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/signal.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 <linux/mm_types.h>
19 #include <asm/pgalloc.h>
23 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
24 * Refer to asm/processor.h for System Memory Map
26 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
27 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
29 noinline static int handle_kernel_vaddr_fault(unsigned long address)
32 * Synchronize this task's top level page-table
33 * with the 'reference' page table.
39 pgd = pgd_offset_fast(current->active_mm, address);
40 pgd_k = pgd_offset_k(address);
42 if (!pgd_present(*pgd_k))
45 pud = pud_offset(pgd, address);
46 pud_k = pud_offset(pgd_k, address);
47 if (!pud_present(*pud_k))
50 pmd = pmd_offset(pud, address);
51 pmd_k = pmd_offset(pud_k, address);
52 if (!pmd_present(*pmd_k))
57 /* XXX: create the TLB entry here */
64 void do_page_fault(unsigned long address, struct pt_regs *regs)
66 struct vm_area_struct *vma = NULL;
67 struct task_struct *tsk = current;
68 struct mm_struct *mm = tsk->mm;
72 int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
73 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
76 * We fault-in kernel-space virtual memory on-demand. The
77 * 'reference' page table is init_mm.pgd.
79 * NOTE! We MUST NOT take any locks for this case. We may
80 * be in an interrupt or a critical region, and should
81 * only copy the information from the master page table,
84 if (address >= VMALLOC_START) {
85 ret = handle_kernel_vaddr_fault(address);
87 goto bad_area_nosemaphore;
92 si_code = SEGV_MAPERR;
95 * If we're in an interrupt or have no user
96 * context, we must not take the fault..
98 if (faulthandler_disabled() || !mm)
102 flags |= FAULT_FLAG_USER;
104 down_read(&mm->mmap_sem);
105 vma = find_vma(mm, address);
108 if (vma->vm_start <= address)
110 if (!(vma->vm_flags & VM_GROWSDOWN))
112 if (expand_stack(vma, address))
116 * Ok, we have a good vm_area for this memory access, so
120 si_code = SEGV_ACCERR;
122 /* Handle protection violation, execute on heap or stack */
124 if ((regs->ecr_vec == ECR_V_PROTV) &&
125 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
129 if (!(vma->vm_flags & VM_WRITE))
131 flags |= FAULT_FLAG_WRITE;
133 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
138 * If for any reason at all we couldn't handle the fault,
139 * make sure we exit gracefully rather than endlessly redo
142 fault = handle_mm_fault(vma, address, flags);
144 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
145 if (unlikely(fatal_signal_pending(current))) {
146 if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY))
147 up_read(&mm->mmap_sem);
152 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
154 if (likely(!(fault & VM_FAULT_ERROR))) {
155 if (flags & FAULT_FLAG_ALLOW_RETRY) {
156 /* To avoid updating stats twice for retry case */
157 if (fault & VM_FAULT_MAJOR) {
159 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
163 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
167 if (fault & VM_FAULT_RETRY) {
168 flags &= ~FAULT_FLAG_ALLOW_RETRY;
169 flags |= FAULT_FLAG_TRIED;
174 /* Fault Handled Gracefully */
175 up_read(&mm->mmap_sem);
179 if (fault & VM_FAULT_OOM)
181 else if (fault & VM_FAULT_SIGSEGV)
183 else if (fault & VM_FAULT_SIGBUS)
190 * Something tried to access memory that isn't in our memory map..
191 * Fix it, but check if it's kernel or user first..
194 up_read(&mm->mmap_sem);
196 bad_area_nosemaphore:
197 /* User mode accesses just cause a SIGSEGV */
198 if (user_mode(regs)) {
199 tsk->thread.fault_address = address;
200 force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
205 /* Are we prepared to handle this kernel fault?
207 * (The kernel has valid exception-points in the source
208 * when it accesses user-memory. When it fails in one
209 * of those points, we find it in a table and do a jump
210 * to some fixup code that loads an appropriate error
213 if (fixup_exception(regs))
216 die("Oops", regs, address);
219 up_read(&mm->mmap_sem);
221 if (user_mode(regs)) {
222 pagefault_out_of_memory();
229 up_read(&mm->mmap_sem);
231 if (!user_mode(regs))
234 tsk->thread.fault_address = address;
235 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);