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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * PowerPC version |
3 | * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) | |
4 | * | |
5 | * Derived from "arch/i386/mm/fault.c" | |
6 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
7 | * | |
8 | * Modified by Cort Dougan and Paul Mackerras. | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License | |
12 | * as published by the Free Software Foundation; either version | |
13 | * 2 of the License, or (at your option) any later version. | |
14 | */ | |
15 | ||
16 | #include <linux/config.h> | |
17 | #include <linux/signal.h> | |
18 | #include <linux/sched.h> | |
19 | #include <linux/kernel.h> | |
20 | #include <linux/errno.h> | |
21 | #include <linux/string.h> | |
22 | #include <linux/types.h> | |
23 | #include <linux/ptrace.h> | |
24 | #include <linux/mman.h> | |
25 | #include <linux/mm.h> | |
26 | #include <linux/interrupt.h> | |
27 | #include <linux/highmem.h> | |
28 | #include <linux/module.h> | |
29 | ||
30 | #include <asm/page.h> | |
31 | #include <asm/pgtable.h> | |
32 | #include <asm/mmu.h> | |
33 | #include <asm/mmu_context.h> | |
34 | #include <asm/system.h> | |
35 | #include <asm/uaccess.h> | |
36 | #include <asm/tlbflush.h> | |
37 | ||
38 | #if defined(CONFIG_XMON) || defined(CONFIG_KGDB) | |
39 | extern void (*debugger)(struct pt_regs *); | |
40 | extern void (*debugger_fault_handler)(struct pt_regs *); | |
41 | extern int (*debugger_dabr_match)(struct pt_regs *); | |
42 | int debugger_kernel_faults = 1; | |
43 | #endif | |
44 | ||
45 | unsigned long htab_reloads; /* updated by hashtable.S:hash_page() */ | |
46 | unsigned long htab_evicts; /* updated by hashtable.S:hash_page() */ | |
47 | unsigned long htab_preloads; /* updated by hashtable.S:add_hash_page() */ | |
48 | unsigned long pte_misses; /* updated by do_page_fault() */ | |
49 | unsigned long pte_errors; /* updated by do_page_fault() */ | |
50 | unsigned int probingmem; | |
51 | ||
52 | /* | |
53 | * Check whether the instruction at regs->nip is a store using | |
54 | * an update addressing form which will update r1. | |
55 | */ | |
56 | static int store_updates_sp(struct pt_regs *regs) | |
57 | { | |
58 | unsigned int inst; | |
59 | ||
60 | if (get_user(inst, (unsigned int __user *)regs->nip)) | |
61 | return 0; | |
62 | /* check for 1 in the rA field */ | |
63 | if (((inst >> 16) & 0x1f) != 1) | |
64 | return 0; | |
65 | /* check major opcode */ | |
66 | switch (inst >> 26) { | |
67 | case 37: /* stwu */ | |
68 | case 39: /* stbu */ | |
69 | case 45: /* sthu */ | |
70 | case 53: /* stfsu */ | |
71 | case 55: /* stfdu */ | |
72 | return 1; | |
73 | case 31: | |
74 | /* check minor opcode */ | |
75 | switch ((inst >> 1) & 0x3ff) { | |
76 | case 183: /* stwux */ | |
77 | case 247: /* stbux */ | |
78 | case 439: /* sthux */ | |
79 | case 695: /* stfsux */ | |
80 | case 759: /* stfdux */ | |
81 | return 1; | |
82 | } | |
83 | } | |
84 | return 0; | |
85 | } | |
86 | ||
87 | /* | |
88 | * For 600- and 800-family processors, the error_code parameter is DSISR | |
89 | * for a data fault, SRR1 for an instruction fault. For 400-family processors | |
90 | * the error_code parameter is ESR for a data fault, 0 for an instruction | |
91 | * fault. | |
92 | */ | |
93 | int do_page_fault(struct pt_regs *regs, unsigned long address, | |
94 | unsigned long error_code) | |
95 | { | |
96 | struct vm_area_struct * vma; | |
97 | struct mm_struct *mm = current->mm; | |
98 | siginfo_t info; | |
99 | int code = SEGV_MAPERR; | |
100 | #if defined(CONFIG_4xx) || defined (CONFIG_BOOKE) | |
101 | int is_write = error_code & ESR_DST; | |
102 | #else | |
103 | int is_write = 0; | |
104 | ||
105 | /* | |
106 | * Fortunately the bit assignments in SRR1 for an instruction | |
107 | * fault and DSISR for a data fault are mostly the same for the | |
108 | * bits we are interested in. But there are some bits which | |
109 | * indicate errors in DSISR but can validly be set in SRR1. | |
110 | */ | |
111 | if (TRAP(regs) == 0x400) | |
112 | error_code &= 0x48200000; | |
113 | else | |
114 | is_write = error_code & 0x02000000; | |
115 | #endif /* CONFIG_4xx || CONFIG_BOOKE */ | |
116 | ||
117 | #if defined(CONFIG_XMON) || defined(CONFIG_KGDB) | |
118 | if (debugger_fault_handler && TRAP(regs) == 0x300) { | |
119 | debugger_fault_handler(regs); | |
120 | return 0; | |
121 | } | |
122 | #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) | |
123 | if (error_code & 0x00400000) { | |
124 | /* DABR match */ | |
125 | if (debugger_dabr_match(regs)) | |
126 | return 0; | |
127 | } | |
128 | #endif /* !(CONFIG_4xx || CONFIG_BOOKE)*/ | |
129 | #endif /* CONFIG_XMON || CONFIG_KGDB */ | |
130 | ||
131 | if (in_atomic() || mm == NULL) | |
132 | return SIGSEGV; | |
133 | ||
134 | down_read(&mm->mmap_sem); | |
135 | vma = find_vma(mm, address); | |
136 | if (!vma) | |
137 | goto bad_area; | |
138 | if (vma->vm_start <= address) | |
139 | goto good_area; | |
140 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
141 | goto bad_area; | |
142 | if (!is_write) | |
143 | goto bad_area; | |
144 | ||
145 | /* | |
146 | * N.B. The rs6000/xcoff ABI allows programs to access up to | |
147 | * a few hundred bytes below the stack pointer. | |
148 | * The kernel signal delivery code writes up to about 1.5kB | |
149 | * below the stack pointer (r1) before decrementing it. | |
150 | * The exec code can write slightly over 640kB to the stack | |
151 | * before setting the user r1. Thus we allow the stack to | |
152 | * expand to 1MB without further checks. | |
153 | */ | |
154 | if (address + 0x100000 < vma->vm_end) { | |
155 | /* get user regs even if this fault is in kernel mode */ | |
156 | struct pt_regs *uregs = current->thread.regs; | |
157 | if (uregs == NULL) | |
158 | goto bad_area; | |
159 | ||
160 | /* | |
161 | * A user-mode access to an address a long way below | |
162 | * the stack pointer is only valid if the instruction | |
163 | * is one which would update the stack pointer to the | |
164 | * address accessed if the instruction completed, | |
165 | * i.e. either stwu rs,n(r1) or stwux rs,r1,rb | |
166 | * (or the byte, halfword, float or double forms). | |
167 | * | |
168 | * If we don't check this then any write to the area | |
169 | * between the last mapped region and the stack will | |
170 | * expand the stack rather than segfaulting. | |
171 | */ | |
172 | if (address + 2048 < uregs->gpr[1] | |
173 | && (!user_mode(regs) || !store_updates_sp(regs))) | |
174 | goto bad_area; | |
175 | } | |
176 | if (expand_stack(vma, address)) | |
177 | goto bad_area; | |
178 | ||
179 | good_area: | |
180 | code = SEGV_ACCERR; | |
181 | #if defined(CONFIG_6xx) | |
182 | if (error_code & 0x95700000) | |
183 | /* an error such as lwarx to I/O controller space, | |
184 | address matching DABR, eciwx, etc. */ | |
185 | goto bad_area; | |
186 | #endif /* CONFIG_6xx */ | |
187 | #if defined(CONFIG_8xx) | |
188 | /* The MPC8xx seems to always set 0x80000000, which is | |
189 | * "undefined". Of those that can be set, this is the only | |
190 | * one which seems bad. | |
191 | */ | |
192 | if (error_code & 0x10000000) | |
193 | /* Guarded storage error. */ | |
194 | goto bad_area; | |
195 | #endif /* CONFIG_8xx */ | |
196 | ||
197 | /* a write */ | |
198 | if (is_write) { | |
199 | if (!(vma->vm_flags & VM_WRITE)) | |
200 | goto bad_area; | |
201 | #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE) | |
202 | /* an exec - 4xx/Book-E allows for per-page execute permission */ | |
203 | } else if (TRAP(regs) == 0x400) { | |
204 | pte_t *ptep; | |
205 | ||
206 | #if 0 | |
207 | /* It would be nice to actually enforce the VM execute | |
208 | permission on CPUs which can do so, but far too | |
209 | much stuff in userspace doesn't get the permissions | |
210 | right, so we let any page be executed for now. */ | |
211 | if (! (vma->vm_flags & VM_EXEC)) | |
212 | goto bad_area; | |
213 | #endif | |
214 | ||
215 | /* Since 4xx/Book-E supports per-page execute permission, | |
216 | * we lazily flush dcache to icache. */ | |
217 | ptep = NULL; | |
218 | if (get_pteptr(mm, address, &ptep) && pte_present(*ptep)) { | |
219 | struct page *page = pte_page(*ptep); | |
220 | ||
221 | if (! test_bit(PG_arch_1, &page->flags)) { | |
222 | flush_dcache_icache_page(page); | |
223 | set_bit(PG_arch_1, &page->flags); | |
224 | } | |
225 | pte_update(ptep, 0, _PAGE_HWEXEC); | |
226 | _tlbie(address); | |
227 | pte_unmap(ptep); | |
228 | up_read(&mm->mmap_sem); | |
229 | return 0; | |
230 | } | |
231 | if (ptep != NULL) | |
232 | pte_unmap(ptep); | |
233 | #endif | |
234 | /* a read */ | |
235 | } else { | |
236 | /* protection fault */ | |
237 | if (error_code & 0x08000000) | |
238 | goto bad_area; | |
239 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
240 | goto bad_area; | |
241 | } | |
242 | ||
243 | /* | |
244 | * If for any reason at all we couldn't handle the fault, | |
245 | * make sure we exit gracefully rather than endlessly redo | |
246 | * the fault. | |
247 | */ | |
248 | survive: | |
249 | switch (handle_mm_fault(mm, vma, address, is_write)) { | |
250 | case VM_FAULT_MINOR: | |
251 | current->min_flt++; | |
252 | break; | |
253 | case VM_FAULT_MAJOR: | |
254 | current->maj_flt++; | |
255 | break; | |
256 | case VM_FAULT_SIGBUS: | |
257 | goto do_sigbus; | |
258 | case VM_FAULT_OOM: | |
259 | goto out_of_memory; | |
260 | default: | |
261 | BUG(); | |
262 | } | |
263 | ||
264 | up_read(&mm->mmap_sem); | |
265 | /* | |
266 | * keep track of tlb+htab misses that are good addrs but | |
267 | * just need pte's created via handle_mm_fault() | |
268 | * -- Cort | |
269 | */ | |
270 | pte_misses++; | |
271 | return 0; | |
272 | ||
273 | bad_area: | |
274 | up_read(&mm->mmap_sem); | |
275 | pte_errors++; | |
276 | ||
277 | /* User mode accesses cause a SIGSEGV */ | |
278 | if (user_mode(regs)) { | |
bb0bb3b6 | 279 | _exception(SIGSEGV, regs, code, address); |
1da177e4 LT |
280 | return 0; |
281 | } | |
282 | ||
283 | return SIGSEGV; | |
284 | ||
285 | /* | |
286 | * We ran out of memory, or some other thing happened to us that made | |
287 | * us unable to handle the page fault gracefully. | |
288 | */ | |
289 | out_of_memory: | |
290 | up_read(&mm->mmap_sem); | |
291 | if (current->pid == 1) { | |
292 | yield(); | |
293 | down_read(&mm->mmap_sem); | |
294 | goto survive; | |
295 | } | |
296 | printk("VM: killing process %s\n", current->comm); | |
297 | if (user_mode(regs)) | |
298 | do_exit(SIGKILL); | |
299 | return SIGKILL; | |
300 | ||
301 | do_sigbus: | |
302 | up_read(&mm->mmap_sem); | |
303 | info.si_signo = SIGBUS; | |
304 | info.si_errno = 0; | |
305 | info.si_code = BUS_ADRERR; | |
306 | info.si_addr = (void __user *)address; | |
307 | force_sig_info (SIGBUS, &info, current); | |
308 | if (!user_mode(regs)) | |
309 | return SIGBUS; | |
310 | return 0; | |
311 | } | |
312 | ||
313 | /* | |
314 | * bad_page_fault is called when we have a bad access from the kernel. | |
315 | * It is called from the DSI and ISI handlers in head.S and from some | |
316 | * of the procedures in traps.c. | |
317 | */ | |
318 | void | |
319 | bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) | |
320 | { | |
321 | const struct exception_table_entry *entry; | |
322 | ||
323 | /* Are we prepared to handle this fault? */ | |
324 | if ((entry = search_exception_tables(regs->nip)) != NULL) { | |
325 | regs->nip = entry->fixup; | |
326 | return; | |
327 | } | |
328 | ||
329 | /* kernel has accessed a bad area */ | |
330 | #if defined(CONFIG_XMON) || defined(CONFIG_KGDB) | |
331 | if (debugger_kernel_faults) | |
332 | debugger(regs); | |
333 | #endif | |
334 | die("kernel access of bad area", regs, sig); | |
335 | } | |
336 | ||
337 | #ifdef CONFIG_8xx | |
338 | ||
339 | /* The pgtable.h claims some functions generically exist, but I | |
340 | * can't find them...... | |
341 | */ | |
342 | pte_t *va_to_pte(unsigned long address) | |
343 | { | |
344 | pgd_t *dir; | |
345 | pmd_t *pmd; | |
346 | pte_t *pte; | |
347 | ||
348 | if (address < TASK_SIZE) | |
349 | return NULL; | |
350 | ||
351 | dir = pgd_offset(&init_mm, address); | |
352 | if (dir) { | |
353 | pmd = pmd_offset(dir, address & PAGE_MASK); | |
354 | if (pmd && pmd_present(*pmd)) { | |
355 | pte = pte_offset_kernel(pmd, address & PAGE_MASK); | |
356 | if (pte && pte_present(*pte)) | |
357 | return(pte); | |
358 | } | |
359 | } | |
360 | return NULL; | |
361 | } | |
362 | ||
363 | unsigned long va_to_phys(unsigned long address) | |
364 | { | |
365 | pte_t *pte; | |
366 | ||
367 | pte = va_to_pte(address); | |
368 | if (pte) | |
369 | return(((unsigned long)(pte_val(*pte)) & PAGE_MASK) | (address & ~(PAGE_MASK))); | |
370 | return (0); | |
371 | } | |
372 | ||
373 | void | |
374 | print_8xx_pte(struct mm_struct *mm, unsigned long addr) | |
375 | { | |
376 | pgd_t * pgd; | |
377 | pmd_t * pmd; | |
378 | pte_t * pte; | |
379 | ||
380 | printk(" pte @ 0x%8lx: ", addr); | |
381 | pgd = pgd_offset(mm, addr & PAGE_MASK); | |
382 | if (pgd) { | |
383 | pmd = pmd_offset(pgd, addr & PAGE_MASK); | |
384 | if (pmd && pmd_present(*pmd)) { | |
385 | pte = pte_offset_kernel(pmd, addr & PAGE_MASK); | |
386 | if (pte) { | |
387 | printk(" (0x%08lx)->(0x%08lx)->0x%08lx\n", | |
388 | (long)pgd, (long)pte, (long)pte_val(*pte)); | |
389 | #define pp ((long)pte_val(*pte)) | |
390 | printk(" RPN: %05lx PP: %lx SPS: %lx SH: %lx " | |
391 | "CI: %lx v: %lx\n", | |
392 | pp>>12, /* rpn */ | |
393 | (pp>>10)&3, /* pp */ | |
394 | (pp>>3)&1, /* small */ | |
395 | (pp>>2)&1, /* shared */ | |
396 | (pp>>1)&1, /* cache inhibit */ | |
397 | pp&1 /* valid */ | |
398 | ); | |
399 | #undef pp | |
400 | } | |
401 | else { | |
402 | printk("no pte\n"); | |
403 | } | |
404 | } | |
405 | else { | |
406 | printk("no pmd\n"); | |
407 | } | |
408 | } | |
409 | else { | |
410 | printk("no pgd\n"); | |
411 | } | |
412 | } | |
413 | ||
414 | int | |
415 | get_8xx_pte(struct mm_struct *mm, unsigned long addr) | |
416 | { | |
417 | pgd_t * pgd; | |
418 | pmd_t * pmd; | |
419 | pte_t * pte; | |
420 | int retval = 0; | |
421 | ||
422 | pgd = pgd_offset(mm, addr & PAGE_MASK); | |
423 | if (pgd) { | |
424 | pmd = pmd_offset(pgd, addr & PAGE_MASK); | |
425 | if (pmd && pmd_present(*pmd)) { | |
426 | pte = pte_offset_kernel(pmd, addr & PAGE_MASK); | |
427 | if (pte) { | |
428 | retval = (int)pte_val(*pte); | |
429 | } | |
430 | } | |
431 | } | |
432 | return(retval); | |
433 | } | |
434 | #endif /* CONFIG_8xx */ |