2 * Page fault handler for SH with an MMU.
4 * Copyright (C) 1999 Niibe Yutaka
5 * Copyright (C) 2003 - 2008 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 <linux/perf_counter.h>
19 #include <asm/io_trapped.h>
20 #include <asm/system.h>
21 #include <asm/mmu_context.h>
22 #include <asm/tlbflush.h>
24 static inline int notify_page_fault(struct pt_regs *regs, int trap)
29 if (!user_mode(regs)) {
31 if (kprobe_running() && kprobe_fault_handler(regs, trap))
41 * This routine handles page faults. It determines the address,
42 * and the problem, and then passes it off to one of the appropriate
45 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
46 unsigned long writeaccess,
47 unsigned long address)
49 struct task_struct *tsk;
51 struct vm_area_struct * vma;
57 * We don't bother with any notifier callbacks here, as they are
58 * all handled through the __do_page_fault() fast-path.
62 si_code = SEGV_MAPERR;
64 if (unlikely(address >= TASK_SIZE)) {
66 * Synchronize this task's top level page-table
67 * with the 'reference' page table.
69 * Do _not_ use "tsk" here. We might be inside
70 * an interrupt in the middle of a task switch..
72 int offset = pgd_index(address);
77 pgd = get_TTB() + offset;
78 pgd_k = swapper_pg_dir + offset;
80 if (!pgd_present(*pgd)) {
81 if (!pgd_present(*pgd_k))
82 goto bad_area_nosemaphore;
87 pud = pud_offset(pgd, address);
88 pud_k = pud_offset(pgd_k, address);
90 if (!pud_present(*pud)) {
91 if (!pud_present(*pud_k))
92 goto bad_area_nosemaphore;
97 pmd = pmd_offset(pud, address);
98 pmd_k = pmd_offset(pud_k, address);
99 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
100 goto bad_area_nosemaphore;
101 set_pmd(pmd, *pmd_k);
108 if (unlikely(notify_page_fault(regs, lookup_exception_vector())))
111 /* Only enable interrupts if they were on before the fault */
112 if ((regs->sr & SR_IMASK) != SR_IMASK)
115 perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
118 * If we're in an interrupt or have no user
119 * context, we must not take the fault..
121 if (in_atomic() || !mm)
124 down_read(&mm->mmap_sem);
126 vma = find_vma(mm, address);
129 if (vma->vm_start <= address)
131 if (!(vma->vm_flags & VM_GROWSDOWN))
133 if (expand_stack(vma, address))
136 * Ok, we have a good vm_area for this memory access, so
140 si_code = SEGV_ACCERR;
142 if (!(vma->vm_flags & VM_WRITE))
145 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
150 * If for any reason at all we couldn't handle the fault,
151 * make sure we exit gracefully rather than endlessly redo
155 fault = handle_mm_fault(mm, vma, address, writeaccess ? FAULT_FLAG_WRITE : 0);
156 if (unlikely(fault & VM_FAULT_ERROR)) {
157 if (fault & VM_FAULT_OOM)
159 else if (fault & VM_FAULT_SIGBUS)
163 if (fault & VM_FAULT_MAJOR) {
165 perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
169 perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
173 up_read(&mm->mmap_sem);
177 * Something tried to access memory that isn't in our memory map..
178 * Fix it, but check if it's kernel or user first..
181 up_read(&mm->mmap_sem);
183 bad_area_nosemaphore:
184 if (user_mode(regs)) {
185 info.si_signo = SIGSEGV;
187 info.si_code = si_code;
188 info.si_addr = (void *) address;
189 force_sig_info(SIGSEGV, &info, tsk);
194 /* Are we prepared to handle this kernel fault? */
195 if (fixup_exception(regs))
198 if (handle_trapped_io(regs, address))
201 * Oops. The kernel tried to access some bad page. We'll have to
202 * terminate things with extreme prejudice.
208 if (oops_may_print()) {
211 if (address < PAGE_SIZE)
212 printk(KERN_ALERT "Unable to handle kernel NULL "
213 "pointer dereference");
215 printk(KERN_ALERT "Unable to handle kernel paging "
217 printk(" at virtual address %08lx\n", address);
218 printk(KERN_ALERT "pc = %08lx\n", regs->pc);
219 page = (unsigned long)get_TTB();
221 page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
222 printk(KERN_ALERT "*pde = %08lx\n", page);
223 if (page & _PAGE_PRESENT) {
225 address &= 0x003ff000;
226 page = ((__typeof__(page) *)
227 __va(page))[address >>
229 printk(KERN_ALERT "*pte = %08lx\n", page);
234 die("Oops", regs, writeaccess);
239 * We ran out of memory, or some other thing happened to us that made
240 * us unable to handle the page fault gracefully.
243 up_read(&mm->mmap_sem);
244 if (is_global_init(current)) {
246 down_read(&mm->mmap_sem);
249 printk("VM: killing process %s\n", tsk->comm);
251 do_group_exit(SIGKILL);
255 up_read(&mm->mmap_sem);
258 * Send a sigbus, regardless of whether we were in kernel
261 info.si_signo = SIGBUS;
263 info.si_code = BUS_ADRERR;
264 info.si_addr = (void *)address;
265 force_sig_info(SIGBUS, &info, tsk);
267 /* Kernel mode? Handle exceptions or die */
268 if (!user_mode(regs))
273 * Called with interrupts disabled.
275 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
276 unsigned long writeaccess,
277 unsigned long address)
287 * We don't take page faults for P1, P2, and parts of P4, these
288 * are always mapped, whether it be due to legacy behaviour in
289 * 29-bit mode, or due to PMB configuration in 32-bit mode.
291 if (address >= P3SEG && address < P3_ADDR_MAX) {
292 pgd = pgd_offset_k(address);
294 if (unlikely(address >= TASK_SIZE || !current->mm))
297 pgd = pgd_offset(current->mm, address);
300 pud = pud_offset(pgd, address);
301 if (pud_none_or_clear_bad(pud))
303 pmd = pmd_offset(pud, address);
304 if (pmd_none_or_clear_bad(pmd))
306 pte = pte_offset_kernel(pmd, address);
308 if (unlikely(pte_none(entry) || pte_not_present(entry)))
310 if (unlikely(writeaccess && !pte_write(entry)))
314 entry = pte_mkdirty(entry);
315 entry = pte_mkyoung(entry);
317 #if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
319 * ITLB is not affected by "ldtlb" instruction.
320 * So, we need to flush the entry by ourselves.
322 local_flush_tlb_one(get_asid(), address & PAGE_MASK);
326 update_mmu_cache(NULL, address, entry);