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867e359b CM |
1 | /* |
2 | * Copyright 2010 Tilera Corporation. All Rights Reserved. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation, version 2. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or | |
11 | * NON INFRINGEMENT. See the GNU General Public License for | |
12 | * more details. | |
13 | * | |
14 | * From i386 code copyright (C) 1995 Linus Torvalds | |
15 | */ | |
16 | ||
17 | #include <linux/signal.h> | |
18 | #include <linux/sched.h> | |
19 | #include <linux/kernel.h> | |
20 | #include <linux/errno.h> | |
21 | #include <linux/string.h> | |
22 | #include <linux/types.h> | |
23 | #include <linux/ptrace.h> | |
24 | #include <linux/mman.h> | |
25 | #include <linux/mm.h> | |
26 | #include <linux/smp.h> | |
867e359b CM |
27 | #include <linux/interrupt.h> |
28 | #include <linux/init.h> | |
29 | #include <linux/tty.h> | |
30 | #include <linux/vt_kern.h> /* For unblank_screen() */ | |
31 | #include <linux/highmem.h> | |
32 | #include <linux/module.h> | |
33 | #include <linux/kprobes.h> | |
34 | #include <linux/hugetlb.h> | |
35 | #include <linux/syscalls.h> | |
36 | #include <linux/uaccess.h> | |
3fa17c39 | 37 | #include <linux/kdebug.h> |
49e4e156 | 38 | #include <linux/context_tracking.h> |
867e359b | 39 | |
867e359b CM |
40 | #include <asm/pgalloc.h> |
41 | #include <asm/sections.h> | |
0707ad30 CM |
42 | #include <asm/traps.h> |
43 | #include <asm/syscalls.h> | |
867e359b CM |
44 | |
45 | #include <arch/interrupts.h> | |
46 | ||
571d76ac CM |
47 | static noinline void force_sig_info_fault(const char *type, int si_signo, |
48 | int si_code, unsigned long address, | |
49 | int fault_num, | |
50 | struct task_struct *tsk, | |
51 | struct pt_regs *regs) | |
867e359b CM |
52 | { |
53 | siginfo_t info; | |
54 | ||
55 | if (unlikely(tsk->pid < 2)) { | |
56 | panic("Signal %d (code %d) at %#lx sent to %s!", | |
57 | si_signo, si_code & 0xffff, address, | |
a95f8817 | 58 | is_idle_task(tsk) ? "the idle task" : "init"); |
867e359b CM |
59 | } |
60 | ||
61 | info.si_signo = si_signo; | |
62 | info.si_errno = 0; | |
63 | info.si_code = si_code; | |
64 | info.si_addr = (void __user *)address; | |
65 | info.si_trapno = fault_num; | |
571d76ac | 66 | trace_unhandled_signal(type, regs, address, si_signo); |
867e359b CM |
67 | force_sig_info(si_signo, &info, tsk); |
68 | } | |
69 | ||
70 | #ifndef __tilegx__ | |
71 | /* | |
72 | * Synthesize the fault a PL0 process would get by doing a word-load of | |
d929b6ae | 73 | * an unaligned address or a high kernel address. |
867e359b | 74 | */ |
6b14e419 | 75 | SYSCALL_DEFINE1(cmpxchg_badaddr, unsigned long, address) |
867e359b | 76 | { |
6b14e419 CM |
77 | struct pt_regs *regs = current_pt_regs(); |
78 | ||
867e359b | 79 | if (address >= PAGE_OFFSET) |
571d76ac CM |
80 | force_sig_info_fault("atomic segfault", SIGSEGV, SEGV_MAPERR, |
81 | address, INT_DTLB_MISS, current, regs); | |
867e359b | 82 | else |
571d76ac CM |
83 | force_sig_info_fault("atomic alignment fault", SIGBUS, |
84 | BUS_ADRALN, address, | |
85 | INT_UNALIGN_DATA, current, regs); | |
867e359b CM |
86 | |
87 | /* | |
88 | * Adjust pc to point at the actual instruction, which is unusual | |
89 | * for syscalls normally, but is appropriate when we are claiming | |
90 | * that a syscall swint1 caused a page fault or bus error. | |
91 | */ | |
92 | regs->pc -= 8; | |
93 | ||
94 | /* | |
95 | * Mark this as a caller-save interrupt, like a normal page fault, | |
96 | * so that when we go through the signal handler path we will | |
97 | * properly restore r0, r1, and r2 for the signal handler arguments. | |
98 | */ | |
99 | regs->flags |= PT_FLAGS_CALLER_SAVES; | |
100 | ||
101 | return 0; | |
102 | } | |
103 | #endif | |
104 | ||
105 | static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address) | |
106 | { | |
107 | unsigned index = pgd_index(address); | |
108 | pgd_t *pgd_k; | |
109 | pud_t *pud, *pud_k; | |
110 | pmd_t *pmd, *pmd_k; | |
111 | ||
112 | pgd += index; | |
113 | pgd_k = init_mm.pgd + index; | |
114 | ||
115 | if (!pgd_present(*pgd_k)) | |
116 | return NULL; | |
117 | ||
118 | pud = pud_offset(pgd, address); | |
119 | pud_k = pud_offset(pgd_k, address); | |
120 | if (!pud_present(*pud_k)) | |
121 | return NULL; | |
122 | ||
123 | pmd = pmd_offset(pud, address); | |
124 | pmd_k = pmd_offset(pud_k, address); | |
125 | if (!pmd_present(*pmd_k)) | |
126 | return NULL; | |
1182b69c | 127 | if (!pmd_present(*pmd)) |
867e359b | 128 | set_pmd(pmd, *pmd_k); |
1182b69c | 129 | else |
867e359b CM |
130 | BUG_ON(pmd_ptfn(*pmd) != pmd_ptfn(*pmd_k)); |
131 | return pmd_k; | |
132 | } | |
133 | ||
134 | /* | |
51bcdf88 | 135 | * Handle a fault on the vmalloc area. |
867e359b CM |
136 | */ |
137 | static inline int vmalloc_fault(pgd_t *pgd, unsigned long address) | |
138 | { | |
139 | pmd_t *pmd_k; | |
140 | pte_t *pte_k; | |
141 | ||
142 | /* Make sure we are in vmalloc area */ | |
143 | if (!(address >= VMALLOC_START && address < VMALLOC_END)) | |
144 | return -1; | |
145 | ||
146 | /* | |
147 | * Synchronize this task's top level page-table | |
148 | * with the 'reference' page table. | |
149 | */ | |
150 | pmd_k = vmalloc_sync_one(pgd, address); | |
151 | if (!pmd_k) | |
152 | return -1; | |
867e359b CM |
153 | pte_k = pte_offset_kernel(pmd_k, address); |
154 | if (!pte_present(*pte_k)) | |
155 | return -1; | |
156 | return 0; | |
157 | } | |
158 | ||
159 | /* Wait until this PTE has completed migration. */ | |
160 | static void wait_for_migration(pte_t *pte) | |
161 | { | |
162 | if (pte_migrating(*pte)) { | |
163 | /* | |
164 | * Wait until the migrater fixes up this pte. | |
165 | * We scale the loop count by the clock rate so we'll wait for | |
166 | * a few seconds here. | |
167 | */ | |
168 | int retries = 0; | |
169 | int bound = get_clock_rate(); | |
170 | while (pte_migrating(*pte)) { | |
171 | barrier(); | |
172 | if (++retries > bound) | |
f4743673 | 173 | panic("Hit migrating PTE (%#llx) and page PFN %#lx still migrating", |
867e359b CM |
174 | pte->val, pte_pfn(*pte)); |
175 | } | |
176 | } | |
177 | } | |
178 | ||
179 | /* | |
180 | * It's not generally safe to use "current" to get the page table pointer, | |
181 | * since we might be running an oprofile interrupt in the middle of a | |
182 | * task switch. | |
183 | */ | |
184 | static pgd_t *get_current_pgd(void) | |
185 | { | |
186 | HV_Context ctx = hv_inquire_context(); | |
187 | unsigned long pgd_pfn = ctx.page_table >> PAGE_SHIFT; | |
188 | struct page *pgd_page = pfn_to_page(pgd_pfn); | |
621b1955 | 189 | BUG_ON(PageHighMem(pgd_page)); |
867e359b CM |
190 | return (pgd_t *) __va(ctx.page_table); |
191 | } | |
192 | ||
193 | /* | |
194 | * We can receive a page fault from a migrating PTE at any time. | |
195 | * Handle it by just waiting until the fault resolves. | |
196 | * | |
197 | * It's also possible to get a migrating kernel PTE that resolves | |
198 | * itself during the downcall from hypervisor to Linux. We just check | |
199 | * here to see if the PTE seems valid, and if so we retry it. | |
200 | * | |
201 | * NOTE! We MUST NOT take any locks for this case. We may be in an | |
202 | * interrupt or a critical region, and must do as little as possible. | |
203 | * Similarly, we can't use atomic ops here, since we may be handling a | |
204 | * fault caused by an atomic op access. | |
48292738 CM |
205 | * |
206 | * If we find a migrating PTE while we're in an NMI context, and we're | |
207 | * at a PC that has a registered exception handler, we don't wait, | |
208 | * since this thread may (e.g.) have been interrupted while migrating | |
209 | * its own stack, which would then cause us to self-deadlock. | |
867e359b CM |
210 | */ |
211 | static int handle_migrating_pte(pgd_t *pgd, int fault_num, | |
48292738 | 212 | unsigned long address, unsigned long pc, |
867e359b CM |
213 | int is_kernel_mode, int write) |
214 | { | |
215 | pud_t *pud; | |
216 | pmd_t *pmd; | |
217 | pte_t *pte; | |
218 | pte_t pteval; | |
219 | ||
220 | if (pgd_addr_invalid(address)) | |
221 | return 0; | |
222 | ||
223 | pgd += pgd_index(address); | |
224 | pud = pud_offset(pgd, address); | |
225 | if (!pud || !pud_present(*pud)) | |
226 | return 0; | |
227 | pmd = pmd_offset(pud, address); | |
228 | if (!pmd || !pmd_present(*pmd)) | |
229 | return 0; | |
230 | pte = pmd_huge_page(*pmd) ? ((pte_t *)pmd) : | |
231 | pte_offset_kernel(pmd, address); | |
232 | pteval = *pte; | |
233 | if (pte_migrating(pteval)) { | |
48292738 CM |
234 | if (in_nmi() && search_exception_tables(pc)) |
235 | return 0; | |
867e359b CM |
236 | wait_for_migration(pte); |
237 | return 1; | |
238 | } | |
239 | ||
240 | if (!is_kernel_mode || !pte_present(pteval)) | |
241 | return 0; | |
242 | if (fault_num == INT_ITLB_MISS) { | |
243 | if (pte_exec(pteval)) | |
244 | return 1; | |
245 | } else if (write) { | |
246 | if (pte_write(pteval)) | |
247 | return 1; | |
248 | } else { | |
249 | if (pte_read(pteval)) | |
250 | return 1; | |
251 | } | |
252 | ||
253 | return 0; | |
254 | } | |
255 | ||
256 | /* | |
257 | * This routine is responsible for faulting in user pages. | |
258 | * It passes the work off to one of the appropriate routines. | |
259 | * It returns true if the fault was successfully handled. | |
260 | */ | |
261 | static int handle_page_fault(struct pt_regs *regs, | |
262 | int fault_num, | |
263 | int is_page_fault, | |
264 | unsigned long address, | |
265 | int write) | |
266 | { | |
267 | struct task_struct *tsk; | |
268 | struct mm_struct *mm; | |
269 | struct vm_area_struct *vma; | |
270 | unsigned long stack_offset; | |
271 | int fault; | |
272 | int si_code; | |
273 | int is_kernel_mode; | |
274 | pgd_t *pgd; | |
4ce6bea2 | 275 | unsigned int flags; |
867e359b CM |
276 | |
277 | /* on TILE, protection faults are always writes */ | |
278 | if (!is_page_fault) | |
279 | write = 1; | |
280 | ||
759496ba | 281 | flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
4ce6bea2 | 282 | |
051168df | 283 | is_kernel_mode = !user_mode(regs); |
867e359b CM |
284 | |
285 | tsk = validate_current(); | |
286 | ||
287 | /* | |
288 | * Check to see if we might be overwriting the stack, and bail | |
289 | * out if so. The page fault code is a relatively likely | |
290 | * place to get trapped in an infinite regress, and once we | |
291 | * overwrite the whole stack, it becomes very hard to recover. | |
292 | */ | |
293 | stack_offset = stack_pointer & (THREAD_SIZE-1); | |
294 | if (stack_offset < THREAD_SIZE / 8) { | |
f4743673 | 295 | pr_alert("Potential stack overrun: sp %#lx\n", stack_pointer); |
867e359b | 296 | show_regs(regs); |
0707ad30 | 297 | pr_alert("Killing current process %d/%s\n", |
f4743673 | 298 | tsk->pid, tsk->comm); |
867e359b CM |
299 | do_group_exit(SIGKILL); |
300 | } | |
301 | ||
302 | /* | |
303 | * Early on, we need to check for migrating PTE entries; | |
304 | * see homecache.c. If we find a migrating PTE, we wait until | |
25985edc | 305 | * the backing page claims to be done migrating, then we proceed. |
867e359b CM |
306 | * For kernel PTEs, we rewrite the PTE and return and retry. |
307 | * Otherwise, we treat the fault like a normal "no PTE" fault, | |
308 | * rather than trying to patch up the existing PTE. | |
309 | */ | |
310 | pgd = get_current_pgd(); | |
48292738 | 311 | if (handle_migrating_pte(pgd, fault_num, address, regs->pc, |
867e359b CM |
312 | is_kernel_mode, write)) |
313 | return 1; | |
314 | ||
315 | si_code = SEGV_MAPERR; | |
316 | ||
317 | /* | |
318 | * We fault-in kernel-space virtual memory on-demand. The | |
319 | * 'reference' page table is init_mm.pgd. | |
320 | * | |
321 | * NOTE! We MUST NOT take any locks for this case. We may | |
322 | * be in an interrupt or a critical region, and should | |
323 | * only copy the information from the master page table, | |
324 | * nothing more. | |
325 | * | |
326 | * This verifies that the fault happens in kernel space | |
327 | * and that the fault was not a protection fault. | |
328 | */ | |
329 | if (unlikely(address >= TASK_SIZE && | |
330 | !is_arch_mappable_range(address, 0))) { | |
331 | if (is_kernel_mode && is_page_fault && | |
332 | vmalloc_fault(pgd, address) >= 0) | |
333 | return 1; | |
334 | /* | |
335 | * Don't take the mm semaphore here. If we fixup a prefetch | |
336 | * fault we could otherwise deadlock. | |
337 | */ | |
338 | mm = NULL; /* happy compiler */ | |
339 | vma = NULL; | |
340 | goto bad_area_nosemaphore; | |
341 | } | |
342 | ||
343 | /* | |
344 | * If we're trying to touch user-space addresses, we must | |
345 | * be either at PL0, or else with interrupts enabled in the | |
b230ff2d CM |
346 | * kernel, so either way we can re-enable interrupts here |
347 | * unless we are doing atomic access to user space with | |
348 | * interrupts disabled. | |
867e359b | 349 | */ |
b230ff2d CM |
350 | if (!(regs->flags & PT_FLAGS_DISABLE_IRQ)) |
351 | local_irq_enable(); | |
867e359b CM |
352 | |
353 | mm = tsk->mm; | |
354 | ||
355 | /* | |
356 | * If we're in an interrupt, have no user context or are running in an | |
357 | * atomic region then we must not take the fault. | |
358 | */ | |
359 | if (in_atomic() || !mm) { | |
360 | vma = NULL; /* happy compiler */ | |
361 | goto bad_area_nosemaphore; | |
362 | } | |
363 | ||
759496ba JW |
364 | if (!is_kernel_mode) |
365 | flags |= FAULT_FLAG_USER; | |
366 | ||
867e359b CM |
367 | /* |
368 | * When running in the kernel we expect faults to occur only to | |
369 | * addresses in user space. All other faults represent errors in the | |
370 | * kernel and should generate an OOPS. Unfortunately, in the case of an | |
371 | * erroneous fault occurring in a code path which already holds mmap_sem | |
372 | * we will deadlock attempting to validate the fault against the | |
373 | * address space. Luckily the kernel only validly references user | |
374 | * space from well defined areas of code, which are listed in the | |
375 | * exceptions table. | |
376 | * | |
377 | * As the vast majority of faults will be valid we will only perform | |
378 | * the source reference check when there is a possibility of a deadlock. | |
379 | * Attempt to lock the address space, if we cannot we then validate the | |
380 | * source. If this is invalid we can skip the address space check, | |
381 | * thus avoiding the deadlock. | |
382 | */ | |
383 | if (!down_read_trylock(&mm->mmap_sem)) { | |
384 | if (is_kernel_mode && | |
385 | !search_exception_tables(regs->pc)) { | |
386 | vma = NULL; /* happy compiler */ | |
387 | goto bad_area_nosemaphore; | |
388 | } | |
4ce6bea2 KC |
389 | |
390 | retry: | |
867e359b CM |
391 | down_read(&mm->mmap_sem); |
392 | } | |
393 | ||
394 | vma = find_vma(mm, address); | |
395 | if (!vma) | |
396 | goto bad_area; | |
397 | if (vma->vm_start <= address) | |
398 | goto good_area; | |
399 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
400 | goto bad_area; | |
401 | if (regs->sp < PAGE_OFFSET) { | |
402 | /* | |
403 | * accessing the stack below sp is always a bug. | |
404 | */ | |
405 | if (address < regs->sp) | |
406 | goto bad_area; | |
407 | } | |
408 | if (expand_stack(vma, address)) | |
409 | goto bad_area; | |
410 | ||
411 | /* | |
412 | * Ok, we have a good vm_area for this memory access, so | |
413 | * we can handle it.. | |
414 | */ | |
415 | good_area: | |
416 | si_code = SEGV_ACCERR; | |
417 | if (fault_num == INT_ITLB_MISS) { | |
418 | if (!(vma->vm_flags & VM_EXEC)) | |
419 | goto bad_area; | |
420 | } else if (write) { | |
421 | #ifdef TEST_VERIFY_AREA | |
422 | if (!is_page_fault && regs->cs == KERNEL_CS) | |
f4743673 | 423 | pr_err("WP fault at " REGFMT "\n", regs->eip); |
867e359b CM |
424 | #endif |
425 | if (!(vma->vm_flags & VM_WRITE)) | |
426 | goto bad_area; | |
759496ba | 427 | flags |= FAULT_FLAG_WRITE; |
867e359b CM |
428 | } else { |
429 | if (!is_page_fault || !(vma->vm_flags & VM_READ)) | |
430 | goto bad_area; | |
431 | } | |
432 | ||
867e359b CM |
433 | /* |
434 | * If for any reason at all we couldn't handle the fault, | |
435 | * make sure we exit gracefully rather than endlessly redo | |
436 | * the fault. | |
437 | */ | |
4ce6bea2 KC |
438 | fault = handle_mm_fault(mm, vma, address, flags); |
439 | ||
440 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
441 | return 0; | |
442 | ||
867e359b CM |
443 | if (unlikely(fault & VM_FAULT_ERROR)) { |
444 | if (fault & VM_FAULT_OOM) | |
445 | goto out_of_memory; | |
33692f27 LT |
446 | else if (fault & VM_FAULT_SIGSEGV) |
447 | goto bad_area; | |
867e359b CM |
448 | else if (fault & VM_FAULT_SIGBUS) |
449 | goto do_sigbus; | |
450 | BUG(); | |
451 | } | |
4ce6bea2 KC |
452 | if (flags & FAULT_FLAG_ALLOW_RETRY) { |
453 | if (fault & VM_FAULT_MAJOR) | |
454 | tsk->maj_flt++; | |
455 | else | |
456 | tsk->min_flt++; | |
457 | if (fault & VM_FAULT_RETRY) { | |
458 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
45cac65b | 459 | flags |= FAULT_FLAG_TRIED; |
4ce6bea2 KC |
460 | |
461 | /* | |
462 | * No need to up_read(&mm->mmap_sem) as we would | |
463 | * have already released it in __lock_page_or_retry | |
464 | * in mm/filemap.c. | |
465 | */ | |
466 | goto retry; | |
467 | } | |
468 | } | |
867e359b | 469 | |
867e359b | 470 | #if CHIP_HAS_TILE_DMA() |
d7c96611 CM |
471 | /* If this was a DMA TLB fault, restart the DMA engine. */ |
472 | switch (fault_num) { | |
867e359b CM |
473 | case INT_DMATLB_MISS: |
474 | case INT_DMATLB_MISS_DWNCL: | |
475 | case INT_DMATLB_ACCESS: | |
476 | case INT_DMATLB_ACCESS_DWNCL: | |
477 | __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK); | |
478 | break; | |
867e359b | 479 | } |
0707ad30 | 480 | #endif |
867e359b CM |
481 | |
482 | up_read(&mm->mmap_sem); | |
483 | return 1; | |
484 | ||
485 | /* | |
486 | * Something tried to access memory that isn't in our memory map.. | |
487 | * Fix it, but check if it's kernel or user first.. | |
488 | */ | |
489 | bad_area: | |
490 | up_read(&mm->mmap_sem); | |
491 | ||
492 | bad_area_nosemaphore: | |
493 | /* User mode accesses just cause a SIGSEGV */ | |
494 | if (!is_kernel_mode) { | |
495 | /* | |
496 | * It's possible to have interrupts off here. | |
497 | */ | |
498 | local_irq_enable(); | |
499 | ||
571d76ac CM |
500 | force_sig_info_fault("segfault", SIGSEGV, si_code, address, |
501 | fault_num, tsk, regs); | |
867e359b CM |
502 | return 0; |
503 | } | |
504 | ||
505 | no_context: | |
506 | /* Are we prepared to handle this kernel fault? */ | |
507 | if (fixup_exception(regs)) | |
508 | return 0; | |
509 | ||
510 | /* | |
511 | * Oops. The kernel tried to access some bad page. We'll have to | |
512 | * terminate things with extreme prejudice. | |
513 | */ | |
514 | ||
515 | bust_spinlocks(1); | |
516 | ||
517 | /* FIXME: no lookup_address() yet */ | |
518 | #ifdef SUPPORT_LOOKUP_ADDRESS | |
519 | if (fault_num == INT_ITLB_MISS) { | |
520 | pte_t *pte = lookup_address(address); | |
521 | ||
522 | if (pte && pte_present(*pte) && !pte_exec_kernel(*pte)) | |
f4743673 JP |
523 | pr_crit("kernel tried to execute non-executable page - exploit attempt? (uid: %d)\n", |
524 | current->uid); | |
867e359b CM |
525 | } |
526 | #endif | |
527 | if (address < PAGE_SIZE) | |
0707ad30 | 528 | pr_alert("Unable to handle kernel NULL pointer dereference\n"); |
867e359b | 529 | else |
0707ad30 | 530 | pr_alert("Unable to handle kernel paging request\n"); |
f4743673 | 531 | pr_alert(" at virtual address " REGFMT ", pc " REGFMT "\n", |
0707ad30 | 532 | address, regs->pc); |
867e359b CM |
533 | |
534 | show_regs(regs); | |
535 | ||
536 | if (unlikely(tsk->pid < 2)) { | |
537 | panic("Kernel page fault running %s!", | |
a95f8817 | 538 | is_idle_task(tsk) ? "the idle task" : "init"); |
867e359b CM |
539 | } |
540 | ||
541 | /* | |
542 | * More FIXME: we should probably copy the i386 here and | |
543 | * implement a generic die() routine. Not today. | |
544 | */ | |
545 | #ifdef SUPPORT_DIE | |
546 | die("Oops", regs); | |
547 | #endif | |
548 | bust_spinlocks(1); | |
549 | ||
550 | do_group_exit(SIGKILL); | |
551 | ||
552 | /* | |
553 | * We ran out of memory, or some other thing happened to us that made | |
554 | * us unable to handle the page fault gracefully. | |
555 | */ | |
556 | out_of_memory: | |
557 | up_read(&mm->mmap_sem); | |
609838cf JW |
558 | if (is_kernel_mode) |
559 | goto no_context; | |
560 | pagefault_out_of_memory(); | |
561 | return 0; | |
867e359b CM |
562 | |
563 | do_sigbus: | |
564 | up_read(&mm->mmap_sem); | |
565 | ||
566 | /* Kernel mode? Handle exceptions or die */ | |
567 | if (is_kernel_mode) | |
568 | goto no_context; | |
569 | ||
571d76ac CM |
570 | force_sig_info_fault("bus error", SIGBUS, BUS_ADRERR, address, |
571 | fault_num, tsk, regs); | |
867e359b CM |
572 | return 0; |
573 | } | |
574 | ||
575 | #ifndef __tilegx__ | |
576 | ||
867e359b | 577 | /* We must release ICS before panicking or we won't get anywhere. */ |
f4743673 JP |
578 | #define ics_panic(fmt, ...) \ |
579 | do { \ | |
580 | __insn_mtspr(SPR_INTERRUPT_CRITICAL_SECTION, 0); \ | |
581 | panic(fmt, ##__VA_ARGS__); \ | |
867e359b CM |
582 | } while (0) |
583 | ||
867e359b CM |
584 | /* |
585 | * When we take an ITLB or DTLB fault or access violation in the | |
586 | * supervisor while the critical section bit is set, the hypervisor is | |
a78c942d | 587 | * reluctant to write new values into the EX_CONTEXT_K_x registers, |
867e359b CM |
588 | * since that might indicate we have not yet squirreled the SPR |
589 | * contents away and can thus safely take a recursive interrupt. | |
a78c942d | 590 | * Accordingly, the hypervisor passes us the PC via SYSTEM_SAVE_K_2. |
c745a8a1 CM |
591 | * |
592 | * Note that this routine is called before homecache_tlb_defer_enter(), | |
593 | * which means that we can properly unlock any atomics that might | |
594 | * be used there (good), but also means we must be very sensitive | |
595 | * to not touch any data structures that might be located in memory | |
596 | * that could migrate, as we could be entering the kernel on a dataplane | |
597 | * cpu that has been deferring kernel TLB updates. This means, for | |
598 | * example, that we can't migrate init_mm or its pgd. | |
867e359b CM |
599 | */ |
600 | struct intvec_state do_page_fault_ics(struct pt_regs *regs, int fault_num, | |
601 | unsigned long address, | |
602 | unsigned long info) | |
603 | { | |
604 | unsigned long pc = info & ~1; | |
605 | int write = info & 1; | |
606 | pgd_t *pgd = get_current_pgd(); | |
607 | ||
608 | /* Retval is 1 at first since we will handle the fault fully. */ | |
609 | struct intvec_state state = { | |
610 | do_page_fault, fault_num, address, write, 1 | |
611 | }; | |
612 | ||
613 | /* Validate that we are plausibly in the right routine. */ | |
614 | if ((pc & 0x7) != 0 || pc < PAGE_OFFSET || | |
615 | (fault_num != INT_DTLB_MISS && | |
616 | fault_num != INT_DTLB_ACCESS)) { | |
617 | unsigned long old_pc = regs->pc; | |
618 | regs->pc = pc; | |
f4743673 | 619 | ics_panic("Bad ICS page fault args: old PC %#lx, fault %d/%d at %#lx", |
867e359b CM |
620 | old_pc, fault_num, write, address); |
621 | } | |
622 | ||
623 | /* We might be faulting on a vmalloc page, so check that first. */ | |
624 | if (fault_num != INT_DTLB_ACCESS && vmalloc_fault(pgd, address) >= 0) | |
625 | return state; | |
626 | ||
627 | /* | |
628 | * If we faulted with ICS set in sys_cmpxchg, we are providing | |
629 | * a user syscall service that should generate a signal on | |
630 | * fault. We didn't set up a kernel stack on initial entry to | |
631 | * sys_cmpxchg, but instead had one set up by the fault, which | |
632 | * (because sys_cmpxchg never releases ICS) came to us via the | |
a78c942d | 633 | * SYSTEM_SAVE_K_2 mechanism, and thus EX_CONTEXT_K_[01] are |
867e359b CM |
634 | * still referencing the original user code. We release the |
635 | * atomic lock and rewrite pt_regs so that it appears that we | |
636 | * came from user-space directly, and after we finish the | |
637 | * fault we'll go back to user space and re-issue the swint. | |
638 | * This way the backtrace information is correct if we need to | |
639 | * emit a stack dump at any point while handling this. | |
640 | * | |
641 | * Must match register use in sys_cmpxchg(). | |
642 | */ | |
643 | if (pc >= (unsigned long) sys_cmpxchg && | |
644 | pc < (unsigned long) __sys_cmpxchg_end) { | |
645 | #ifdef CONFIG_SMP | |
646 | /* Don't unlock before we could have locked. */ | |
647 | if (pc >= (unsigned long)__sys_cmpxchg_grab_lock) { | |
648 | int *lock_ptr = (int *)(regs->regs[ATOMIC_LOCK_REG]); | |
649 | __atomic_fault_unlock(lock_ptr); | |
650 | } | |
651 | #endif | |
652 | regs->sp = regs->regs[27]; | |
653 | } | |
654 | ||
655 | /* | |
656 | * We can also fault in the atomic assembly, in which | |
657 | * case we use the exception table to do the first-level fixup. | |
658 | * We may re-fixup again in the real fault handler if it | |
659 | * turns out the faulting address is just bad, and not, | |
660 | * for example, migrating. | |
661 | */ | |
662 | else if (pc >= (unsigned long) __start_atomic_asm_code && | |
663 | pc < (unsigned long) __end_atomic_asm_code) { | |
664 | const struct exception_table_entry *fixup; | |
665 | #ifdef CONFIG_SMP | |
666 | /* Unlock the atomic lock. */ | |
667 | int *lock_ptr = (int *)(regs->regs[ATOMIC_LOCK_REG]); | |
668 | __atomic_fault_unlock(lock_ptr); | |
669 | #endif | |
670 | fixup = search_exception_tables(pc); | |
671 | if (!fixup) | |
f4743673 JP |
672 | ics_panic("ICS atomic fault not in table: PC %#lx, fault %d", |
673 | pc, fault_num); | |
867e359b CM |
674 | regs->pc = fixup->fixup; |
675 | regs->ex1 = PL_ICS_EX1(KERNEL_PL, 0); | |
676 | } | |
677 | ||
867e359b CM |
678 | /* |
679 | * Now that we have released the atomic lock (if necessary), | |
680 | * it's safe to spin if the PTE that caused the fault was migrating. | |
681 | */ | |
682 | if (fault_num == INT_DTLB_ACCESS) | |
683 | write = 1; | |
48292738 | 684 | if (handle_migrating_pte(pgd, fault_num, address, pc, 1, write)) |
867e359b CM |
685 | return state; |
686 | ||
687 | /* Return zero so that we continue on with normal fault handling. */ | |
688 | state.retval = 0; | |
689 | return state; | |
690 | } | |
691 | ||
692 | #endif /* !__tilegx__ */ | |
693 | ||
694 | /* | |
695 | * This routine handles page faults. It determines the address, and the | |
696 | * problem, and then passes it handle_page_fault() for normal DTLB and | |
697 | * ITLB issues, and for DMA or SN processor faults when we are in user | |
698 | * space. For the latter, if we're in kernel mode, we just save the | |
699 | * interrupt away appropriately and return immediately. We can't do | |
700 | * page faults for user code while in kernel mode. | |
701 | */ | |
702 | void do_page_fault(struct pt_regs *regs, int fault_num, | |
703 | unsigned long address, unsigned long write) | |
704 | { | |
705 | int is_page_fault; | |
49e4e156 | 706 | enum ctx_state prev_state = exception_enter(); |
867e359b | 707 | |
3fa17c39 TL |
708 | #ifdef CONFIG_KPROBES |
709 | /* | |
710 | * This is to notify the fault handler of the kprobes. The | |
711 | * exception code is redundant as it is also carried in REGS, | |
712 | * but we pass it anyhow. | |
713 | */ | |
714 | if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1, | |
715 | regs->faultnum, SIGSEGV) == NOTIFY_STOP) | |
49e4e156 | 716 | goto done; |
3fa17c39 TL |
717 | #endif |
718 | ||
2f9ac29e CM |
719 | #ifdef __tilegx__ |
720 | /* | |
721 | * We don't need early do_page_fault_ics() support, since unlike | |
722 | * Pro we don't need to worry about unlocking the atomic locks. | |
723 | * There is only one current case in GX where we touch any memory | |
724 | * under ICS other than our own kernel stack, and we handle that | |
725 | * here. (If we crash due to trying to touch our own stack, | |
726 | * we're in too much trouble for C code to help out anyway.) | |
727 | */ | |
728 | if (write & ~1) { | |
729 | unsigned long pc = write & ~1; | |
730 | if (pc >= (unsigned long) __start_unalign_asm_code && | |
731 | pc < (unsigned long) __end_unalign_asm_code) { | |
732 | struct thread_info *ti = current_thread_info(); | |
733 | /* | |
734 | * Our EX_CONTEXT is still what it was from the | |
735 | * initial unalign exception, but now we've faulted | |
736 | * on the JIT page. We would like to complete the | |
737 | * page fault however is appropriate, and then retry | |
738 | * the instruction that caused the unalign exception. | |
739 | * Our state has been "corrupted" by setting the low | |
740 | * bit in "sp", and stashing r0..r3 in the | |
741 | * thread_info area, so we revert all of that, then | |
742 | * continue as if this were a normal page fault. | |
743 | */ | |
744 | regs->sp &= ~1UL; | |
745 | regs->regs[0] = ti->unalign_jit_tmp[0]; | |
746 | regs->regs[1] = ti->unalign_jit_tmp[1]; | |
747 | regs->regs[2] = ti->unalign_jit_tmp[2]; | |
748 | regs->regs[3] = ti->unalign_jit_tmp[3]; | |
749 | write &= 1; | |
750 | } else { | |
751 | pr_alert("%s/%d: ICS set at page fault at %#lx: %#lx\n", | |
752 | current->comm, current->pid, pc, address); | |
753 | show_regs(regs); | |
754 | do_group_exit(SIGKILL); | |
2f9ac29e CM |
755 | } |
756 | } | |
757 | #else | |
867e359b CM |
758 | /* This case should have been handled by do_page_fault_ics(). */ |
759 | BUG_ON(write & ~1); | |
2f9ac29e | 760 | #endif |
867e359b CM |
761 | |
762 | #if CHIP_HAS_TILE_DMA() | |
763 | /* | |
764 | * If it's a DMA fault, suspend the transfer while we're | |
765 | * handling the miss; we'll restart after it's handled. If we | |
766 | * don't suspend, it's possible that this process could swap | |
767 | * out and back in, and restart the engine since the DMA is | |
768 | * still 'running'. | |
769 | */ | |
770 | if (fault_num == INT_DMATLB_MISS || | |
771 | fault_num == INT_DMATLB_ACCESS || | |
772 | fault_num == INT_DMATLB_MISS_DWNCL || | |
773 | fault_num == INT_DMATLB_ACCESS_DWNCL) { | |
774 | __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__SUSPEND_MASK); | |
775 | while (__insn_mfspr(SPR_DMA_USER_STATUS) & | |
776 | SPR_DMA_STATUS__BUSY_MASK) | |
777 | ; | |
778 | } | |
779 | #endif | |
780 | ||
781 | /* Validate fault num and decide if this is a first-time page fault. */ | |
782 | switch (fault_num) { | |
783 | case INT_ITLB_MISS: | |
784 | case INT_DTLB_MISS: | |
785 | #if CHIP_HAS_TILE_DMA() | |
786 | case INT_DMATLB_MISS: | |
787 | case INT_DMATLB_MISS_DWNCL: | |
867e359b CM |
788 | #endif |
789 | is_page_fault = 1; | |
790 | break; | |
791 | ||
792 | case INT_DTLB_ACCESS: | |
793 | #if CHIP_HAS_TILE_DMA() | |
794 | case INT_DMATLB_ACCESS: | |
795 | case INT_DMATLB_ACCESS_DWNCL: | |
796 | #endif | |
797 | is_page_fault = 0; | |
798 | break; | |
799 | ||
800 | default: | |
801 | panic("Bad fault number %d in do_page_fault", fault_num); | |
802 | } | |
803 | ||
d7c96611 | 804 | #if CHIP_HAS_TILE_DMA() |
051168df | 805 | if (!user_mode(regs)) { |
867e359b CM |
806 | struct async_tlb *async; |
807 | switch (fault_num) { | |
808 | #if CHIP_HAS_TILE_DMA() | |
809 | case INT_DMATLB_MISS: | |
810 | case INT_DMATLB_ACCESS: | |
811 | case INT_DMATLB_MISS_DWNCL: | |
812 | case INT_DMATLB_ACCESS_DWNCL: | |
813 | async = ¤t->thread.dma_async_tlb; | |
814 | break; | |
867e359b CM |
815 | #endif |
816 | default: | |
817 | async = NULL; | |
818 | } | |
819 | if (async) { | |
820 | ||
821 | /* | |
822 | * No vmalloc check required, so we can allow | |
823 | * interrupts immediately at this point. | |
824 | */ | |
825 | local_irq_enable(); | |
826 | ||
827 | set_thread_flag(TIF_ASYNC_TLB); | |
828 | if (async->fault_num != 0) { | |
f4743673 | 829 | panic("Second async fault %d; old fault was %d (%#lx/%ld)", |
867e359b CM |
830 | fault_num, async->fault_num, |
831 | address, write); | |
832 | } | |
833 | BUG_ON(fault_num == 0); | |
834 | async->fault_num = fault_num; | |
835 | async->is_fault = is_page_fault; | |
836 | async->is_write = write; | |
837 | async->address = address; | |
49e4e156 | 838 | goto done; |
867e359b CM |
839 | } |
840 | } | |
313ce674 | 841 | #endif |
867e359b CM |
842 | |
843 | handle_page_fault(regs, fault_num, is_page_fault, address, write); | |
49e4e156 CM |
844 | |
845 | done: | |
846 | exception_exit(prev_state); | |
867e359b CM |
847 | } |
848 | ||
849 | ||
d7c96611 | 850 | #if CHIP_HAS_TILE_DMA() |
867e359b | 851 | /* |
d7c96611 CM |
852 | * This routine effectively re-issues asynchronous page faults |
853 | * when we are returning to user space. | |
867e359b | 854 | */ |
d7c96611 | 855 | void do_async_page_fault(struct pt_regs *regs) |
867e359b | 856 | { |
d7c96611 CM |
857 | struct async_tlb *async = ¤t->thread.dma_async_tlb; |
858 | ||
859 | /* | |
860 | * Clear thread flag early. If we re-interrupt while processing | |
861 | * code here, we will reset it and recall this routine before | |
862 | * returning to user space. | |
863 | */ | |
864 | clear_thread_flag(TIF_ASYNC_TLB); | |
865 | ||
867e359b CM |
866 | if (async->fault_num) { |
867 | /* | |
868 | * Clear async->fault_num before calling the page-fault | |
869 | * handler so that if we re-interrupt before returning | |
870 | * from the function we have somewhere to put the | |
871 | * information from the new interrupt. | |
872 | */ | |
873 | int fault_num = async->fault_num; | |
874 | async->fault_num = 0; | |
875 | handle_page_fault(regs, fault_num, async->is_fault, | |
876 | async->address, async->is_write); | |
877 | } | |
878 | } | |
d7c96611 | 879 | #endif /* CHIP_HAS_TILE_DMA() */ |
313ce674 | 880 | |
867e359b CM |
881 | |
882 | void vmalloc_sync_all(void) | |
883 | { | |
884 | #ifdef __tilegx__ | |
885 | /* Currently all L1 kernel pmd's are static and shared. */ | |
e5f7bd43 CM |
886 | BUILD_BUG_ON(pgd_index(VMALLOC_END - PAGE_SIZE) != |
887 | pgd_index(VMALLOC_START)); | |
867e359b CM |
888 | #else |
889 | /* | |
890 | * Note that races in the updates of insync and start aren't | |
891 | * problematic: insync can only get set bits added, and updates to | |
892 | * start are only improving performance (without affecting correctness | |
893 | * if undone). | |
894 | */ | |
895 | static DECLARE_BITMAP(insync, PTRS_PER_PGD); | |
896 | static unsigned long start = PAGE_OFFSET; | |
897 | unsigned long address; | |
898 | ||
899 | BUILD_BUG_ON(PAGE_OFFSET & ~PGDIR_MASK); | |
900 | for (address = start; address >= PAGE_OFFSET; address += PGDIR_SIZE) { | |
901 | if (!test_bit(pgd_index(address), insync)) { | |
902 | unsigned long flags; | |
903 | struct list_head *pos; | |
904 | ||
905 | spin_lock_irqsave(&pgd_lock, flags); | |
906 | list_for_each(pos, &pgd_list) | |
907 | if (!vmalloc_sync_one(list_to_pgd(pos), | |
908 | address)) { | |
909 | /* Must be at first entry in list. */ | |
910 | BUG_ON(pos != pgd_list.next); | |
911 | break; | |
912 | } | |
913 | spin_unlock_irqrestore(&pgd_lock, flags); | |
914 | if (pos != pgd_list.next) | |
915 | set_bit(pgd_index(address), insync); | |
916 | } | |
917 | if (address == start && test_bit(pgd_index(address), insync)) | |
918 | start = address + PGDIR_SIZE; | |
919 | } | |
920 | #endif | |
921 | } |