Commit | Line | Data |
---|---|---|
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> | |
12 | #include <linux/sched.h> | |
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> |
fbd7053a | 18 | #include <asm/pgalloc.h> |
da1677b0 | 19 | #include <asm/mmu.h> |
fbd7053a | 20 | |
9c41f4ee | 21 | static int handle_vmalloc_fault(unsigned long address) |
fbd7053a VG |
22 | { |
23 | /* | |
24 | * Synchronize this task's top level page-table | |
25 | * with the 'reference' page table. | |
26 | */ | |
27 | pgd_t *pgd, *pgd_k; | |
28 | pud_t *pud, *pud_k; | |
29 | pmd_t *pmd, *pmd_k; | |
30 | ||
9c41f4ee | 31 | pgd = pgd_offset_fast(current->active_mm, address); |
fbd7053a VG |
32 | pgd_k = pgd_offset_k(address); |
33 | ||
34 | if (!pgd_present(*pgd_k)) | |
35 | goto bad_area; | |
36 | ||
37 | pud = pud_offset(pgd, address); | |
38 | pud_k = pud_offset(pgd_k, address); | |
39 | if (!pud_present(*pud_k)) | |
40 | goto bad_area; | |
41 | ||
42 | pmd = pmd_offset(pud, address); | |
43 | pmd_k = pmd_offset(pud_k, address); | |
44 | if (!pmd_present(*pmd_k)) | |
45 | goto bad_area; | |
46 | ||
47 | set_pmd(pmd, *pmd_k); | |
48 | ||
49 | /* XXX: create the TLB entry here */ | |
50 | return 0; | |
51 | ||
52 | bad_area: | |
53 | return 1; | |
54 | } | |
55 | ||
21a63b56 | 56 | void do_page_fault(unsigned long address, struct pt_regs *regs) |
fbd7053a VG |
57 | { |
58 | struct vm_area_struct *vma = NULL; | |
59 | struct task_struct *tsk = current; | |
60 | struct mm_struct *mm = tsk->mm; | |
61 | siginfo_t info; | |
62 | int fault, ret; | |
38a9ff6d | 63 | int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ |
759496ba | 64 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
fbd7053a VG |
65 | |
66 | /* | |
67 | * We fault-in kernel-space virtual memory on-demand. The | |
68 | * 'reference' page table is init_mm.pgd. | |
69 | * | |
70 | * NOTE! We MUST NOT take any locks for this case. We may | |
71 | * be in an interrupt or a critical region, and should | |
72 | * only copy the information from the master page table, | |
73 | * nothing more. | |
74 | */ | |
75 | if (address >= VMALLOC_START && address <= VMALLOC_END) { | |
9c41f4ee | 76 | ret = handle_vmalloc_fault(address); |
fbd7053a VG |
77 | if (unlikely(ret)) |
78 | goto bad_area_nosemaphore; | |
79 | else | |
80 | return; | |
81 | } | |
82 | ||
83 | info.si_code = SEGV_MAPERR; | |
84 | ||
85 | /* | |
86 | * If we're in an interrupt or have no user | |
87 | * context, we must not take the fault.. | |
88 | */ | |
89 | if (in_atomic() || !mm) | |
90 | goto no_context; | |
91 | ||
759496ba JW |
92 | if (user_mode(regs)) |
93 | flags |= FAULT_FLAG_USER; | |
fbd7053a VG |
94 | retry: |
95 | down_read(&mm->mmap_sem); | |
96 | vma = find_vma(mm, address); | |
97 | if (!vma) | |
98 | goto bad_area; | |
99 | if (vma->vm_start <= address) | |
100 | goto good_area; | |
101 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
102 | goto bad_area; | |
103 | if (expand_stack(vma, address)) | |
104 | goto bad_area; | |
105 | ||
106 | /* | |
107 | * Ok, we have a good vm_area for this memory access, so | |
108 | * we can handle it.. | |
109 | */ | |
110 | good_area: | |
111 | info.si_code = SEGV_ACCERR; | |
112 | ||
113 | /* Handle protection violation, execute on heap or stack */ | |
114 | ||
38a9ff6d VG |
115 | if ((regs->ecr_vec == ECR_V_PROTV) && |
116 | (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) | |
fbd7053a VG |
117 | goto bad_area; |
118 | ||
119 | if (write) { | |
120 | if (!(vma->vm_flags & VM_WRITE)) | |
121 | goto bad_area; | |
759496ba | 122 | flags |= FAULT_FLAG_WRITE; |
fbd7053a VG |
123 | } else { |
124 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
125 | goto bad_area; | |
126 | } | |
127 | ||
fbd7053a VG |
128 | /* |
129 | * If for any reason at all we couldn't handle the fault, | |
130 | * make sure we exit gracefully rather than endlessly redo | |
131 | * the fault. | |
132 | */ | |
133 | fault = handle_mm_fault(mm, vma, address, flags); | |
134 | ||
135 | /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */ | |
136 | if (unlikely(fatal_signal_pending(current))) { | |
137 | if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY)) | |
138 | up_read(&mm->mmap_sem); | |
139 | if (user_mode(regs)) | |
140 | return; | |
141 | } | |
142 | ||
ceed97ab VG |
143 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
144 | ||
fbd7053a VG |
145 | if (likely(!(fault & VM_FAULT_ERROR))) { |
146 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
147 | /* To avoid updating stats twice for retry case */ | |
ceed97ab | 148 | if (fault & VM_FAULT_MAJOR) { |
fbd7053a | 149 | tsk->maj_flt++; |
ceed97ab VG |
150 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, |
151 | regs, address); | |
152 | } else { | |
fbd7053a | 153 | tsk->min_flt++; |
ceed97ab VG |
154 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, |
155 | regs, address); | |
156 | } | |
fbd7053a VG |
157 | |
158 | if (fault & VM_FAULT_RETRY) { | |
159 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
160 | flags |= FAULT_FLAG_TRIED; | |
161 | goto retry; | |
162 | } | |
163 | } | |
164 | ||
165 | /* Fault Handled Gracefully */ | |
166 | up_read(&mm->mmap_sem); | |
167 | return; | |
168 | } | |
169 | ||
fbd7053a VG |
170 | if (fault & VM_FAULT_OOM) |
171 | goto out_of_memory; | |
e262eb93 | 172 | else if (fault & VM_FAULT_SIGSEGV) |
33692f27 | 173 | goto bad_area; |
fbd7053a VG |
174 | else if (fault & VM_FAULT_SIGBUS) |
175 | goto do_sigbus; | |
176 | ||
177 | /* no man's land */ | |
178 | BUG(); | |
179 | ||
180 | /* | |
181 | * Something tried to access memory that isn't in our memory map.. | |
182 | * Fix it, but check if it's kernel or user first.. | |
183 | */ | |
184 | bad_area: | |
185 | up_read(&mm->mmap_sem); | |
186 | ||
187 | bad_area_nosemaphore: | |
188 | /* User mode accesses just cause a SIGSEGV */ | |
189 | if (user_mode(regs)) { | |
190 | tsk->thread.fault_address = address; | |
fbd7053a VG |
191 | info.si_signo = SIGSEGV; |
192 | info.si_errno = 0; | |
193 | /* info.si_code has been set above */ | |
194 | info.si_addr = (void __user *)address; | |
195 | force_sig_info(SIGSEGV, &info, tsk); | |
196 | return; | |
197 | } | |
198 | ||
199 | no_context: | |
200 | /* Are we prepared to handle this kernel fault? | |
201 | * | |
202 | * (The kernel has valid exception-points in the source | |
203 | * when it acesses user-memory. When it fails in one | |
204 | * of those points, we find it in a table and do a jump | |
205 | * to some fixup code that loads an appropriate error | |
206 | * code) | |
207 | */ | |
208 | if (fixup_exception(regs)) | |
209 | return; | |
210 | ||
38a9ff6d | 211 | die("Oops", regs, address); |
fbd7053a VG |
212 | |
213 | out_of_memory: | |
fbd7053a VG |
214 | up_read(&mm->mmap_sem); |
215 | ||
609838cf JW |
216 | if (user_mode(regs)) { |
217 | pagefault_out_of_memory(); | |
218 | return; | |
219 | } | |
fbd7053a VG |
220 | |
221 | goto no_context; | |
222 | ||
223 | do_sigbus: | |
224 | up_read(&mm->mmap_sem); | |
225 | ||
226 | if (!user_mode(regs)) | |
227 | goto no_context; | |
228 | ||
229 | tsk->thread.fault_address = address; | |
fbd7053a VG |
230 | info.si_signo = SIGBUS; |
231 | info.si_errno = 0; | |
232 | info.si_code = BUS_ADRERR; | |
233 | info.si_addr = (void __user *)address; | |
234 | force_sig_info(SIGBUS, &info, tsk); | |
235 | } |