2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
6 * Copyright (C) 1995 - 2000 by Ralf Baechle
8 #include <linux/signal.h>
9 #include <linux/sched.h>
10 #include <linux/interrupt.h>
11 #include <linux/kernel.h>
12 #include <linux/errno.h>
13 #include <linux/string.h>
14 #include <linux/types.h>
15 #include <linux/ptrace.h>
16 #include <linux/mman.h>
18 #include <linux/smp.h>
19 #include <linux/module.h>
20 #include <linux/kprobes.h>
21 #include <linux/perf_event.h>
23 #include <asm/branch.h>
24 #include <asm/mmu_context.h>
25 #include <asm/uaccess.h>
26 #include <asm/ptrace.h>
27 #include <asm/highmem.h> /* For VMALLOC_END */
28 #include <linux/kdebug.h>
31 * This routine handles page faults. It determines the address,
32 * and the problem, and then passes it off to one of the appropriate
35 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long write,
36 unsigned long address)
38 struct vm_area_struct * vma = NULL;
39 struct task_struct *tsk = current;
40 struct mm_struct *mm = tsk->mm;
41 const int field = sizeof(unsigned long) * 2;
44 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
45 (write ? FAULT_FLAG_WRITE : 0);
48 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
49 current->comm, current->pid, field, address, write,
50 field, regs->cp0_epc);
55 * This is to notify the fault handler of the kprobes. The
56 * exception code is redundant as it is also carried in REGS,
57 * but we pass it anyhow.
59 if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
60 (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP)
64 info.si_code = SEGV_MAPERR;
67 * We fault-in kernel-space virtual memory on-demand. The
68 * 'reference' page table is init_mm.pgd.
70 * NOTE! We MUST NOT take any locks for this case. We may
71 * be in an interrupt or a critical region, and should
72 * only copy the information from the master page table,
76 # define VMALLOC_FAULT_TARGET no_context
78 # define VMALLOC_FAULT_TARGET vmalloc_fault
81 if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
82 goto VMALLOC_FAULT_TARGET;
84 if (unlikely(address >= MODULE_START && address < MODULE_END))
85 goto VMALLOC_FAULT_TARGET;
89 * If we're in an interrupt or have no user
90 * context, we must not take the fault..
92 if (in_atomic() || !mm)
93 goto bad_area_nosemaphore;
96 down_read(&mm->mmap_sem);
97 vma = find_vma(mm, address);
100 if (vma->vm_start <= address)
102 if (!(vma->vm_flags & VM_GROWSDOWN))
104 if (expand_stack(vma, address))
107 * Ok, we have a good vm_area for this memory access, so
111 info.si_code = SEGV_ACCERR;
114 if (!(vma->vm_flags & VM_WRITE))
118 if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
120 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
121 raw_smp_processor_id(),
122 current->comm, current->pid,
123 field, address, write,
124 field, regs->cp0_epc);
128 if (!(vma->vm_flags & VM_READ)) {
130 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n",
131 raw_smp_processor_id(),
132 current->comm, current->pid,
133 field, address, write,
134 field, regs->cp0_epc);
139 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
145 * If for any reason at all we couldn't handle the fault,
146 * make sure we exit gracefully rather than endlessly redo
149 fault = handle_mm_fault(mm, vma, address, flags);
151 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
154 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
155 if (unlikely(fault & VM_FAULT_ERROR)) {
156 if (fault & VM_FAULT_OOM)
158 else if (fault & VM_FAULT_SIGBUS)
162 if (flags & FAULT_FLAG_ALLOW_RETRY) {
163 if (fault & VM_FAULT_MAJOR) {
164 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
168 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
172 if (fault & VM_FAULT_RETRY) {
173 flags &= ~FAULT_FLAG_ALLOW_RETRY;
174 flags |= FAULT_FLAG_TRIED;
177 * No need to up_read(&mm->mmap_sem) as we would
178 * have already released it in __lock_page_or_retry
186 up_read(&mm->mmap_sem);
190 * Something tried to access memory that isn't in our memory map..
191 * Fix it, but check if it's kernel or user first..
194 up_read(&mm->mmap_sem);
196 bad_area_nosemaphore:
197 /* User mode accesses just cause a SIGSEGV */
198 if (user_mode(regs)) {
199 tsk->thread.cp0_badvaddr = address;
200 tsk->thread.error_code = write;
202 printk("do_page_fault() #2: sending SIGSEGV to %s for "
203 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
205 write ? "write access to" : "read access from",
207 field, (unsigned long) regs->cp0_epc,
208 field, (unsigned long) regs->regs[31]);
210 info.si_signo = SIGSEGV;
212 /* info.si_code has been set above */
213 info.si_addr = (void __user *) address;
214 force_sig_info(SIGSEGV, &info, tsk);
219 /* Are we prepared to handle this kernel fault? */
220 if (fixup_exception(regs)) {
221 current->thread.cp0_baduaddr = address;
226 * Oops. The kernel tried to access some bad page. We'll have to
227 * terminate things with extreme prejudice.
231 printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
232 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
233 raw_smp_processor_id(), field, address, field, regs->cp0_epc,
234 field, regs->regs[31]);
239 * We ran out of memory, call the OOM killer, and return the userspace
240 * (which will retry the fault, or kill us if we got oom-killed).
242 up_read(&mm->mmap_sem);
243 pagefault_out_of_memory();
247 up_read(&mm->mmap_sem);
249 /* Kernel mode? Handle exceptions or die */
250 if (!user_mode(regs))
254 * Send a sigbus, regardless of whether we were in kernel
258 printk("do_page_fault() #3: sending SIGBUS to %s for "
259 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
261 write ? "write access to" : "read access from",
263 field, (unsigned long) regs->cp0_epc,
264 field, (unsigned long) regs->regs[31]);
266 tsk->thread.cp0_badvaddr = address;
267 info.si_signo = SIGBUS;
269 info.si_code = BUS_ADRERR;
270 info.si_addr = (void __user *) address;
271 force_sig_info(SIGBUS, &info, tsk);
278 * Synchronize this task's top level page-table
279 * with the 'reference' page table.
281 * Do _not_ use "tsk" here. We might be inside
282 * an interrupt in the middle of a task switch..
284 int offset = __pgd_offset(address);
290 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
291 pgd_k = init_mm.pgd + offset;
293 if (!pgd_present(*pgd_k))
295 set_pgd(pgd, *pgd_k);
297 pud = pud_offset(pgd, address);
298 pud_k = pud_offset(pgd_k, address);
299 if (!pud_present(*pud_k))
302 pmd = pmd_offset(pud, address);
303 pmd_k = pmd_offset(pud_k, address);
304 if (!pmd_present(*pmd_k))
306 set_pmd(pmd, *pmd_k);
308 pte_k = pte_offset_kernel(pmd_k, address);
309 if (!pte_present(*pte_k))