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3f65ce4d CZ |
1 | // TODO VM_EXEC flag work-around, cache aliasing |
2 | /* | |
3 | * arch/xtensa/mm/fault.c | |
4 | * | |
5 | * This file is subject to the terms and conditions of the GNU General Public | |
6 | * License. See the file "COPYING" in the main directory of this archive | |
7 | * for more details. | |
8 | * | |
9 | * Copyright (C) 2001 - 2005 Tensilica Inc. | |
10 | * | |
11 | * Chris Zankel <chris@zankel.net> | |
12 | * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com> | |
13 | */ | |
14 | ||
15 | #include <linux/mm.h> | |
16 | #include <linux/module.h> | |
5a891ed5 | 17 | #include <linux/hardirq.h> |
3f65ce4d CZ |
18 | #include <asm/mmu_context.h> |
19 | #include <asm/cacheflush.h> | |
20 | #include <asm/hardirq.h> | |
21 | #include <asm/uaccess.h> | |
22 | #include <asm/system.h> | |
23 | #include <asm/pgalloc.h> | |
24 | ||
173d6681 | 25 | unsigned long asid_cache = ASID_USER_FIRST; |
3f65ce4d CZ |
26 | void bad_page_fault(struct pt_regs*, unsigned long, int); |
27 | ||
6656920b CZ |
28 | #undef DEBUG_PAGE_FAULT |
29 | ||
3f65ce4d CZ |
30 | /* |
31 | * This routine handles page faults. It determines the address, | |
32 | * and the problem, and then passes it off to one of the appropriate | |
33 | * routines. | |
34 | * | |
35 | * Note: does not handle Miss and MultiHit. | |
36 | */ | |
37 | ||
38 | void do_page_fault(struct pt_regs *regs) | |
39 | { | |
40 | struct vm_area_struct * vma; | |
41 | struct mm_struct *mm = current->mm; | |
42 | unsigned int exccause = regs->exccause; | |
43 | unsigned int address = regs->excvaddr; | |
44 | siginfo_t info; | |
45 | ||
46 | int is_write, is_exec; | |
83c54070 | 47 | int fault; |
3f65ce4d CZ |
48 | |
49 | info.si_code = SEGV_MAPERR; | |
50 | ||
51 | /* We fault-in kernel-space virtual memory on-demand. The | |
52 | * 'reference' page table is init_mm.pgd. | |
53 | */ | |
54 | if (address >= TASK_SIZE && !user_mode(regs)) | |
55 | goto vmalloc_fault; | |
56 | ||
57 | /* If we're in an interrupt or have no user | |
58 | * context, we must not take the fault.. | |
59 | */ | |
60 | if (in_atomic() || !mm) { | |
61 | bad_page_fault(regs, address, SIGSEGV); | |
62 | return; | |
63 | } | |
64 | ||
173d6681 CZ |
65 | is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0; |
66 | is_exec = (exccause == EXCCAUSE_ITLB_PRIVILEGE || | |
67 | exccause == EXCCAUSE_ITLB_MISS || | |
68 | exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0; | |
3f65ce4d | 69 | |
6656920b | 70 | #ifdef DEBUG_PAGE_FAULT |
3f65ce4d CZ |
71 | printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid, |
72 | address, exccause, regs->pc, is_write? "w":"", is_exec? "x":""); | |
73 | #endif | |
74 | ||
75 | down_read(&mm->mmap_sem); | |
76 | vma = find_vma(mm, address); | |
77 | ||
78 | if (!vma) | |
79 | goto bad_area; | |
80 | if (vma->vm_start <= address) | |
81 | goto good_area; | |
82 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
83 | goto bad_area; | |
84 | if (expand_stack(vma, address)) | |
85 | goto bad_area; | |
86 | ||
87 | /* Ok, we have a good vm_area for this memory access, so | |
88 | * we can handle it.. | |
89 | */ | |
90 | ||
91 | good_area: | |
92 | info.si_code = SEGV_ACCERR; | |
93 | ||
94 | if (is_write) { | |
95 | if (!(vma->vm_flags & VM_WRITE)) | |
96 | goto bad_area; | |
97 | } else if (is_exec) { | |
98 | if (!(vma->vm_flags & VM_EXEC)) | |
99 | goto bad_area; | |
100 | } else /* Allow read even from write-only pages. */ | |
101 | if (!(vma->vm_flags & (VM_READ | VM_WRITE))) | |
102 | goto bad_area; | |
103 | ||
104 | /* If for any reason at all we couldn't handle the fault, | |
105 | * make sure we exit gracefully rather than endlessly redo | |
106 | * the fault. | |
107 | */ | |
108 | survive: | |
d06063cc | 109 | fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0); |
83c54070 NP |
110 | if (unlikely(fault & VM_FAULT_ERROR)) { |
111 | if (fault & VM_FAULT_OOM) | |
112 | goto out_of_memory; | |
113 | else if (fault & VM_FAULT_SIGBUS) | |
114 | goto do_sigbus; | |
3f65ce4d CZ |
115 | BUG(); |
116 | } | |
83c54070 NP |
117 | if (fault & VM_FAULT_MAJOR) |
118 | current->maj_flt++; | |
119 | else | |
120 | current->min_flt++; | |
3f65ce4d CZ |
121 | |
122 | up_read(&mm->mmap_sem); | |
123 | return; | |
124 | ||
125 | /* Something tried to access memory that isn't in our memory map.. | |
126 | * Fix it, but check if it's kernel or user first.. | |
127 | */ | |
128 | bad_area: | |
129 | up_read(&mm->mmap_sem); | |
130 | if (user_mode(regs)) { | |
131 | current->thread.bad_vaddr = address; | |
132 | current->thread.error_code = is_write; | |
133 | info.si_signo = SIGSEGV; | |
134 | info.si_errno = 0; | |
135 | /* info.si_code has been set above */ | |
136 | info.si_addr = (void *) address; | |
137 | force_sig_info(SIGSEGV, &info, current); | |
138 | return; | |
139 | } | |
140 | bad_page_fault(regs, address, SIGSEGV); | |
141 | return; | |
142 | ||
143 | ||
144 | /* We ran out of memory, or some other thing happened to us that made | |
145 | * us unable to handle the page fault gracefully. | |
146 | */ | |
147 | out_of_memory: | |
148 | up_read(&mm->mmap_sem); | |
b460cbc5 | 149 | if (is_global_init(current)) { |
3f65ce4d CZ |
150 | yield(); |
151 | down_read(&mm->mmap_sem); | |
152 | goto survive; | |
153 | } | |
154 | printk("VM: killing process %s\n", current->comm); | |
155 | if (user_mode(regs)) | |
dcca2bde | 156 | do_group_exit(SIGKILL); |
3f65ce4d CZ |
157 | bad_page_fault(regs, address, SIGKILL); |
158 | return; | |
159 | ||
160 | do_sigbus: | |
161 | up_read(&mm->mmap_sem); | |
162 | ||
163 | /* Send a sigbus, regardless of whether we were in kernel | |
164 | * or user mode. | |
165 | */ | |
166 | current->thread.bad_vaddr = address; | |
167 | info.si_code = SIGBUS; | |
168 | info.si_errno = 0; | |
169 | info.si_code = BUS_ADRERR; | |
170 | info.si_addr = (void *) address; | |
171 | force_sig_info(SIGBUS, &info, current); | |
172 | ||
173 | /* Kernel mode? Handle exceptions or die */ | |
174 | if (!user_mode(regs)) | |
175 | bad_page_fault(regs, address, SIGBUS); | |
176 | ||
177 | vmalloc_fault: | |
178 | { | |
179 | /* Synchronize this task's top level page-table | |
180 | * with the 'reference' page table. | |
181 | */ | |
182 | struct mm_struct *act_mm = current->active_mm; | |
183 | int index = pgd_index(address); | |
184 | pgd_t *pgd, *pgd_k; | |
185 | pmd_t *pmd, *pmd_k; | |
186 | pte_t *pte_k; | |
187 | ||
188 | if (act_mm == NULL) | |
189 | goto bad_page_fault; | |
190 | ||
191 | pgd = act_mm->pgd + index; | |
192 | pgd_k = init_mm.pgd + index; | |
193 | ||
194 | if (!pgd_present(*pgd_k)) | |
195 | goto bad_page_fault; | |
196 | ||
197 | pgd_val(*pgd) = pgd_val(*pgd_k); | |
198 | ||
199 | pmd = pmd_offset(pgd, address); | |
200 | pmd_k = pmd_offset(pgd_k, address); | |
201 | if (!pmd_present(*pmd) || !pmd_present(*pmd_k)) | |
202 | goto bad_page_fault; | |
203 | ||
204 | pmd_val(*pmd) = pmd_val(*pmd_k); | |
205 | pte_k = pte_offset_kernel(pmd_k, address); | |
206 | ||
207 | if (!pte_present(*pte_k)) | |
208 | goto bad_page_fault; | |
209 | return; | |
210 | } | |
211 | bad_page_fault: | |
212 | bad_page_fault(regs, address, SIGKILL); | |
213 | return; | |
214 | } | |
215 | ||
216 | ||
217 | void | |
218 | bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) | |
219 | { | |
220 | extern void die(const char*, struct pt_regs*, long); | |
221 | const struct exception_table_entry *entry; | |
222 | ||
223 | /* Are we prepared to handle this kernel fault? */ | |
224 | if ((entry = search_exception_tables(regs->pc)) != NULL) { | |
6656920b | 225 | #ifdef DEBUG_PAGE_FAULT |
3f65ce4d CZ |
226 | printk(KERN_DEBUG "%s: Exception at pc=%#010lx (%lx)\n", |
227 | current->comm, regs->pc, entry->fixup); | |
228 | #endif | |
229 | current->thread.bad_uaddr = address; | |
230 | regs->pc = entry->fixup; | |
231 | return; | |
232 | } | |
233 | ||
234 | /* Oops. The kernel tried to access some bad page. We'll have to | |
235 | * terminate things with extreme prejudice. | |
236 | */ | |
237 | printk(KERN_ALERT "Unable to handle kernel paging request at virtual " | |
238 | "address %08lx\n pc = %08lx, ra = %08lx\n", | |
239 | address, regs->pc, regs->areg[0]); | |
240 | die("Oops", regs, sig); | |
241 | do_exit(sig); | |
242 | } | |
243 |