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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 | 2 | /* |
1da177e4 | 3 | * S390 version |
a53c8fab | 4 | * Copyright IBM Corp. 1999 |
1da177e4 LT |
5 | * Author(s): Hartmut Penner (hp@de.ibm.com) |
6 | * Ulrich Weigand (uweigand@de.ibm.com) | |
7 | * | |
8 | * Derived from "arch/i386/mm/fault.c" | |
9 | * Copyright (C) 1995 Linus Torvalds | |
10 | */ | |
11 | ||
052ff461 | 12 | #include <linux/kernel_stat.h> |
cdd6c482 | 13 | #include <linux/perf_event.h> |
1da177e4 LT |
14 | #include <linux/signal.h> |
15 | #include <linux/sched.h> | |
b17b0153 | 16 | #include <linux/sched/debug.h> |
1da177e4 LT |
17 | #include <linux/kernel.h> |
18 | #include <linux/errno.h> | |
19 | #include <linux/string.h> | |
20 | #include <linux/types.h> | |
21 | #include <linux/ptrace.h> | |
22 | #include <linux/mman.h> | |
23 | #include <linux/mm.h> | |
7757591a | 24 | #include <linux/compat.h> |
1da177e4 | 25 | #include <linux/smp.h> |
1eeb66a1 | 26 | #include <linux/kdebug.h> |
1da177e4 LT |
27 | #include <linux/init.h> |
28 | #include <linux/console.h> | |
dcc096c5 | 29 | #include <linux/extable.h> |
1da177e4 | 30 | #include <linux/hardirq.h> |
4ba069b8 | 31 | #include <linux/kprobes.h> |
be5ec363 | 32 | #include <linux/uaccess.h> |
53492b1d | 33 | #include <linux/hugetlb.h> |
cbb870c8 | 34 | #include <asm/asm-offsets.h> |
1ec2772e | 35 | #include <asm/diag.h> |
1da177e4 | 36 | #include <asm/pgtable.h> |
1e133ab2 | 37 | #include <asm/gmap.h> |
d7b250e2 | 38 | #include <asm/irq.h> |
6252d702 | 39 | #include <asm/mmu_context.h> |
a0616cde | 40 | #include <asm/facility.h> |
a806170e | 41 | #include "../kernel/entry.h" |
1da177e4 | 42 | |
1da177e4 | 43 | #define __FAIL_ADDR_MASK -4096L |
1da177e4 LT |
44 | #define __SUBCODE_MASK 0x0600 |
45 | #define __PF_RES_FIELD 0x8000000000000000ULL | |
1da177e4 | 46 | |
50d7280d MS |
47 | #define VM_FAULT_BADCONTEXT 0x010000 |
48 | #define VM_FAULT_BADMAP 0x020000 | |
49 | #define VM_FAULT_BADACCESS 0x040000 | |
a4f32bdb | 50 | #define VM_FAULT_SIGNAL 0x080000 |
24eb3a82 | 51 | #define VM_FAULT_PFAULT 0x100000 |
50d7280d | 52 | |
0aaba41b MS |
53 | enum fault_type { |
54 | KERNEL_FAULT, | |
55 | USER_FAULT, | |
56 | VDSO_FAULT, | |
57 | GMAP_FAULT, | |
58 | }; | |
59 | ||
a4f32bdb | 60 | static unsigned long store_indication __read_mostly; |
92f842ea | 61 | |
a4f32bdb | 62 | static int __init fault_init(void) |
92f842ea | 63 | { |
a4f32bdb | 64 | if (test_facility(75)) |
92f842ea | 65 | store_indication = 0xc00; |
a4f32bdb | 66 | return 0; |
92f842ea | 67 | } |
a4f32bdb | 68 | early_initcall(fault_init); |
92f842ea | 69 | |
7ecb344a | 70 | static inline int notify_page_fault(struct pt_regs *regs) |
10c1031f | 71 | { |
33464e3b CH |
72 | int ret = 0; |
73 | ||
74 | /* kprobe_running() needs smp_processor_id() */ | |
22e0a046 | 75 | if (kprobes_built_in() && !user_mode(regs)) { |
33464e3b CH |
76 | preempt_disable(); |
77 | if (kprobe_running() && kprobe_fault_handler(regs, 14)) | |
78 | ret = 1; | |
79 | preempt_enable(); | |
80 | } | |
33464e3b | 81 | return ret; |
4ba069b8 | 82 | } |
4ba069b8 | 83 | |
1da177e4 | 84 | /* |
0aaba41b | 85 | * Find out which address space caused the exception. |
1da177e4 | 86 | */ |
bf2f1eee | 87 | static enum fault_type get_fault_type(struct pt_regs *regs) |
1da177e4 | 88 | { |
457f2180 HC |
89 | unsigned long trans_exc_code; |
90 | ||
457f2180 | 91 | trans_exc_code = regs->int_parm_long & 3; |
0aaba41b MS |
92 | if (likely(trans_exc_code == 0)) { |
93 | /* primary space exception */ | |
94 | if (IS_ENABLED(CONFIG_PGSTE) && | |
95 | test_pt_regs_flag(regs, PIF_GUEST_FAULT)) | |
96 | return GMAP_FAULT; | |
97 | if (current->thread.mm_segment == USER_DS) | |
98 | return USER_FAULT; | |
99 | return KERNEL_FAULT; | |
100 | } | |
101 | if (trans_exc_code == 2) { | |
102 | /* secondary space exception */ | |
103 | if (current->thread.mm_segment & 1) { | |
104 | if (current->thread.mm_segment == USER_DS_SACF) | |
105 | return USER_FAULT; | |
106 | return KERNEL_FAULT; | |
107 | } | |
108 | return VDSO_FAULT; | |
109 | } | |
962f0af8 GS |
110 | if (trans_exc_code == 1) { |
111 | /* access register mode, not used in the kernel */ | |
112 | return USER_FAULT; | |
113 | } | |
0aaba41b MS |
114 | /* home space exception -> access via kernel ASCE */ |
115 | return KERNEL_FAULT; | |
1da177e4 LT |
116 | } |
117 | ||
3b7df342 HC |
118 | static int bad_address(void *p) |
119 | { | |
120 | unsigned long dummy; | |
121 | ||
122 | return probe_kernel_address((unsigned long *)p, dummy); | |
123 | } | |
124 | ||
3b7df342 HC |
125 | static void dump_pagetable(unsigned long asce, unsigned long address) |
126 | { | |
fe7b2747 | 127 | unsigned long *table = __va(asce & _ASCE_ORIGIN); |
3b7df342 HC |
128 | |
129 | pr_alert("AS:%016lx ", asce); | |
130 | switch (asce & _ASCE_TYPE_MASK) { | |
131 | case _ASCE_TYPE_REGION1: | |
f1c1174f | 132 | table += (address & _REGION1_INDEX) >> _REGION1_SHIFT; |
3b7df342 HC |
133 | if (bad_address(table)) |
134 | goto bad; | |
135 | pr_cont("R1:%016lx ", *table); | |
136 | if (*table & _REGION_ENTRY_INVALID) | |
137 | goto out; | |
138 | table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
139 | /* fallthrough */ | |
140 | case _ASCE_TYPE_REGION2: | |
f1c1174f | 141 | table += (address & _REGION2_INDEX) >> _REGION2_SHIFT; |
3b7df342 HC |
142 | if (bad_address(table)) |
143 | goto bad; | |
144 | pr_cont("R2:%016lx ", *table); | |
145 | if (*table & _REGION_ENTRY_INVALID) | |
146 | goto out; | |
147 | table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
148 | /* fallthrough */ | |
149 | case _ASCE_TYPE_REGION3: | |
f1c1174f | 150 | table += (address & _REGION3_INDEX) >> _REGION3_SHIFT; |
3b7df342 HC |
151 | if (bad_address(table)) |
152 | goto bad; | |
153 | pr_cont("R3:%016lx ", *table); | |
154 | if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) | |
155 | goto out; | |
156 | table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
157 | /* fallthrough */ | |
158 | case _ASCE_TYPE_SEGMENT: | |
f1c1174f | 159 | table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; |
3b7df342 HC |
160 | if (bad_address(table)) |
161 | goto bad; | |
91c0837e | 162 | pr_cont("S:%016lx ", *table); |
3b7df342 HC |
163 | if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) |
164 | goto out; | |
165 | table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); | |
166 | } | |
f1c1174f | 167 | table += (address & _PAGE_INDEX) >> _PAGE_SHIFT; |
3b7df342 HC |
168 | if (bad_address(table)) |
169 | goto bad; | |
170 | pr_cont("P:%016lx ", *table); | |
171 | out: | |
172 | pr_cont("\n"); | |
173 | return; | |
174 | bad: | |
175 | pr_cont("BAD\n"); | |
176 | } | |
177 | ||
3b7df342 HC |
178 | static void dump_fault_info(struct pt_regs *regs) |
179 | { | |
180 | unsigned long asce; | |
181 | ||
5d7eccec HC |
182 | pr_alert("Failing address: %016lx TEID: %016lx\n", |
183 | regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); | |
3b7df342 HC |
184 | pr_alert("Fault in "); |
185 | switch (regs->int_parm_long & 3) { | |
186 | case 3: | |
187 | pr_cont("home space "); | |
188 | break; | |
189 | case 2: | |
190 | pr_cont("secondary space "); | |
191 | break; | |
192 | case 1: | |
193 | pr_cont("access register "); | |
194 | break; | |
195 | case 0: | |
196 | pr_cont("primary space "); | |
197 | break; | |
198 | } | |
199 | pr_cont("mode while using "); | |
0aaba41b MS |
200 | switch (get_fault_type(regs)) { |
201 | case USER_FAULT: | |
3b7df342 HC |
202 | asce = S390_lowcore.user_asce; |
203 | pr_cont("user "); | |
0aaba41b MS |
204 | break; |
205 | case VDSO_FAULT: | |
206 | asce = S390_lowcore.vdso_asce; | |
207 | pr_cont("vdso "); | |
208 | break; | |
209 | case GMAP_FAULT: | |
210 | asce = ((struct gmap *) S390_lowcore.gmap)->asce; | |
211 | pr_cont("gmap "); | |
212 | break; | |
213 | case KERNEL_FAULT: | |
214 | asce = S390_lowcore.kernel_asce; | |
215 | pr_cont("kernel "); | |
216 | break; | |
bf2f1eee MY |
217 | default: |
218 | unreachable(); | |
3b7df342 HC |
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 | 248 | { |
5d7eccec | 249 | report_user_fault(regs, SIGSEGV, 1); |
9507a5d0 EB |
250 | force_sig_fault(SIGSEGV, si_code, |
251 | (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK), | |
252 | current); | |
1da177e4 LT |
253 | } |
254 | ||
a80313ff GS |
255 | const struct exception_table_entry *s390_search_extables(unsigned long addr) |
256 | { | |
257 | const struct exception_table_entry *fixup; | |
258 | ||
259 | fixup = search_extable(__start_dma_ex_table, | |
260 | __stop_dma_ex_table - __start_dma_ex_table, | |
261 | addr); | |
262 | if (!fixup) | |
263 | fixup = search_exception_tables(addr); | |
264 | return fixup; | |
265 | } | |
266 | ||
aa33c8cb | 267 | static noinline void do_no_context(struct pt_regs *regs) |
10c1031f MS |
268 | { |
269 | const struct exception_table_entry *fixup; | |
270 | ||
271 | /* Are we prepared to handle this kernel fault? */ | |
a80313ff | 272 | fixup = s390_search_extables(regs->psw.addr); |
10c1031f | 273 | if (fixup) { |
fecc868a | 274 | regs->psw.addr = extable_fixup(fixup); |
10c1031f MS |
275 | return; |
276 | } | |
277 | ||
278 | /* | |
279 | * Oops. The kernel tried to access some bad page. We'll have to | |
280 | * terminate things with extreme prejudice. | |
281 | */ | |
0aaba41b | 282 | if (get_fault_type(regs) == KERNEL_FAULT) |
10c1031f | 283 | printk(KERN_ALERT "Unable to handle kernel pointer dereference" |
3b7df342 | 284 | " in virtual kernel address space\n"); |
10c1031f MS |
285 | else |
286 | printk(KERN_ALERT "Unable to handle kernel paging request" | |
3b7df342 | 287 | " in virtual user address space\n"); |
3b7df342 | 288 | dump_fault_info(regs); |
aa33c8cb | 289 | die(regs, "Oops"); |
10c1031f MS |
290 | do_exit(SIGKILL); |
291 | } | |
292 | ||
aa33c8cb | 293 | static noinline void do_low_address(struct pt_regs *regs) |
10c1031f MS |
294 | { |
295 | /* Low-address protection hit in kernel mode means | |
296 | NULL pointer write access in kernel mode. */ | |
297 | if (regs->psw.mask & PSW_MASK_PSTATE) { | |
298 | /* Low-address protection hit in user mode 'cannot happen'. */ | |
aa33c8cb | 299 | die (regs, "Low-address protection"); |
10c1031f MS |
300 | do_exit(SIGKILL); |
301 | } | |
302 | ||
aa33c8cb | 303 | do_no_context(regs); |
10c1031f MS |
304 | } |
305 | ||
aa33c8cb | 306 | static noinline void do_sigbus(struct pt_regs *regs) |
10c1031f | 307 | { |
10c1031f MS |
308 | /* |
309 | * Send a sigbus, regardless of whether we were in kernel | |
310 | * or user mode. | |
311 | */ | |
9507a5d0 EB |
312 | force_sig_fault(SIGBUS, BUS_ADRERR, |
313 | (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK), | |
314 | current); | |
10c1031f MS |
315 | } |
316 | ||
57d7f939 MS |
317 | static noinline int signal_return(struct pt_regs *regs) |
318 | { | |
319 | u16 instruction; | |
320 | int rc; | |
321 | ||
322 | rc = __get_user(instruction, (u16 __user *) regs->psw.addr); | |
323 | if (rc) | |
324 | return rc; | |
325 | if (instruction == 0x0a77) { | |
326 | set_pt_regs_flag(regs, PIF_SYSCALL); | |
327 | regs->int_code = 0x00040077; | |
328 | return 0; | |
329 | } else if (instruction == 0x0aad) { | |
330 | set_pt_regs_flag(regs, PIF_SYSCALL); | |
331 | regs->int_code = 0x000400ad; | |
332 | return 0; | |
333 | } | |
334 | return -EACCES; | |
335 | } | |
336 | ||
50a7ca3c SJ |
337 | static noinline void do_fault_error(struct pt_regs *regs, int access, |
338 | vm_fault_t fault) | |
50d7280d MS |
339 | { |
340 | int si_code; | |
341 | ||
342 | switch (fault) { | |
343 | case VM_FAULT_BADACCESS: | |
57d7f939 MS |
344 | if (access == VM_EXEC && signal_return(regs) == 0) |
345 | break; | |
50d7280d MS |
346 | case VM_FAULT_BADMAP: |
347 | /* Bad memory access. Check if it is kernel or user space. */ | |
7d256175 | 348 | if (user_mode(regs)) { |
50d7280d MS |
349 | /* User mode accesses just cause a SIGSEGV */ |
350 | si_code = (fault == VM_FAULT_BADMAP) ? | |
351 | SEGV_MAPERR : SEGV_ACCERR; | |
aa33c8cb | 352 | do_sigsegv(regs, si_code); |
57d7f939 | 353 | break; |
50d7280d MS |
354 | } |
355 | case VM_FAULT_BADCONTEXT: | |
24eb3a82 | 356 | case VM_FAULT_PFAULT: |
aa33c8cb | 357 | do_no_context(regs); |
50d7280d | 358 | break; |
f2c76e3b HC |
359 | case VM_FAULT_SIGNAL: |
360 | if (!user_mode(regs)) | |
361 | do_no_context(regs); | |
362 | break; | |
50d7280d | 363 | default: /* fault & VM_FAULT_ERROR */ |
99583181 | 364 | if (fault & VM_FAULT_OOM) { |
7d256175 | 365 | if (!user_mode(regs)) |
aa33c8cb | 366 | do_no_context(regs); |
99583181 HC |
367 | else |
368 | pagefault_out_of_memory(); | |
33692f27 LT |
369 | } else if (fault & VM_FAULT_SIGSEGV) { |
370 | /* Kernel mode? Handle exceptions or die */ | |
371 | if (!user_mode(regs)) | |
372 | do_no_context(regs); | |
373 | else | |
374 | do_sigsegv(regs, SEGV_MAPERR); | |
99583181 | 375 | } else if (fault & VM_FAULT_SIGBUS) { |
50d7280d | 376 | /* Kernel mode? Handle exceptions or die */ |
7d256175 | 377 | if (!user_mode(regs)) |
aa33c8cb | 378 | do_no_context(regs); |
36bf9680 | 379 | else |
aa33c8cb | 380 | do_sigbus(regs); |
50d7280d MS |
381 | } else |
382 | BUG(); | |
383 | break; | |
384 | } | |
385 | } | |
386 | ||
1da177e4 LT |
387 | /* |
388 | * This routine handles page faults. It determines the address, | |
389 | * and the problem, and then passes it off to one of the appropriate | |
390 | * routines. | |
391 | * | |
50d7280d | 392 | * interruption code (int_code): |
1da177e4 LT |
393 | * 04 Protection -> Write-Protection (suprression) |
394 | * 10 Segment translation -> Not present (nullification) | |
395 | * 11 Page translation -> Not present (nullification) | |
396 | * 3b Region third trans. -> Not present (nullification) | |
397 | */ | |
50a7ca3c | 398 | static inline vm_fault_t do_exception(struct pt_regs *regs, int access) |
1da177e4 | 399 | { |
24eb3a82 | 400 | struct gmap *gmap; |
10c1031f MS |
401 | struct task_struct *tsk; |
402 | struct mm_struct *mm; | |
403 | struct vm_area_struct *vma; | |
0aaba41b | 404 | enum fault_type type; |
aa33c8cb | 405 | unsigned long trans_exc_code; |
10c1031f | 406 | unsigned long address; |
33ce6140 | 407 | unsigned int flags; |
50a7ca3c | 408 | vm_fault_t fault; |
1da177e4 | 409 | |
39efd4ec MS |
410 | tsk = current; |
411 | /* | |
412 | * The instruction that caused the program check has | |
413 | * been nullified. Don't signal single step via SIGTRAP. | |
414 | */ | |
d3a73acb | 415 | clear_pt_regs_flag(regs, PIF_PER_TRAP); |
39efd4ec | 416 | |
7ecb344a | 417 | if (notify_page_fault(regs)) |
50d7280d | 418 | return 0; |
4ba069b8 | 419 | |
10c1031f | 420 | mm = tsk->mm; |
aa33c8cb | 421 | trans_exc_code = regs->int_parm_long; |
1da177e4 | 422 | |
1da177e4 LT |
423 | /* |
424 | * Verify that the fault happened in user space, that | |
425 | * we are not in an interrupt and that there is a | |
426 | * user context. | |
427 | */ | |
50d7280d | 428 | fault = VM_FAULT_BADCONTEXT; |
0aaba41b MS |
429 | type = get_fault_type(regs); |
430 | switch (type) { | |
431 | case KERNEL_FAULT: | |
432 | goto out; | |
433 | case VDSO_FAULT: | |
434 | fault = VM_FAULT_BADMAP; | |
50d7280d | 435 | goto out; |
0aaba41b MS |
436 | case USER_FAULT: |
437 | case GMAP_FAULT: | |
438 | if (faulthandler_disabled() || !mm) | |
439 | goto out; | |
440 | break; | |
441 | } | |
1da177e4 | 442 | |
61365e13 | 443 | address = trans_exc_code & __FAIL_ADDR_MASK; |
a8b0ca17 | 444 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
f2c76e3b | 445 | flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
759496ba JW |
446 | if (user_mode(regs)) |
447 | flags |= FAULT_FLAG_USER; | |
33ce6140 HC |
448 | if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) |
449 | flags |= FAULT_FLAG_WRITE; | |
10c1031f | 450 | down_read(&mm->mmap_sem); |
1da177e4 | 451 | |
0aaba41b MS |
452 | gmap = NULL; |
453 | if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { | |
454 | gmap = (struct gmap *) S390_lowcore.gmap; | |
527e30b4 | 455 | current->thread.gmap_addr = address; |
4be130a0 | 456 | current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); |
4a494439 | 457 | current->thread.gmap_int_code = regs->int_code & 0xffff; |
527e30b4 | 458 | address = __gmap_translate(gmap, address); |
e5992f2e MS |
459 | if (address == -EFAULT) { |
460 | fault = VM_FAULT_BADMAP; | |
461 | goto out_up; | |
462 | } | |
24eb3a82 DD |
463 | if (gmap->pfault_enabled) |
464 | flags |= FAULT_FLAG_RETRY_NOWAIT; | |
e5992f2e | 465 | } |
e5992f2e MS |
466 | |
467 | retry: | |
50d7280d | 468 | fault = VM_FAULT_BADMAP; |
482b05dd GS |
469 | vma = find_vma(mm, address); |
470 | if (!vma) | |
50d7280d | 471 | goto out_up; |
c1821c2e | 472 | |
50d7280d MS |
473 | if (unlikely(vma->vm_start > address)) { |
474 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
475 | goto out_up; | |
476 | if (expand_stack(vma, address)) | |
477 | goto out_up; | |
478 | } | |
479 | ||
480 | /* | |
481 | * Ok, we have a good vm_area for this memory access, so | |
482 | * we can handle it.. | |
483 | */ | |
484 | fault = VM_FAULT_BADACCESS; | |
1ab947de | 485 | if (unlikely(!(vma->vm_flags & access))) |
50d7280d | 486 | goto out_up; |
1da177e4 | 487 | |
53492b1d GS |
488 | if (is_vm_hugetlb_page(vma)) |
489 | address &= HPAGE_MASK; | |
1da177e4 LT |
490 | /* |
491 | * If for any reason at all we couldn't handle the fault, | |
492 | * make sure we exit gracefully rather than endlessly redo | |
493 | * the fault. | |
494 | */ | |
dcddffd4 | 495 | fault = handle_mm_fault(vma, address, flags); |
f2c76e3b HC |
496 | /* No reason to continue if interrupted by SIGKILL. */ |
497 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { | |
498 | fault = VM_FAULT_SIGNAL; | |
306d6c49 CI |
499 | if (flags & FAULT_FLAG_RETRY_NOWAIT) |
500 | goto out_up; | |
f2c76e3b HC |
501 | goto out; |
502 | } | |
50d7280d MS |
503 | if (unlikely(fault & VM_FAULT_ERROR)) |
504 | goto out_up; | |
505 | ||
33ce6140 HC |
506 | /* |
507 | * Major/minor page fault accounting is only done on the | |
508 | * initial attempt. If we go through a retry, it is extremely | |
509 | * likely that the page will be found in page cache at that point. | |
510 | */ | |
511 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
512 | if (fault & VM_FAULT_MAJOR) { | |
513 | tsk->maj_flt++; | |
a8b0ca17 | 514 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, |
33ce6140 HC |
515 | regs, address); |
516 | } else { | |
517 | tsk->min_flt++; | |
a8b0ca17 | 518 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, |
33ce6140 HC |
519 | regs, address); |
520 | } | |
521 | if (fault & VM_FAULT_RETRY) { | |
0aaba41b MS |
522 | if (IS_ENABLED(CONFIG_PGSTE) && gmap && |
523 | (flags & FAULT_FLAG_RETRY_NOWAIT)) { | |
24eb3a82 DD |
524 | /* FAULT_FLAG_RETRY_NOWAIT has been set, |
525 | * mmap_sem has not been released */ | |
526 | current->thread.gmap_pfault = 1; | |
527 | fault = VM_FAULT_PFAULT; | |
528 | goto out_up; | |
529 | } | |
33ce6140 HC |
530 | /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk |
531 | * of starvation. */ | |
24eb3a82 DD |
532 | flags &= ~(FAULT_FLAG_ALLOW_RETRY | |
533 | FAULT_FLAG_RETRY_NOWAIT); | |
45cac65b | 534 | flags |= FAULT_FLAG_TRIED; |
e5992f2e | 535 | down_read(&mm->mmap_sem); |
33ce6140 HC |
536 | goto retry; |
537 | } | |
bde69af2 | 538 | } |
0aaba41b | 539 | if (IS_ENABLED(CONFIG_PGSTE) && gmap) { |
527e30b4 MS |
540 | address = __gmap_link(gmap, current->thread.gmap_addr, |
541 | address); | |
542 | if (address == -EFAULT) { | |
543 | fault = VM_FAULT_BADMAP; | |
544 | goto out_up; | |
545 | } | |
546 | if (address == -ENOMEM) { | |
547 | fault = VM_FAULT_OOM; | |
548 | goto out_up; | |
549 | } | |
550 | } | |
50d7280d MS |
551 | fault = 0; |
552 | out_up: | |
10c1031f | 553 | up_read(&mm->mmap_sem); |
50d7280d MS |
554 | out: |
555 | return fault; | |
1da177e4 LT |
556 | } |
557 | ||
7a5388de | 558 | void do_protection_exception(struct pt_regs *regs) |
1da177e4 | 559 | { |
aa33c8cb | 560 | unsigned long trans_exc_code; |
50a7ca3c SJ |
561 | int access; |
562 | vm_fault_t fault; | |
61365e13 | 563 | |
aa33c8cb | 564 | trans_exc_code = regs->int_parm_long; |
f752ac4d MS |
565 | /* |
566 | * Protection exceptions are suppressing, decrement psw address. | |
567 | * The exception to this rule are aborted transactions, for these | |
568 | * the PSW already points to the correct location. | |
569 | */ | |
570 | if (!(regs->int_code & 0x200)) | |
571 | regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); | |
10c1031f MS |
572 | /* |
573 | * Check for low-address protection. This needs to be treated | |
574 | * as a special case because the translation exception code | |
575 | * field is not guaranteed to contain valid data in this case. | |
576 | */ | |
61365e13 | 577 | if (unlikely(!(trans_exc_code & 4))) { |
aa33c8cb | 578 | do_low_address(regs); |
10c1031f MS |
579 | return; |
580 | } | |
57d7f939 MS |
581 | if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { |
582 | regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | | |
583 | (regs->psw.addr & PAGE_MASK); | |
584 | access = VM_EXEC; | |
585 | fault = VM_FAULT_BADACCESS; | |
586 | } else { | |
587 | access = VM_WRITE; | |
588 | fault = do_exception(regs, access); | |
589 | } | |
50d7280d | 590 | if (unlikely(fault)) |
57d7f939 | 591 | do_fault_error(regs, access, fault); |
1da177e4 | 592 | } |
7a5388de | 593 | NOKPROBE_SYMBOL(do_protection_exception); |
1da177e4 | 594 | |
7a5388de | 595 | void do_dat_exception(struct pt_regs *regs) |
1da177e4 | 596 | { |
50a7ca3c SJ |
597 | int access; |
598 | vm_fault_t fault; | |
50d7280d | 599 | |
1ab947de | 600 | access = VM_READ | VM_EXEC | VM_WRITE; |
aa33c8cb | 601 | fault = do_exception(regs, access); |
50d7280d | 602 | if (unlikely(fault)) |
57d7f939 | 603 | do_fault_error(regs, access, fault); |
1da177e4 | 604 | } |
7a5388de | 605 | NOKPROBE_SYMBOL(do_dat_exception); |
1da177e4 | 606 | |
1da177e4 LT |
607 | #ifdef CONFIG_PFAULT |
608 | /* | |
609 | * 'pfault' pseudo page faults routines. | |
610 | */ | |
fb0a9d7e | 611 | static int pfault_disable; |
1da177e4 LT |
612 | |
613 | static int __init nopfault(char *str) | |
614 | { | |
615 | pfault_disable = 1; | |
616 | return 1; | |
617 | } | |
618 | ||
619 | __setup("nopfault", nopfault); | |
620 | ||
7dd8fe1f HC |
621 | struct pfault_refbk { |
622 | u16 refdiagc; | |
623 | u16 reffcode; | |
624 | u16 refdwlen; | |
625 | u16 refversn; | |
626 | u64 refgaddr; | |
627 | u64 refselmk; | |
628 | u64 refcmpmk; | |
629 | u64 reserved; | |
630 | } __attribute__ ((packed, aligned(8))); | |
1da177e4 | 631 | |
00e9e664 MS |
632 | static struct pfault_refbk pfault_init_refbk = { |
633 | .refdiagc = 0x258, | |
634 | .reffcode = 0, | |
635 | .refdwlen = 5, | |
636 | .refversn = 2, | |
637 | .refgaddr = __LC_LPP, | |
638 | .refselmk = 1ULL << 48, | |
639 | .refcmpmk = 1ULL << 48, | |
640 | .reserved = __PF_RES_FIELD | |
641 | }; | |
642 | ||
1da177e4 LT |
643 | int pfault_init(void) |
644 | { | |
1da177e4 LT |
645 | int rc; |
646 | ||
f32269a0 | 647 | if (pfault_disable) |
1da177e4 | 648 | return -1; |
1ec2772e | 649 | diag_stat_inc(DIAG_STAT_X258); |
94c12cc7 MS |
650 | asm volatile( |
651 | " diag %1,%0,0x258\n" | |
652 | "0: j 2f\n" | |
653 | "1: la %0,8\n" | |
1da177e4 | 654 | "2:\n" |
94c12cc7 | 655 | EX_TABLE(0b,1b) |
00e9e664 MS |
656 | : "=d" (rc) |
657 | : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); | |
1da177e4 LT |
658 | return rc; |
659 | } | |
660 | ||
00e9e664 MS |
661 | static struct pfault_refbk pfault_fini_refbk = { |
662 | .refdiagc = 0x258, | |
663 | .reffcode = 1, | |
664 | .refdwlen = 5, | |
665 | .refversn = 2, | |
666 | }; | |
667 | ||
1da177e4 LT |
668 | void pfault_fini(void) |
669 | { | |
1da177e4 | 670 | |
f32269a0 | 671 | if (pfault_disable) |
1da177e4 | 672 | return; |
1ec2772e | 673 | diag_stat_inc(DIAG_STAT_X258); |
94c12cc7 MS |
674 | asm volatile( |
675 | " diag %0,0,0x258\n" | |
6c22c986 | 676 | "0: nopr %%r7\n" |
94c12cc7 | 677 | EX_TABLE(0b,0b) |
00e9e664 | 678 | : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); |
1da177e4 LT |
679 | } |
680 | ||
f2db2e6c HC |
681 | static DEFINE_SPINLOCK(pfault_lock); |
682 | static LIST_HEAD(pfault_list); | |
683 | ||
0227f7c4 PZ |
684 | #define PF_COMPLETE 0x0080 |
685 | ||
686 | /* | |
687 | * The mechanism of our pfault code: if Linux is running as guest, runs a user | |
688 | * space process and the user space process accesses a page that the host has | |
689 | * paged out we get a pfault interrupt. | |
690 | * | |
691 | * This allows us, within the guest, to schedule a different process. Without | |
692 | * this mechanism the host would have to suspend the whole virtual cpu until | |
693 | * the page has been paged in. | |
694 | * | |
695 | * So when we get such an interrupt then we set the state of the current task | |
696 | * to uninterruptible and also set the need_resched flag. Both happens within | |
697 | * interrupt context(!). If we later on want to return to user space we | |
698 | * recognize the need_resched flag and then call schedule(). It's not very | |
699 | * obvious how this works... | |
700 | * | |
701 | * Of course we have a lot of additional fun with the completion interrupt (-> | |
702 | * host signals that a page of a process has been paged in and the process can | |
703 | * continue to run). This interrupt can arrive on any cpu and, since we have | |
704 | * virtual cpus, actually appear before the interrupt that signals that a page | |
705 | * is missing. | |
706 | */ | |
fde15c3a | 707 | static void pfault_interrupt(struct ext_code ext_code, |
f6649a7e | 708 | unsigned int param32, unsigned long param64) |
1da177e4 LT |
709 | { |
710 | struct task_struct *tsk; | |
711 | __u16 subcode; | |
f2db2e6c | 712 | pid_t pid; |
1da177e4 LT |
713 | |
714 | /* | |
0227f7c4 PZ |
715 | * Get the external interruption subcode & pfault initial/completion |
716 | * signal bit. VM stores this in the 'cpu address' field associated | |
717 | * with the external interrupt. | |
1da177e4 | 718 | */ |
fde15c3a | 719 | subcode = ext_code.subcode; |
1da177e4 LT |
720 | if ((subcode & 0xff00) != __SUBCODE_MASK) |
721 | return; | |
420f42ec | 722 | inc_irq_stat(IRQEXT_PFL); |
54c27791 | 723 | /* Get the token (= pid of the affected task). */ |
544e8dd7 | 724 | pid = param64 & LPP_PID_MASK; |
54c27791 HC |
725 | rcu_read_lock(); |
726 | tsk = find_task_by_pid_ns(pid, &init_pid_ns); | |
727 | if (tsk) | |
728 | get_task_struct(tsk); | |
729 | rcu_read_unlock(); | |
730 | if (!tsk) | |
731 | return; | |
f2db2e6c | 732 | spin_lock(&pfault_lock); |
0227f7c4 | 733 | if (subcode & PF_COMPLETE) { |
1da177e4 | 734 | /* signal bit is set -> a page has been swapped in by VM */ |
f2db2e6c | 735 | if (tsk->thread.pfault_wait == 1) { |
1da177e4 LT |
736 | /* Initial interrupt was faster than the completion |
737 | * interrupt. pfault_wait is valid. Set pfault_wait | |
738 | * back to zero and wake up the process. This can | |
739 | * safely be done because the task is still sleeping | |
b6d09449 | 740 | * and can't produce new pfaults. */ |
1da177e4 | 741 | tsk->thread.pfault_wait = 0; |
f2db2e6c | 742 | list_del(&tsk->thread.list); |
1da177e4 | 743 | wake_up_process(tsk); |
d5e50a51 | 744 | put_task_struct(tsk); |
f2db2e6c HC |
745 | } else { |
746 | /* Completion interrupt was faster than initial | |
747 | * interrupt. Set pfault_wait to -1 so the initial | |
fa2fb2f4 HC |
748 | * interrupt doesn't put the task to sleep. |
749 | * If the task is not running, ignore the completion | |
750 | * interrupt since it must be a leftover of a PFAULT | |
751 | * CANCEL operation which didn't remove all pending | |
752 | * completion interrupts. */ | |
753 | if (tsk->state == TASK_RUNNING) | |
754 | tsk->thread.pfault_wait = -1; | |
1da177e4 LT |
755 | } |
756 | } else { | |
757 | /* signal bit not set -> a real page is missing. */ | |
d49f47f8 HC |
758 | if (WARN_ON_ONCE(tsk != current)) |
759 | goto out; | |
d5e50a51 HC |
760 | if (tsk->thread.pfault_wait == 1) { |
761 | /* Already on the list with a reference: put to sleep */ | |
0227f7c4 | 762 | goto block; |
d5e50a51 | 763 | } else if (tsk->thread.pfault_wait == -1) { |
1da177e4 | 764 | /* Completion interrupt was faster than the initial |
f2db2e6c HC |
765 | * interrupt (pfault_wait == -1). Set pfault_wait |
766 | * back to zero and exit. */ | |
1da177e4 | 767 | tsk->thread.pfault_wait = 0; |
f2db2e6c HC |
768 | } else { |
769 | /* Initial interrupt arrived before completion | |
d5e50a51 HC |
770 | * interrupt. Let the task sleep. |
771 | * An extra task reference is needed since a different | |
772 | * cpu may set the task state to TASK_RUNNING again | |
773 | * before the scheduler is reached. */ | |
774 | get_task_struct(tsk); | |
f2db2e6c HC |
775 | tsk->thread.pfault_wait = 1; |
776 | list_add(&tsk->thread.list, &pfault_list); | |
0227f7c4 PZ |
777 | block: |
778 | /* Since this must be a userspace fault, there | |
779 | * is no kernel task state to trample. Rely on the | |
780 | * return to userspace schedule() to block. */ | |
781 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
1da177e4 | 782 | set_tsk_need_resched(tsk); |
c360192b | 783 | set_preempt_need_resched(); |
f2db2e6c HC |
784 | } |
785 | } | |
d49f47f8 | 786 | out: |
f2db2e6c | 787 | spin_unlock(&pfault_lock); |
54c27791 | 788 | put_task_struct(tsk); |
f2db2e6c HC |
789 | } |
790 | ||
84c9ceef | 791 | static int pfault_cpu_dead(unsigned int cpu) |
f2db2e6c HC |
792 | { |
793 | struct thread_struct *thread, *next; | |
794 | struct task_struct *tsk; | |
795 | ||
84c9ceef SAS |
796 | spin_lock_irq(&pfault_lock); |
797 | list_for_each_entry_safe(thread, next, &pfault_list, list) { | |
798 | thread->pfault_wait = 0; | |
799 | list_del(&thread->list); | |
800 | tsk = container_of(thread, struct task_struct, thread); | |
801 | wake_up_process(tsk); | |
802 | put_task_struct(tsk); | |
1da177e4 | 803 | } |
84c9ceef SAS |
804 | spin_unlock_irq(&pfault_lock); |
805 | return 0; | |
1da177e4 | 806 | } |
1da177e4 | 807 | |
fb0a9d7e | 808 | static int __init pfault_irq_init(void) |
29b08d2b | 809 | { |
fb0a9d7e | 810 | int rc; |
29b08d2b | 811 | |
1dad093b | 812 | rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); |
7dd8fe1f HC |
813 | if (rc) |
814 | goto out_extint; | |
815 | rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; | |
816 | if (rc) | |
817 | goto out_pfault; | |
82003c3e | 818 | irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); |
84c9ceef SAS |
819 | cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", |
820 | NULL, pfault_cpu_dead); | |
7dd8fe1f | 821 | return 0; |
29b08d2b | 822 | |
7dd8fe1f | 823 | out_pfault: |
1dad093b | 824 | unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); |
7dd8fe1f HC |
825 | out_extint: |
826 | pfault_disable = 1; | |
827 | return rc; | |
29b08d2b | 828 | } |
fb0a9d7e HC |
829 | early_initcall(pfault_irq_init); |
830 | ||
7dd8fe1f | 831 | #endif /* CONFIG_PFAULT */ |