1// SPDX-License-Identifier: GPL-2.0-only 2/* Page Fault Handling for ARC (TLB Miss / ProtV) 3 * 4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 5 */ 6 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/mmu.h> 17 18/* 19 * kernel virtual address is required to implement vmalloc/pkmap/fixmap 20 * Refer to asm/processor.h for System Memory Map 21 * 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 24 */ 25noinline static int handle_kernel_vaddr_fault(unsigned long address) 26{ 27 /* 28 * Synchronize this task's top level page-table 29 * with the 'reference' page table. 30 */ 31 pgd_t *pgd, *pgd_k; 32 p4d_t *p4d, *p4d_k; 33 pud_t *pud, *pud_k; 34 pmd_t *pmd, *pmd_k; 35 36 pgd = pgd_offset_fast(current->active_mm, address); 37 pgd_k = pgd_offset_k(address); 38 39 if (!pgd_present(*pgd_k)) 40 goto bad_area; 41 42 p4d = p4d_offset(pgd, address); 43 p4d_k = p4d_offset(pgd_k, address); 44 if (!p4d_present(*p4d_k)) 45 goto bad_area; 46 47 pud = pud_offset(p4d, address); 48 pud_k = pud_offset(p4d_k, address); 49 if (!pud_present(*pud_k)) 50 goto bad_area; 51 52 pmd = pmd_offset(pud, address); 53 pmd_k = pmd_offset(pud_k, address); 54 if (!pmd_present(*pmd_k)) 55 goto bad_area; 56 57 set_pmd(pmd, *pmd_k); 58 59 /* XXX: create the TLB entry here */ 60 return 0; 61 62bad_area: 63 return 1; 64} 65 66void do_page_fault(unsigned long address, struct pt_regs *regs) 67{ 68 struct vm_area_struct *vma = NULL; 69 struct task_struct *tsk = current; 70 struct mm_struct *mm = tsk->mm; 71 int sig, si_code = SEGV_MAPERR; 72 unsigned int write = 0, exec = 0, mask; 73 vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */ 74 unsigned int flags; /* handle_mm_fault() input */ 75 76 /* 77 * NOTE! We MUST NOT take any locks for this case. We may 78 * be in an interrupt or a critical region, and should 79 * only copy the information from the master page table, 80 * nothing more. 81 */ 82 if (address >= VMALLOC_START && !user_mode(regs)) { 83 if (unlikely(handle_kernel_vaddr_fault(address))) 84 goto no_context; 85 else 86 return; 87 } 88 89 /* 90 * If we're in an interrupt or have no user 91 * context, we must not take the fault.. 92 */ 93 if (faulthandler_disabled() || !mm) 94 goto no_context; 95 96 if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */ 97 write = 1; 98 else if ((regs->ecr_vec == ECR_V_PROTV) && 99 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) 100 exec = 1; 101 102 flags = FAULT_FLAG_DEFAULT; 103 if (user_mode(regs)) 104 flags |= FAULT_FLAG_USER; 105 if (write) 106 flags |= FAULT_FLAG_WRITE; 107 108 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 109retry: 110 mmap_read_lock(mm); 111 112 vma = find_vma(mm, address); 113 if (!vma) 114 goto bad_area; 115 if (unlikely(address < vma->vm_start)) { 116 if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address)) 117 goto bad_area; 118 } 119 120 /* 121 * vm_area is good, now check permissions for this memory access 122 */ 123 mask = VM_READ; 124 if (write) 125 mask = VM_WRITE; 126 if (exec) 127 mask = VM_EXEC; 128 129 if (!(vma->vm_flags & mask)) { 130 si_code = SEGV_ACCERR; 131 goto bad_area; 132 } 133 134 fault = handle_mm_fault(vma, address, flags, regs); 135 136 /* Quick path to respond to signals */ 137 if (fault_signal_pending(fault, regs)) { 138 if (!user_mode(regs)) 139 goto no_context; 140 return; 141 } 142 143 /* 144 * Fault retry nuances, mmap_lock already relinquished by core mm 145 */ 146 if (unlikely((fault & VM_FAULT_RETRY) && 147 (flags & FAULT_FLAG_ALLOW_RETRY))) { 148 flags |= FAULT_FLAG_TRIED; 149 goto retry; 150 } 151 152bad_area: 153 mmap_read_unlock(mm); 154 155 /* 156 * Major/minor page fault accounting 157 * (in case of retry we only land here once) 158 */ 159 if (likely(!(fault & VM_FAULT_ERROR))) 160 /* Normal return path: fault Handled Gracefully */ 161 return; 162 163 if (!user_mode(regs)) 164 goto no_context; 165 166 if (fault & VM_FAULT_OOM) { 167 pagefault_out_of_memory(); 168 return; 169 } 170 171 if (fault & VM_FAULT_SIGBUS) { 172 sig = SIGBUS; 173 si_code = BUS_ADRERR; 174 } 175 else { 176 sig = SIGSEGV; 177 } 178 179 tsk->thread.fault_address = address; 180 force_sig_fault(sig, si_code, (void __user *)address); 181 return; 182 183no_context: 184 if (fixup_exception(regs)) 185 return; 186 187 die("Oops", regs, address); 188} 189