SH with an MMU.
4 * Copyright (C) 1999 Niibe Yutaka
5 * Copyright (C) 2003 Paul Mundt
7 * Based on linux/arch/i386/mm/fault.c:
8 * Copyright (C) 1995 Linus Torvalds
10 * This file is subject to the terms and conditions of the GNU General Public
11 * License. See the file "COPYING" in the main directory of this archive
14 #include <linux/kernel.h>
16 #include <linux/hardirq.h>
17 #include <linux/kprobes.h>
18 #include <asm/system.h>
19 #include <asm/mmu_context.h>
22 extern void die(const char *,struct pt_regs *,long);
25 * This routine handles page faults. It determines the address,
26 * and the problem, and then passes it off to one of the appropriate
29 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
30 unsigned long writeaccess,
31 unsigned long address)
33 struct task_struct *tsk;
35 struct vm_area_struct * vma;
41 if (kgdb_nofault && kgdb_bus_err_hook)
47 si_code = SEGV_MAPERR;
49 if (unlikely(address >= TASK_SIZE)) {
51 * Synchronize this task's top level page-table
52 * with the 'reference' page table.
54 * Do _not_ use "tsk" here. We might be inside
55 * an interrupt in the middle of a task switch..
57 int offset = pgd_index(address);
62 pgd = get_TTB() + offset;
63 pgd_k = swapper_pg_dir + offset;
65 /* This will never happen with the folded page table. */
66 if (!pgd_present(*pgd)) {
67 if (!pgd_present(*pgd_k))
68 goto bad_area_nosemaphore;
73 pud = pud_offset(pgd, address);
74 pud_k = pud_offset(pgd_k, address);
75 if (pud_present(*pud) || !pud_present(*pud_k))
76 goto bad_area_nosemaphore;
79 pmd = pmd_offset(pud, address);
80 pmd_k = pmd_offset(pud_k, address);
81 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
82 goto bad_area_nosemaphore;
89 * If we're in an interrupt or have no user
90 * context, we must not take the fault..
92 if (in_atomic() || !mm)
95 down_read(&mm->mmap_sem);
97 vma = find_vma(mm, address);
100 if (vma->vm_start <= address)
102 if (!(vma->vm_flags & VM_GROWSDOWN))
104 if (expand_stack(vma, address))
107 * Ok, we have a good vm_area for this memory access, so
111 si_code = SEGV_ACCERR;
113 if (!(vma->vm_flags & VM_WRITE))
116 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
121 * If for any reason at all we couldn't handle the fault,
122 * make sure we exit gracefully rather than endlessly redo
126 switch (handle_mm_fault(mm, vma, address, writeaccess)) {
133 case VM_FAULT_SIGBUS:
141 up_read(&mm->mmap_sem);
145 * Something tried to access memory that isn't in our memory map..
146 * Fix it, but check if it's kernel or user first..
149 up_read(&mm->mmap_sem);
151 bad_area_nosemaphore:
152 if (user_mode(regs)) {
153 info.si_signo = SIGSEGV;
155 info.si_code = si_code;
156 info.si_addr = (void *) address;
157 force_sig_info(SIGSEGV, &info, tsk);
162 /* Are we prepared to handle this kernel fault? */
163 if (fixup_exception(regs))
167 * Oops. The kernel tried to access some bad page. We'll have to
168 * terminate things with extreme prejudice.
171 if (address < PAGE_SIZE)
172 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
174 printk(KERN_ALERT "Unable to handle kernel paging request");
175 printk(" at virtual address %08lx\n", address);
176 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
177 asm volatile("mov.l %1, %0"
179 : "m" (__m(MMU_TTB)));
181 page = ((unsigned long *) page)[address >> 22];
182 printk(KERN_ALERT "*pde = %08lx\n", page);
183 if (page & _PAGE_PRESENT) {
185 address &= 0x003ff000;
186 page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
187 printk(KERN_ALERT "*pte = %08lx\n", page);
190 die("Oops", regs, writeaccess);
194 * We ran out of memory, or some other thing happened to us that made
195 * us unable to handle the page fault gracefully.
198 up_read(&mm->mmap_sem);
199 if (is_init(current)) {
201 down_read(&mm->mmap_sem);
204 printk("VM: killing process %s\n", tsk->comm);
210 up_read(&mm->mmap_sem);
213 * Send a sigbus, regardless of whether we were in kernel
216 info.si_signo = SIGBUS;
218 info.si_code = BUS_ADRERR;
219 info.si_addr = (void *)address;
220 force_sig_info(SIGBUS, &info, tsk);
222 /* Kernel mode? Handle exceptions or die */
223 if (!user_mode(regs))
227 #ifdef CONFIG_SH_STORE_QUEUES
229 * This is a special case for the SH-4 store queues, as pages for this
230 * space still need to be faulted in before it's possible to flush the
231 * store queue cache for writeout to the remapped region.
233 #define P3_ADDR_MAX (P4SEG_STORE_QUE + 0x04000000)
235 #define P3_ADDR_MAX P4SEG
239 * Called with interrupts disabled.
241 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
242 unsigned long writeaccess,
243 unsigned long address)
250 struct mm_struct *mm = current->mm;
254 #ifdef CONFIG_SH_KGDB
255 if (kgdb_nofault && kgdb_bus_err_hook)
260 * We don't take page faults for P1, P2, and parts of P4, these
261 * are always mapped, whether it be due to legacy behaviour in
262 * 29-bit mode, or due to PMB configuration in 32-bit mode.
264 if (address >= P3SEG && address < P3_ADDR_MAX) {
265 pgd = pgd_offset_k(address);
268 if (unlikely(address >= TASK_SIZE || !mm))
271 pgd = pgd_offset(mm, address);
274 pud = pud_offset(pgd, address);
275 if (pud_none_or_clear_bad(pud))
277 pmd = pmd_offset(pud, address);
278 if (pmd_none_or_clear_bad(pmd))
282 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
284 pte = pte_offset_kernel(pmd, address);
287 if (unlikely(pte_none(entry) || pte_not_present(entry)))
289 if (unlikely(writeaccess && !pte_write(entry)))
293 entry = pte_mkdirty(entry);
294 entry = pte_mkyoung(entry);
296 #ifdef CONFIG_CPU_SH4
298 * ITLB is not affected by "ldtlb" instruction.
299 * So, we need to flush the entry by ourselves.
301 __flush_tlb_page(get_asid(), address & PAGE_MASK);
305 update_mmu_cache(NULL, address, entry);
309 pte_unmap_unlock(pte, ptl);