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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
fbd7053a VG |
2 | /* Page Fault Handling for ARC (TLB Miss / ProtV) |
3 | * | |
4 | * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) | |
fbd7053a VG |
5 | */ |
6 | ||
7 | #include <linux/signal.h> | |
8 | #include <linux/interrupt.h> | |
3f07c014 | 9 | #include <linux/sched/signal.h> |
fbd7053a VG |
10 | #include <linux/errno.h> |
11 | #include <linux/ptrace.h> | |
fbd7053a VG |
12 | #include <linux/uaccess.h> |
13 | #include <linux/kdebug.h> | |
ceed97ab | 14 | #include <linux/perf_event.h> |
50a7ca3c | 15 | #include <linux/mm_types.h> |
fbd7053a | 16 | #include <asm/pgalloc.h> |
da1677b0 | 17 | #include <asm/mmu.h> |
fbd7053a | 18 | |
336e2136 VG |
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 | */ | |
26 | noinline static int handle_kernel_vaddr_fault(unsigned long address) | |
fbd7053a VG |
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 | pud_t *pud, *pud_k; | |
34 | pmd_t *pmd, *pmd_k; | |
35 | ||
9c41f4ee | 36 | pgd = pgd_offset_fast(current->active_mm, address); |
fbd7053a VG |
37 | pgd_k = pgd_offset_k(address); |
38 | ||
39 | if (!pgd_present(*pgd_k)) | |
40 | goto bad_area; | |
41 | ||
42 | pud = pud_offset(pgd, address); | |
43 | pud_k = pud_offset(pgd_k, address); | |
44 | if (!pud_present(*pud_k)) | |
45 | goto bad_area; | |
46 | ||
47 | pmd = pmd_offset(pud, address); | |
48 | pmd_k = pmd_offset(pud_k, address); | |
49 | if (!pmd_present(*pmd_k)) | |
50 | goto bad_area; | |
51 | ||
52 | set_pmd(pmd, *pmd_k); | |
53 | ||
54 | /* XXX: create the TLB entry here */ | |
55 | return 0; | |
56 | ||
57 | bad_area: | |
58 | return 1; | |
59 | } | |
60 | ||
21a63b56 | 61 | void do_page_fault(unsigned long address, struct pt_regs *regs) |
fbd7053a VG |
62 | { |
63 | struct vm_area_struct *vma = NULL; | |
64 | struct task_struct *tsk = current; | |
65 | struct mm_struct *mm = tsk->mm; | |
a8c715b4 | 66 | int si_code = SEGV_MAPERR; |
50a7ca3c SJ |
67 | int ret; |
68 | vm_fault_t fault; | |
38a9ff6d | 69 | int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ |
759496ba | 70 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
fbd7053a VG |
71 | |
72 | /* | |
73 | * We fault-in kernel-space virtual memory on-demand. The | |
74 | * 'reference' page table is init_mm.pgd. | |
75 | * | |
76 | * NOTE! We MUST NOT take any locks for this case. We may | |
77 | * be in an interrupt or a critical region, and should | |
78 | * only copy the information from the master page table, | |
79 | * nothing more. | |
80 | */ | |
a8c715b4 | 81 | if (address >= VMALLOC_START && !user_mode(regs)) { |
336e2136 | 82 | ret = handle_kernel_vaddr_fault(address); |
fbd7053a | 83 | if (unlikely(ret)) |
a8c715b4 | 84 | goto no_context; |
fbd7053a VG |
85 | else |
86 | return; | |
87 | } | |
88 | ||
fbd7053a VG |
89 | /* |
90 | * If we're in an interrupt or have no user | |
91 | * context, we must not take the fault.. | |
92 | */ | |
70ffdb93 | 93 | if (faulthandler_disabled() || !mm) |
fbd7053a VG |
94 | goto no_context; |
95 | ||
759496ba JW |
96 | if (user_mode(regs)) |
97 | flags |= FAULT_FLAG_USER; | |
fbd7053a VG |
98 | retry: |
99 | down_read(&mm->mmap_sem); | |
100 | vma = find_vma(mm, address); | |
101 | if (!vma) | |
102 | goto bad_area; | |
103 | if (vma->vm_start <= address) | |
104 | goto good_area; | |
105 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
106 | goto bad_area; | |
107 | if (expand_stack(vma, address)) | |
108 | goto bad_area; | |
109 | ||
110 | /* | |
111 | * Ok, we have a good vm_area for this memory access, so | |
112 | * we can handle it.. | |
113 | */ | |
114 | good_area: | |
15773ae9 | 115 | si_code = SEGV_ACCERR; |
fbd7053a VG |
116 | |
117 | /* Handle protection violation, execute on heap or stack */ | |
118 | ||
38a9ff6d VG |
119 | if ((regs->ecr_vec == ECR_V_PROTV) && |
120 | (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) | |
fbd7053a VG |
121 | goto bad_area; |
122 | ||
123 | if (write) { | |
124 | if (!(vma->vm_flags & VM_WRITE)) | |
125 | goto bad_area; | |
759496ba | 126 | flags |= FAULT_FLAG_WRITE; |
fbd7053a VG |
127 | } else { |
128 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
129 | goto bad_area; | |
130 | } | |
131 | ||
fbd7053a VG |
132 | /* |
133 | * If for any reason at all we couldn't handle the fault, | |
134 | * make sure we exit gracefully rather than endlessly redo | |
135 | * the fault. | |
136 | */ | |
dcddffd4 | 137 | fault = handle_mm_fault(vma, address, flags); |
fbd7053a | 138 | |
d8d7d842 | 139 | if (fatal_signal_pending(current)) { |
4d447455 VG |
140 | |
141 | /* | |
142 | * if fault retry, mmap_sem already relinquished by core mm | |
143 | * so OK to return to user mode (with signal handled first) | |
144 | */ | |
145 | if (fault & VM_FAULT_RETRY) { | |
146 | if (!user_mode(regs)) | |
147 | goto no_context; | |
fbd7053a | 148 | return; |
4d447455 | 149 | } |
fbd7053a VG |
150 | } |
151 | ||
ceed97ab VG |
152 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
153 | ||
fbd7053a VG |
154 | if (likely(!(fault & VM_FAULT_ERROR))) { |
155 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
156 | /* To avoid updating stats twice for retry case */ | |
ceed97ab | 157 | if (fault & VM_FAULT_MAJOR) { |
fbd7053a | 158 | tsk->maj_flt++; |
ceed97ab VG |
159 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, |
160 | regs, address); | |
161 | } else { | |
fbd7053a | 162 | tsk->min_flt++; |
ceed97ab VG |
163 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, |
164 | regs, address); | |
165 | } | |
fbd7053a VG |
166 | |
167 | if (fault & VM_FAULT_RETRY) { | |
168 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
169 | flags |= FAULT_FLAG_TRIED; | |
170 | goto retry; | |
171 | } | |
172 | } | |
173 | ||
174 | /* Fault Handled Gracefully */ | |
175 | up_read(&mm->mmap_sem); | |
176 | return; | |
177 | } | |
178 | ||
fbd7053a VG |
179 | if (fault & VM_FAULT_OOM) |
180 | goto out_of_memory; | |
e262eb93 | 181 | else if (fault & VM_FAULT_SIGSEGV) |
33692f27 | 182 | goto bad_area; |
fbd7053a VG |
183 | else if (fault & VM_FAULT_SIGBUS) |
184 | goto do_sigbus; | |
185 | ||
186 | /* no man's land */ | |
187 | BUG(); | |
188 | ||
189 | /* | |
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.. | |
192 | */ | |
193 | bad_area: | |
194 | up_read(&mm->mmap_sem); | |
195 | ||
fbd7053a VG |
196 | /* User mode accesses just cause a SIGSEGV */ |
197 | if (user_mode(regs)) { | |
198 | tsk->thread.fault_address = address; | |
15773ae9 | 199 | force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk); |
fbd7053a VG |
200 | return; |
201 | } | |
202 | ||
203 | no_context: | |
204 | /* Are we prepared to handle this kernel fault? | |
205 | * | |
206 | * (The kernel has valid exception-points in the source | |
ddf720f8 | 207 | * when it accesses user-memory. When it fails in one |
fbd7053a VG |
208 | * of those points, we find it in a table and do a jump |
209 | * to some fixup code that loads an appropriate error | |
210 | * code) | |
211 | */ | |
212 | if (fixup_exception(regs)) | |
213 | return; | |
214 | ||
38a9ff6d | 215 | die("Oops", regs, address); |
fbd7053a VG |
216 | |
217 | out_of_memory: | |
fbd7053a VG |
218 | up_read(&mm->mmap_sem); |
219 | ||
609838cf JW |
220 | if (user_mode(regs)) { |
221 | pagefault_out_of_memory(); | |
222 | return; | |
223 | } | |
fbd7053a VG |
224 | |
225 | goto no_context; | |
226 | ||
227 | do_sigbus: | |
228 | up_read(&mm->mmap_sem); | |
229 | ||
230 | if (!user_mode(regs)) | |
231 | goto no_context; | |
232 | ||
233 | tsk->thread.fault_address = address; | |
15773ae9 | 234 | force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk); |
fbd7053a | 235 | } |