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>
12 #include <linux/vs_memory.h>
14 #include <asm/pgtable.h>
15 #include <asm/processor.h>
16 #include <asm/system.h>
17 #include <asm/uaccess.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->signal->rlim[RLIMIT_STACK].rlim_cur
37 || (((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) >
38 current->signal->rlim[RLIMIT_AS].rlim_cur))
40 if (!vx_vmpages_avail(vma->vm_mm, grow) ||
41 ((vma->vm_flags & VM_LOCKED) &&
42 !vx_vmlocked_avail(vma->vm_mm, grow)))
44 vma->vm_end += PAGE_SIZE;
45 // vma->vm_mm->total_vm += grow;
46 vx_vmpages_add(vma->vm_mm, grow);
47 if (vma->vm_flags & VM_LOCKED) {
48 // vma->vm_mm->locked_vm += grow;
49 vx_vmlocked_add(vma->vm_mm, grow);
51 __vm_stat_account(vma->vm_mm, vma->vm_flags, vma->vm_file, grow);
56 * Return TRUE if ADDRESS points at a page in the kernel's mapped segment
57 * (inside region 5, on ia64) and that page is present.
60 mapped_kernel_page_is_present (unsigned long address)
66 pgd = pgd_offset_k(address);
67 if (pgd_none(*pgd) || pgd_bad(*pgd))
70 pmd = pmd_offset(pgd, address);
71 if (pmd_none(*pmd) || pmd_bad(*pmd))
74 ptep = pte_offset_kernel(pmd, address);
79 return pte_present(pte);
83 ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *regs)
85 int signal = SIGSEGV, code = SEGV_MAPERR;
86 struct vm_area_struct *vma, *prev_vma;
87 struct mm_struct *mm = current->mm;
92 * If we're in an interrupt or have no user context, we must not take the fault..
94 if (in_atomic() || !mm)
97 #ifdef CONFIG_VIRTUAL_MEM_MAP
99 * If fault is in region 5 and we are in the kernel, we may already
100 * have the mmap_sem (pfn_valid macro is called during mmap). There
101 * is no vma for region 5 addr's anyway, so skip getting the semaphore
102 * and go directly to the exception handling code.
105 if ((REGION_NUMBER(address) == 5) && !user_mode(regs))
109 down_read(&mm->mmap_sem);
111 vma = find_vma_prev(mm, address, &prev_vma);
115 /* find_vma_prev() returns vma such that address < vma->vm_end or NULL */
116 if (address < vma->vm_start)
117 goto check_expansion;
122 /* OK, we've got a good vm_area for this memory area. Check the access permissions: */
124 # define VM_READ_BIT 0
125 # define VM_WRITE_BIT 1
126 # define VM_EXEC_BIT 2
128 # if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
129 || (1 << VM_EXEC_BIT) != VM_EXEC)
130 # error File is out of sync with <linux/mm.h>. Please update.
133 mask = ( (((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
134 | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT)
135 | (((isr >> IA64_ISR_R_BIT) & 1UL) << VM_READ_BIT));
137 if ((vma->vm_flags & mask) != mask)
142 * If for any reason at all we couldn't handle the fault, make
143 * sure we exit gracefully rather than endlessly redo the
146 switch (handle_mm_fault(mm, vma, address, (mask & VM_WRITE) != 0)) {
153 case VM_FAULT_SIGBUS:
155 * We ran out of memory, or some other thing happened
156 * to us that made us unable to handle the page fault
166 up_read(&mm->mmap_sem);
170 if (!(prev_vma && (prev_vma->vm_flags & VM_GROWSUP) && (address == prev_vma->vm_end))) {
171 if (!(vma->vm_flags & VM_GROWSDOWN))
173 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
174 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
176 if (expand_stack(vma, address))
180 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
181 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
183 if (expand_backing_store(vma, address))
189 up_read(&mm->mmap_sem);
190 #ifdef CONFIG_VIRTUAL_MEM_MAP
193 if ((isr & IA64_ISR_SP)
194 || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
197 * This fault was due to a speculative load or lfetch.fault, set the "ed"
198 * bit in the psr to ensure forward progress. (Target register will get a
199 * NaT for ld.s, lfetch will be canceled.)
201 ia64_psr(regs)->ed = 1;
204 if (user_mode(regs)) {
205 si.si_signo = signal;
208 si.si_addr = (void __user *) address;
210 si.si_flags = __ISR_VALID;
211 force_sig_info(signal, &si, current);
216 if (isr & IA64_ISR_SP) {
218 * This fault was due to a speculative load set the "ed" bit in the psr to
219 * ensure forward progress (target register will get a NaT).
221 ia64_psr(regs)->ed = 1;
225 if (ia64_done_with_exception(regs))
229 * Since we have no vma's for region 5, we might get here even if the address is
230 * valid, due to the VHPT walker inserting a non present translation that becomes
231 * stale. If that happens, the non present fault handler already purged the stale
232 * translation, which fixed the problem. So, we check to see if the translation is
233 * valid, and return if it is.
235 if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
239 * Oops. The kernel tried to access some bad page. We'll have to terminate things
240 * with extreme prejudice.
244 if (address < PAGE_SIZE)
245 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference (address %016lx)\n", address);
247 printk(KERN_ALERT "Unable to handle kernel paging request at "
248 "virtual address %016lx\n", address);
249 die("Oops", regs, isr);
255 up_read(&mm->mmap_sem);
256 if (current->pid == 1) {
258 down_read(&mm->mmap_sem);
261 printk(KERN_CRIT "VM: killing process %s\n", current->comm);