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;
65 * We fault-in kernel-space virtual memory on-demand. The
66 * 'reference' page table is init_mm.pgd.
68 * NOTE! We MUST NOT take any locks for this case. We may
69 * be in an interrupt or a critical region, and should
70 * only copy the information from the master page table,
73 if (address >= VMALLOC_START && address <= VMALLOC_END) {
74 ret = handle_vmalloc_fault(address);
76 goto bad_area_nosemaphore;
81 info.si_code = SEGV_MAPERR;
84 * If we're in an interrupt or have no user
85 * context, we must not take the fault..
87 if (in_atomic() || !mm)
91 flags |= FAULT_FLAG_USER;
93 down_read(&mm->mmap_sem);
94 vma = find_vma(mm, address);
97 if (vma->vm_start <= address)
99 if (!(vma->vm_flags & VM_GROWSDOWN))
101 if (expand_stack(vma, address))
105 * Ok, we have a good vm_area for this memory access, so
109 info.si_code = SEGV_ACCERR;
111 /* Handle protection violation, execute on heap or stack */
113 if (cause_code == ((ECR_V_PROTV << 16) | ECR_C_PROTV_INST_FETCH))
117 if (!(vma->vm_flags & VM_WRITE))
119 flags |= FAULT_FLAG_WRITE;
121 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
126 * If for any reason at all we couldn't handle the fault,
127 * make sure we exit gracefully rather than endlessly redo
130 fault = handle_mm_fault(mm, vma, address, flags);
132 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
133 if (unlikely(fatal_signal_pending(current))) {
134 if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY))
135 up_read(&mm->mmap_sem);
140 if (likely(!(fault & VM_FAULT_ERROR))) {
141 if (flags & FAULT_FLAG_ALLOW_RETRY) {
142 /* To avoid updating stats twice for retry case */
143 if (fault & VM_FAULT_MAJOR)
148 if (fault & VM_FAULT_RETRY) {
149 flags &= ~FAULT_FLAG_ALLOW_RETRY;
150 flags |= FAULT_FLAG_TRIED;
155 /* Fault Handled Gracefully */
156 up_read(&mm->mmap_sem);
160 /* TBD: switch to pagefault_out_of_memory() */
161 if (fault & VM_FAULT_OOM)
163 else if (fault & VM_FAULT_SIGBUS)
170 * Something tried to access memory that isn't in our memory map..
171 * Fix it, but check if it's kernel or user first..
174 up_read(&mm->mmap_sem);
176 bad_area_nosemaphore:
177 /* User mode accesses just cause a SIGSEGV */
178 if (user_mode(regs)) {
179 tsk->thread.fault_address = address;
180 tsk->thread.cause_code = cause_code;
181 info.si_signo = SIGSEGV;
183 /* info.si_code has been set above */
184 info.si_addr = (void __user *)address;
185 force_sig_info(SIGSEGV, &info, tsk);
190 /* Are we prepared to handle this kernel fault?
192 * (The kernel has valid exception-points in the source
193 * when it acesses user-memory. When it fails in one
194 * of those points, we find it in a table and do a jump
195 * to some fixup code that loads an appropriate error
198 if (fixup_exception(regs))
201 die("Oops", regs, address, cause_code);
204 up_read(&mm->mmap_sem);
206 if (user_mode(regs)) {
207 pagefault_out_of_memory();
214 up_read(&mm->mmap_sem);
216 if (!user_mode(regs))
219 tsk->thread.fault_address = address;
220 tsk->thread.cause_code = cause_code;
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);