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>
20 static int handle_vmalloc_fault(unsigned long address)
23 * Synchronize this task's top level page-table
24 * with the 'reference' page table.
30 pgd = pgd_offset_fast(current->active_mm, address);
31 pgd_k = pgd_offset_k(address);
33 if (!pgd_present(*pgd_k))
36 pud = pud_offset(pgd, address);
37 pud_k = pud_offset(pgd_k, address);
38 if (!pud_present(*pud_k))
41 pmd = pmd_offset(pud, address);
42 pmd_k = pmd_offset(pud_k, address);
43 if (!pmd_present(*pmd_k))
48 /* XXX: create the TLB entry here */
55 void do_page_fault(unsigned long address, struct pt_regs *regs)
57 struct vm_area_struct *vma = NULL;
58 struct task_struct *tsk = current;
59 struct mm_struct *mm = tsk->mm;
62 int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
63 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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 flags |= FAULT_FLAG_USER;
94 down_read(&mm->mmap_sem);
95 vma = find_vma(mm, address);
98 if (vma->vm_start <= address)
100 if (!(vma->vm_flags & VM_GROWSDOWN))
102 if (expand_stack(vma, address))
106 * Ok, we have a good vm_area for this memory access, so
110 info.si_code = SEGV_ACCERR;
112 /* Handle protection violation, execute on heap or stack */
114 if ((regs->ecr_vec == ECR_V_PROTV) &&
115 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
119 if (!(vma->vm_flags & VM_WRITE))
121 flags |= FAULT_FLAG_WRITE;
123 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
128 * If for any reason at all we couldn't handle the fault,
129 * make sure we exit gracefully rather than endlessly redo
132 fault = handle_mm_fault(mm, vma, address, flags);
134 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
135 if (unlikely(fatal_signal_pending(current))) {
136 if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY))
137 up_read(&mm->mmap_sem);
142 if (likely(!(fault & VM_FAULT_ERROR))) {
143 if (flags & FAULT_FLAG_ALLOW_RETRY) {
144 /* To avoid updating stats twice for retry case */
145 if (fault & VM_FAULT_MAJOR)
150 if (fault & VM_FAULT_RETRY) {
151 flags &= ~FAULT_FLAG_ALLOW_RETRY;
152 flags |= FAULT_FLAG_TRIED;
157 /* Fault Handled Gracefully */
158 up_read(&mm->mmap_sem);
162 /* TBD: switch to pagefault_out_of_memory() */
163 if (fault & VM_FAULT_OOM)
165 else if (fault & VM_FAULT_SIGBUS)
172 * Something tried to access memory that isn't in our memory map..
173 * Fix it, but check if it's kernel or user first..
176 up_read(&mm->mmap_sem);
178 bad_area_nosemaphore:
179 /* User mode accesses just cause a SIGSEGV */
180 if (user_mode(regs)) {
181 tsk->thread.fault_address = address;
182 info.si_signo = SIGSEGV;
184 /* info.si_code has been set above */
185 info.si_addr = (void __user *)address;
186 force_sig_info(SIGSEGV, &info, tsk);
191 /* Are we prepared to handle this kernel fault?
193 * (The kernel has valid exception-points in the source
194 * when it acesses user-memory. When it fails in one
195 * of those points, we find it in a table and do a jump
196 * to some fixup code that loads an appropriate error
199 if (fixup_exception(regs))
202 die("Oops", regs, address);
205 up_read(&mm->mmap_sem);
207 if (user_mode(regs)) {
208 pagefault_out_of_memory();
215 up_read(&mm->mmap_sem);
217 if (!user_mode(regs))
220 tsk->thread.fault_address = address;
221 info.si_signo = SIGBUS;
223 info.si_code = BUS_ADRERR;
224 info.si_addr = (void __user *)address;
225 force_sig_info(SIGBUS, &info, tsk);