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fbd7053a VG |
1 | /* Page Fault Handling for ARC (TLB Miss / ProtV) |
2 | * | |
3 | * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License version 2 as | |
7 | * published by the Free Software Foundation. | |
8 | */ | |
9 | ||
10 | #include <linux/signal.h> | |
11 | #include <linux/interrupt.h> | |
3f07c014 | 12 | #include <linux/sched/signal.h> |
fbd7053a VG |
13 | #include <linux/errno.h> |
14 | #include <linux/ptrace.h> | |
fbd7053a VG |
15 | #include <linux/uaccess.h> |
16 | #include <linux/kdebug.h> | |
ceed97ab | 17 | #include <linux/perf_event.h> |
50a7ca3c | 18 | #include <linux/mm_types.h> |
fbd7053a | 19 | #include <asm/pgalloc.h> |
da1677b0 | 20 | #include <asm/mmu.h> |
fbd7053a | 21 | |
336e2136 VG |
22 | /* |
23 | * kernel virtual address is required to implement vmalloc/pkmap/fixmap | |
24 | * Refer to asm/processor.h for System Memory Map | |
25 | * | |
26 | * It simply copies the PMD entry (pointer to 2nd level page table or hugepage) | |
27 | * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared | |
28 | */ | |
29 | noinline static int handle_kernel_vaddr_fault(unsigned long address) | |
fbd7053a VG |
30 | { |
31 | /* | |
32 | * Synchronize this task's top level page-table | |
33 | * with the 'reference' page table. | |
34 | */ | |
35 | pgd_t *pgd, *pgd_k; | |
36 | pud_t *pud, *pud_k; | |
37 | pmd_t *pmd, *pmd_k; | |
38 | ||
9c41f4ee | 39 | pgd = pgd_offset_fast(current->active_mm, address); |
fbd7053a VG |
40 | pgd_k = pgd_offset_k(address); |
41 | ||
42 | if (!pgd_present(*pgd_k)) | |
43 | goto bad_area; | |
44 | ||
45 | pud = pud_offset(pgd, address); | |
46 | pud_k = pud_offset(pgd_k, address); | |
47 | if (!pud_present(*pud_k)) | |
48 | goto bad_area; | |
49 | ||
50 | pmd = pmd_offset(pud, address); | |
51 | pmd_k = pmd_offset(pud_k, address); | |
52 | if (!pmd_present(*pmd_k)) | |
53 | goto bad_area; | |
54 | ||
55 | set_pmd(pmd, *pmd_k); | |
56 | ||
57 | /* XXX: create the TLB entry here */ | |
58 | return 0; | |
59 | ||
60 | bad_area: | |
61 | return 1; | |
62 | } | |
63 | ||
21a63b56 | 64 | void do_page_fault(unsigned long address, struct pt_regs *regs) |
fbd7053a VG |
65 | { |
66 | struct vm_area_struct *vma = NULL; | |
67 | struct task_struct *tsk = current; | |
68 | struct mm_struct *mm = tsk->mm; | |
69 | siginfo_t info; | |
50a7ca3c SJ |
70 | int ret; |
71 | vm_fault_t fault; | |
38a9ff6d | 72 | int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ |
759496ba | 73 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
fbd7053a | 74 | |
3eb0f519 EB |
75 | clear_siginfo(&info); |
76 | ||
fbd7053a VG |
77 | /* |
78 | * We fault-in kernel-space virtual memory on-demand. The | |
79 | * 'reference' page table is init_mm.pgd. | |
80 | * | |
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, | |
84 | * nothing more. | |
85 | */ | |
336e2136 VG |
86 | if (address >= VMALLOC_START) { |
87 | ret = handle_kernel_vaddr_fault(address); | |
fbd7053a VG |
88 | if (unlikely(ret)) |
89 | goto bad_area_nosemaphore; | |
90 | else | |
91 | return; | |
92 | } | |
93 | ||
94 | info.si_code = SEGV_MAPERR; | |
95 | ||
96 | /* | |
97 | * If we're in an interrupt or have no user | |
98 | * context, we must not take the fault.. | |
99 | */ | |
70ffdb93 | 100 | if (faulthandler_disabled() || !mm) |
fbd7053a VG |
101 | goto no_context; |
102 | ||
759496ba JW |
103 | if (user_mode(regs)) |
104 | flags |= FAULT_FLAG_USER; | |
fbd7053a VG |
105 | retry: |
106 | down_read(&mm->mmap_sem); | |
107 | vma = find_vma(mm, address); | |
108 | if (!vma) | |
109 | goto bad_area; | |
110 | if (vma->vm_start <= address) | |
111 | goto good_area; | |
112 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
113 | goto bad_area; | |
114 | if (expand_stack(vma, address)) | |
115 | goto bad_area; | |
116 | ||
117 | /* | |
118 | * Ok, we have a good vm_area for this memory access, so | |
119 | * we can handle it.. | |
120 | */ | |
121 | good_area: | |
122 | info.si_code = SEGV_ACCERR; | |
123 | ||
124 | /* Handle protection violation, execute on heap or stack */ | |
125 | ||
38a9ff6d VG |
126 | if ((regs->ecr_vec == ECR_V_PROTV) && |
127 | (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) | |
fbd7053a VG |
128 | goto bad_area; |
129 | ||
130 | if (write) { | |
131 | if (!(vma->vm_flags & VM_WRITE)) | |
132 | goto bad_area; | |
759496ba | 133 | flags |= FAULT_FLAG_WRITE; |
fbd7053a VG |
134 | } else { |
135 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
136 | goto bad_area; | |
137 | } | |
138 | ||
fbd7053a VG |
139 | /* |
140 | * If for any reason at all we couldn't handle the fault, | |
141 | * make sure we exit gracefully rather than endlessly redo | |
142 | * the fault. | |
143 | */ | |
dcddffd4 | 144 | fault = handle_mm_fault(vma, address, flags); |
fbd7053a VG |
145 | |
146 | /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */ | |
147 | if (unlikely(fatal_signal_pending(current))) { | |
148 | if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY)) | |
149 | up_read(&mm->mmap_sem); | |
150 | if (user_mode(regs)) | |
151 | return; | |
152 | } | |
153 | ||
ceed97ab VG |
154 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
155 | ||
fbd7053a VG |
156 | if (likely(!(fault & VM_FAULT_ERROR))) { |
157 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
158 | /* To avoid updating stats twice for retry case */ | |
ceed97ab | 159 | if (fault & VM_FAULT_MAJOR) { |
fbd7053a | 160 | tsk->maj_flt++; |
ceed97ab VG |
161 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, |
162 | regs, address); | |
163 | } else { | |
fbd7053a | 164 | tsk->min_flt++; |
ceed97ab VG |
165 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, |
166 | regs, address); | |
167 | } | |
fbd7053a VG |
168 | |
169 | if (fault & VM_FAULT_RETRY) { | |
170 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
171 | flags |= FAULT_FLAG_TRIED; | |
172 | goto retry; | |
173 | } | |
174 | } | |
175 | ||
176 | /* Fault Handled Gracefully */ | |
177 | up_read(&mm->mmap_sem); | |
178 | return; | |
179 | } | |
180 | ||
fbd7053a VG |
181 | if (fault & VM_FAULT_OOM) |
182 | goto out_of_memory; | |
e262eb93 | 183 | else if (fault & VM_FAULT_SIGSEGV) |
33692f27 | 184 | goto bad_area; |
fbd7053a VG |
185 | else if (fault & VM_FAULT_SIGBUS) |
186 | goto do_sigbus; | |
187 | ||
188 | /* no man's land */ | |
189 | BUG(); | |
190 | ||
191 | /* | |
192 | * Something tried to access memory that isn't in our memory map.. | |
193 | * Fix it, but check if it's kernel or user first.. | |
194 | */ | |
195 | bad_area: | |
196 | up_read(&mm->mmap_sem); | |
197 | ||
198 | bad_area_nosemaphore: | |
199 | /* User mode accesses just cause a SIGSEGV */ | |
200 | if (user_mode(regs)) { | |
201 | tsk->thread.fault_address = address; | |
fbd7053a VG |
202 | info.si_signo = SIGSEGV; |
203 | info.si_errno = 0; | |
204 | /* info.si_code has been set above */ | |
205 | info.si_addr = (void __user *)address; | |
206 | force_sig_info(SIGSEGV, &info, tsk); | |
207 | return; | |
208 | } | |
209 | ||
210 | no_context: | |
211 | /* Are we prepared to handle this kernel fault? | |
212 | * | |
213 | * (The kernel has valid exception-points in the source | |
ddf720f8 | 214 | * when it accesses user-memory. When it fails in one |
fbd7053a VG |
215 | * of those points, we find it in a table and do a jump |
216 | * to some fixup code that loads an appropriate error | |
217 | * code) | |
218 | */ | |
219 | if (fixup_exception(regs)) | |
220 | return; | |
221 | ||
38a9ff6d | 222 | die("Oops", regs, address); |
fbd7053a VG |
223 | |
224 | out_of_memory: | |
fbd7053a VG |
225 | up_read(&mm->mmap_sem); |
226 | ||
609838cf JW |
227 | if (user_mode(regs)) { |
228 | pagefault_out_of_memory(); | |
229 | return; | |
230 | } | |
fbd7053a VG |
231 | |
232 | goto no_context; | |
233 | ||
234 | do_sigbus: | |
235 | up_read(&mm->mmap_sem); | |
236 | ||
237 | if (!user_mode(regs)) | |
238 | goto no_context; | |
239 | ||
240 | tsk->thread.fault_address = address; | |
fbd7053a VG |
241 | info.si_signo = SIGBUS; |
242 | info.si_errno = 0; | |
243 | info.si_code = BUS_ADRERR; | |
244 | info.si_addr = (void __user *)address; | |
245 | force_sig_info(SIGBUS, &info, tsk); | |
246 | } |