1 // SPDX-License-Identifier: GPL-2.0
3 * MMU fault handling support.
5 * Copyright (C) 1998-2002 Hewlett-Packard Co
8 #include <linux/sched/signal.h>
9 #include <linux/kernel.h>
11 #include <linux/extable.h>
12 #include <linux/interrupt.h>
13 #include <linux/kprobes.h>
14 #include <linux/kdebug.h>
15 #include <linux/prefetch.h>
16 #include <linux/uaccess.h>
18 #include <asm/pgtable.h>
19 #include <asm/processor.h>
20 #include <asm/exception.h>
22 extern int die(char *, struct pt_regs *, long);
25 static inline int notify_page_fault(struct pt_regs *regs, int trap)
29 if (!user_mode(regs)) {
30 /* kprobe_running() needs smp_processor_id() */
32 if (kprobe_running() && kprobe_fault_handler(regs, trap))
40 static inline int notify_page_fault(struct pt_regs *regs, int trap)
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)
58 pgd = pgd_offset_k(address);
59 if (pgd_none(*pgd) || pgd_bad(*pgd))
62 pud = pud_offset(pgd, address);
63 if (pud_none(*pud) || pud_bad(*pud))
66 pmd = pmd_offset(pud, address);
67 if (pmd_none(*pmd) || pmd_bad(*pmd))
70 ptep = pte_offset_kernel(pmd, address);
75 return pte_present(pte);
78 # define VM_READ_BIT 0
79 # define VM_WRITE_BIT 1
80 # define VM_EXEC_BIT 2
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;
91 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
93 mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
94 | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
96 /* mmap_sem is performance critical.... */
97 prefetchw(&mm->mmap_sem);
100 * If we're in an interrupt or have no user context, we must not take the fault..
102 if (faulthandler_disabled() || !mm)
105 #ifdef CONFIG_VIRTUAL_MEM_MAP
107 * If fault is in region 5 and we are in the kernel, we may already
108 * have the mmap_sem (pfn_valid macro is called during mmap). There
109 * is no vma for region 5 addr's anyway, so skip getting the semaphore
110 * and go directly to the exception handling code.
113 if ((REGION_NUMBER(address) == 5) && !user_mode(regs))
118 * This is to handle the kprobes on user space access instructions
120 if (notify_page_fault(regs, TRAP_BRKPT))
124 flags |= FAULT_FLAG_USER;
126 flags |= FAULT_FLAG_WRITE;
128 down_read(&mm->mmap_sem);
130 vma = find_vma_prev(mm, address, &prev_vma);
131 if (!vma && !prev_vma )
135 * find_vma_prev() returns vma such that address < vma->vm_end or NULL
137 * May find no vma, but could be that the last vm area is the
138 * register backing store that needs to expand upwards, in
139 * this case vma will be null, but prev_vma will ne non-null
141 if (( !vma && prev_vma ) || (address < vma->vm_start) )
142 goto check_expansion;
147 /* OK, we've got a good vm_area for this memory area. Check the access permissions: */
149 # if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
150 || (1 << VM_EXEC_BIT) != VM_EXEC)
151 # error File is out of sync with <linux/mm.h>. Please update.
154 if (((isr >> IA64_ISR_R_BIT) & 1UL) && (!(vma->vm_flags & (VM_READ | VM_WRITE))))
157 if ((vma->vm_flags & mask) != mask)
161 * If for any reason at all we couldn't handle the fault, make
162 * sure we exit gracefully rather than endlessly redo the
165 fault = handle_mm_fault(vma, address, flags);
167 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
170 if (unlikely(fault & VM_FAULT_ERROR)) {
172 * We ran out of memory, or some other thing happened
173 * to us that made us unable to handle the page fault
176 if (fault & VM_FAULT_OOM) {
178 } else if (fault & VM_FAULT_SIGSEGV) {
180 } else if (fault & VM_FAULT_SIGBUS) {
187 if (flags & FAULT_FLAG_ALLOW_RETRY) {
188 if (fault & VM_FAULT_MAJOR)
192 if (fault & VM_FAULT_RETRY) {
193 flags &= ~FAULT_FLAG_ALLOW_RETRY;
194 flags |= FAULT_FLAG_TRIED;
196 /* No need to up_read(&mm->mmap_sem) as we would
197 * have already released it in __lock_page_or_retry
205 up_read(&mm->mmap_sem);
209 if (!(prev_vma && (prev_vma->vm_flags & VM_GROWSUP) && (address == prev_vma->vm_end))) {
212 if (!(vma->vm_flags & VM_GROWSDOWN))
214 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
215 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
217 if (expand_stack(vma, address))
221 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
222 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
225 * Since the register backing store is accessed sequentially,
226 * we disallow growing it by more than a page at a time.
228 if (address > vma->vm_end + PAGE_SIZE - sizeof(long))
230 if (expand_upwards(vma, address))
236 up_read(&mm->mmap_sem);
237 #ifdef CONFIG_VIRTUAL_MEM_MAP
240 if ((isr & IA64_ISR_SP)
241 || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
244 * This fault was due to a speculative load or lfetch.fault, set the "ed"
245 * bit in the psr to ensure forward progress. (Target register will get a
246 * NaT for ld.s, lfetch will be canceled.)
248 ia64_psr(regs)->ed = 1;
251 if (user_mode(regs)) {
252 si.si_signo = signal;
255 si.si_addr = (void __user *) address;
257 si.si_flags = __ISR_VALID;
258 force_sig_info(signal, &si, current);
263 if ((isr & IA64_ISR_SP)
264 || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
267 * This fault was due to a speculative load or lfetch.fault, set the "ed"
268 * bit in the psr to ensure forward progress. (Target register will get a
269 * NaT for ld.s, lfetch will be canceled.)
271 ia64_psr(regs)->ed = 1;
276 * Since we have no vma's for region 5, we might get here even if the address is
277 * valid, due to the VHPT walker inserting a non present translation that becomes
278 * stale. If that happens, the non present fault handler already purged the stale
279 * translation, which fixed the problem. So, we check to see if the translation is
280 * valid, and return if it is.
282 if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
285 if (ia64_done_with_exception(regs))
289 * Oops. The kernel tried to access some bad page. We'll have to terminate things
290 * with extreme prejudice.
294 if (address < PAGE_SIZE)
295 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference (address %016lx)\n", address);
297 printk(KERN_ALERT "Unable to handle kernel paging request at "
298 "virtual address %016lx\n", address);
299 if (die("Oops", regs, isr))
307 up_read(&mm->mmap_sem);
308 if (!user_mode(regs))
310 pagefault_out_of_memory();