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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> | |
17 | #include <asm/mmu_context.h> | |
18 | #include <asm/cacheflush.h> | |
19 | #include <asm/hardirq.h> | |
20 | #include <asm/uaccess.h> | |
21 | #include <asm/system.h> | |
22 | #include <asm/pgalloc.h> | |
23 | ||
173d6681 | 24 | unsigned long asid_cache = ASID_USER_FIRST; |
3f65ce4d CZ |
25 | void bad_page_fault(struct pt_regs*, unsigned long, int); |
26 | ||
6656920b CZ |
27 | #undef DEBUG_PAGE_FAULT |
28 | ||
3f65ce4d CZ |
29 | /* |
30 | * This routine handles page faults. It determines the address, | |
31 | * and the problem, and then passes it off to one of the appropriate | |
32 | * routines. | |
33 | * | |
34 | * Note: does not handle Miss and MultiHit. | |
35 | */ | |
36 | ||
37 | void do_page_fault(struct pt_regs *regs) | |
38 | { | |
39 | struct vm_area_struct * vma; | |
40 | struct mm_struct *mm = current->mm; | |
41 | unsigned int exccause = regs->exccause; | |
42 | unsigned int address = regs->excvaddr; | |
43 | siginfo_t info; | |
44 | ||
45 | int is_write, is_exec; | |
83c54070 | 46 | int fault; |
3f65ce4d CZ |
47 | |
48 | info.si_code = SEGV_MAPERR; | |
49 | ||
50 | /* We fault-in kernel-space virtual memory on-demand. The | |
51 | * 'reference' page table is init_mm.pgd. | |
52 | */ | |
53 | if (address >= TASK_SIZE && !user_mode(regs)) | |
54 | goto vmalloc_fault; | |
55 | ||
56 | /* If we're in an interrupt or have no user | |
57 | * context, we must not take the fault.. | |
58 | */ | |
59 | if (in_atomic() || !mm) { | |
60 | bad_page_fault(regs, address, SIGSEGV); | |
61 | return; | |
62 | } | |
63 | ||
173d6681 CZ |
64 | is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0; |
65 | is_exec = (exccause == EXCCAUSE_ITLB_PRIVILEGE || | |
66 | exccause == EXCCAUSE_ITLB_MISS || | |
67 | exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0; | |
3f65ce4d | 68 | |
6656920b | 69 | #ifdef DEBUG_PAGE_FAULT |
3f65ce4d CZ |
70 | printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid, |
71 | address, exccause, regs->pc, is_write? "w":"", is_exec? "x":""); | |
72 | #endif | |
73 | ||
74 | down_read(&mm->mmap_sem); | |
75 | vma = find_vma(mm, address); | |
76 | ||
77 | if (!vma) | |
78 | goto bad_area; | |
79 | if (vma->vm_start <= address) | |
80 | goto good_area; | |
81 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
82 | goto bad_area; | |
83 | if (expand_stack(vma, address)) | |
84 | goto bad_area; | |
85 | ||
86 | /* Ok, we have a good vm_area for this memory access, so | |
87 | * we can handle it.. | |
88 | */ | |
89 | ||
90 | good_area: | |
91 | info.si_code = SEGV_ACCERR; | |
92 | ||
93 | if (is_write) { | |
94 | if (!(vma->vm_flags & VM_WRITE)) | |
95 | goto bad_area; | |
96 | } else if (is_exec) { | |
97 | if (!(vma->vm_flags & VM_EXEC)) | |
98 | goto bad_area; | |
99 | } else /* Allow read even from write-only pages. */ | |
100 | if (!(vma->vm_flags & (VM_READ | VM_WRITE))) | |
101 | goto bad_area; | |
102 | ||
103 | /* If for any reason at all we couldn't handle the fault, | |
104 | * make sure we exit gracefully rather than endlessly redo | |
105 | * the fault. | |
106 | */ | |
107 | survive: | |
83c54070 NP |
108 | fault = handle_mm_fault(mm, vma, address, is_write); |
109 | if (unlikely(fault & VM_FAULT_ERROR)) { | |
110 | if (fault & VM_FAULT_OOM) | |
111 | goto out_of_memory; | |
112 | else if (fault & VM_FAULT_SIGBUS) | |
113 | goto do_sigbus; | |
3f65ce4d CZ |
114 | BUG(); |
115 | } | |
83c54070 NP |
116 | if (fault & VM_FAULT_MAJOR) |
117 | current->maj_flt++; | |
118 | else | |
119 | current->min_flt++; | |
3f65ce4d CZ |
120 | |
121 | up_read(&mm->mmap_sem); | |
122 | return; | |
123 | ||
124 | /* Something tried to access memory that isn't in our memory map.. | |
125 | * Fix it, but check if it's kernel or user first.. | |
126 | */ | |
127 | bad_area: | |
128 | up_read(&mm->mmap_sem); | |
129 | if (user_mode(regs)) { | |
130 | current->thread.bad_vaddr = address; | |
131 | current->thread.error_code = is_write; | |
132 | info.si_signo = SIGSEGV; | |
133 | info.si_errno = 0; | |
134 | /* info.si_code has been set above */ | |
135 | info.si_addr = (void *) address; | |
136 | force_sig_info(SIGSEGV, &info, current); | |
137 | return; | |
138 | } | |
139 | bad_page_fault(regs, address, SIGSEGV); | |
140 | return; | |
141 | ||
142 | ||
143 | /* We ran out of memory, or some other thing happened to us that made | |
144 | * us unable to handle the page fault gracefully. | |
145 | */ | |
146 | out_of_memory: | |
147 | up_read(&mm->mmap_sem); | |
f400e198 | 148 | if (is_init(current)) { |
3f65ce4d CZ |
149 | yield(); |
150 | down_read(&mm->mmap_sem); | |
151 | goto survive; | |
152 | } | |
153 | printk("VM: killing process %s\n", current->comm); | |
154 | if (user_mode(regs)) | |
155 | do_exit(SIGKILL); | |
156 | bad_page_fault(regs, address, SIGKILL); | |
157 | return; | |
158 | ||
159 | do_sigbus: | |
160 | up_read(&mm->mmap_sem); | |
161 | ||
162 | /* Send a sigbus, regardless of whether we were in kernel | |
163 | * or user mode. | |
164 | */ | |
165 | current->thread.bad_vaddr = address; | |
166 | info.si_code = SIGBUS; | |
167 | info.si_errno = 0; | |
168 | info.si_code = BUS_ADRERR; | |
169 | info.si_addr = (void *) address; | |
170 | force_sig_info(SIGBUS, &info, current); | |
171 | ||
172 | /* Kernel mode? Handle exceptions or die */ | |
173 | if (!user_mode(regs)) | |
174 | bad_page_fault(regs, address, SIGBUS); | |
175 | ||
176 | vmalloc_fault: | |
177 | { | |
178 | /* Synchronize this task's top level page-table | |
179 | * with the 'reference' page table. | |
180 | */ | |
181 | struct mm_struct *act_mm = current->active_mm; | |
182 | int index = pgd_index(address); | |
183 | pgd_t *pgd, *pgd_k; | |
184 | pmd_t *pmd, *pmd_k; | |
185 | pte_t *pte_k; | |
186 | ||
187 | if (act_mm == NULL) | |
188 | goto bad_page_fault; | |
189 | ||
190 | pgd = act_mm->pgd + index; | |
191 | pgd_k = init_mm.pgd + index; | |
192 | ||
193 | if (!pgd_present(*pgd_k)) | |
194 | goto bad_page_fault; | |
195 | ||
196 | pgd_val(*pgd) = pgd_val(*pgd_k); | |
197 | ||
198 | pmd = pmd_offset(pgd, address); | |
199 | pmd_k = pmd_offset(pgd_k, address); | |
200 | if (!pmd_present(*pmd) || !pmd_present(*pmd_k)) | |
201 | goto bad_page_fault; | |
202 | ||
203 | pmd_val(*pmd) = pmd_val(*pmd_k); | |
204 | pte_k = pte_offset_kernel(pmd_k, address); | |
205 | ||
206 | if (!pte_present(*pte_k)) | |
207 | goto bad_page_fault; | |
208 | return; | |
209 | } | |
210 | bad_page_fault: | |
211 | bad_page_fault(regs, address, SIGKILL); | |
212 | return; | |
213 | } | |
214 | ||
215 | ||
216 | void | |
217 | bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) | |
218 | { | |
219 | extern void die(const char*, struct pt_regs*, long); | |
220 | const struct exception_table_entry *entry; | |
221 | ||
222 | /* Are we prepared to handle this kernel fault? */ | |
223 | if ((entry = search_exception_tables(regs->pc)) != NULL) { | |
6656920b | 224 | #ifdef DEBUG_PAGE_FAULT |
3f65ce4d CZ |
225 | printk(KERN_DEBUG "%s: Exception at pc=%#010lx (%lx)\n", |
226 | current->comm, regs->pc, entry->fixup); | |
227 | #endif | |
228 | current->thread.bad_uaddr = address; | |
229 | regs->pc = entry->fixup; | |
230 | return; | |
231 | } | |
232 | ||
233 | /* Oops. The kernel tried to access some bad page. We'll have to | |
234 | * terminate things with extreme prejudice. | |
235 | */ | |
236 | printk(KERN_ALERT "Unable to handle kernel paging request at virtual " | |
237 | "address %08lx\n pc = %08lx, ra = %08lx\n", | |
238 | address, regs->pc, regs->areg[0]); | |
239 | die("Oops", regs, sig); | |
240 | do_exit(sig); | |
241 | } | |
242 |