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/vt_kern.h> /* For unblank_screen() */
20 #include <linux/module.h>
22 #include <asm/branch.h>
23 #include <asm/mmu_context.h>
24 #include <asm/system.h>
25 #include <asm/uaccess.h>
26 #include <asm/ptrace.h>
27 #include <asm/highmem.h> /* For VMALLOC_END */
30 * This routine handles page faults. It determines the address,
31 * and the problem, and then passes it off to one of the appropriate
34 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
35 unsigned long address)
37 struct vm_area_struct * vma = NULL;
38 struct task_struct *tsk = current;
39 struct mm_struct *mm = tsk->mm;
40 const int field = sizeof(unsigned long) * 2;
45 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
46 current->comm, current->pid, field, address, write,
47 field, regs->cp0_epc);
50 info.si_code = SEGV_MAPERR;
53 * We fault-in kernel-space virtual memory on-demand. The
54 * 'reference' page table is init_mm.pgd.
56 * NOTE! We MUST NOT take any locks for this case. We may
57 * be in an interrupt or a critical region, and should
58 * only copy the information from the master page table,
62 # define VMALLOC_FAULT_TARGET no_context
64 # define VMALLOC_FAULT_TARGET vmalloc_fault
67 if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
68 goto VMALLOC_FAULT_TARGET;
70 if (unlikely(address >= MODULE_START && address < MODULE_END))
71 goto VMALLOC_FAULT_TARGET;
75 * If we're in an interrupt or have no user
76 * context, we must not take the fault..
78 if (in_atomic() || !mm)
79 goto bad_area_nosemaphore;
81 down_read(&mm->mmap_sem);
82 vma = find_vma(mm, address);
85 if (vma->vm_start <= address)
87 if (!(vma->vm_flags & VM_GROWSDOWN))
89 if (expand_stack(vma, address))
92 * Ok, we have a good vm_area for this memory access, so
96 info.si_code = SEGV_ACCERR;
99 if (!(vma->vm_flags & VM_WRITE))
102 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
107 * If for any reason at all we couldn't handle the fault,
108 * make sure we exit gracefully rather than endlessly redo
111 fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
112 if (unlikely(fault & VM_FAULT_ERROR)) {
113 if (fault & VM_FAULT_OOM)
115 else if (fault & VM_FAULT_SIGBUS)
119 if (fault & VM_FAULT_MAJOR)
124 up_read(&mm->mmap_sem);
128 * Something tried to access memory that isn't in our memory map..
129 * Fix it, but check if it's kernel or user first..
132 up_read(&mm->mmap_sem);
134 bad_area_nosemaphore:
135 /* User mode accesses just cause a SIGSEGV */
136 if (user_mode(regs)) {
137 tsk->thread.cp0_badvaddr = address;
138 tsk->thread.error_code = write;
140 printk("do_page_fault() #2: sending SIGSEGV to %s for "
141 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
143 write ? "write access to" : "read access from",
145 field, (unsigned long) regs->cp0_epc,
146 field, (unsigned long) regs->regs[31]);
148 info.si_signo = SIGSEGV;
150 /* info.si_code has been set above */
151 info.si_addr = (void __user *) address;
152 force_sig_info(SIGSEGV, &info, tsk);
157 /* Are we prepared to handle this kernel fault? */
158 if (fixup_exception(regs)) {
159 current->thread.cp0_baduaddr = address;
164 * Oops. The kernel tried to access some bad page. We'll have to
165 * terminate things with extreme prejudice.
169 printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
170 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
171 raw_smp_processor_id(), field, address, field, regs->cp0_epc,
172 field, regs->regs[31]);
177 * We ran out of memory, call the OOM killer, and return the userspace
178 * (which will retry the fault, or kill us if we got oom-killed).
180 up_read(&mm->mmap_sem);
181 pagefault_out_of_memory();
185 up_read(&mm->mmap_sem);
187 /* Kernel mode? Handle exceptions or die */
188 if (!user_mode(regs))
192 * Send a sigbus, regardless of whether we were in kernel
196 printk("do_page_fault() #3: sending SIGBUS to %s for "
197 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
199 write ? "write access to" : "read access from",
201 field, (unsigned long) regs->cp0_epc,
202 field, (unsigned long) regs->regs[31]);
204 tsk->thread.cp0_badvaddr = address;
205 info.si_signo = SIGBUS;
207 info.si_code = BUS_ADRERR;
208 info.si_addr = (void __user *) address;
209 force_sig_info(SIGBUS, &info, tsk);
216 * Synchronize this task's top level page-table
217 * with the 'reference' page table.
219 * Do _not_ use "tsk" here. We might be inside
220 * an interrupt in the middle of a task switch..
222 int offset = __pgd_offset(address);
228 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
229 pgd_k = init_mm.pgd + offset;
231 if (!pgd_present(*pgd_k))
233 set_pgd(pgd, *pgd_k);
235 pud = pud_offset(pgd, address);
236 pud_k = pud_offset(pgd_k, address);
237 if (!pud_present(*pud_k))
240 pmd = pmd_offset(pud, address);
241 pmd_k = pmd_offset(pud_k, address);
242 if (!pmd_present(*pmd_k))
244 set_pmd(pmd, *pmd_k);
246 pte_k = pte_offset_kernel(pmd_k, address);
247 if (!pte_present(*pte_k))