1 // SPDX-License-Identifier: GPL-2.0
3 * MMU fault handling support.
5 * Copyright (C) 1998-2002 Hewlett-Packard Co
6 * David Mosberger-Tang <davidm@hpl.hp.com>
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;
90 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
92 mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
93 | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
95 /* mmap_sem is performance critical.... */
96 prefetchw(&mm->mmap_sem);
99 * If we're in an interrupt or have no user context, we must not take the fault..
101 if (faulthandler_disabled() || !mm)
104 #ifdef CONFIG_VIRTUAL_MEM_MAP
106 * If fault is in region 5 and we are in the kernel, we may already
107 * have the mmap_sem (pfn_valid macro is called during mmap). There
108 * is no vma for region 5 addr's anyway, so skip getting the semaphore
109 * and go directly to the exception handling code.
112 if ((REGION_NUMBER(address) == 5) && !user_mode(regs))
117 * This is to handle the kprobes on user space access instructions
119 if (notify_page_fault(regs, TRAP_BRKPT))
123 flags |= FAULT_FLAG_USER;
125 flags |= FAULT_FLAG_WRITE;
127 down_read(&mm->mmap_sem);
129 vma = find_vma_prev(mm, address, &prev_vma);
130 if (!vma && !prev_vma )
134 * find_vma_prev() returns vma such that address < vma->vm_end or NULL
136 * May find no vma, but could be that the last vm area is the
137 * register backing store that needs to expand upwards, in
138 * this case vma will be null, but prev_vma will ne non-null
140 if (( !vma && prev_vma ) || (address < vma->vm_start) )
141 goto check_expansion;
146 /* OK, we've got a good vm_area for this memory area. Check the access permissions: */
148 # if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
149 || (1 << VM_EXEC_BIT) != VM_EXEC)
150 # error File is out of sync with <linux/mm.h>. Please update.
153 if (((isr >> IA64_ISR_R_BIT) & 1UL) && (!(vma->vm_flags & (VM_READ | VM_WRITE))))
156 if ((vma->vm_flags & mask) != mask)
160 * If for any reason at all we couldn't handle the fault, make
161 * sure we exit gracefully rather than endlessly redo the
164 fault = handle_mm_fault(vma, address, flags);
166 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
169 if (unlikely(fault & VM_FAULT_ERROR)) {
171 * We ran out of memory, or some other thing happened
172 * to us that made us unable to handle the page fault
175 if (fault & VM_FAULT_OOM) {
177 } else if (fault & VM_FAULT_SIGSEGV) {
179 } else if (fault & VM_FAULT_SIGBUS) {
186 if (flags & FAULT_FLAG_ALLOW_RETRY) {
187 if (fault & VM_FAULT_MAJOR)
191 if (fault & VM_FAULT_RETRY) {
192 flags &= ~FAULT_FLAG_ALLOW_RETRY;
193 flags |= FAULT_FLAG_TRIED;
195 /* No need to up_read(&mm->mmap_sem) as we would
196 * have already released it in __lock_page_or_retry
204 up_read(&mm->mmap_sem);
208 if (!(prev_vma && (prev_vma->vm_flags & VM_GROWSUP) && (address == prev_vma->vm_end))) {
211 if (!(vma->vm_flags & VM_GROWSDOWN))
213 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
214 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
216 if (expand_stack(vma, address))
220 if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
221 || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
224 * Since the register backing store is accessed sequentially,
225 * we disallow growing it by more than a page at a time.
227 if (address > vma->vm_end + PAGE_SIZE - sizeof(long))
229 if (expand_upwards(vma, address))
235 up_read(&mm->mmap_sem);
236 #ifdef CONFIG_VIRTUAL_MEM_MAP
239 if ((isr & IA64_ISR_SP)
240 || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
243 * This fault was due to a speculative load or lfetch.fault, set the "ed"
244 * bit in the psr to ensure forward progress. (Target register will get a
245 * NaT for ld.s, lfetch will be canceled.)
247 ia64_psr(regs)->ed = 1;
250 if (user_mode(regs)) {
254 si.si_signo = signal;
257 si.si_addr = (void __user *) address;
259 si.si_flags = __ISR_VALID;
260 force_sig_info(signal, &si, current);
265 if ((isr & IA64_ISR_SP)
266 || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
269 * This fault was due to a speculative load or lfetch.fault, set the "ed"
270 * bit in the psr to ensure forward progress. (Target register will get a
271 * NaT for ld.s, lfetch will be canceled.)
273 ia64_psr(regs)->ed = 1;
278 * Since we have no vma's for region 5, we might get here even if the address is
279 * valid, due to the VHPT walker inserting a non present translation that becomes
280 * stale. If that happens, the non present fault handler already purged the stale
281 * translation, which fixed the problem. So, we check to see if the translation is
282 * valid, and return if it is.
284 if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
287 if (ia64_done_with_exception(regs))
291 * Oops. The kernel tried to access some bad page. We'll have to terminate things
292 * with extreme prejudice.
296 if (address < PAGE_SIZE)
297 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference (address %016lx)\n", address);
299 printk(KERN_ALERT "Unable to handle kernel paging request at "
300 "virtual address %016lx\n", address);
301 if (die("Oops", regs, isr))
309 up_read(&mm->mmap_sem);
310 if (!user_mode(regs))
312 pagefault_out_of_memory();