Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 | 2 | * S390 version |
a53c8fab | 3 | * Copyright IBM Corp. 1999 |
1da177e4 LT |
4 | * Author(s): Hartmut Penner (hp@de.ibm.com) |
5 | * Ulrich Weigand (uweigand@de.ibm.com) | |
6 | * | |
7 | * Derived from "arch/i386/mm/fault.c" | |
8 | * Copyright (C) 1995 Linus Torvalds | |
9 | */ | |
10 | ||
052ff461 | 11 | #include <linux/kernel_stat.h> |
cdd6c482 | 12 | #include <linux/perf_event.h> |
1da177e4 LT |
13 | #include <linux/signal.h> |
14 | #include <linux/sched.h> | |
15 | #include <linux/kernel.h> | |
16 | #include <linux/errno.h> | |
17 | #include <linux/string.h> | |
18 | #include <linux/types.h> | |
19 | #include <linux/ptrace.h> | |
20 | #include <linux/mman.h> | |
21 | #include <linux/mm.h> | |
7757591a | 22 | #include <linux/compat.h> |
1da177e4 | 23 | #include <linux/smp.h> |
1eeb66a1 | 24 | #include <linux/kdebug.h> |
1da177e4 LT |
25 | #include <linux/init.h> |
26 | #include <linux/console.h> | |
27 | #include <linux/module.h> | |
28 | #include <linux/hardirq.h> | |
4ba069b8 | 29 | #include <linux/kprobes.h> |
be5ec363 | 30 | #include <linux/uaccess.h> |
53492b1d | 31 | #include <linux/hugetlb.h> |
cbb870c8 | 32 | #include <asm/asm-offsets.h> |
1ec2772e | 33 | #include <asm/diag.h> |
1da177e4 | 34 | #include <asm/pgtable.h> |
1e133ab2 | 35 | #include <asm/gmap.h> |
d7b250e2 | 36 | #include <asm/irq.h> |
6252d702 | 37 | #include <asm/mmu_context.h> |
a0616cde | 38 | #include <asm/facility.h> |
a806170e | 39 | #include "../kernel/entry.h" |
1da177e4 | 40 | |
1da177e4 | 41 | #define __FAIL_ADDR_MASK -4096L |
1da177e4 LT |
42 | #define __SUBCODE_MASK 0x0600 |
43 | #define __PF_RES_FIELD 0x8000000000000000ULL | |
1da177e4 | 44 | |
50d7280d MS |
45 | #define VM_FAULT_BADCONTEXT 0x010000 |
46 | #define VM_FAULT_BADMAP 0x020000 | |
47 | #define VM_FAULT_BADACCESS 0x040000 | |
a4f32bdb | 48 | #define VM_FAULT_SIGNAL 0x080000 |
24eb3a82 | 49 | #define VM_FAULT_PFAULT 0x100000 |
50d7280d | 50 | |
a4f32bdb | 51 | static unsigned long store_indication __read_mostly; |
92f842ea | 52 | |
a4f32bdb | 53 | static int __init fault_init(void) |
92f842ea | 54 | { |
a4f32bdb | 55 | if (test_facility(75)) |
92f842ea | 56 | store_indication = 0xc00; |
a4f32bdb | 57 | return 0; |
92f842ea | 58 | } |
a4f32bdb | 59 | early_initcall(fault_init); |
92f842ea | 60 | |
7ecb344a | 61 | static inline int notify_page_fault(struct pt_regs *regs) |
10c1031f | 62 | { |
33464e3b CH |
63 | int ret = 0; |
64 | ||
65 | /* kprobe_running() needs smp_processor_id() */ | |
22e0a046 | 66 | if (kprobes_built_in() && !user_mode(regs)) { |
33464e3b CH |
67 | preempt_disable(); |
68 | if (kprobe_running() && kprobe_fault_handler(regs, 14)) | |
69 | ret = 1; | |
70 | preempt_enable(); | |
71 | } | |
33464e3b | 72 | return ret; |
4ba069b8 | 73 | } |
4ba069b8 | 74 | |
1da177e4 LT |
75 | |
76 | /* | |
77 | * Unlock any spinlocks which will prevent us from getting the | |
cefc8be8 | 78 | * message out. |
1da177e4 LT |
79 | */ |
80 | void bust_spinlocks(int yes) | |
81 | { | |
82 | if (yes) { | |
83 | oops_in_progress = 1; | |
84 | } else { | |
85 | int loglevel_save = console_loglevel; | |
86 | console_unblank(); | |
87 | oops_in_progress = 0; | |
88 | /* | |
89 | * OK, the message is on the console. Now we call printk() | |
90 | * without oops_in_progress set so that printk will give klogd | |
91 | * a poke. Hold onto your hats... | |
92 | */ | |
93 | console_loglevel = 15; | |
94 | printk(" "); | |
95 | console_loglevel = loglevel_save; | |
96 | } | |
97 | } | |
98 | ||
99 | /* | |
482b05dd | 100 | * Returns the address space associated with the fault. |
61365e13 | 101 | * Returns 0 for kernel space and 1 for user space. |
1da177e4 | 102 | */ |
457f2180 | 103 | static inline int user_space_fault(struct pt_regs *regs) |
1da177e4 | 104 | { |
457f2180 HC |
105 | unsigned long trans_exc_code; |
106 | ||
1da177e4 | 107 | /* |
61365e13 MS |
108 | * The lowest two bits of the translation exception |
109 | * identification indicate which paging table was used. | |
1da177e4 | 110 | */ |
457f2180 HC |
111 | trans_exc_code = regs->int_parm_long & 3; |
112 | if (trans_exc_code == 3) /* home space -> kernel */ | |
113 | return 0; | |
114 | if (user_mode(regs)) | |
115 | return 1; | |
116 | if (trans_exc_code == 2) /* secondary space -> set_fs */ | |
61365e13 | 117 | return current->thread.mm_segment.ar4; |
457f2180 HC |
118 | if (current->flags & PF_VCPU) |
119 | return 1; | |
120 | return 0; | |
1da177e4 LT |
121 | } |
122 | ||
3b7df342 HC |
123 | static int bad_address(void *p) |
124 | { | |
125 | unsigned long dummy; | |
126 | ||
127 | return probe_kernel_address((unsigned long *)p, dummy); | |
128 | } | |
129 | ||
3b7df342 HC |
130 | static void dump_pagetable(unsigned long asce, unsigned long address) |
131 | { | |
132 | unsigned long *table = __va(asce & PAGE_MASK); | |
133 | ||
134 | pr_alert("AS:%016lx ", asce); | |
135 | switch (asce & _ASCE_TYPE_MASK) { | |
136 | case _ASCE_TYPE_REGION1: | |
137 | table = table + ((address >> 53) & 0x7ff); | |
138 | if (bad_address(table)) | |
139 | goto bad; | |
140 | pr_cont("R1:%016lx ", *table); | |
141 | if (*table & _REGION_ENTRY_INVALID) | |
142 | goto out; | |
143 | table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
144 | /* fallthrough */ | |
145 | case _ASCE_TYPE_REGION2: | |
146 | table = table + ((address >> 42) & 0x7ff); | |
147 | if (bad_address(table)) | |
148 | goto bad; | |
149 | pr_cont("R2:%016lx ", *table); | |
150 | if (*table & _REGION_ENTRY_INVALID) | |
151 | goto out; | |
152 | table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
153 | /* fallthrough */ | |
154 | case _ASCE_TYPE_REGION3: | |
155 | table = table + ((address >> 31) & 0x7ff); | |
156 | if (bad_address(table)) | |
157 | goto bad; | |
158 | pr_cont("R3:%016lx ", *table); | |
159 | if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) | |
160 | goto out; | |
161 | table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
162 | /* fallthrough */ | |
163 | case _ASCE_TYPE_SEGMENT: | |
164 | table = table + ((address >> 20) & 0x7ff); | |
165 | if (bad_address(table)) | |
166 | goto bad; | |
91c0837e | 167 | pr_cont("S:%016lx ", *table); |
3b7df342 HC |
168 | if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) |
169 | goto out; | |
170 | table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); | |
171 | } | |
172 | table = table + ((address >> 12) & 0xff); | |
173 | if (bad_address(table)) | |
174 | goto bad; | |
175 | pr_cont("P:%016lx ", *table); | |
176 | out: | |
177 | pr_cont("\n"); | |
178 | return; | |
179 | bad: | |
180 | pr_cont("BAD\n"); | |
181 | } | |
182 | ||
3b7df342 HC |
183 | static void dump_fault_info(struct pt_regs *regs) |
184 | { | |
185 | unsigned long asce; | |
186 | ||
5d7eccec HC |
187 | pr_alert("Failing address: %016lx TEID: %016lx\n", |
188 | regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); | |
3b7df342 HC |
189 | pr_alert("Fault in "); |
190 | switch (regs->int_parm_long & 3) { | |
191 | case 3: | |
192 | pr_cont("home space "); | |
193 | break; | |
194 | case 2: | |
195 | pr_cont("secondary space "); | |
196 | break; | |
197 | case 1: | |
198 | pr_cont("access register "); | |
199 | break; | |
200 | case 0: | |
201 | pr_cont("primary space "); | |
202 | break; | |
203 | } | |
204 | pr_cont("mode while using "); | |
205 | if (!user_space_fault(regs)) { | |
206 | asce = S390_lowcore.kernel_asce; | |
207 | pr_cont("kernel "); | |
208 | } | |
209 | #ifdef CONFIG_PGSTE | |
210 | else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) { | |
211 | struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; | |
212 | asce = gmap->asce; | |
213 | pr_cont("gmap "); | |
214 | } | |
215 | #endif | |
216 | else { | |
217 | asce = S390_lowcore.user_asce; | |
218 | pr_cont("user "); | |
219 | } | |
220 | pr_cont("ASCE.\n"); | |
221 | dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); | |
222 | } | |
223 | ||
5d7eccec HC |
224 | int show_unhandled_signals = 1; |
225 | ||
226 | void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) | |
ab3c68ee HC |
227 | { |
228 | if ((task_pid_nr(current) > 1) && !show_unhandled_signals) | |
229 | return; | |
230 | if (!unhandled_signal(current, signr)) | |
231 | return; | |
232 | if (!printk_ratelimit()) | |
233 | return; | |
db1177ee | 234 | printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", |
413d4047 | 235 | regs->int_code & 0xffff, regs->int_code >> 17); |
9cb1ccec | 236 | print_vma_addr(KERN_CONT "in ", regs->psw.addr); |
aa33c8cb | 237 | printk(KERN_CONT "\n"); |
5d7eccec HC |
238 | if (is_mm_fault) |
239 | dump_fault_info(regs); | |
ab3c68ee HC |
240 | show_regs(regs); |
241 | } | |
242 | ||
1da177e4 LT |
243 | /* |
244 | * Send SIGSEGV to task. This is an external routine | |
245 | * to keep the stack usage of do_page_fault small. | |
246 | */ | |
aa33c8cb | 247 | static noinline void do_sigsegv(struct pt_regs *regs, int si_code) |
1da177e4 LT |
248 | { |
249 | struct siginfo si; | |
250 | ||
5d7eccec | 251 | report_user_fault(regs, SIGSEGV, 1); |
1da177e4 | 252 | si.si_signo = SIGSEGV; |
cf0d44d5 | 253 | si.si_errno = 0; |
1da177e4 | 254 | si.si_code = si_code; |
aa33c8cb | 255 | si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); |
1da177e4 LT |
256 | force_sig_info(SIGSEGV, &si, current); |
257 | } | |
258 | ||
aa33c8cb | 259 | static noinline void do_no_context(struct pt_regs *regs) |
10c1031f MS |
260 | { |
261 | const struct exception_table_entry *fixup; | |
262 | ||
263 | /* Are we prepared to handle this kernel fault? */ | |
9cb1ccec | 264 | fixup = search_exception_tables(regs->psw.addr); |
10c1031f | 265 | if (fixup) { |
fecc868a | 266 | regs->psw.addr = extable_fixup(fixup); |
10c1031f MS |
267 | return; |
268 | } | |
269 | ||
270 | /* | |
271 | * Oops. The kernel tried to access some bad page. We'll have to | |
272 | * terminate things with extreme prejudice. | |
273 | */ | |
457f2180 | 274 | if (!user_space_fault(regs)) |
10c1031f | 275 | printk(KERN_ALERT "Unable to handle kernel pointer dereference" |
3b7df342 | 276 | " in virtual kernel address space\n"); |
10c1031f MS |
277 | else |
278 | printk(KERN_ALERT "Unable to handle kernel paging request" | |
3b7df342 | 279 | " in virtual user address space\n"); |
3b7df342 | 280 | dump_fault_info(regs); |
aa33c8cb | 281 | die(regs, "Oops"); |
10c1031f MS |
282 | do_exit(SIGKILL); |
283 | } | |
284 | ||
aa33c8cb | 285 | static noinline void do_low_address(struct pt_regs *regs) |
10c1031f MS |
286 | { |
287 | /* Low-address protection hit in kernel mode means | |
288 | NULL pointer write access in kernel mode. */ | |
289 | if (regs->psw.mask & PSW_MASK_PSTATE) { | |
290 | /* Low-address protection hit in user mode 'cannot happen'. */ | |
aa33c8cb | 291 | die (regs, "Low-address protection"); |
10c1031f MS |
292 | do_exit(SIGKILL); |
293 | } | |
294 | ||
aa33c8cb | 295 | do_no_context(regs); |
10c1031f MS |
296 | } |
297 | ||
aa33c8cb | 298 | static noinline void do_sigbus(struct pt_regs *regs) |
10c1031f MS |
299 | { |
300 | struct task_struct *tsk = current; | |
36bf9680 | 301 | struct siginfo si; |
10c1031f | 302 | |
10c1031f MS |
303 | /* |
304 | * Send a sigbus, regardless of whether we were in kernel | |
305 | * or user mode. | |
306 | */ | |
36bf9680 MS |
307 | si.si_signo = SIGBUS; |
308 | si.si_errno = 0; | |
309 | si.si_code = BUS_ADRERR; | |
aa33c8cb | 310 | si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); |
36bf9680 | 311 | force_sig_info(SIGBUS, &si, tsk); |
10c1031f MS |
312 | } |
313 | ||
aa33c8cb | 314 | static noinline void do_fault_error(struct pt_regs *regs, int fault) |
50d7280d MS |
315 | { |
316 | int si_code; | |
317 | ||
318 | switch (fault) { | |
319 | case VM_FAULT_BADACCESS: | |
50d7280d MS |
320 | case VM_FAULT_BADMAP: |
321 | /* Bad memory access. Check if it is kernel or user space. */ | |
7d256175 | 322 | if (user_mode(regs)) { |
50d7280d MS |
323 | /* User mode accesses just cause a SIGSEGV */ |
324 | si_code = (fault == VM_FAULT_BADMAP) ? | |
325 | SEGV_MAPERR : SEGV_ACCERR; | |
aa33c8cb | 326 | do_sigsegv(regs, si_code); |
50d7280d MS |
327 | return; |
328 | } | |
329 | case VM_FAULT_BADCONTEXT: | |
24eb3a82 | 330 | case VM_FAULT_PFAULT: |
aa33c8cb | 331 | do_no_context(regs); |
50d7280d | 332 | break; |
f2c76e3b HC |
333 | case VM_FAULT_SIGNAL: |
334 | if (!user_mode(regs)) | |
335 | do_no_context(regs); | |
336 | break; | |
50d7280d | 337 | default: /* fault & VM_FAULT_ERROR */ |
99583181 | 338 | if (fault & VM_FAULT_OOM) { |
7d256175 | 339 | if (!user_mode(regs)) |
aa33c8cb | 340 | do_no_context(regs); |
99583181 HC |
341 | else |
342 | pagefault_out_of_memory(); | |
33692f27 LT |
343 | } else if (fault & VM_FAULT_SIGSEGV) { |
344 | /* Kernel mode? Handle exceptions or die */ | |
345 | if (!user_mode(regs)) | |
346 | do_no_context(regs); | |
347 | else | |
348 | do_sigsegv(regs, SEGV_MAPERR); | |
99583181 | 349 | } else if (fault & VM_FAULT_SIGBUS) { |
50d7280d | 350 | /* Kernel mode? Handle exceptions or die */ |
7d256175 | 351 | if (!user_mode(regs)) |
aa33c8cb | 352 | do_no_context(regs); |
36bf9680 | 353 | else |
aa33c8cb | 354 | do_sigbus(regs); |
50d7280d MS |
355 | } else |
356 | BUG(); | |
357 | break; | |
358 | } | |
359 | } | |
360 | ||
1da177e4 LT |
361 | /* |
362 | * This routine handles page faults. It determines the address, | |
363 | * and the problem, and then passes it off to one of the appropriate | |
364 | * routines. | |
365 | * | |
50d7280d | 366 | * interruption code (int_code): |
1da177e4 LT |
367 | * 04 Protection -> Write-Protection (suprression) |
368 | * 10 Segment translation -> Not present (nullification) | |
369 | * 11 Page translation -> Not present (nullification) | |
370 | * 3b Region third trans. -> Not present (nullification) | |
371 | */ | |
aa33c8cb | 372 | static inline int do_exception(struct pt_regs *regs, int access) |
1da177e4 | 373 | { |
24eb3a82 DD |
374 | #ifdef CONFIG_PGSTE |
375 | struct gmap *gmap; | |
376 | #endif | |
10c1031f MS |
377 | struct task_struct *tsk; |
378 | struct mm_struct *mm; | |
379 | struct vm_area_struct *vma; | |
aa33c8cb | 380 | unsigned long trans_exc_code; |
10c1031f | 381 | unsigned long address; |
33ce6140 HC |
382 | unsigned int flags; |
383 | int fault; | |
1da177e4 | 384 | |
39efd4ec MS |
385 | tsk = current; |
386 | /* | |
387 | * The instruction that caused the program check has | |
388 | * been nullified. Don't signal single step via SIGTRAP. | |
389 | */ | |
d3a73acb | 390 | clear_pt_regs_flag(regs, PIF_PER_TRAP); |
39efd4ec | 391 | |
7ecb344a | 392 | if (notify_page_fault(regs)) |
50d7280d | 393 | return 0; |
4ba069b8 | 394 | |
10c1031f | 395 | mm = tsk->mm; |
aa33c8cb | 396 | trans_exc_code = regs->int_parm_long; |
1da177e4 | 397 | |
1da177e4 LT |
398 | /* |
399 | * Verify that the fault happened in user space, that | |
400 | * we are not in an interrupt and that there is a | |
401 | * user context. | |
402 | */ | |
50d7280d | 403 | fault = VM_FAULT_BADCONTEXT; |
70ffdb93 | 404 | if (unlikely(!user_space_fault(regs) || faulthandler_disabled() || !mm)) |
50d7280d | 405 | goto out; |
1da177e4 | 406 | |
61365e13 | 407 | address = trans_exc_code & __FAIL_ADDR_MASK; |
a8b0ca17 | 408 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
f2c76e3b | 409 | flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
759496ba JW |
410 | if (user_mode(regs)) |
411 | flags |= FAULT_FLAG_USER; | |
33ce6140 HC |
412 | if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) |
413 | flags |= FAULT_FLAG_WRITE; | |
10c1031f | 414 | down_read(&mm->mmap_sem); |
1da177e4 | 415 | |
e5992f2e | 416 | #ifdef CONFIG_PGSTE |
527e30b4 MS |
417 | gmap = (current->flags & PF_VCPU) ? |
418 | (struct gmap *) S390_lowcore.gmap : NULL; | |
24eb3a82 | 419 | if (gmap) { |
527e30b4 | 420 | current->thread.gmap_addr = address; |
4be130a0 | 421 | current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); |
4a494439 | 422 | current->thread.gmap_int_code = regs->int_code & 0xffff; |
527e30b4 | 423 | address = __gmap_translate(gmap, address); |
e5992f2e MS |
424 | if (address == -EFAULT) { |
425 | fault = VM_FAULT_BADMAP; | |
426 | goto out_up; | |
427 | } | |
24eb3a82 DD |
428 | if (gmap->pfault_enabled) |
429 | flags |= FAULT_FLAG_RETRY_NOWAIT; | |
e5992f2e MS |
430 | } |
431 | #endif | |
432 | ||
433 | retry: | |
50d7280d | 434 | fault = VM_FAULT_BADMAP; |
482b05dd GS |
435 | vma = find_vma(mm, address); |
436 | if (!vma) | |
50d7280d | 437 | goto out_up; |
c1821c2e | 438 | |
50d7280d MS |
439 | if (unlikely(vma->vm_start > address)) { |
440 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
441 | goto out_up; | |
442 | if (expand_stack(vma, address)) | |
443 | goto out_up; | |
444 | } | |
445 | ||
446 | /* | |
447 | * Ok, we have a good vm_area for this memory access, so | |
448 | * we can handle it.. | |
449 | */ | |
450 | fault = VM_FAULT_BADACCESS; | |
1ab947de | 451 | if (unlikely(!(vma->vm_flags & access))) |
50d7280d | 452 | goto out_up; |
1da177e4 | 453 | |
53492b1d GS |
454 | if (is_vm_hugetlb_page(vma)) |
455 | address &= HPAGE_MASK; | |
1da177e4 LT |
456 | /* |
457 | * If for any reason at all we couldn't handle the fault, | |
458 | * make sure we exit gracefully rather than endlessly redo | |
459 | * the fault. | |
460 | */ | |
dcddffd4 | 461 | fault = handle_mm_fault(vma, address, flags); |
f2c76e3b HC |
462 | /* No reason to continue if interrupted by SIGKILL. */ |
463 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { | |
464 | fault = VM_FAULT_SIGNAL; | |
465 | goto out; | |
466 | } | |
50d7280d MS |
467 | if (unlikely(fault & VM_FAULT_ERROR)) |
468 | goto out_up; | |
469 | ||
33ce6140 HC |
470 | /* |
471 | * Major/minor page fault accounting is only done on the | |
472 | * initial attempt. If we go through a retry, it is extremely | |
473 | * likely that the page will be found in page cache at that point. | |
474 | */ | |
475 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
476 | if (fault & VM_FAULT_MAJOR) { | |
477 | tsk->maj_flt++; | |
a8b0ca17 | 478 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, |
33ce6140 HC |
479 | regs, address); |
480 | } else { | |
481 | tsk->min_flt++; | |
a8b0ca17 | 482 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, |
33ce6140 HC |
483 | regs, address); |
484 | } | |
485 | if (fault & VM_FAULT_RETRY) { | |
24eb3a82 DD |
486 | #ifdef CONFIG_PGSTE |
487 | if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) { | |
488 | /* FAULT_FLAG_RETRY_NOWAIT has been set, | |
489 | * mmap_sem has not been released */ | |
490 | current->thread.gmap_pfault = 1; | |
491 | fault = VM_FAULT_PFAULT; | |
492 | goto out_up; | |
493 | } | |
494 | #endif | |
33ce6140 HC |
495 | /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk |
496 | * of starvation. */ | |
24eb3a82 DD |
497 | flags &= ~(FAULT_FLAG_ALLOW_RETRY | |
498 | FAULT_FLAG_RETRY_NOWAIT); | |
45cac65b | 499 | flags |= FAULT_FLAG_TRIED; |
e5992f2e | 500 | down_read(&mm->mmap_sem); |
33ce6140 HC |
501 | goto retry; |
502 | } | |
bde69af2 | 503 | } |
527e30b4 MS |
504 | #ifdef CONFIG_PGSTE |
505 | if (gmap) { | |
506 | address = __gmap_link(gmap, current->thread.gmap_addr, | |
507 | address); | |
508 | if (address == -EFAULT) { | |
509 | fault = VM_FAULT_BADMAP; | |
510 | goto out_up; | |
511 | } | |
512 | if (address == -ENOMEM) { | |
513 | fault = VM_FAULT_OOM; | |
514 | goto out_up; | |
515 | } | |
516 | } | |
517 | #endif | |
50d7280d MS |
518 | fault = 0; |
519 | out_up: | |
10c1031f | 520 | up_read(&mm->mmap_sem); |
50d7280d MS |
521 | out: |
522 | return fault; | |
1da177e4 LT |
523 | } |
524 | ||
7a5388de | 525 | void do_protection_exception(struct pt_regs *regs) |
1da177e4 | 526 | { |
aa33c8cb | 527 | unsigned long trans_exc_code; |
50d7280d | 528 | int fault; |
61365e13 | 529 | |
aa33c8cb | 530 | trans_exc_code = regs->int_parm_long; |
f752ac4d MS |
531 | /* |
532 | * Protection exceptions are suppressing, decrement psw address. | |
533 | * The exception to this rule are aborted transactions, for these | |
534 | * the PSW already points to the correct location. | |
535 | */ | |
536 | if (!(regs->int_code & 0x200)) | |
537 | regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); | |
10c1031f MS |
538 | /* |
539 | * Check for low-address protection. This needs to be treated | |
540 | * as a special case because the translation exception code | |
541 | * field is not guaranteed to contain valid data in this case. | |
542 | */ | |
61365e13 | 543 | if (unlikely(!(trans_exc_code & 4))) { |
aa33c8cb | 544 | do_low_address(regs); |
10c1031f MS |
545 | return; |
546 | } | |
aa33c8cb | 547 | fault = do_exception(regs, VM_WRITE); |
50d7280d | 548 | if (unlikely(fault)) |
aa33c8cb | 549 | do_fault_error(regs, fault); |
1da177e4 | 550 | } |
7a5388de | 551 | NOKPROBE_SYMBOL(do_protection_exception); |
1da177e4 | 552 | |
7a5388de | 553 | void do_dat_exception(struct pt_regs *regs) |
1da177e4 | 554 | { |
1ab947de | 555 | int access, fault; |
50d7280d | 556 | |
1ab947de | 557 | access = VM_READ | VM_EXEC | VM_WRITE; |
aa33c8cb | 558 | fault = do_exception(regs, access); |
50d7280d | 559 | if (unlikely(fault)) |
aa33c8cb | 560 | do_fault_error(regs, fault); |
1da177e4 | 561 | } |
7a5388de | 562 | NOKPROBE_SYMBOL(do_dat_exception); |
1da177e4 | 563 | |
1da177e4 LT |
564 | #ifdef CONFIG_PFAULT |
565 | /* | |
566 | * 'pfault' pseudo page faults routines. | |
567 | */ | |
fb0a9d7e | 568 | static int pfault_disable; |
1da177e4 LT |
569 | |
570 | static int __init nopfault(char *str) | |
571 | { | |
572 | pfault_disable = 1; | |
573 | return 1; | |
574 | } | |
575 | ||
576 | __setup("nopfault", nopfault); | |
577 | ||
7dd8fe1f HC |
578 | struct pfault_refbk { |
579 | u16 refdiagc; | |
580 | u16 reffcode; | |
581 | u16 refdwlen; | |
582 | u16 refversn; | |
583 | u64 refgaddr; | |
584 | u64 refselmk; | |
585 | u64 refcmpmk; | |
586 | u64 reserved; | |
587 | } __attribute__ ((packed, aligned(8))); | |
1da177e4 LT |
588 | |
589 | int pfault_init(void) | |
590 | { | |
7dd8fe1f HC |
591 | struct pfault_refbk refbk = { |
592 | .refdiagc = 0x258, | |
593 | .reffcode = 0, | |
594 | .refdwlen = 5, | |
595 | .refversn = 2, | |
e22cf8ca | 596 | .refgaddr = __LC_LPP, |
7dd8fe1f HC |
597 | .refselmk = 1ULL << 48, |
598 | .refcmpmk = 1ULL << 48, | |
599 | .reserved = __PF_RES_FIELD }; | |
1da177e4 LT |
600 | int rc; |
601 | ||
f32269a0 | 602 | if (pfault_disable) |
1da177e4 | 603 | return -1; |
1ec2772e | 604 | diag_stat_inc(DIAG_STAT_X258); |
94c12cc7 MS |
605 | asm volatile( |
606 | " diag %1,%0,0x258\n" | |
607 | "0: j 2f\n" | |
608 | "1: la %0,8\n" | |
1da177e4 | 609 | "2:\n" |
94c12cc7 MS |
610 | EX_TABLE(0b,1b) |
611 | : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc"); | |
1da177e4 LT |
612 | return rc; |
613 | } | |
614 | ||
615 | void pfault_fini(void) | |
616 | { | |
7dd8fe1f HC |
617 | struct pfault_refbk refbk = { |
618 | .refdiagc = 0x258, | |
619 | .reffcode = 1, | |
620 | .refdwlen = 5, | |
621 | .refversn = 2, | |
622 | }; | |
1da177e4 | 623 | |
f32269a0 | 624 | if (pfault_disable) |
1da177e4 | 625 | return; |
1ec2772e | 626 | diag_stat_inc(DIAG_STAT_X258); |
94c12cc7 MS |
627 | asm volatile( |
628 | " diag %0,0,0x258\n" | |
6c22c986 | 629 | "0: nopr %%r7\n" |
94c12cc7 MS |
630 | EX_TABLE(0b,0b) |
631 | : : "a" (&refbk), "m" (refbk) : "cc"); | |
1da177e4 LT |
632 | } |
633 | ||
f2db2e6c HC |
634 | static DEFINE_SPINLOCK(pfault_lock); |
635 | static LIST_HEAD(pfault_list); | |
636 | ||
0227f7c4 PZ |
637 | #define PF_COMPLETE 0x0080 |
638 | ||
639 | /* | |
640 | * The mechanism of our pfault code: if Linux is running as guest, runs a user | |
641 | * space process and the user space process accesses a page that the host has | |
642 | * paged out we get a pfault interrupt. | |
643 | * | |
644 | * This allows us, within the guest, to schedule a different process. Without | |
645 | * this mechanism the host would have to suspend the whole virtual cpu until | |
646 | * the page has been paged in. | |
647 | * | |
648 | * So when we get such an interrupt then we set the state of the current task | |
649 | * to uninterruptible and also set the need_resched flag. Both happens within | |
650 | * interrupt context(!). If we later on want to return to user space we | |
651 | * recognize the need_resched flag and then call schedule(). It's not very | |
652 | * obvious how this works... | |
653 | * | |
654 | * Of course we have a lot of additional fun with the completion interrupt (-> | |
655 | * host signals that a page of a process has been paged in and the process can | |
656 | * continue to run). This interrupt can arrive on any cpu and, since we have | |
657 | * virtual cpus, actually appear before the interrupt that signals that a page | |
658 | * is missing. | |
659 | */ | |
fde15c3a | 660 | static void pfault_interrupt(struct ext_code ext_code, |
f6649a7e | 661 | unsigned int param32, unsigned long param64) |
1da177e4 LT |
662 | { |
663 | struct task_struct *tsk; | |
664 | __u16 subcode; | |
f2db2e6c | 665 | pid_t pid; |
1da177e4 LT |
666 | |
667 | /* | |
0227f7c4 PZ |
668 | * Get the external interruption subcode & pfault initial/completion |
669 | * signal bit. VM stores this in the 'cpu address' field associated | |
670 | * with the external interrupt. | |
1da177e4 | 671 | */ |
fde15c3a | 672 | subcode = ext_code.subcode; |
1da177e4 LT |
673 | if ((subcode & 0xff00) != __SUBCODE_MASK) |
674 | return; | |
420f42ec | 675 | inc_irq_stat(IRQEXT_PFL); |
54c27791 | 676 | /* Get the token (= pid of the affected task). */ |
e22cf8ca | 677 | pid = param64 & LPP_PFAULT_PID_MASK; |
54c27791 HC |
678 | rcu_read_lock(); |
679 | tsk = find_task_by_pid_ns(pid, &init_pid_ns); | |
680 | if (tsk) | |
681 | get_task_struct(tsk); | |
682 | rcu_read_unlock(); | |
683 | if (!tsk) | |
684 | return; | |
f2db2e6c | 685 | spin_lock(&pfault_lock); |
0227f7c4 | 686 | if (subcode & PF_COMPLETE) { |
1da177e4 | 687 | /* signal bit is set -> a page has been swapped in by VM */ |
f2db2e6c | 688 | if (tsk->thread.pfault_wait == 1) { |
1da177e4 LT |
689 | /* Initial interrupt was faster than the completion |
690 | * interrupt. pfault_wait is valid. Set pfault_wait | |
691 | * back to zero and wake up the process. This can | |
692 | * safely be done because the task is still sleeping | |
b6d09449 | 693 | * and can't produce new pfaults. */ |
1da177e4 | 694 | tsk->thread.pfault_wait = 0; |
f2db2e6c | 695 | list_del(&tsk->thread.list); |
1da177e4 | 696 | wake_up_process(tsk); |
d5e50a51 | 697 | put_task_struct(tsk); |
f2db2e6c HC |
698 | } else { |
699 | /* Completion interrupt was faster than initial | |
700 | * interrupt. Set pfault_wait to -1 so the initial | |
fa2fb2f4 HC |
701 | * interrupt doesn't put the task to sleep. |
702 | * If the task is not running, ignore the completion | |
703 | * interrupt since it must be a leftover of a PFAULT | |
704 | * CANCEL operation which didn't remove all pending | |
705 | * completion interrupts. */ | |
706 | if (tsk->state == TASK_RUNNING) | |
707 | tsk->thread.pfault_wait = -1; | |
1da177e4 LT |
708 | } |
709 | } else { | |
710 | /* signal bit not set -> a real page is missing. */ | |
d49f47f8 HC |
711 | if (WARN_ON_ONCE(tsk != current)) |
712 | goto out; | |
d5e50a51 HC |
713 | if (tsk->thread.pfault_wait == 1) { |
714 | /* Already on the list with a reference: put to sleep */ | |
0227f7c4 | 715 | goto block; |
d5e50a51 | 716 | } else if (tsk->thread.pfault_wait == -1) { |
1da177e4 | 717 | /* Completion interrupt was faster than the initial |
f2db2e6c HC |
718 | * interrupt (pfault_wait == -1). Set pfault_wait |
719 | * back to zero and exit. */ | |
1da177e4 | 720 | tsk->thread.pfault_wait = 0; |
f2db2e6c HC |
721 | } else { |
722 | /* Initial interrupt arrived before completion | |
d5e50a51 HC |
723 | * interrupt. Let the task sleep. |
724 | * An extra task reference is needed since a different | |
725 | * cpu may set the task state to TASK_RUNNING again | |
726 | * before the scheduler is reached. */ | |
727 | get_task_struct(tsk); | |
f2db2e6c HC |
728 | tsk->thread.pfault_wait = 1; |
729 | list_add(&tsk->thread.list, &pfault_list); | |
0227f7c4 PZ |
730 | block: |
731 | /* Since this must be a userspace fault, there | |
732 | * is no kernel task state to trample. Rely on the | |
733 | * return to userspace schedule() to block. */ | |
734 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
1da177e4 | 735 | set_tsk_need_resched(tsk); |
f2db2e6c HC |
736 | } |
737 | } | |
d49f47f8 | 738 | out: |
f2db2e6c | 739 | spin_unlock(&pfault_lock); |
54c27791 | 740 | put_task_struct(tsk); |
f2db2e6c HC |
741 | } |
742 | ||
e2741f17 PG |
743 | static int pfault_cpu_notify(struct notifier_block *self, unsigned long action, |
744 | void *hcpu) | |
f2db2e6c HC |
745 | { |
746 | struct thread_struct *thread, *next; | |
747 | struct task_struct *tsk; | |
748 | ||
1c725922 | 749 | switch (action & ~CPU_TASKS_FROZEN) { |
f2db2e6c | 750 | case CPU_DEAD: |
f2db2e6c HC |
751 | spin_lock_irq(&pfault_lock); |
752 | list_for_each_entry_safe(thread, next, &pfault_list, list) { | |
753 | thread->pfault_wait = 0; | |
754 | list_del(&thread->list); | |
755 | tsk = container_of(thread, struct task_struct, thread); | |
756 | wake_up_process(tsk); | |
d5e50a51 | 757 | put_task_struct(tsk); |
f2db2e6c HC |
758 | } |
759 | spin_unlock_irq(&pfault_lock); | |
760 | break; | |
761 | default: | |
762 | break; | |
1da177e4 | 763 | } |
f2db2e6c | 764 | return NOTIFY_OK; |
1da177e4 | 765 | } |
1da177e4 | 766 | |
fb0a9d7e | 767 | static int __init pfault_irq_init(void) |
29b08d2b | 768 | { |
fb0a9d7e | 769 | int rc; |
29b08d2b | 770 | |
1dad093b | 771 | rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); |
7dd8fe1f HC |
772 | if (rc) |
773 | goto out_extint; | |
774 | rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; | |
775 | if (rc) | |
776 | goto out_pfault; | |
82003c3e | 777 | irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); |
7dd8fe1f HC |
778 | hotcpu_notifier(pfault_cpu_notify, 0); |
779 | return 0; | |
29b08d2b | 780 | |
7dd8fe1f | 781 | out_pfault: |
1dad093b | 782 | unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); |
7dd8fe1f HC |
783 | out_extint: |
784 | pfault_disable = 1; | |
785 | return rc; | |
29b08d2b | 786 | } |
fb0a9d7e HC |
787 | early_initcall(pfault_irq_init); |
788 | ||
7dd8fe1f | 789 | #endif /* CONFIG_PFAULT */ |