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 <linux/perf_event.h>
18 #include <asm/pgalloc.h>
21 static int handle_vmalloc_fault(unsigned long address)
24 * Synchronize this task's top level page-table
25 * with the 'reference' page table.
31 pgd = pgd_offset_fast(current->active_mm, address);
32 pgd_k = pgd_offset_k(address);
34 if (!pgd_present(*pgd_k))
37 pud = pud_offset(pgd, address);
38 pud_k = pud_offset(pgd_k, address);
39 if (!pud_present(*pud_k))
42 pmd = pmd_offset(pud, address);
43 pmd_k = pmd_offset(pud_k, address);
44 if (!pmd_present(*pmd_k))
49 /* XXX: create the TLB entry here */
56 void do_page_fault(unsigned long address, struct pt_regs *regs)
58 struct vm_area_struct *vma = NULL;
59 struct task_struct *tsk = current;
60 struct mm_struct *mm = tsk->mm;
63 int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
64 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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,
75 if (address >= VMALLOC_START && address <= VMALLOC_END) {
76 ret = handle_vmalloc_fault(address);
78 goto bad_area_nosemaphore;
83 info.si_code = SEGV_MAPERR;
86 * If we're in an interrupt or have no user
87 * context, we must not take the fault..
89 if (faulthandler_disabled() || !mm)
93 flags |= FAULT_FLAG_USER;
95 down_read(&mm->mmap_sem);
96 vma = find_vma(mm, address);
99 if (vma->vm_start <= address)
101 if (!(vma->vm_flags & VM_GROWSDOWN))
103 if (expand_stack(vma, address))
107 * Ok, we have a good vm_area for this memory access, so
111 info.si_code = SEGV_ACCERR;
113 /* Handle protection violation, execute on heap or stack */
115 if ((regs->ecr_vec == ECR_V_PROTV) &&
116 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
120 if (!(vma->vm_flags & VM_WRITE))
122 flags |= FAULT_FLAG_WRITE;
124 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
129 * If for any reason at all we couldn't handle the fault,
130 * make sure we exit gracefully rather than endlessly redo
133 fault = handle_mm_fault(mm, vma, address, flags);
135 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
136 if (unlikely(fatal_signal_pending(current))) {
137 if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY))
138 up_read(&mm->mmap_sem);
143 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
145 if (likely(!(fault & VM_FAULT_ERROR))) {
146 if (flags & FAULT_FLAG_ALLOW_RETRY) {
147 /* To avoid updating stats twice for retry case */
148 if (fault & VM_FAULT_MAJOR) {
150 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
154 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
158 if (fault & VM_FAULT_RETRY) {
159 flags &= ~FAULT_FLAG_ALLOW_RETRY;
160 flags |= FAULT_FLAG_TRIED;
165 /* Fault Handled Gracefully */
166 up_read(&mm->mmap_sem);
170 if (fault & VM_FAULT_OOM)
172 else if (fault & VM_FAULT_SIGSEGV)
174 else if (fault & VM_FAULT_SIGBUS)
181 * Something tried to access memory that isn't in our memory map..
182 * Fix it, but check if it's kernel or user first..
185 up_read(&mm->mmap_sem);
187 bad_area_nosemaphore:
188 /* User mode accesses just cause a SIGSEGV */
189 if (user_mode(regs)) {
190 tsk->thread.fault_address = address;
191 info.si_signo = SIGSEGV;
193 /* info.si_code has been set above */
194 info.si_addr = (void __user *)address;
195 force_sig_info(SIGSEGV, &info, tsk);
200 /* Are we prepared to handle this kernel fault?
202 * (The kernel has valid exception-points in the source
203 * when it acesses user-memory. When it fails in one
204 * of those points, we find it in a table and do a jump
205 * to some fixup code that loads an appropriate error
208 if (fixup_exception(regs))
211 die("Oops", regs, address);
214 up_read(&mm->mmap_sem);
216 if (user_mode(regs)) {
217 pagefault_out_of_memory();
224 up_read(&mm->mmap_sem);
226 if (!user_mode(regs))
229 tsk->thread.fault_address = address;
230 info.si_signo = SIGBUS;
232 info.si_code = BUS_ADRERR;
233 info.si_addr = (void __user *)address;
234 force_sig_info(SIGBUS, &info, tsk);