2 * Page fault handler for SH with an MMU.
4 * Copyright (C) 1999 Niibe Yutaka
5 * Copyright (C) 2003 - 2007 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>
20 #include <asm/tlbflush.h>
24 * This routine handles page faults. It determines the address,
25 * and the problem, and then passes it off to one of the appropriate
28 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
29 unsigned long writeaccess,
30 unsigned long address)
32 struct task_struct *tsk;
34 struct vm_area_struct * vma;
43 if (kgdb_nofault && kgdb_bus_err_hook)
49 si_code = SEGV_MAPERR;
51 if (unlikely(address >= TASK_SIZE)) {
53 * Synchronize this task's top level page-table
54 * with the 'reference' page table.
56 * Do _not_ use "tsk" here. We might be inside
57 * an interrupt in the middle of a task switch..
59 int offset = pgd_index(address);
64 pgd = get_TTB() + offset;
65 pgd_k = swapper_pg_dir + offset;
67 /* This will never happen with the folded page table. */
68 if (!pgd_present(*pgd)) {
69 if (!pgd_present(*pgd_k))
70 goto bad_area_nosemaphore;
75 pud = pud_offset(pgd, address);
76 pud_k = pud_offset(pgd_k, address);
77 if (pud_present(*pud) || !pud_present(*pud_k))
78 goto bad_area_nosemaphore;
81 pmd = pmd_offset(pud, address);
82 pmd_k = pmd_offset(pud_k, address);
83 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
84 goto bad_area_nosemaphore;
91 * If we're in an interrupt or have no user
92 * context, we must not take the fault..
94 if (in_atomic() || !mm)
97 down_read(&mm->mmap_sem);
99 vma = find_vma(mm, address);
102 if (vma->vm_start <= address)
104 if (!(vma->vm_flags & VM_GROWSDOWN))
106 if (expand_stack(vma, address))
109 * Ok, we have a good vm_area for this memory access, so
113 si_code = SEGV_ACCERR;
115 if (!(vma->vm_flags & VM_WRITE))
118 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
123 * If for any reason at all we couldn't handle the fault,
124 * make sure we exit gracefully rather than endlessly redo
128 switch (handle_mm_fault(mm, vma, address, writeaccess)) {
135 case VM_FAULT_SIGBUS:
143 up_read(&mm->mmap_sem);
147 * Something tried to access memory that isn't in our memory map..
148 * Fix it, but check if it's kernel or user first..
151 up_read(&mm->mmap_sem);
153 bad_area_nosemaphore:
154 if (user_mode(regs)) {
155 info.si_signo = SIGSEGV;
157 info.si_code = si_code;
158 info.si_addr = (void *) address;
159 force_sig_info(SIGSEGV, &info, tsk);
164 /* Are we prepared to handle this kernel fault? */
165 if (fixup_exception(regs))
169 * Oops. The kernel tried to access some bad page. We'll have to
170 * terminate things with extreme prejudice.
173 if (address < PAGE_SIZE)
174 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
176 printk(KERN_ALERT "Unable to handle kernel paging request");
177 printk(" at virtual address %08lx\n", address);
178 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
179 page = (unsigned long)get_TTB();
181 page = ((unsigned long *) page)[address >> PGDIR_SHIFT];
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;
251 spinlock_t *ptl = NULL;
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 local_flush_tlb_one(get_asid(), address & PAGE_MASK);
305 update_mmu_cache(NULL, address, entry);
309 pte_unmap_unlock(pte, ptl);