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/entry.h> 17#include <asm/mmu.h> 18 19/* 20 * kernel virtual address is required to implement vmalloc/pkmap/fixmap 21 * Refer to asm/processor.h for System Memory Map 22 * 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 25 */ 26noinline static int handle_kernel_vaddr_fault(unsigned long address) 27{ 28 /* 29 * Synchronize this task's top level page-table 30 * with the 'reference' page table. 31 */ 32 pgd_t *pgd, *pgd_k; 33 p4d_t *p4d, *p4d_k; 34 pud_t *pud, *pud_k; 35 pmd_t *pmd, *pmd_k; 36 37 pgd = pgd_offset(current->active_mm, address); 38 pgd_k = pgd_offset_k(address); 39 40 if (pgd_none (*pgd_k)) 41 goto bad_area; 42 if (!pgd_present(*pgd)) 43 set_pgd(pgd, *pgd_k); 44 45 p4d = p4d_offset(pgd, address); 46 p4d_k = p4d_offset(pgd_k, address); 47 if (p4d_none(*p4d_k)) 48 goto bad_area; 49 if (!p4d_present(*p4d)) 50 set_p4d(p4d, *p4d_k); 51 52 pud = pud_offset(p4d, address); 53 pud_k = pud_offset(p4d_k, address); 54 if (pud_none(*pud_k)) 55 goto bad_area; 56 if (!pud_present(*pud)) 57 set_pud(pud, *pud_k); 58 59 pmd = pmd_offset(pud, address); 60 pmd_k = pmd_offset(pud_k, address); 61 if (pmd_none(*pmd_k)) 62 goto bad_area; 63 if (!pmd_present(*pmd)) 64 set_pmd(pmd, *pmd_k); 65 66 /* XXX: create the TLB entry here */ 67 return 0; 68 69bad_area: 70 return 1; 71} 72 73void do_page_fault(unsigned long address, struct pt_regs *regs) 74{ 75 struct vm_area_struct *vma = NULL; 76 struct task_struct *tsk = current; 77 struct mm_struct *mm = tsk->mm; 78 int sig, si_code = SEGV_MAPERR; 79 unsigned int write = 0, exec = 0, mask; 80 vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */ 81 unsigned int flags; /* handle_mm_fault() input */ 82 83 /* 84 * NOTE! We MUST NOT take any locks for this case. We may 85 * be in an interrupt or a critical region, and should 86 * only copy the information from the master page table, 87 * nothing more. 88 */ 89 if (address >= VMALLOC_START && !user_mode(regs)) { 90 if (unlikely(handle_kernel_vaddr_fault(address))) 91 goto no_context; 92 else 93 return; 94 } 95 96 /* 97 * If we're in an interrupt or have no user 98 * context, we must not take the fault.. 99 */ 100 if (faulthandler_disabled() || !mm) 101 goto no_context; 102 103 if (regs->ecr.cause & ECR_C_PROTV_STORE) /* ST/EX */ 104 write = 1; 105 else if ((regs->ecr.vec == ECR_V_PROTV) && 106 (regs->ecr.cause == ECR_C_PROTV_INST_FETCH)) 107 exec = 1; 108 109 flags = FAULT_FLAG_DEFAULT; 110 if (user_mode(regs)) 111 flags |= FAULT_FLAG_USER; 112 if (write) 113 flags |= FAULT_FLAG_WRITE; 114 115 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 116retry: 117 vma = lock_mm_and_find_vma(mm, address, regs); 118 if (!vma) 119 goto bad_area_nosemaphore; 120 121 /* 122 * vm_area is good, now check permissions for this memory access 123 */ 124 mask = VM_READ; 125 if (write) 126 mask = VM_WRITE; 127 if (exec) 128 mask = VM_EXEC; 129 130 if (!(vma->vm_flags & mask)) { 131 si_code = SEGV_ACCERR; 132 goto bad_area; 133 } 134 135 fault = handle_mm_fault(vma, address, flags, regs); 136 137 /* Quick path to respond to signals */ 138 if (fault_signal_pending(fault, regs)) { 139 if (!user_mode(regs)) 140 goto no_context; 141 return; 142 } 143 144 /* The fault is fully completed (including releasing mmap lock) */ 145 if (fault & VM_FAULT_COMPLETED) 146 return; 147 148 /* 149 * Fault retry nuances, mmap_lock already relinquished by core mm 150 */ 151 if (unlikely(fault & VM_FAULT_RETRY)) { 152 flags |= FAULT_FLAG_TRIED; 153 goto retry; 154 } 155 156bad_area: 157 mmap_read_unlock(mm); 158 159bad_area_nosemaphore: 160 /* 161 * Major/minor page fault accounting 162 * (in case of retry we only land here once) 163 */ 164 if (likely(!(fault & VM_FAULT_ERROR))) 165 /* Normal return path: fault Handled Gracefully */ 166 return; 167 168 if (!user_mode(regs)) 169 goto no_context; 170 171 if (fault & VM_FAULT_OOM) { 172 pagefault_out_of_memory(); 173 return; 174 } 175 176 if (fault & VM_FAULT_SIGBUS) { 177 sig = SIGBUS; 178 si_code = BUS_ADRERR; 179 } 180 else { 181 sig = SIGSEGV; 182 } 183 184 tsk->thread.fault_address = address; 185 force_sig_fault(sig, si_code, (void __user *)address); 186 return; 187 188no_context: 189 if (fixup_exception(regs)) 190 return; 191 192 die("Oops", regs, address); 193} 194