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>
19 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
20 * Refer to asm/processor.h for System Memory Map
22 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
23 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
25 noinline static int handle_kernel_vaddr_fault(unsigned long address)
28 * Synchronize this task's top level page-table
29 * with the 'reference' page table.
36 pgd = pgd_offset(current->active_mm, address);
37 pgd_k = pgd_offset_k(address);
39 if (!pgd_present(*pgd_k))
44 p4d = p4d_offset(pgd, address);
45 p4d_k = p4d_offset(pgd_k, address);
46 if (!p4d_present(*p4d_k))
49 pud = pud_offset(p4d, address);
50 pud_k = pud_offset(p4d_k, address);
51 if (!pud_present(*pud_k))
56 pmd = pmd_offset(pud, address);
57 pmd_k = pmd_offset(pud_k, address);
58 if (!pmd_present(*pmd_k))
63 /* XXX: create the TLB entry here */
70 void do_page_fault(unsigned long address, struct pt_regs *regs)
72 struct vm_area_struct *vma = NULL;
73 struct task_struct *tsk = current;
74 struct mm_struct *mm = tsk->mm;
75 int sig, si_code = SEGV_MAPERR;
76 unsigned int write = 0, exec = 0, mask;
77 vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */
78 unsigned int flags; /* handle_mm_fault() input */
81 * NOTE! We MUST NOT take any locks for this case. We may
82 * be in an interrupt or a critical region, and should
83 * only copy the information from the master page table,
86 if (address >= VMALLOC_START && !user_mode(regs)) {
87 if (unlikely(handle_kernel_vaddr_fault(address)))
94 * If we're in an interrupt or have no user
95 * context, we must not take the fault..
97 if (faulthandler_disabled() || !mm)
100 if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */
102 else if ((regs->ecr_vec == ECR_V_PROTV) &&
103 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
106 flags = FAULT_FLAG_DEFAULT;
108 flags |= FAULT_FLAG_USER;
110 flags |= FAULT_FLAG_WRITE;
112 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
116 vma = find_vma(mm, address);
119 if (unlikely(address < vma->vm_start)) {
120 if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address))
125 * vm_area is good, now check permissions for this memory access
133 if (!(vma->vm_flags & mask)) {
134 si_code = SEGV_ACCERR;
138 fault = handle_mm_fault(vma, address, flags, regs);
140 /* Quick path to respond to signals */
141 if (fault_signal_pending(fault, regs)) {
142 if (!user_mode(regs))
148 * Fault retry nuances, mmap_lock already relinquished by core mm
150 if (unlikely((fault & VM_FAULT_RETRY) &&
151 (flags & FAULT_FLAG_ALLOW_RETRY))) {
152 flags |= FAULT_FLAG_TRIED;
157 mmap_read_unlock(mm);
160 * Major/minor page fault accounting
161 * (in case of retry we only land here once)
163 if (likely(!(fault & VM_FAULT_ERROR)))
164 /* Normal return path: fault Handled Gracefully */
167 if (!user_mode(regs))
170 if (fault & VM_FAULT_OOM) {
171 pagefault_out_of_memory();
175 if (fault & VM_FAULT_SIGBUS) {
177 si_code = BUS_ADRERR;
183 tsk->thread.fault_address = address;
184 force_sig_fault(sig, si_code, (void __user *)address);
188 if (fixup_exception(regs))
191 die("Oops", regs, address);