Commit | Line | Data |
---|---|---|
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 | ||
14cf11af PM |
18 | #include <linux/signal.h> |
19 | #include <linux/sched.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/errno.h> | |
22 | #include <linux/string.h> | |
23 | #include <linux/types.h> | |
24 | #include <linux/ptrace.h> | |
25 | #include <linux/mman.h> | |
26 | #include <linux/mm.h> | |
27 | #include <linux/interrupt.h> | |
28 | #include <linux/highmem.h> | |
29 | #include <linux/module.h> | |
30 | #include <linux/kprobes.h> | |
1eeb66a1 | 31 | #include <linux/kdebug.h> |
14cf11af | 32 | |
40900194 | 33 | #include <asm/firmware.h> |
14cf11af PM |
34 | #include <asm/page.h> |
35 | #include <asm/pgtable.h> | |
36 | #include <asm/mmu.h> | |
37 | #include <asm/mmu_context.h> | |
38 | #include <asm/system.h> | |
39 | #include <asm/uaccess.h> | |
40 | #include <asm/tlbflush.h> | |
14cf11af PM |
41 | #include <asm/siginfo.h> |
42 | ||
4f9e87c0 | 43 | |
9f90b997 CH |
44 | #ifdef CONFIG_KPROBES |
45 | static inline int notify_page_fault(struct pt_regs *regs) | |
4f9e87c0 | 46 | { |
9f90b997 CH |
47 | int ret = 0; |
48 | ||
49 | /* kprobe_running() needs smp_processor_id() */ | |
50 | if (!user_mode(regs)) { | |
51 | preempt_disable(); | |
52 | if (kprobe_running() && kprobe_fault_handler(regs, 11)) | |
53 | ret = 1; | |
54 | preempt_enable(); | |
55 | } | |
4f9e87c0 | 56 | |
9f90b997 | 57 | return ret; |
4f9e87c0 AK |
58 | } |
59 | #else | |
9f90b997 | 60 | static inline int notify_page_fault(struct pt_regs *regs) |
4f9e87c0 | 61 | { |
9f90b997 | 62 | return 0; |
4f9e87c0 AK |
63 | } |
64 | #endif | |
65 | ||
14cf11af PM |
66 | /* |
67 | * Check whether the instruction at regs->nip is a store using | |
68 | * an update addressing form which will update r1. | |
69 | */ | |
70 | static int store_updates_sp(struct pt_regs *regs) | |
71 | { | |
72 | unsigned int inst; | |
73 | ||
74 | if (get_user(inst, (unsigned int __user *)regs->nip)) | |
75 | return 0; | |
76 | /* check for 1 in the rA field */ | |
77 | if (((inst >> 16) & 0x1f) != 1) | |
78 | return 0; | |
79 | /* check major opcode */ | |
80 | switch (inst >> 26) { | |
81 | case 37: /* stwu */ | |
82 | case 39: /* stbu */ | |
83 | case 45: /* sthu */ | |
84 | case 53: /* stfsu */ | |
85 | case 55: /* stfdu */ | |
86 | return 1; | |
87 | case 62: /* std or stdu */ | |
88 | return (inst & 3) == 1; | |
89 | case 31: | |
90 | /* check minor opcode */ | |
91 | switch ((inst >> 1) & 0x3ff) { | |
92 | case 181: /* stdux */ | |
93 | case 183: /* stwux */ | |
94 | case 247: /* stbux */ | |
95 | case 439: /* sthux */ | |
96 | case 695: /* stfsux */ | |
97 | case 759: /* stfdux */ | |
98 | return 1; | |
99 | } | |
100 | } | |
101 | return 0; | |
102 | } | |
103 | ||
14cf11af PM |
104 | /* |
105 | * For 600- and 800-family processors, the error_code parameter is DSISR | |
106 | * for a data fault, SRR1 for an instruction fault. For 400-family processors | |
107 | * the error_code parameter is ESR for a data fault, 0 for an instruction | |
108 | * fault. | |
109 | * For 64-bit processors, the error_code parameter is | |
110 | * - DSISR for a non-SLB data access fault, | |
111 | * - SRR1 & 0x08000000 for a non-SLB instruction access fault | |
112 | * - 0 any SLB fault. | |
113 | * | |
114 | * The return value is 0 if the fault was handled, or the signal | |
115 | * number if this is a kernel fault that can't be handled here. | |
116 | */ | |
117 | int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address, | |
118 | unsigned long error_code) | |
119 | { | |
120 | struct vm_area_struct * vma; | |
121 | struct mm_struct *mm = current->mm; | |
122 | siginfo_t info; | |
123 | int code = SEGV_MAPERR; | |
83c54070 | 124 | int is_write = 0, ret; |
14cf11af PM |
125 | int trap = TRAP(regs); |
126 | int is_exec = trap == 0x400; | |
127 | ||
128 | #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) | |
129 | /* | |
130 | * Fortunately the bit assignments in SRR1 for an instruction | |
131 | * fault and DSISR for a data fault are mostly the same for the | |
132 | * bits we are interested in. But there are some bits which | |
133 | * indicate errors in DSISR but can validly be set in SRR1. | |
134 | */ | |
135 | if (trap == 0x400) | |
136 | error_code &= 0x48200000; | |
137 | else | |
138 | is_write = error_code & DSISR_ISSTORE; | |
139 | #else | |
140 | is_write = error_code & ESR_DST; | |
141 | #endif /* CONFIG_4xx || CONFIG_BOOKE */ | |
142 | ||
9f90b997 | 143 | if (notify_page_fault(regs)) |
14cf11af PM |
144 | return 0; |
145 | ||
c3b75bd7 MN |
146 | if (unlikely(debugger_fault_handler(regs))) |
147 | return 0; | |
14cf11af PM |
148 | |
149 | /* On a kernel SLB miss we can only check for a valid exception entry */ | |
150 | if (!user_mode(regs) && (address >= TASK_SIZE)) | |
151 | return SIGSEGV; | |
152 | ||
153 | #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) | |
154 | if (error_code & DSISR_DABRMATCH) { | |
155 | /* DABR match */ | |
bce6c5fd | 156 | do_dabr(regs, address, error_code); |
14cf11af PM |
157 | return 0; |
158 | } | |
159 | #endif /* !(CONFIG_4xx || CONFIG_BOOKE)*/ | |
160 | ||
161 | if (in_atomic() || mm == NULL) { | |
162 | if (!user_mode(regs)) | |
163 | return SIGSEGV; | |
164 | /* in_atomic() in user mode is really bad, | |
165 | as is current->mm == NULL. */ | |
df3c9019 | 166 | printk(KERN_EMERG "Page fault in user mode with " |
14cf11af PM |
167 | "in_atomic() = %d mm = %p\n", in_atomic(), mm); |
168 | printk(KERN_EMERG "NIP = %lx MSR = %lx\n", | |
169 | regs->nip, regs->msr); | |
170 | die("Weird page fault", regs, SIGSEGV); | |
171 | } | |
172 | ||
173 | /* When running in the kernel we expect faults to occur only to | |
174 | * addresses in user space. All other faults represent errors in the | |
fc5266ea AB |
175 | * kernel and should generate an OOPS. Unfortunately, in the case of an |
176 | * erroneous fault occurring in a code path which already holds mmap_sem | |
14cf11af PM |
177 | * we will deadlock attempting to validate the fault against the |
178 | * address space. Luckily the kernel only validly references user | |
179 | * space from well defined areas of code, which are listed in the | |
180 | * exceptions table. | |
181 | * | |
182 | * As the vast majority of faults will be valid we will only perform | |
fc5266ea | 183 | * the source reference check when there is a possibility of a deadlock. |
14cf11af PM |
184 | * Attempt to lock the address space, if we cannot we then validate the |
185 | * source. If this is invalid we can skip the address space check, | |
186 | * thus avoiding the deadlock. | |
187 | */ | |
188 | if (!down_read_trylock(&mm->mmap_sem)) { | |
189 | if (!user_mode(regs) && !search_exception_tables(regs->nip)) | |
190 | goto bad_area_nosemaphore; | |
191 | ||
192 | down_read(&mm->mmap_sem); | |
193 | } | |
194 | ||
195 | vma = find_vma(mm, address); | |
196 | if (!vma) | |
197 | goto bad_area; | |
198 | if (vma->vm_start <= address) | |
199 | goto good_area; | |
200 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
201 | goto bad_area; | |
202 | ||
203 | /* | |
204 | * N.B. The POWER/Open ABI allows programs to access up to | |
205 | * 288 bytes below the stack pointer. | |
206 | * The kernel signal delivery code writes up to about 1.5kB | |
207 | * below the stack pointer (r1) before decrementing it. | |
208 | * The exec code can write slightly over 640kB to the stack | |
209 | * before setting the user r1. Thus we allow the stack to | |
210 | * expand to 1MB without further checks. | |
211 | */ | |
212 | if (address + 0x100000 < vma->vm_end) { | |
213 | /* get user regs even if this fault is in kernel mode */ | |
214 | struct pt_regs *uregs = current->thread.regs; | |
215 | if (uregs == NULL) | |
216 | goto bad_area; | |
217 | ||
218 | /* | |
219 | * A user-mode access to an address a long way below | |
220 | * the stack pointer is only valid if the instruction | |
221 | * is one which would update the stack pointer to the | |
222 | * address accessed if the instruction completed, | |
223 | * i.e. either stwu rs,n(r1) or stwux rs,r1,rb | |
224 | * (or the byte, halfword, float or double forms). | |
225 | * | |
226 | * If we don't check this then any write to the area | |
227 | * between the last mapped region and the stack will | |
228 | * expand the stack rather than segfaulting. | |
229 | */ | |
230 | if (address + 2048 < uregs->gpr[1] | |
231 | && (!user_mode(regs) || !store_updates_sp(regs))) | |
232 | goto bad_area; | |
233 | } | |
234 | if (expand_stack(vma, address)) | |
235 | goto bad_area; | |
236 | ||
237 | good_area: | |
238 | code = SEGV_ACCERR; | |
239 | #if defined(CONFIG_6xx) | |
240 | if (error_code & 0x95700000) | |
241 | /* an error such as lwarx to I/O controller space, | |
242 | address matching DABR, eciwx, etc. */ | |
243 | goto bad_area; | |
244 | #endif /* CONFIG_6xx */ | |
245 | #if defined(CONFIG_8xx) | |
246 | /* The MPC8xx seems to always set 0x80000000, which is | |
247 | * "undefined". Of those that can be set, this is the only | |
248 | * one which seems bad. | |
249 | */ | |
250 | if (error_code & 0x10000000) | |
251 | /* Guarded storage error. */ | |
252 | goto bad_area; | |
253 | #endif /* CONFIG_8xx */ | |
254 | ||
255 | if (is_exec) { | |
9ba4ace3 | 256 | #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) |
14cf11af PM |
257 | /* protection fault */ |
258 | if (error_code & DSISR_PROTFAULT) | |
259 | goto bad_area; | |
08ae6cc1 PM |
260 | /* |
261 | * Allow execution from readable areas if the MMU does not | |
262 | * provide separate controls over reading and executing. | |
263 | */ | |
264 | if (!(vma->vm_flags & VM_EXEC) && | |
265 | (cpu_has_feature(CPU_FTR_NOEXECUTE) || | |
266 | !(vma->vm_flags & (VM_READ | VM_WRITE)))) | |
14cf11af | 267 | goto bad_area; |
9ba4ace3 | 268 | #else |
14cf11af | 269 | pte_t *ptep; |
bab70a4a | 270 | pmd_t *pmdp; |
14cf11af PM |
271 | |
272 | /* Since 4xx/Book-E supports per-page execute permission, | |
273 | * we lazily flush dcache to icache. */ | |
274 | ptep = NULL; | |
bab70a4a ES |
275 | if (get_pteptr(mm, address, &ptep, &pmdp)) { |
276 | spinlock_t *ptl = pte_lockptr(mm, pmdp); | |
277 | spin_lock(ptl); | |
278 | if (pte_present(*ptep)) { | |
279 | struct page *page = pte_page(*ptep); | |
14cf11af | 280 | |
bab70a4a ES |
281 | if (!test_bit(PG_arch_1, &page->flags)) { |
282 | flush_dcache_icache_page(page); | |
283 | set_bit(PG_arch_1, &page->flags); | |
284 | } | |
1bc54c03 BH |
285 | pte_update(ptep, 0, _PAGE_HWEXEC | |
286 | _PAGE_ACCESSED); | |
f048aace | 287 | local_flush_tlb_page(vma, address); |
bab70a4a ES |
288 | pte_unmap_unlock(ptep, ptl); |
289 | up_read(&mm->mmap_sem); | |
290 | return 0; | |
14cf11af | 291 | } |
bab70a4a | 292 | pte_unmap_unlock(ptep, ptl); |
14cf11af | 293 | } |
14cf11af PM |
294 | #endif |
295 | /* a write */ | |
296 | } else if (is_write) { | |
297 | if (!(vma->vm_flags & VM_WRITE)) | |
298 | goto bad_area; | |
299 | /* a read */ | |
300 | } else { | |
301 | /* protection fault */ | |
302 | if (error_code & 0x08000000) | |
303 | goto bad_area; | |
df67b3da | 304 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
14cf11af PM |
305 | goto bad_area; |
306 | } | |
307 | ||
308 | /* | |
309 | * If for any reason at all we couldn't handle the fault, | |
310 | * make sure we exit gracefully rather than endlessly redo | |
311 | * the fault. | |
312 | */ | |
313 | survive: | |
83c54070 NP |
314 | ret = handle_mm_fault(mm, vma, address, is_write); |
315 | if (unlikely(ret & VM_FAULT_ERROR)) { | |
316 | if (ret & VM_FAULT_OOM) | |
317 | goto out_of_memory; | |
318 | else if (ret & VM_FAULT_SIGBUS) | |
319 | goto do_sigbus; | |
14cf11af PM |
320 | BUG(); |
321 | } | |
40900194 | 322 | if (ret & VM_FAULT_MAJOR) { |
83c54070 | 323 | current->maj_flt++; |
40900194 BK |
324 | #ifdef CONFIG_PPC_SMLPAR |
325 | if (firmware_has_feature(FW_FEATURE_CMO)) { | |
326 | preempt_disable(); | |
a6326e98 | 327 | get_lppaca()->page_ins += (1 << PAGE_FACTOR); |
40900194 BK |
328 | preempt_enable(); |
329 | } | |
330 | #endif | |
331 | } else | |
83c54070 | 332 | current->min_flt++; |
14cf11af PM |
333 | up_read(&mm->mmap_sem); |
334 | return 0; | |
335 | ||
336 | bad_area: | |
337 | up_read(&mm->mmap_sem); | |
338 | ||
339 | bad_area_nosemaphore: | |
340 | /* User mode accesses cause a SIGSEGV */ | |
341 | if (user_mode(regs)) { | |
342 | _exception(SIGSEGV, regs, code, address); | |
343 | return 0; | |
344 | } | |
345 | ||
346 | if (is_exec && (error_code & DSISR_PROTFAULT) | |
347 | && printk_ratelimit()) | |
348 | printk(KERN_CRIT "kernel tried to execute NX-protected" | |
349 | " page (%lx) - exploit attempt? (uid: %d)\n", | |
350 | address, current->uid); | |
351 | ||
352 | return SIGSEGV; | |
353 | ||
354 | /* | |
355 | * We ran out of memory, or some other thing happened to us that made | |
356 | * us unable to handle the page fault gracefully. | |
357 | */ | |
358 | out_of_memory: | |
359 | up_read(&mm->mmap_sem); | |
b460cbc5 | 360 | if (is_global_init(current)) { |
14cf11af PM |
361 | yield(); |
362 | down_read(&mm->mmap_sem); | |
363 | goto survive; | |
364 | } | |
365 | printk("VM: killing process %s\n", current->comm); | |
366 | if (user_mode(regs)) | |
effe24bd | 367 | do_group_exit(SIGKILL); |
14cf11af PM |
368 | return SIGKILL; |
369 | ||
370 | do_sigbus: | |
371 | up_read(&mm->mmap_sem); | |
372 | if (user_mode(regs)) { | |
373 | info.si_signo = SIGBUS; | |
374 | info.si_errno = 0; | |
375 | info.si_code = BUS_ADRERR; | |
376 | info.si_addr = (void __user *)address; | |
377 | force_sig_info(SIGBUS, &info, current); | |
378 | return 0; | |
379 | } | |
380 | return SIGBUS; | |
381 | } | |
382 | ||
383 | /* | |
384 | * bad_page_fault is called when we have a bad access from the kernel. | |
385 | * It is called from the DSI and ISI handlers in head.S and from some | |
386 | * of the procedures in traps.c. | |
387 | */ | |
388 | void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) | |
389 | { | |
390 | const struct exception_table_entry *entry; | |
391 | ||
392 | /* Are we prepared to handle this fault? */ | |
393 | if ((entry = search_exception_tables(regs->nip)) != NULL) { | |
394 | regs->nip = entry->fixup; | |
395 | return; | |
396 | } | |
397 | ||
398 | /* kernel has accessed a bad area */ | |
723925b7 | 399 | |
723925b7 | 400 | switch (regs->trap) { |
a416dd8d ME |
401 | case 0x300: |
402 | case 0x380: | |
403 | printk(KERN_ALERT "Unable to handle kernel paging request for " | |
404 | "data at address 0x%08lx\n", regs->dar); | |
405 | break; | |
406 | case 0x400: | |
407 | case 0x480: | |
408 | printk(KERN_ALERT "Unable to handle kernel paging request for " | |
409 | "instruction fetch\n"); | |
410 | break; | |
411 | default: | |
412 | printk(KERN_ALERT "Unable to handle kernel paging request for " | |
413 | "unknown fault\n"); | |
414 | break; | |
723925b7 OJ |
415 | } |
416 | printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n", | |
417 | regs->nip); | |
418 | ||
14cf11af PM |
419 | die("Kernel access of bad area", regs, sig); |
420 | } |