1 // TODO VM_EXEC flag work-around, cache aliasing
3 * arch/xtensa/mm/fault.c
5 * This file is subject to the terms and conditions of the GNU General Public
6 * License. See the file "COPYING" in the main directory of this archive
9 * Copyright (C) 2001 - 2005 Tensilica Inc.
11 * Chris Zankel <chris@zankel.net>
12 * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
16 #include <linux/module.h>
17 #include <linux/hardirq.h>
18 #include <asm/mmu_context.h>
19 #include <asm/cacheflush.h>
20 #include <asm/hardirq.h>
21 #include <asm/uaccess.h>
22 #include <asm/pgalloc.h>
24 unsigned long asid_cache = ASID_USER_FIRST;
25 void bad_page_fault(struct pt_regs*, unsigned long, int);
27 #undef DEBUG_PAGE_FAULT
30 * This routine handles page faults. It determines the address,
31 * and the problem, and then passes it off to one of the appropriate
34 * Note: does not handle Miss and MultiHit.
37 void do_page_fault(struct pt_regs *regs)
39 struct vm_area_struct * vma;
40 struct mm_struct *mm = current->mm;
41 unsigned int exccause = regs->exccause;
42 unsigned int address = regs->excvaddr;
45 int is_write, is_exec;
47 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
49 info.si_code = SEGV_MAPERR;
51 /* We fault-in kernel-space virtual memory on-demand. The
52 * 'reference' page table is init_mm.pgd.
54 if (address >= TASK_SIZE && !user_mode(regs))
57 /* If we're in an interrupt or have no user
58 * context, we must not take the fault..
60 if (in_atomic() || !mm) {
61 bad_page_fault(regs, address, SIGSEGV);
65 is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0;
66 is_exec = (exccause == EXCCAUSE_ITLB_PRIVILEGE ||
67 exccause == EXCCAUSE_ITLB_MISS ||
68 exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0;
70 #ifdef DEBUG_PAGE_FAULT
71 printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid,
72 address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
76 down_read(&mm->mmap_sem);
77 vma = find_vma(mm, address);
81 if (vma->vm_start <= address)
83 if (!(vma->vm_flags & VM_GROWSDOWN))
85 if (expand_stack(vma, address))
88 /* Ok, we have a good vm_area for this memory access, so
93 info.si_code = SEGV_ACCERR;
96 if (!(vma->vm_flags & VM_WRITE))
98 flags |= FAULT_FLAG_WRITE;
100 if (!(vma->vm_flags & VM_EXEC))
102 } else /* Allow read even from write-only pages. */
103 if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
106 /* If for any reason at all we couldn't handle the fault,
107 * make sure we exit gracefully rather than endlessly redo
110 fault = handle_mm_fault(mm, vma, address, flags);
112 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
115 if (unlikely(fault & VM_FAULT_ERROR)) {
116 if (fault & VM_FAULT_OOM)
118 else if (fault & VM_FAULT_SIGBUS)
122 if (flags & FAULT_FLAG_ALLOW_RETRY) {
123 if (fault & VM_FAULT_MAJOR)
127 if (fault & VM_FAULT_RETRY) {
128 flags &= ~FAULT_FLAG_ALLOW_RETRY;
129 flags |= FAULT_FLAG_TRIED;
131 /* No need to up_read(&mm->mmap_sem) as we would
132 * have already released it in __lock_page_or_retry
140 up_read(&mm->mmap_sem);
143 /* Something tried to access memory that isn't in our memory map..
144 * Fix it, but check if it's kernel or user first..
147 up_read(&mm->mmap_sem);
148 if (user_mode(regs)) {
149 current->thread.bad_vaddr = address;
150 current->thread.error_code = is_write;
151 info.si_signo = SIGSEGV;
153 /* info.si_code has been set above */
154 info.si_addr = (void *) address;
155 force_sig_info(SIGSEGV, &info, current);
158 bad_page_fault(regs, address, SIGSEGV);
162 /* We ran out of memory, or some other thing happened to us that made
163 * us unable to handle the page fault gracefully.
166 up_read(&mm->mmap_sem);
167 if (!user_mode(regs))
168 bad_page_fault(regs, address, SIGKILL);
170 pagefault_out_of_memory();
174 up_read(&mm->mmap_sem);
176 /* Send a sigbus, regardless of whether we were in kernel
179 current->thread.bad_vaddr = address;
180 info.si_code = SIGBUS;
182 info.si_code = BUS_ADRERR;
183 info.si_addr = (void *) address;
184 force_sig_info(SIGBUS, &info, current);
186 /* Kernel mode? Handle exceptions or die */
187 if (!user_mode(regs))
188 bad_page_fault(regs, address, SIGBUS);
192 /* Synchronize this task's top level page-table
193 * with the 'reference' page table.
195 struct mm_struct *act_mm = current->active_mm;
196 int index = pgd_index(address);
204 pgd = act_mm->pgd + index;
205 pgd_k = init_mm.pgd + index;
207 if (!pgd_present(*pgd_k))
210 pgd_val(*pgd) = pgd_val(*pgd_k);
212 pmd = pmd_offset(pgd, address);
213 pmd_k = pmd_offset(pgd_k, address);
214 if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
217 pmd_val(*pmd) = pmd_val(*pmd_k);
218 pte_k = pte_offset_kernel(pmd_k, address);
220 if (!pte_present(*pte_k))
225 bad_page_fault(regs, address, SIGKILL);
231 bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
233 extern void die(const char*, struct pt_regs*, long);
234 const struct exception_table_entry *entry;
236 /* Are we prepared to handle this kernel fault? */
237 if ((entry = search_exception_tables(regs->pc)) != NULL) {
238 #ifdef DEBUG_PAGE_FAULT
239 printk(KERN_DEBUG "%s: Exception at pc=%#010lx (%lx)\n",
240 current->comm, regs->pc, entry->fixup);
242 current->thread.bad_uaddr = address;
243 regs->pc = entry->fixup;
247 /* Oops. The kernel tried to access some bad page. We'll have to
248 * terminate things with extreme prejudice.
250 printk(KERN_ALERT "Unable to handle kernel paging request at virtual "
251 "address %08lx\n pc = %08lx, ra = %08lx\n",
252 address, regs->pc, regs->areg[0]);
253 die("Oops", regs, sig);