2 * MMU fault handling support.
4 * Copyright (C) 1998-2002 Hewlett-Packard Co
5 * David Mosberger-Tang <davidm@hpl.hp.com>
7 #include <linux/sched.h>
8 #include <linux/kernel.h>
10 #include <linux/smp_lock.h>
11 #include <linux/interrupt.h>
13 #include <asm/pgtable.h>
14 #include <asm/processor.h>
15 #include <asm/system.h>
16 #include <asm/uaccess.h>
17 #include <asm/hardirq.h>
19 extern void die (char *, struct pt_regs *, long);
22 * This routine is analogous to expand_stack() but instead grows the
23 * register backing store (which grows towards higher addresses).
24 * Since the register backing store is access sequentially, we
25 * disallow growing the RBS by more than a page at a time. Note that
26 * the VM_GROWSUP flag can be set on any VM area but that's fine
27 * because the total process size is still limited by RLIMIT_STACK and
31 expand_backing_store (struct vm_area_struct *vma, unsigned long address)
35 grow = PAGE_SIZE >> PAGE_SHIFT;
36 if (address - vma->vm_start > current->rlim[RLIMIT_STACK].rlim_cur
37 || (((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->rlim[RLIMIT_AS].rlim_cur))
39 vma->vm_end += PAGE_SIZE;
40 vma->vm_mm->total_vm += grow;
41 if (vma->vm_flags & VM_LOCKED)
42 vma->vm_mm->locked_vm += grow;
47 * Return TRUE if ADDRESS points at a page in the kernel's mapped segment
48 * (inside region 5, on ia64) and that page is present.
51 mapped_kernel_page_is_present (unsigned long address)
57 pgd = pgd_offset_k(address);
58 if (pgd_none(*pgd) || pgd_bad(*pgd))
61 pmd = pmd_offset(pgd, address);
62 if (pmd_none(*pmd) || pmd_bad(*pmd))
65 ptep = pte_offset_kernel(pmd, address);
70 return pte_present(pte);
74 ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *regs)
76 int signal = SIGSEGV, code = SEGV_MAPERR;
77 struct vm_area_struct *vma, *prev_vma;
78 struct mm_struct *mm = current->mm;
83 * If we're in an interrupt or have no user context, we must not take the fault..
85 if (in_atomic() || !mm)
88 #ifdef CONFIG_VIRTUAL_MEM_MAP
90 * If fault is in region 5 and we are in the kernel, we may already
91 * have the mmap_sem (pfn_valid macro is called during mmap). There
92 * is no vma for region 5 addr's anyway, so skip getting the semaphore
93 * and go directly to the exception handling code.
96 if ((REGION_NUMBER(address) == 5) && !user_mode(regs))
100 down_read(&mm->mmap_sem);
102 vma = find_vma_prev(mm, address, &prev_vma);
106 /* find_vma_prev() returns vma such that address < vma->vm_end or NULL */
107 if (address < vma->vm_start)
108 goto check_expansion;
113 /* OK, we've got a good vm_area for this memory area. Check the access permissions: */
115 # define VM_READ_BIT 0
116 # define VM_WRITE_BIT 1
117 # define VM_EXEC_BIT 2
119 # if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
120 || (1 << VM_EXEC_BIT) != VM_EXEC)
121 # error File is out of sync with <linux/mm.h>. Please update.
124 mask = ( (((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
125 | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT)
126 | (((isr >> IA64_ISR_R_BIT) & 1UL) << VM_READ_BIT));
128 if ((vma->vm_flags & mask) != mask)
133 * If for any reason at all we couldn't handle the fault, make
134 * sure we exit gracefully rather than endlessly redo the
137 switch (handle_mm_fault(mm, vma, address, (mask & VM_WRITE) != 0)) {
144 case VM_FAULT_SIGBUS:
146 * We ran out of memory, or some other thing happened
147 * to us that made us unable to handle the page fault
157 up_read(&mm->mmap_sem);
161 if (!(prev_vma && (prev_vma->vm_flags & VM_GROWSUP) && (address == prev_vma->vm_end))) {
162 if (!(vma->vm_flags & VM_GROWSDOWN))
164 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
165 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
167 if (expand_stack(vma, address))
171 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
172 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
174 if (expand_backing_store(vma, address))
180 up_read(&mm->mmap_sem);
181 #ifdef CONFIG_VIRTUAL_MEM_MAP
184 if ((isr & IA64_ISR_SP)
185 || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
188 * This fault was due to a speculative load or lfetch.fault, set the "ed"
189 * bit in the psr to ensure forward progress. (Target register will get a
190 * NaT for ld.s, lfetch will be canceled.)
192 ia64_psr(regs)->ed = 1;
195 if (user_mode(regs)) {
196 si.si_signo = signal;
199 si.si_addr = (void *) address;
201 si.si_flags = __ISR_VALID;
202 force_sig_info(signal, &si, current);
207 if (isr & IA64_ISR_SP) {
209 * This fault was due to a speculative load set the "ed" bit in the psr to
210 * ensure forward progress (target register will get a NaT).
212 ia64_psr(regs)->ed = 1;
216 if (ia64_done_with_exception(regs))
220 * Since we have no vma's for region 5, we might get here even if the address is
221 * valid, due to the VHPT walker inserting a non present translation that becomes
222 * stale. If that happens, the non present fault handler already purged the stale
223 * translation, which fixed the problem. So, we check to see if the translation is
224 * valid, and return if it is.
226 if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
230 * Oops. The kernel tried to access some bad page. We'll have to terminate things
231 * with extreme prejudice.
235 if (address < PAGE_SIZE)
236 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference (address %016lx)\n", address);
238 printk(KERN_ALERT "Unable to handle kernel paging request at "
239 "virtual address %016lx\n", address);
240 die("Oops", regs, isr);
246 up_read(&mm->mmap_sem);
247 if (current->pid == 1) {
249 down_read(&mm->mmap_sem);
252 printk(KERN_CRIT "VM: killing process %s\n", current->comm);