1 /* Page Fault Handling for ARC (TLB Miss / ProtV)
3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
10 #include <linux/signal.h>
11 #include <linux/interrupt.h>
12 #include <linux/sched.h>
13 #include <linux/errno.h>
14 #include <linux/ptrace.h>
15 #include <linux/uaccess.h>
16 #include <linux/kdebug.h>
17 #include <asm/pgalloc.h>
19 static int handle_vmalloc_fault(unsigned long address)
22 * Synchronize this task's top level page-table
23 * with the 'reference' page table.
29 pgd = pgd_offset_fast(current->active_mm, address);
30 pgd_k = pgd_offset_k(address);
32 if (!pgd_present(*pgd_k))
35 pud = pud_offset(pgd, address);
36 pud_k = pud_offset(pgd_k, address);
37 if (!pud_present(*pud_k))
40 pmd = pmd_offset(pud, address);
41 pmd_k = pmd_offset(pud_k, address);
42 if (!pmd_present(*pmd_k))
47 /* XXX: create the TLB entry here */
54 void do_page_fault(struct pt_regs *regs, int write, unsigned long address,
55 unsigned long cause_code)
57 struct vm_area_struct *vma = NULL;
58 struct task_struct *tsk = current;
59 struct mm_struct *mm = tsk->mm;
62 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
63 (write ? FAULT_FLAG_WRITE : 0);
66 * We fault-in kernel-space virtual memory on-demand. The
67 * 'reference' page table is init_mm.pgd.
69 * NOTE! We MUST NOT take any locks for this case. We may
70 * be in an interrupt or a critical region, and should
71 * only copy the information from the master page table,
74 if (address >= VMALLOC_START && address <= VMALLOC_END) {
75 ret = handle_vmalloc_fault(address);
77 goto bad_area_nosemaphore;
82 info.si_code = SEGV_MAPERR;
85 * If we're in an interrupt or have no user
86 * context, we must not take the fault..
88 if (in_atomic() || !mm)
92 down_read(&mm->mmap_sem);
93 vma = find_vma(mm, address);
96 if (vma->vm_start <= address)
98 if (!(vma->vm_flags & VM_GROWSDOWN))
100 if (expand_stack(vma, address))
104 * Ok, we have a good vm_area for this memory access, so
108 info.si_code = SEGV_ACCERR;
110 /* Handle protection violation, execute on heap or stack */
112 if (cause_code == ((ECR_V_PROTV << 16) | ECR_C_PROTV_INST_FETCH))
116 if (!(vma->vm_flags & VM_WRITE))
119 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
125 * If for any reason at all we couldn't handle the fault,
126 * make sure we exit gracefully rather than endlessly redo
129 fault = handle_mm_fault(mm, vma, address, flags);
131 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
132 if (unlikely(fatal_signal_pending(current))) {
133 if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY))
134 up_read(&mm->mmap_sem);
139 if (likely(!(fault & VM_FAULT_ERROR))) {
140 if (flags & FAULT_FLAG_ALLOW_RETRY) {
141 /* To avoid updating stats twice for retry case */
142 if (fault & VM_FAULT_MAJOR)
147 if (fault & VM_FAULT_RETRY) {
148 flags &= ~FAULT_FLAG_ALLOW_RETRY;
149 flags |= FAULT_FLAG_TRIED;
154 /* Fault Handled Gracefully */
155 up_read(&mm->mmap_sem);
159 /* TBD: switch to pagefault_out_of_memory() */
160 if (fault & VM_FAULT_OOM)
162 else if (fault & VM_FAULT_SIGBUS)
169 * Something tried to access memory that isn't in our memory map..
170 * Fix it, but check if it's kernel or user first..
173 up_read(&mm->mmap_sem);
175 bad_area_nosemaphore:
176 /* User mode accesses just cause a SIGSEGV */
177 if (user_mode(regs)) {
178 tsk->thread.fault_address = address;
179 tsk->thread.cause_code = cause_code;
180 info.si_signo = SIGSEGV;
182 /* info.si_code has been set above */
183 info.si_addr = (void __user *)address;
184 force_sig_info(SIGSEGV, &info, tsk);
189 /* Are we prepared to handle this kernel fault?
191 * (The kernel has valid exception-points in the source
192 * when it acesses user-memory. When it fails in one
193 * of those points, we find it in a table and do a jump
194 * to some fixup code that loads an appropriate error
197 if (fixup_exception(regs))
200 die("Oops", regs, address, cause_code);
203 if (is_global_init(tsk)) {
207 up_read(&mm->mmap_sem);
210 do_group_exit(SIGKILL); /* This will never return */
215 up_read(&mm->mmap_sem);
217 if (!user_mode(regs))
220 tsk->thread.fault_address = address;
221 tsk->thread.cause_code = cause_code;
222 info.si_signo = SIGBUS;
224 info.si_code = BUS_ADRERR;
225 info.si_addr = (void __user *)address;
226 force_sig_info(SIGBUS, &info, tsk);