Commit | Line | Data |
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14cf11af | 1 | /* |
14cf11af PM |
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 | * Modified for PPC64 by Dave Engebretsen (engebret@ibm.com) | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU General Public License | |
14 | * as published by the Free Software Foundation; either version | |
15 | * 2 of the License, or (at your option) any later version. | |
16 | */ | |
17 | ||
18 | #include <linux/config.h> | |
19 | #include <linux/signal.h> | |
20 | #include <linux/sched.h> | |
21 | #include <linux/kernel.h> | |
22 | #include <linux/errno.h> | |
23 | #include <linux/string.h> | |
24 | #include <linux/types.h> | |
25 | #include <linux/ptrace.h> | |
26 | #include <linux/mman.h> | |
27 | #include <linux/mm.h> | |
28 | #include <linux/interrupt.h> | |
29 | #include <linux/highmem.h> | |
30 | #include <linux/module.h> | |
31 | #include <linux/kprobes.h> | |
32 | ||
33 | #include <asm/page.h> | |
34 | #include <asm/pgtable.h> | |
35 | #include <asm/mmu.h> | |
36 | #include <asm/mmu_context.h> | |
37 | #include <asm/system.h> | |
38 | #include <asm/uaccess.h> | |
39 | #include <asm/tlbflush.h> | |
40 | #include <asm/kdebug.h> | |
41 | #include <asm/siginfo.h> | |
42 | ||
43 | /* | |
44 | * Check whether the instruction at regs->nip is a store using | |
45 | * an update addressing form which will update r1. | |
46 | */ | |
47 | static int store_updates_sp(struct pt_regs *regs) | |
48 | { | |
49 | unsigned int inst; | |
50 | ||
51 | if (get_user(inst, (unsigned int __user *)regs->nip)) | |
52 | return 0; | |
53 | /* check for 1 in the rA field */ | |
54 | if (((inst >> 16) & 0x1f) != 1) | |
55 | return 0; | |
56 | /* check major opcode */ | |
57 | switch (inst >> 26) { | |
58 | case 37: /* stwu */ | |
59 | case 39: /* stbu */ | |
60 | case 45: /* sthu */ | |
61 | case 53: /* stfsu */ | |
62 | case 55: /* stfdu */ | |
63 | return 1; | |
64 | case 62: /* std or stdu */ | |
65 | return (inst & 3) == 1; | |
66 | case 31: | |
67 | /* check minor opcode */ | |
68 | switch ((inst >> 1) & 0x3ff) { | |
69 | case 181: /* stdux */ | |
70 | case 183: /* stwux */ | |
71 | case 247: /* stbux */ | |
72 | case 439: /* sthux */ | |
73 | case 695: /* stfsux */ | |
74 | case 759: /* stfdux */ | |
75 | return 1; | |
76 | } | |
77 | } | |
78 | return 0; | |
79 | } | |
80 | ||
cffb09ce | 81 | #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) |
bce6c5fd AB |
82 | static void do_dabr(struct pt_regs *regs, unsigned long address, |
83 | unsigned long error_code) | |
14cf11af PM |
84 | { |
85 | siginfo_t info; | |
86 | ||
87 | if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code, | |
88 | 11, SIGSEGV) == NOTIFY_STOP) | |
89 | return; | |
90 | ||
91 | if (debugger_dabr_match(regs)) | |
92 | return; | |
93 | ||
94 | /* Clear the DABR */ | |
95 | set_dabr(0); | |
96 | ||
97 | /* Deliver the signal to userspace */ | |
98 | info.si_signo = SIGTRAP; | |
99 | info.si_errno = 0; | |
100 | info.si_code = TRAP_HWBKPT; | |
bce6c5fd | 101 | info.si_addr = (void __user *)address; |
14cf11af PM |
102 | force_sig_info(SIGTRAP, &info, current); |
103 | } | |
cffb09ce | 104 | #endif /* !(CONFIG_4xx || CONFIG_BOOKE)*/ |
14cf11af PM |
105 | |
106 | /* | |
107 | * For 600- and 800-family processors, the error_code parameter is DSISR | |
108 | * for a data fault, SRR1 for an instruction fault. For 400-family processors | |
109 | * the error_code parameter is ESR for a data fault, 0 for an instruction | |
110 | * fault. | |
111 | * For 64-bit processors, the error_code parameter is | |
112 | * - DSISR for a non-SLB data access fault, | |
113 | * - SRR1 & 0x08000000 for a non-SLB instruction access fault | |
114 | * - 0 any SLB fault. | |
115 | * | |
116 | * The return value is 0 if the fault was handled, or the signal | |
117 | * number if this is a kernel fault that can't be handled here. | |
118 | */ | |
119 | int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address, | |
120 | unsigned long error_code) | |
121 | { | |
122 | struct vm_area_struct * vma; | |
123 | struct mm_struct *mm = current->mm; | |
124 | siginfo_t info; | |
125 | int code = SEGV_MAPERR; | |
126 | int is_write = 0; | |
127 | int trap = TRAP(regs); | |
128 | int is_exec = trap == 0x400; | |
129 | ||
130 | #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) | |
131 | /* | |
132 | * Fortunately the bit assignments in SRR1 for an instruction | |
133 | * fault and DSISR for a data fault are mostly the same for the | |
134 | * bits we are interested in. But there are some bits which | |
135 | * indicate errors in DSISR but can validly be set in SRR1. | |
136 | */ | |
137 | if (trap == 0x400) | |
138 | error_code &= 0x48200000; | |
139 | else | |
140 | is_write = error_code & DSISR_ISSTORE; | |
141 | #else | |
142 | is_write = error_code & ESR_DST; | |
143 | #endif /* CONFIG_4xx || CONFIG_BOOKE */ | |
144 | ||
145 | if (notify_die(DIE_PAGE_FAULT, "page_fault", regs, error_code, | |
146 | 11, SIGSEGV) == NOTIFY_STOP) | |
147 | return 0; | |
148 | ||
149 | if (trap == 0x300) { | |
150 | if (debugger_fault_handler(regs)) | |
151 | return 0; | |
152 | } | |
153 | ||
154 | /* On a kernel SLB miss we can only check for a valid exception entry */ | |
155 | if (!user_mode(regs) && (address >= TASK_SIZE)) | |
156 | return SIGSEGV; | |
157 | ||
158 | #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) | |
159 | if (error_code & DSISR_DABRMATCH) { | |
160 | /* DABR match */ | |
bce6c5fd | 161 | do_dabr(regs, address, error_code); |
14cf11af PM |
162 | return 0; |
163 | } | |
164 | #endif /* !(CONFIG_4xx || CONFIG_BOOKE)*/ | |
165 | ||
166 | if (in_atomic() || mm == NULL) { | |
167 | if (!user_mode(regs)) | |
168 | return SIGSEGV; | |
169 | /* in_atomic() in user mode is really bad, | |
170 | as is current->mm == NULL. */ | |
171 | printk(KERN_EMERG "Page fault in user mode with" | |
172 | "in_atomic() = %d mm = %p\n", in_atomic(), mm); | |
173 | printk(KERN_EMERG "NIP = %lx MSR = %lx\n", | |
174 | regs->nip, regs->msr); | |
175 | die("Weird page fault", regs, SIGSEGV); | |
176 | } | |
177 | ||
178 | /* When running in the kernel we expect faults to occur only to | |
179 | * addresses in user space. All other faults represent errors in the | |
180 | * kernel and should generate an OOPS. Unfortunatly, in the case of an | |
181 | * erroneous fault occuring in a code path which already holds mmap_sem | |
182 | * we will deadlock attempting to validate the fault against the | |
183 | * address space. Luckily the kernel only validly references user | |
184 | * space from well defined areas of code, which are listed in the | |
185 | * exceptions table. | |
186 | * | |
187 | * As the vast majority of faults will be valid we will only perform | |
188 | * the source reference check when there is a possibilty of a deadlock. | |
189 | * Attempt to lock the address space, if we cannot we then validate the | |
190 | * source. If this is invalid we can skip the address space check, | |
191 | * thus avoiding the deadlock. | |
192 | */ | |
193 | if (!down_read_trylock(&mm->mmap_sem)) { | |
194 | if (!user_mode(regs) && !search_exception_tables(regs->nip)) | |
195 | goto bad_area_nosemaphore; | |
196 | ||
197 | down_read(&mm->mmap_sem); | |
198 | } | |
199 | ||
200 | vma = find_vma(mm, address); | |
201 | if (!vma) | |
202 | goto bad_area; | |
203 | if (vma->vm_start <= address) | |
204 | goto good_area; | |
205 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
206 | goto bad_area; | |
207 | ||
208 | /* | |
209 | * N.B. The POWER/Open ABI allows programs to access up to | |
210 | * 288 bytes below the stack pointer. | |
211 | * The kernel signal delivery code writes up to about 1.5kB | |
212 | * below the stack pointer (r1) before decrementing it. | |
213 | * The exec code can write slightly over 640kB to the stack | |
214 | * before setting the user r1. Thus we allow the stack to | |
215 | * expand to 1MB without further checks. | |
216 | */ | |
217 | if (address + 0x100000 < vma->vm_end) { | |
218 | /* get user regs even if this fault is in kernel mode */ | |
219 | struct pt_regs *uregs = current->thread.regs; | |
220 | if (uregs == NULL) | |
221 | goto bad_area; | |
222 | ||
223 | /* | |
224 | * A user-mode access to an address a long way below | |
225 | * the stack pointer is only valid if the instruction | |
226 | * is one which would update the stack pointer to the | |
227 | * address accessed if the instruction completed, | |
228 | * i.e. either stwu rs,n(r1) or stwux rs,r1,rb | |
229 | * (or the byte, halfword, float or double forms). | |
230 | * | |
231 | * If we don't check this then any write to the area | |
232 | * between the last mapped region and the stack will | |
233 | * expand the stack rather than segfaulting. | |
234 | */ | |
235 | if (address + 2048 < uregs->gpr[1] | |
236 | && (!user_mode(regs) || !store_updates_sp(regs))) | |
237 | goto bad_area; | |
238 | } | |
239 | if (expand_stack(vma, address)) | |
240 | goto bad_area; | |
241 | ||
242 | good_area: | |
243 | code = SEGV_ACCERR; | |
244 | #if defined(CONFIG_6xx) | |
245 | if (error_code & 0x95700000) | |
246 | /* an error such as lwarx to I/O controller space, | |
247 | address matching DABR, eciwx, etc. */ | |
248 | goto bad_area; | |
249 | #endif /* CONFIG_6xx */ | |
250 | #if defined(CONFIG_8xx) | |
251 | /* The MPC8xx seems to always set 0x80000000, which is | |
252 | * "undefined". Of those that can be set, this is the only | |
253 | * one which seems bad. | |
254 | */ | |
255 | if (error_code & 0x10000000) | |
256 | /* Guarded storage error. */ | |
257 | goto bad_area; | |
258 | #endif /* CONFIG_8xx */ | |
259 | ||
260 | if (is_exec) { | |
261 | #ifdef CONFIG_PPC64 | |
262 | /* protection fault */ | |
263 | if (error_code & DSISR_PROTFAULT) | |
264 | goto bad_area; | |
265 | if (!(vma->vm_flags & VM_EXEC)) | |
266 | goto bad_area; | |
267 | #endif | |
268 | #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE) | |
269 | pte_t *ptep; | |
270 | ||
271 | /* Since 4xx/Book-E supports per-page execute permission, | |
272 | * we lazily flush dcache to icache. */ | |
273 | ptep = NULL; | |
274 | if (get_pteptr(mm, address, &ptep) && pte_present(*ptep)) { | |
275 | struct page *page = pte_page(*ptep); | |
276 | ||
277 | if (! test_bit(PG_arch_1, &page->flags)) { | |
278 | flush_dcache_icache_page(page); | |
279 | set_bit(PG_arch_1, &page->flags); | |
280 | } | |
281 | pte_update(ptep, 0, _PAGE_HWEXEC); | |
282 | _tlbie(address); | |
283 | pte_unmap(ptep); | |
284 | up_read(&mm->mmap_sem); | |
285 | return 0; | |
286 | } | |
287 | if (ptep != NULL) | |
288 | pte_unmap(ptep); | |
289 | #endif | |
290 | /* a write */ | |
291 | } else if (is_write) { | |
292 | if (!(vma->vm_flags & VM_WRITE)) | |
293 | goto bad_area; | |
294 | /* a read */ | |
295 | } else { | |
296 | /* protection fault */ | |
297 | if (error_code & 0x08000000) | |
298 | goto bad_area; | |
299 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
300 | goto bad_area; | |
301 | } | |
302 | ||
303 | /* | |
304 | * If for any reason at all we couldn't handle the fault, | |
305 | * make sure we exit gracefully rather than endlessly redo | |
306 | * the fault. | |
307 | */ | |
308 | survive: | |
309 | switch (handle_mm_fault(mm, vma, address, is_write)) { | |
310 | ||
311 | case VM_FAULT_MINOR: | |
312 | current->min_flt++; | |
313 | break; | |
314 | case VM_FAULT_MAJOR: | |
315 | current->maj_flt++; | |
316 | break; | |
317 | case VM_FAULT_SIGBUS: | |
318 | goto do_sigbus; | |
319 | case VM_FAULT_OOM: | |
320 | goto out_of_memory; | |
321 | default: | |
322 | BUG(); | |
323 | } | |
324 | ||
325 | up_read(&mm->mmap_sem); | |
326 | return 0; | |
327 | ||
328 | bad_area: | |
329 | up_read(&mm->mmap_sem); | |
330 | ||
331 | bad_area_nosemaphore: | |
332 | /* User mode accesses cause a SIGSEGV */ | |
333 | if (user_mode(regs)) { | |
334 | _exception(SIGSEGV, regs, code, address); | |
335 | return 0; | |
336 | } | |
337 | ||
338 | if (is_exec && (error_code & DSISR_PROTFAULT) | |
339 | && printk_ratelimit()) | |
340 | printk(KERN_CRIT "kernel tried to execute NX-protected" | |
341 | " page (%lx) - exploit attempt? (uid: %d)\n", | |
342 | address, current->uid); | |
343 | ||
344 | return SIGSEGV; | |
345 | ||
346 | /* | |
347 | * We ran out of memory, or some other thing happened to us that made | |
348 | * us unable to handle the page fault gracefully. | |
349 | */ | |
350 | out_of_memory: | |
351 | up_read(&mm->mmap_sem); | |
352 | if (current->pid == 1) { | |
353 | yield(); | |
354 | down_read(&mm->mmap_sem); | |
355 | goto survive; | |
356 | } | |
357 | printk("VM: killing process %s\n", current->comm); | |
358 | if (user_mode(regs)) | |
359 | do_exit(SIGKILL); | |
360 | return SIGKILL; | |
361 | ||
362 | do_sigbus: | |
363 | up_read(&mm->mmap_sem); | |
364 | if (user_mode(regs)) { | |
365 | info.si_signo = SIGBUS; | |
366 | info.si_errno = 0; | |
367 | info.si_code = BUS_ADRERR; | |
368 | info.si_addr = (void __user *)address; | |
369 | force_sig_info(SIGBUS, &info, current); | |
370 | return 0; | |
371 | } | |
372 | return SIGBUS; | |
373 | } | |
374 | ||
375 | /* | |
376 | * bad_page_fault is called when we have a bad access from the kernel. | |
377 | * It is called from the DSI and ISI handlers in head.S and from some | |
378 | * of the procedures in traps.c. | |
379 | */ | |
380 | void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) | |
381 | { | |
382 | const struct exception_table_entry *entry; | |
383 | ||
384 | /* Are we prepared to handle this fault? */ | |
385 | if ((entry = search_exception_tables(regs->nip)) != NULL) { | |
386 | regs->nip = entry->fixup; | |
387 | return; | |
388 | } | |
389 | ||
390 | /* kernel has accessed a bad area */ | |
723925b7 OJ |
391 | |
392 | printk(KERN_ALERT "Unable to handle kernel paging request for "); | |
393 | switch (regs->trap) { | |
394 | case 0x300: | |
395 | case 0x380: | |
396 | printk("data at address 0x%08lx\n", regs->dar); | |
397 | break; | |
398 | case 0x400: | |
399 | case 0x480: | |
400 | printk("instruction fetch\n"); | |
401 | break; | |
402 | default: | |
403 | printk("unknown fault\n"); | |
404 | } | |
405 | printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n", | |
406 | regs->nip); | |
407 | ||
14cf11af PM |
408 | die("Kernel access of bad area", regs, sig); |
409 | } |