]>
Commit | Line | Data |
---|---|---|
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 LT |
84 | |
85 | /* | |
86 | * Unlock any spinlocks which will prevent us from getting the | |
cefc8be8 | 87 | * message out. |
1da177e4 LT |
88 | */ |
89 | void bust_spinlocks(int yes) | |
90 | { | |
91 | if (yes) { | |
92 | oops_in_progress = 1; | |
93 | } else { | |
94 | int loglevel_save = console_loglevel; | |
95 | console_unblank(); | |
96 | oops_in_progress = 0; | |
97 | /* | |
98 | * OK, the message is on the console. Now we call printk() | |
99 | * without oops_in_progress set so that printk will give klogd | |
100 | * a poke. Hold onto your hats... | |
101 | */ | |
102 | console_loglevel = 15; | |
103 | printk(" "); | |
104 | console_loglevel = loglevel_save; | |
105 | } | |
106 | } | |
107 | ||
108 | /* | |
0aaba41b MS |
109 | * Find out which address space caused the exception. |
110 | * Access register mode is impossible, ignore space == 3. | |
1da177e4 | 111 | */ |
0aaba41b | 112 | static inline enum fault_type get_fault_type(struct pt_regs *regs) |
1da177e4 | 113 | { |
457f2180 HC |
114 | unsigned long trans_exc_code; |
115 | ||
457f2180 | 116 | trans_exc_code = regs->int_parm_long & 3; |
0aaba41b MS |
117 | if (likely(trans_exc_code == 0)) { |
118 | /* primary space exception */ | |
119 | if (IS_ENABLED(CONFIG_PGSTE) && | |
120 | test_pt_regs_flag(regs, PIF_GUEST_FAULT)) | |
121 | return GMAP_FAULT; | |
122 | if (current->thread.mm_segment == USER_DS) | |
123 | return USER_FAULT; | |
124 | return KERNEL_FAULT; | |
125 | } | |
126 | if (trans_exc_code == 2) { | |
127 | /* secondary space exception */ | |
128 | if (current->thread.mm_segment & 1) { | |
129 | if (current->thread.mm_segment == USER_DS_SACF) | |
130 | return USER_FAULT; | |
131 | return KERNEL_FAULT; | |
132 | } | |
133 | return VDSO_FAULT; | |
134 | } | |
135 | /* home space exception -> access via kernel ASCE */ | |
136 | return KERNEL_FAULT; | |
1da177e4 LT |
137 | } |
138 | ||
3b7df342 HC |
139 | static int bad_address(void *p) |
140 | { | |
141 | unsigned long dummy; | |
142 | ||
143 | return probe_kernel_address((unsigned long *)p, dummy); | |
144 | } | |
145 | ||
3b7df342 HC |
146 | static void dump_pagetable(unsigned long asce, unsigned long address) |
147 | { | |
fe7b2747 | 148 | unsigned long *table = __va(asce & _ASCE_ORIGIN); |
3b7df342 HC |
149 | |
150 | pr_alert("AS:%016lx ", asce); | |
151 | switch (asce & _ASCE_TYPE_MASK) { | |
152 | case _ASCE_TYPE_REGION1: | |
f1c1174f | 153 | table += (address & _REGION1_INDEX) >> _REGION1_SHIFT; |
3b7df342 HC |
154 | if (bad_address(table)) |
155 | goto bad; | |
156 | pr_cont("R1:%016lx ", *table); | |
157 | if (*table & _REGION_ENTRY_INVALID) | |
158 | goto out; | |
159 | table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
160 | /* fallthrough */ | |
161 | case _ASCE_TYPE_REGION2: | |
f1c1174f | 162 | table += (address & _REGION2_INDEX) >> _REGION2_SHIFT; |
3b7df342 HC |
163 | if (bad_address(table)) |
164 | goto bad; | |
165 | pr_cont("R2:%016lx ", *table); | |
166 | if (*table & _REGION_ENTRY_INVALID) | |
167 | goto out; | |
168 | table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
169 | /* fallthrough */ | |
170 | case _ASCE_TYPE_REGION3: | |
f1c1174f | 171 | table += (address & _REGION3_INDEX) >> _REGION3_SHIFT; |
3b7df342 HC |
172 | if (bad_address(table)) |
173 | goto bad; | |
174 | pr_cont("R3:%016lx ", *table); | |
175 | if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) | |
176 | goto out; | |
177 | table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); | |
178 | /* fallthrough */ | |
179 | case _ASCE_TYPE_SEGMENT: | |
f1c1174f | 180 | table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; |
3b7df342 HC |
181 | if (bad_address(table)) |
182 | goto bad; | |
91c0837e | 183 | pr_cont("S:%016lx ", *table); |
3b7df342 HC |
184 | if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) |
185 | goto out; | |
186 | table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); | |
187 | } | |
f1c1174f | 188 | table += (address & _PAGE_INDEX) >> _PAGE_SHIFT; |
3b7df342 HC |
189 | if (bad_address(table)) |
190 | goto bad; | |
191 | pr_cont("P:%016lx ", *table); | |
192 | out: | |
193 | pr_cont("\n"); | |
194 | return; | |
195 | bad: | |
196 | pr_cont("BAD\n"); | |
197 | } | |
198 | ||
3b7df342 HC |
199 | static void dump_fault_info(struct pt_regs *regs) |
200 | { | |
201 | unsigned long asce; | |
202 | ||
5d7eccec HC |
203 | pr_alert("Failing address: %016lx TEID: %016lx\n", |
204 | regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); | |
3b7df342 HC |
205 | pr_alert("Fault in "); |
206 | switch (regs->int_parm_long & 3) { | |
207 | case 3: | |
208 | pr_cont("home space "); | |
209 | break; | |
210 | case 2: | |
211 | pr_cont("secondary space "); | |
212 | break; | |
213 | case 1: | |
214 | pr_cont("access register "); | |
215 | break; | |
216 | case 0: | |
217 | pr_cont("primary space "); | |
218 | break; | |
219 | } | |
220 | pr_cont("mode while using "); | |
0aaba41b MS |
221 | switch (get_fault_type(regs)) { |
222 | case USER_FAULT: | |
3b7df342 HC |
223 | asce = S390_lowcore.user_asce; |
224 | pr_cont("user "); | |
0aaba41b MS |
225 | break; |
226 | case VDSO_FAULT: | |
227 | asce = S390_lowcore.vdso_asce; | |
228 | pr_cont("vdso "); | |
229 | break; | |
230 | case GMAP_FAULT: | |
231 | asce = ((struct gmap *) S390_lowcore.gmap)->asce; | |
232 | pr_cont("gmap "); | |
233 | break; | |
234 | case KERNEL_FAULT: | |
235 | asce = S390_lowcore.kernel_asce; | |
236 | pr_cont("kernel "); | |
237 | break; | |
3b7df342 HC |
238 | } |
239 | pr_cont("ASCE.\n"); | |
240 | dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); | |
241 | } | |
242 | ||
5d7eccec HC |
243 | int show_unhandled_signals = 1; |
244 | ||
245 | void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) | |
ab3c68ee HC |
246 | { |
247 | if ((task_pid_nr(current) > 1) && !show_unhandled_signals) | |
248 | return; | |
249 | if (!unhandled_signal(current, signr)) | |
250 | return; | |
251 | if (!printk_ratelimit()) | |
252 | return; | |
db1177ee | 253 | printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", |
413d4047 | 254 | regs->int_code & 0xffff, regs->int_code >> 17); |
9cb1ccec | 255 | print_vma_addr(KERN_CONT "in ", regs->psw.addr); |
aa33c8cb | 256 | printk(KERN_CONT "\n"); |
5d7eccec HC |
257 | if (is_mm_fault) |
258 | dump_fault_info(regs); | |
ab3c68ee HC |
259 | show_regs(regs); |
260 | } | |
261 | ||
1da177e4 LT |
262 | /* |
263 | * Send SIGSEGV to task. This is an external routine | |
264 | * to keep the stack usage of do_page_fault small. | |
265 | */ | |
aa33c8cb | 266 | static noinline void do_sigsegv(struct pt_regs *regs, int si_code) |
1da177e4 LT |
267 | { |
268 | struct siginfo si; | |
269 | ||
5d7eccec | 270 | report_user_fault(regs, SIGSEGV, 1); |
3eb0f519 | 271 | clear_siginfo(&si); |
1da177e4 | 272 | si.si_signo = SIGSEGV; |
cf0d44d5 | 273 | si.si_errno = 0; |
1da177e4 | 274 | si.si_code = si_code; |
aa33c8cb | 275 | si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); |
1da177e4 LT |
276 | force_sig_info(SIGSEGV, &si, current); |
277 | } | |
278 | ||
aa33c8cb | 279 | static noinline void do_no_context(struct pt_regs *regs) |
10c1031f MS |
280 | { |
281 | const struct exception_table_entry *fixup; | |
282 | ||
283 | /* Are we prepared to handle this kernel fault? */ | |
9cb1ccec | 284 | fixup = search_exception_tables(regs->psw.addr); |
10c1031f | 285 | if (fixup) { |
fecc868a | 286 | regs->psw.addr = extable_fixup(fixup); |
10c1031f MS |
287 | return; |
288 | } | |
289 | ||
290 | /* | |
291 | * Oops. The kernel tried to access some bad page. We'll have to | |
292 | * terminate things with extreme prejudice. | |
293 | */ | |
0aaba41b | 294 | if (get_fault_type(regs) == KERNEL_FAULT) |
10c1031f | 295 | printk(KERN_ALERT "Unable to handle kernel pointer dereference" |
3b7df342 | 296 | " in virtual kernel address space\n"); |
10c1031f MS |
297 | else |
298 | printk(KERN_ALERT "Unable to handle kernel paging request" | |
3b7df342 | 299 | " in virtual user address space\n"); |
3b7df342 | 300 | dump_fault_info(regs); |
aa33c8cb | 301 | die(regs, "Oops"); |
10c1031f MS |
302 | do_exit(SIGKILL); |
303 | } | |
304 | ||
aa33c8cb | 305 | static noinline void do_low_address(struct pt_regs *regs) |
10c1031f MS |
306 | { |
307 | /* Low-address protection hit in kernel mode means | |
308 | NULL pointer write access in kernel mode. */ | |
309 | if (regs->psw.mask & PSW_MASK_PSTATE) { | |
310 | /* Low-address protection hit in user mode 'cannot happen'. */ | |
aa33c8cb | 311 | die (regs, "Low-address protection"); |
10c1031f MS |
312 | do_exit(SIGKILL); |
313 | } | |
314 | ||
aa33c8cb | 315 | do_no_context(regs); |
10c1031f MS |
316 | } |
317 | ||
aa33c8cb | 318 | static noinline void do_sigbus(struct pt_regs *regs) |
10c1031f MS |
319 | { |
320 | struct task_struct *tsk = current; | |
36bf9680 | 321 | struct siginfo si; |
10c1031f | 322 | |
10c1031f MS |
323 | /* |
324 | * Send a sigbus, regardless of whether we were in kernel | |
325 | * or user mode. | |
326 | */ | |
3eb0f519 | 327 | clear_siginfo(&si); |
36bf9680 MS |
328 | si.si_signo = SIGBUS; |
329 | si.si_errno = 0; | |
330 | si.si_code = BUS_ADRERR; | |
aa33c8cb | 331 | si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); |
36bf9680 | 332 | force_sig_info(SIGBUS, &si, tsk); |
10c1031f MS |
333 | } |
334 | ||
57d7f939 MS |
335 | static noinline int signal_return(struct pt_regs *regs) |
336 | { | |
337 | u16 instruction; | |
338 | int rc; | |
339 | ||
340 | rc = __get_user(instruction, (u16 __user *) regs->psw.addr); | |
341 | if (rc) | |
342 | return rc; | |
343 | if (instruction == 0x0a77) { | |
344 | set_pt_regs_flag(regs, PIF_SYSCALL); | |
345 | regs->int_code = 0x00040077; | |
346 | return 0; | |
347 | } else if (instruction == 0x0aad) { | |
348 | set_pt_regs_flag(regs, PIF_SYSCALL); | |
349 | regs->int_code = 0x000400ad; | |
350 | return 0; | |
351 | } | |
352 | return -EACCES; | |
353 | } | |
354 | ||
355 | static noinline void do_fault_error(struct pt_regs *regs, int access, int fault) | |
50d7280d MS |
356 | { |
357 | int si_code; | |
358 | ||
359 | switch (fault) { | |
360 | case VM_FAULT_BADACCESS: | |
57d7f939 MS |
361 | if (access == VM_EXEC && signal_return(regs) == 0) |
362 | break; | |
50d7280d MS |
363 | case VM_FAULT_BADMAP: |
364 | /* Bad memory access. Check if it is kernel or user space. */ | |
7d256175 | 365 | if (user_mode(regs)) { |
50d7280d MS |
366 | /* User mode accesses just cause a SIGSEGV */ |
367 | si_code = (fault == VM_FAULT_BADMAP) ? | |
368 | SEGV_MAPERR : SEGV_ACCERR; | |
aa33c8cb | 369 | do_sigsegv(regs, si_code); |
57d7f939 | 370 | break; |
50d7280d MS |
371 | } |
372 | case VM_FAULT_BADCONTEXT: | |
24eb3a82 | 373 | case VM_FAULT_PFAULT: |
aa33c8cb | 374 | do_no_context(regs); |
50d7280d | 375 | break; |
f2c76e3b HC |
376 | case VM_FAULT_SIGNAL: |
377 | if (!user_mode(regs)) | |
378 | do_no_context(regs); | |
379 | break; | |
50d7280d | 380 | default: /* fault & VM_FAULT_ERROR */ |
99583181 | 381 | if (fault & VM_FAULT_OOM) { |
7d256175 | 382 | if (!user_mode(regs)) |
aa33c8cb | 383 | do_no_context(regs); |
99583181 HC |
384 | else |
385 | pagefault_out_of_memory(); | |
33692f27 LT |
386 | } else if (fault & VM_FAULT_SIGSEGV) { |
387 | /* Kernel mode? Handle exceptions or die */ | |
388 | if (!user_mode(regs)) | |
389 | do_no_context(regs); | |
390 | else | |
391 | do_sigsegv(regs, SEGV_MAPERR); | |
99583181 | 392 | } else if (fault & VM_FAULT_SIGBUS) { |
50d7280d | 393 | /* Kernel mode? Handle exceptions or die */ |
7d256175 | 394 | if (!user_mode(regs)) |
aa33c8cb | 395 | do_no_context(regs); |
36bf9680 | 396 | else |
aa33c8cb | 397 | do_sigbus(regs); |
50d7280d MS |
398 | } else |
399 | BUG(); | |
400 | break; | |
401 | } | |
402 | } | |
403 | ||
1da177e4 LT |
404 | /* |
405 | * This routine handles page faults. It determines the address, | |
406 | * and the problem, and then passes it off to one of the appropriate | |
407 | * routines. | |
408 | * | |
50d7280d | 409 | * interruption code (int_code): |
1da177e4 LT |
410 | * 04 Protection -> Write-Protection (suprression) |
411 | * 10 Segment translation -> Not present (nullification) | |
412 | * 11 Page translation -> Not present (nullification) | |
413 | * 3b Region third trans. -> Not present (nullification) | |
414 | */ | |
aa33c8cb | 415 | static inline int do_exception(struct pt_regs *regs, int access) |
1da177e4 | 416 | { |
24eb3a82 | 417 | struct gmap *gmap; |
10c1031f MS |
418 | struct task_struct *tsk; |
419 | struct mm_struct *mm; | |
420 | struct vm_area_struct *vma; | |
0aaba41b | 421 | enum fault_type type; |
aa33c8cb | 422 | unsigned long trans_exc_code; |
10c1031f | 423 | unsigned long address; |
33ce6140 HC |
424 | unsigned int flags; |
425 | int fault; | |
1da177e4 | 426 | |
39efd4ec MS |
427 | tsk = current; |
428 | /* | |
429 | * The instruction that caused the program check has | |
430 | * been nullified. Don't signal single step via SIGTRAP. | |
431 | */ | |
d3a73acb | 432 | clear_pt_regs_flag(regs, PIF_PER_TRAP); |
39efd4ec | 433 | |
7ecb344a | 434 | if (notify_page_fault(regs)) |
50d7280d | 435 | return 0; |
4ba069b8 | 436 | |
10c1031f | 437 | mm = tsk->mm; |
aa33c8cb | 438 | trans_exc_code = regs->int_parm_long; |
1da177e4 | 439 | |
1da177e4 LT |
440 | /* |
441 | * Verify that the fault happened in user space, that | |
442 | * we are not in an interrupt and that there is a | |
443 | * user context. | |
444 | */ | |
50d7280d | 445 | fault = VM_FAULT_BADCONTEXT; |
0aaba41b MS |
446 | type = get_fault_type(regs); |
447 | switch (type) { | |
448 | case KERNEL_FAULT: | |
449 | goto out; | |
450 | case VDSO_FAULT: | |
451 | fault = VM_FAULT_BADMAP; | |
50d7280d | 452 | goto out; |
0aaba41b MS |
453 | case USER_FAULT: |
454 | case GMAP_FAULT: | |
455 | if (faulthandler_disabled() || !mm) | |
456 | goto out; | |
457 | break; | |
458 | } | |
1da177e4 | 459 | |
61365e13 | 460 | address = trans_exc_code & __FAIL_ADDR_MASK; |
a8b0ca17 | 461 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
f2c76e3b | 462 | flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
759496ba JW |
463 | if (user_mode(regs)) |
464 | flags |= FAULT_FLAG_USER; | |
33ce6140 HC |
465 | if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) |
466 | flags |= FAULT_FLAG_WRITE; | |
10c1031f | 467 | down_read(&mm->mmap_sem); |
1da177e4 | 468 | |
0aaba41b MS |
469 | gmap = NULL; |
470 | if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { | |
471 | gmap = (struct gmap *) S390_lowcore.gmap; | |
527e30b4 | 472 | current->thread.gmap_addr = address; |
4be130a0 | 473 | current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); |
4a494439 | 474 | current->thread.gmap_int_code = regs->int_code & 0xffff; |
527e30b4 | 475 | address = __gmap_translate(gmap, address); |
e5992f2e MS |
476 | if (address == -EFAULT) { |
477 | fault = VM_FAULT_BADMAP; | |
478 | goto out_up; | |
479 | } | |
24eb3a82 DD |
480 | if (gmap->pfault_enabled) |
481 | flags |= FAULT_FLAG_RETRY_NOWAIT; | |
e5992f2e | 482 | } |
e5992f2e MS |
483 | |
484 | retry: | |
50d7280d | 485 | fault = VM_FAULT_BADMAP; |
482b05dd GS |
486 | vma = find_vma(mm, address); |
487 | if (!vma) | |
50d7280d | 488 | goto out_up; |
c1821c2e | 489 | |
50d7280d MS |
490 | if (unlikely(vma->vm_start > address)) { |
491 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
492 | goto out_up; | |
493 | if (expand_stack(vma, address)) | |
494 | goto out_up; | |
495 | } | |
496 | ||
497 | /* | |
498 | * Ok, we have a good vm_area for this memory access, so | |
499 | * we can handle it.. | |
500 | */ | |
501 | fault = VM_FAULT_BADACCESS; | |
1ab947de | 502 | if (unlikely(!(vma->vm_flags & access))) |
50d7280d | 503 | goto out_up; |
1da177e4 | 504 | |
53492b1d GS |
505 | if (is_vm_hugetlb_page(vma)) |
506 | address &= HPAGE_MASK; | |
1da177e4 LT |
507 | /* |
508 | * If for any reason at all we couldn't handle the fault, | |
509 | * make sure we exit gracefully rather than endlessly redo | |
510 | * the fault. | |
511 | */ | |
dcddffd4 | 512 | fault = handle_mm_fault(vma, address, flags); |
f2c76e3b HC |
513 | /* No reason to continue if interrupted by SIGKILL. */ |
514 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { | |
515 | fault = VM_FAULT_SIGNAL; | |
516 | goto out; | |
517 | } | |
50d7280d MS |
518 | if (unlikely(fault & VM_FAULT_ERROR)) |
519 | goto out_up; | |
520 | ||
33ce6140 HC |
521 | /* |
522 | * Major/minor page fault accounting is only done on the | |
523 | * initial attempt. If we go through a retry, it is extremely | |
524 | * likely that the page will be found in page cache at that point. | |
525 | */ | |
526 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
527 | if (fault & VM_FAULT_MAJOR) { | |
528 | tsk->maj_flt++; | |
a8b0ca17 | 529 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, |
33ce6140 HC |
530 | regs, address); |
531 | } else { | |
532 | tsk->min_flt++; | |
a8b0ca17 | 533 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, |
33ce6140 HC |
534 | regs, address); |
535 | } | |
536 | if (fault & VM_FAULT_RETRY) { | |
0aaba41b MS |
537 | if (IS_ENABLED(CONFIG_PGSTE) && gmap && |
538 | (flags & FAULT_FLAG_RETRY_NOWAIT)) { | |
24eb3a82 DD |
539 | /* FAULT_FLAG_RETRY_NOWAIT has been set, |
540 | * mmap_sem has not been released */ | |
541 | current->thread.gmap_pfault = 1; | |
542 | fault = VM_FAULT_PFAULT; | |
543 | goto out_up; | |
544 | } | |
33ce6140 HC |
545 | /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk |
546 | * of starvation. */ | |
24eb3a82 DD |
547 | flags &= ~(FAULT_FLAG_ALLOW_RETRY | |
548 | FAULT_FLAG_RETRY_NOWAIT); | |
45cac65b | 549 | flags |= FAULT_FLAG_TRIED; |
e5992f2e | 550 | down_read(&mm->mmap_sem); |
33ce6140 HC |
551 | goto retry; |
552 | } | |
bde69af2 | 553 | } |
0aaba41b | 554 | if (IS_ENABLED(CONFIG_PGSTE) && gmap) { |
527e30b4 MS |
555 | address = __gmap_link(gmap, current->thread.gmap_addr, |
556 | address); | |
557 | if (address == -EFAULT) { | |
558 | fault = VM_FAULT_BADMAP; | |
559 | goto out_up; | |
560 | } | |
561 | if (address == -ENOMEM) { | |
562 | fault = VM_FAULT_OOM; | |
563 | goto out_up; | |
564 | } | |
565 | } | |
50d7280d MS |
566 | fault = 0; |
567 | out_up: | |
10c1031f | 568 | up_read(&mm->mmap_sem); |
50d7280d MS |
569 | out: |
570 | return fault; | |
1da177e4 LT |
571 | } |
572 | ||
7a5388de | 573 | void do_protection_exception(struct pt_regs *regs) |
1da177e4 | 574 | { |
aa33c8cb | 575 | unsigned long trans_exc_code; |
57d7f939 | 576 | int access, fault; |
61365e13 | 577 | |
aa33c8cb | 578 | trans_exc_code = regs->int_parm_long; |
f752ac4d MS |
579 | /* |
580 | * Protection exceptions are suppressing, decrement psw address. | |
581 | * The exception to this rule are aborted transactions, for these | |
582 | * the PSW already points to the correct location. | |
583 | */ | |
584 | if (!(regs->int_code & 0x200)) | |
585 | regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); | |
10c1031f MS |
586 | /* |
587 | * Check for low-address protection. This needs to be treated | |
588 | * as a special case because the translation exception code | |
589 | * field is not guaranteed to contain valid data in this case. | |
590 | */ | |
61365e13 | 591 | if (unlikely(!(trans_exc_code & 4))) { |
aa33c8cb | 592 | do_low_address(regs); |
10c1031f MS |
593 | return; |
594 | } | |
57d7f939 MS |
595 | if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { |
596 | regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | | |
597 | (regs->psw.addr & PAGE_MASK); | |
598 | access = VM_EXEC; | |
599 | fault = VM_FAULT_BADACCESS; | |
600 | } else { | |
601 | access = VM_WRITE; | |
602 | fault = do_exception(regs, access); | |
603 | } | |
50d7280d | 604 | if (unlikely(fault)) |
57d7f939 | 605 | do_fault_error(regs, access, fault); |
1da177e4 | 606 | } |
7a5388de | 607 | NOKPROBE_SYMBOL(do_protection_exception); |
1da177e4 | 608 | |
7a5388de | 609 | void do_dat_exception(struct pt_regs *regs) |
1da177e4 | 610 | { |
1ab947de | 611 | int access, fault; |
50d7280d | 612 | |
1ab947de | 613 | access = VM_READ | VM_EXEC | VM_WRITE; |
aa33c8cb | 614 | fault = do_exception(regs, access); |
50d7280d | 615 | if (unlikely(fault)) |
57d7f939 | 616 | do_fault_error(regs, access, fault); |
1da177e4 | 617 | } |
7a5388de | 618 | NOKPROBE_SYMBOL(do_dat_exception); |
1da177e4 | 619 | |
1da177e4 LT |
620 | #ifdef CONFIG_PFAULT |
621 | /* | |
622 | * 'pfault' pseudo page faults routines. | |
623 | */ | |
fb0a9d7e | 624 | static int pfault_disable; |
1da177e4 LT |
625 | |
626 | static int __init nopfault(char *str) | |
627 | { | |
628 | pfault_disable = 1; | |
629 | return 1; | |
630 | } | |
631 | ||
632 | __setup("nopfault", nopfault); | |
633 | ||
7dd8fe1f HC |
634 | struct pfault_refbk { |
635 | u16 refdiagc; | |
636 | u16 reffcode; | |
637 | u16 refdwlen; | |
638 | u16 refversn; | |
639 | u64 refgaddr; | |
640 | u64 refselmk; | |
641 | u64 refcmpmk; | |
642 | u64 reserved; | |
643 | } __attribute__ ((packed, aligned(8))); | |
1da177e4 LT |
644 | |
645 | int pfault_init(void) | |
646 | { | |
7dd8fe1f HC |
647 | struct pfault_refbk refbk = { |
648 | .refdiagc = 0x258, | |
649 | .reffcode = 0, | |
650 | .refdwlen = 5, | |
651 | .refversn = 2, | |
e22cf8ca | 652 | .refgaddr = __LC_LPP, |
7dd8fe1f HC |
653 | .refselmk = 1ULL << 48, |
654 | .refcmpmk = 1ULL << 48, | |
655 | .reserved = __PF_RES_FIELD }; | |
1da177e4 LT |
656 | int rc; |
657 | ||
f32269a0 | 658 | if (pfault_disable) |
1da177e4 | 659 | return -1; |
1ec2772e | 660 | diag_stat_inc(DIAG_STAT_X258); |
94c12cc7 MS |
661 | asm volatile( |
662 | " diag %1,%0,0x258\n" | |
663 | "0: j 2f\n" | |
664 | "1: la %0,8\n" | |
1da177e4 | 665 | "2:\n" |
94c12cc7 MS |
666 | EX_TABLE(0b,1b) |
667 | : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc"); | |
1da177e4 LT |
668 | return rc; |
669 | } | |
670 | ||
671 | void pfault_fini(void) | |
672 | { | |
7dd8fe1f HC |
673 | struct pfault_refbk refbk = { |
674 | .refdiagc = 0x258, | |
675 | .reffcode = 1, | |
676 | .refdwlen = 5, | |
677 | .refversn = 2, | |
678 | }; | |
1da177e4 | 679 | |
f32269a0 | 680 | if (pfault_disable) |
1da177e4 | 681 | return; |
1ec2772e | 682 | diag_stat_inc(DIAG_STAT_X258); |
94c12cc7 MS |
683 | asm volatile( |
684 | " diag %0,0,0x258\n" | |
6c22c986 | 685 | "0: nopr %%r7\n" |
94c12cc7 MS |
686 | EX_TABLE(0b,0b) |
687 | : : "a" (&refbk), "m" (refbk) : "cc"); | |
1da177e4 LT |
688 | } |
689 | ||
f2db2e6c HC |
690 | static DEFINE_SPINLOCK(pfault_lock); |
691 | static LIST_HEAD(pfault_list); | |
692 | ||
0227f7c4 PZ |
693 | #define PF_COMPLETE 0x0080 |
694 | ||
695 | /* | |
696 | * The mechanism of our pfault code: if Linux is running as guest, runs a user | |
697 | * space process and the user space process accesses a page that the host has | |
698 | * paged out we get a pfault interrupt. | |
699 | * | |
700 | * This allows us, within the guest, to schedule a different process. Without | |
701 | * this mechanism the host would have to suspend the whole virtual cpu until | |
702 | * the page has been paged in. | |
703 | * | |
704 | * So when we get such an interrupt then we set the state of the current task | |
705 | * to uninterruptible and also set the need_resched flag. Both happens within | |
706 | * interrupt context(!). If we later on want to return to user space we | |
707 | * recognize the need_resched flag and then call schedule(). It's not very | |
708 | * obvious how this works... | |
709 | * | |
710 | * Of course we have a lot of additional fun with the completion interrupt (-> | |
711 | * host signals that a page of a process has been paged in and the process can | |
712 | * continue to run). This interrupt can arrive on any cpu and, since we have | |
713 | * virtual cpus, actually appear before the interrupt that signals that a page | |
714 | * is missing. | |
715 | */ | |
fde15c3a | 716 | static void pfault_interrupt(struct ext_code ext_code, |
f6649a7e | 717 | unsigned int param32, unsigned long param64) |
1da177e4 LT |
718 | { |
719 | struct task_struct *tsk; | |
720 | __u16 subcode; | |
f2db2e6c | 721 | pid_t pid; |
1da177e4 LT |
722 | |
723 | /* | |
0227f7c4 PZ |
724 | * Get the external interruption subcode & pfault initial/completion |
725 | * signal bit. VM stores this in the 'cpu address' field associated | |
726 | * with the external interrupt. | |
1da177e4 | 727 | */ |
fde15c3a | 728 | subcode = ext_code.subcode; |
1da177e4 LT |
729 | if ((subcode & 0xff00) != __SUBCODE_MASK) |
730 | return; | |
420f42ec | 731 | inc_irq_stat(IRQEXT_PFL); |
54c27791 | 732 | /* Get the token (= pid of the affected task). */ |
544e8dd7 | 733 | pid = param64 & LPP_PID_MASK; |
54c27791 HC |
734 | rcu_read_lock(); |
735 | tsk = find_task_by_pid_ns(pid, &init_pid_ns); | |
736 | if (tsk) | |
737 | get_task_struct(tsk); | |
738 | rcu_read_unlock(); | |
739 | if (!tsk) | |
740 | return; | |
f2db2e6c | 741 | spin_lock(&pfault_lock); |
0227f7c4 | 742 | if (subcode & PF_COMPLETE) { |
1da177e4 | 743 | /* signal bit is set -> a page has been swapped in by VM */ |
f2db2e6c | 744 | if (tsk->thread.pfault_wait == 1) { |
1da177e4 LT |
745 | /* Initial interrupt was faster than the completion |
746 | * interrupt. pfault_wait is valid. Set pfault_wait | |
747 | * back to zero and wake up the process. This can | |
748 | * safely be done because the task is still sleeping | |
b6d09449 | 749 | * and can't produce new pfaults. */ |
1da177e4 | 750 | tsk->thread.pfault_wait = 0; |
f2db2e6c | 751 | list_del(&tsk->thread.list); |
1da177e4 | 752 | wake_up_process(tsk); |
d5e50a51 | 753 | put_task_struct(tsk); |
f2db2e6c HC |
754 | } else { |
755 | /* Completion interrupt was faster than initial | |
756 | * interrupt. Set pfault_wait to -1 so the initial | |
fa2fb2f4 HC |
757 | * interrupt doesn't put the task to sleep. |
758 | * If the task is not running, ignore the completion | |
759 | * interrupt since it must be a leftover of a PFAULT | |
760 | * CANCEL operation which didn't remove all pending | |
761 | * completion interrupts. */ | |
762 | if (tsk->state == TASK_RUNNING) | |
763 | tsk->thread.pfault_wait = -1; | |
1da177e4 LT |
764 | } |
765 | } else { | |
766 | /* signal bit not set -> a real page is missing. */ | |
d49f47f8 HC |
767 | if (WARN_ON_ONCE(tsk != current)) |
768 | goto out; | |
d5e50a51 HC |
769 | if (tsk->thread.pfault_wait == 1) { |
770 | /* Already on the list with a reference: put to sleep */ | |
0227f7c4 | 771 | goto block; |
d5e50a51 | 772 | } else if (tsk->thread.pfault_wait == -1) { |
1da177e4 | 773 | /* Completion interrupt was faster than the initial |
f2db2e6c HC |
774 | * interrupt (pfault_wait == -1). Set pfault_wait |
775 | * back to zero and exit. */ | |
1da177e4 | 776 | tsk->thread.pfault_wait = 0; |
f2db2e6c HC |
777 | } else { |
778 | /* Initial interrupt arrived before completion | |
d5e50a51 HC |
779 | * interrupt. Let the task sleep. |
780 | * An extra task reference is needed since a different | |
781 | * cpu may set the task state to TASK_RUNNING again | |
782 | * before the scheduler is reached. */ | |
783 | get_task_struct(tsk); | |
f2db2e6c HC |
784 | tsk->thread.pfault_wait = 1; |
785 | list_add(&tsk->thread.list, &pfault_list); | |
0227f7c4 PZ |
786 | block: |
787 | /* Since this must be a userspace fault, there | |
788 | * is no kernel task state to trample. Rely on the | |
789 | * return to userspace schedule() to block. */ | |
790 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
1da177e4 | 791 | set_tsk_need_resched(tsk); |
c360192b | 792 | set_preempt_need_resched(); |
f2db2e6c HC |
793 | } |
794 | } | |
d49f47f8 | 795 | out: |
f2db2e6c | 796 | spin_unlock(&pfault_lock); |
54c27791 | 797 | put_task_struct(tsk); |
f2db2e6c HC |
798 | } |
799 | ||
84c9ceef | 800 | static int pfault_cpu_dead(unsigned int cpu) |
f2db2e6c HC |
801 | { |
802 | struct thread_struct *thread, *next; | |
803 | struct task_struct *tsk; | |
804 | ||
84c9ceef SAS |
805 | spin_lock_irq(&pfault_lock); |
806 | list_for_each_entry_safe(thread, next, &pfault_list, list) { | |
807 | thread->pfault_wait = 0; | |
808 | list_del(&thread->list); | |
809 | tsk = container_of(thread, struct task_struct, thread); | |
810 | wake_up_process(tsk); | |
811 | put_task_struct(tsk); | |
1da177e4 | 812 | } |
84c9ceef SAS |
813 | spin_unlock_irq(&pfault_lock); |
814 | return 0; | |
1da177e4 | 815 | } |
1da177e4 | 816 | |
fb0a9d7e | 817 | static int __init pfault_irq_init(void) |
29b08d2b | 818 | { |
fb0a9d7e | 819 | int rc; |
29b08d2b | 820 | |
1dad093b | 821 | rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); |
7dd8fe1f HC |
822 | if (rc) |
823 | goto out_extint; | |
824 | rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; | |
825 | if (rc) | |
826 | goto out_pfault; | |
82003c3e | 827 | irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); |
84c9ceef SAS |
828 | cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", |
829 | NULL, pfault_cpu_dead); | |
7dd8fe1f | 830 | return 0; |
29b08d2b | 831 | |
7dd8fe1f | 832 | out_pfault: |
1dad093b | 833 | unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); |
7dd8fe1f HC |
834 | out_extint: |
835 | pfault_disable = 1; | |
836 | return rc; | |
29b08d2b | 837 | } |
fb0a9d7e HC |
838 | early_initcall(pfault_irq_init); |
839 | ||
7dd8fe1f | 840 | #endif /* CONFIG_PFAULT */ |