1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Page Fault Handling for ARC (TLB Miss / ProtV)
4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
7 #include <linux/signal.h>
8 #include <linux/interrupt.h>
9 #include <linux/sched/signal.h>
10 #include <linux/errno.h>
11 #include <linux/ptrace.h>
12 #include <linux/uaccess.h>
13 #include <linux/kdebug.h>
14 #include <linux/perf_event.h>
15 #include <linux/mm_types.h>
16 #include <asm/pgalloc.h>
20 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
21 * Refer to asm/processor.h for System Memory Map
23 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
24 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
26 noinline static int handle_kernel_vaddr_fault(unsigned long address)
29 * Synchronize this task's top level page-table
30 * with the 'reference' page table.
36 pgd = pgd_offset_fast(current->active_mm, address);
37 pgd_k = pgd_offset_k(address);
39 if (!pgd_present(*pgd_k))
42 pud = pud_offset(pgd, address);
43 pud_k = pud_offset(pgd_k, address);
44 if (!pud_present(*pud_k))
47 pmd = pmd_offset(pud, address);
48 pmd_k = pmd_offset(pud_k, address);
49 if (!pmd_present(*pmd_k))
54 /* XXX: create the TLB entry here */
61 void do_page_fault(unsigned long address, struct pt_regs *regs)
63 struct vm_area_struct *vma = NULL;
64 struct task_struct *tsk = current;
65 struct mm_struct *mm = tsk->mm;
66 int si_code = SEGV_MAPERR;
67 unsigned int write = 0, exec = 0, mask;
68 vm_fault_t fault; /* handle_mm_fault() output */
69 unsigned int flags; /* handle_mm_fault() input */
72 * NOTE! We MUST NOT take any locks for this case. We may
73 * be in an interrupt or a critical region, and should
74 * only copy the information from the master page table,
77 if (address >= VMALLOC_START && !user_mode(regs)) {
78 if (unlikely(handle_kernel_vaddr_fault(address)))
85 * If we're in an interrupt or have no user
86 * context, we must not take the fault..
88 if (faulthandler_disabled() || !mm)
91 if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */
93 else if ((regs->ecr_vec == ECR_V_PROTV) &&
94 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
97 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
99 flags |= FAULT_FLAG_USER;
101 flags |= FAULT_FLAG_WRITE;
104 down_read(&mm->mmap_sem);
106 vma = find_vma(mm, address);
109 if (unlikely(address < vma->vm_start)) {
110 if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address))
115 * vm_area is good, now check permissions for this memory access
123 if (!(vma->vm_flags & mask)) {
124 si_code = SEGV_ACCERR;
128 fault = handle_mm_fault(vma, address, flags);
131 * Fault retry nuances
133 if (unlikely(fault & VM_FAULT_RETRY)) {
136 * If fault needs to be retried, handle any pending signals
137 * first (by returning to user mode).
138 * mmap_sem already relinquished by core mm for RETRY case
140 if (fatal_signal_pending(current)) {
141 if (!user_mode(regs))
146 * retry state machine
148 if (flags & FAULT_FLAG_ALLOW_RETRY) {
149 flags &= ~FAULT_FLAG_ALLOW_RETRY;
150 flags |= FAULT_FLAG_TRIED;
156 * Major/minor page fault accounting
157 * (in case of retry we only land here once)
159 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
161 if (likely(!(fault & VM_FAULT_ERROR))) {
162 if (fault & VM_FAULT_MAJOR) {
164 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
168 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
172 /* Normal return path: fault Handled Gracefully */
173 up_read(&mm->mmap_sem);
177 if (fault & VM_FAULT_OOM)
179 else if (fault & VM_FAULT_SIGSEGV)
181 else if (fault & VM_FAULT_SIGBUS)
188 * Something tried to access memory that isn't in our memory map..
189 * Fix it, but check if it's kernel or user first..
192 up_read(&mm->mmap_sem);
194 /* User mode accesses just cause a SIGSEGV */
195 if (user_mode(regs)) {
196 tsk->thread.fault_address = address;
197 force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
202 /* Are we prepared to handle this kernel fault?
204 * (The kernel has valid exception-points in the source
205 * when it accesses user-memory. When it fails in one
206 * of those points, we find it in a table and do a jump
207 * to some fixup code that loads an appropriate error
210 if (fixup_exception(regs))
213 die("Oops", regs, address);
216 up_read(&mm->mmap_sem);
218 if (user_mode(regs)) {
219 pagefault_out_of_memory();
226 up_read(&mm->mmap_sem);
228 if (!user_mode(regs))
231 tsk->thread.fault_address = address;
232 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);