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2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f 
 kernel/arch/arm/mm/fault.c
....@@ -1,12 +1,9 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  *  linux/arch/arm/mm/fault.c
34  *
45  *  Copyright (C) 1995  Linus Torvalds
56  *  Modifications for ARM processor (c) 1995-2004 Russell King
6
- *
7
- * This program is free software; you can redistribute it and/or modify
8
- * it under the terms of the GNU General Public License version 2 as
9
- * published by the Free Software Foundation.
107  */
118 #include <linux/extable.h>
129 #include <linux/signal.h>
....@@ -21,7 +18,6 @@
2118 #include <linux/highmem.h>
2219 #include <linux/perf_event.h>
2320 
24
-#include <asm/pgtable.h>
2521 #include <asm/system_misc.h>
2622 #include <asm/system_info.h>
2723 #include <asm/tlbflush.h>
....@@ -30,58 +26,37 @@
3026 
3127 #ifdef CONFIG_MMU
3228 
33
-#ifdef CONFIG_KPROBES
34
-static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
35
-{
36
-	int ret = 0;
37
-
38
-	if (!user_mode(regs)) {
39
-		/* kprobe_running() needs smp_processor_id() */
40
-		preempt_disable();
41
-		if (kprobe_running() && kprobe_fault_handler(regs, fsr))
42
-			ret = 1;
43
-		preempt_enable();
44
-	}
45
-
46
-	return ret;
47
-}
48
-#else
49
-static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
50
-{
51
-	return 0;
52
-}
53
-#endif
54
-
5529 /*
5630  * This is useful to dump out the page tables associated with
5731  * 'addr' in mm 'mm'.
5832  */
59
-void show_pte(struct mm_struct *mm, unsigned long addr)
33
+void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
6034 {
6135 	pgd_t *pgd;
6236 
6337 	if (!mm)
6438 		mm = &init_mm;
6539 
66
-	pr_alert("pgd = %p\n", mm->pgd);
40
+	printk("%spgd = %p\n", lvl, mm->pgd);
6741 	pgd = pgd_offset(mm, addr);
68
-	pr_alert("[%08lx] *pgd=%08llx",
69
-			addr, (long long)pgd_val(*pgd));
42
+	printk("%s[%08lx] *pgd=%08llx", lvl, addr, (long long)pgd_val(*pgd));
7043 
7144 	do {
45
+		p4d_t *p4d;
7246 		pud_t *pud;
7347 		pmd_t *pmd;
7448 		pte_t *pte;
7549 
76
-		if (pgd_none(*pgd))
50
+		p4d = p4d_offset(pgd, addr);
51
+		if (p4d_none(*p4d))
7752 			break;
7853 
79
-		if (pgd_bad(*pgd)) {
54
+		if (p4d_bad(*p4d)) {
8055 			pr_cont("(bad)");
8156 			break;
8257 		}
8358 
84
-		pud = pud_offset(pgd, addr);
59
+		pud = pud_offset(p4d, addr);
8560 		if (PTRS_PER_PUD != 1)
8661 			pr_cont(", *pud=%08llx", (long long)pud_val(*pud));
8762 
....@@ -121,7 +96,7 @@
12196 	pr_cont("\n");
12297 }
12398 #else					/* CONFIG_MMU */
124
-void show_pte(struct mm_struct *mm, unsigned long addr)
99
+void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
125100 { }
126101 #endif					/* CONFIG_MMU */
127102 
....@@ -142,11 +117,12 @@
142117 	 * No handler, we'll have to terminate things with extreme prejudice.
143118 	 */
144119 	bust_spinlocks(1);
120
+	pr_alert("8<--- cut here ---\n");
145121 	pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
146122 		 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
147123 		 "paging request", addr);
148124 
149
-	show_pte(mm, addr);
125
+	show_pte(KERN_ALERT, mm, addr);
150126 	die("Oops", regs, fsr);
151127 	bust_spinlocks(0);
152128 	do_exit(SIGKILL);
....@@ -157,35 +133,35 @@
157133  * User mode accesses just cause a SIGSEGV
158134  */
159135 static void
160
-__do_user_fault(struct task_struct *tsk, unsigned long addr,
161
-		unsigned int fsr, unsigned int sig, int code,
162
-		struct pt_regs *regs)
136
+__do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,
137
+		int code, struct pt_regs *regs)
163138 {
164
-	struct siginfo si;
139
+	struct task_struct *tsk = current;
165140 
166141 	if (addr > TASK_SIZE)
167142 		harden_branch_predictor();
168143 
169
-	clear_siginfo(&si);
170
-
171144 #ifdef CONFIG_DEBUG_USER
172145 	if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) ||
173146 	    ((user_debug & UDBG_BUS)  && (sig == SIGBUS))) {
174
-		printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
147
+		pr_err("8<--- cut here ---\n");
148
+		pr_err("%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
175149 		       tsk->comm, sig, addr, fsr);
176
-		show_pte(tsk->mm, addr);
150
+		show_pte(KERN_ERR, tsk->mm, addr);
177151 		show_regs(regs);
178152 	}
153
+#endif
154
+#ifndef CONFIG_KUSER_HELPERS
155
+	if ((sig == SIGSEGV) && ((addr & PAGE_MASK) == 0xffff0000))
156
+		printk_ratelimited(KERN_DEBUG
157
+				   "%s: CONFIG_KUSER_HELPERS disabled at 0x%08lx\n",
158
+				   tsk->comm, addr);
179159 #endif
180160 
181161 	tsk->thread.address = addr;
182162 	tsk->thread.error_code = fsr;
183163 	tsk->thread.trap_no = 14;
184
-	si.si_signo = sig;
185
-	si.si_errno = 0;
186
-	si.si_code = code;
187
-	si.si_addr = (void __user *)addr;
188
-	force_sig_info(sig, &si, tsk);
164
+	force_sig_fault(sig, code, (void __user *)addr);
189165 }
190166 
191167 void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
....@@ -198,7 +174,7 @@
198174 	 * have no context to handle this fault with.
199175 	 */
200176 	if (user_mode(regs))
201
-		__do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
177
+		__do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
202178 	else
203179 		__do_kernel_fault(mm, addr, fsr, regs);
204180 }
....@@ -214,7 +190,7 @@
214190  */
215191 static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
216192 {
217
-	unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
193
+	unsigned int mask = VM_ACCESS_FLAGS;
218194 
219195 	if ((fsr & FSR_WRITE) && !(fsr & FSR_CM))
220196 		mask = VM_WRITE;
....@@ -226,7 +202,8 @@
226202 
227203 static vm_fault_t __kprobes
228204 __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
229
-		unsigned int flags, struct task_struct *tsk)
205
+		unsigned int flags, struct task_struct *tsk,
206
+		struct pt_regs *regs)
230207 {
231208 	struct vm_area_struct *vma;
232209 	vm_fault_t fault;
....@@ -248,7 +225,7 @@
248225 		goto out;
249226 	}
250227 
251
-	return handle_mm_fault(vma, addr & PAGE_MASK, flags);
228
+	return handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
252229 
253230 check_stack:
254231 	/* Don't allow expansion below FIRST_USER_ADDRESS */
....@@ -266,9 +243,9 @@
266243 	struct mm_struct *mm;
267244 	int sig, code;
268245 	vm_fault_t fault;
269
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
246
+	unsigned int flags = FAULT_FLAG_DEFAULT;
270247 
271
-	if (notify_page_fault(regs, fsr))
248
+	if (kprobe_page_fault(regs, fsr))
272249 		return 0;
273250 
274251 	tsk = current;
....@@ -290,16 +267,18 @@
290267 	if ((fsr & FSR_WRITE) && !(fsr & FSR_CM))
291268 		flags |= FAULT_FLAG_WRITE;
292269 
270
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
271
+
293272 	/*
294273 	 * As per x86, we may deadlock here.  However, since the kernel only
295274 	 * validly references user space from well defined areas of the code,
296275 	 * we can bug out early if this is from code which shouldn't.
297276 	 */
298
-	if (!down_read_trylock(&mm->mmap_sem)) {
277
+	if (!mmap_read_trylock(mm)) {
299278 		if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
300279 			goto no_context;
301280 retry:
302
-		down_read(&mm->mmap_sem);
281
+		mmap_read_lock(mm);
303282 	} else {
304283 		/*
305284 		 * The above down_read_trylock() might have succeeded in
....@@ -314,45 +293,26 @@
314293 #endif
315294 	}
316295 
317
-	fault = __do_page_fault(mm, addr, fsr, flags, tsk);
296
+	fault = __do_page_fault(mm, addr, fsr, flags, tsk, regs);
318297 
319298 	/* If we need to retry but a fatal signal is pending, handle the
320
-	 * signal first. We do not need to release the mmap_sem because
299
+	 * signal first. We do not need to release the mmap_lock because
321300 	 * it would already be released in __lock_page_or_retry in
322301 	 * mm/filemap.c. */
323
-	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
302
+	if (fault_signal_pending(fault, regs)) {
324303 		if (!user_mode(regs))
325304 			goto no_context;
326305 		return 0;
327306 	}
328307 
329
-	/*
330
-	 * Major/minor page fault accounting is only done on the
331
-	 * initial attempt. If we go through a retry, it is extremely
332
-	 * likely that the page will be found in page cache at that point.
333
-	 */
334
-
335
-	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
336308 	if (!(fault & VM_FAULT_ERROR) && flags & FAULT_FLAG_ALLOW_RETRY) {
337
-		if (fault & VM_FAULT_MAJOR) {
338
-			tsk->maj_flt++;
339
-			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
340
-					regs, addr);
341
-		} else {
342
-			tsk->min_flt++;
343
-			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
344
-					regs, addr);
345
-		}
346309 		if (fault & VM_FAULT_RETRY) {
347
-			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
348
-			* of starvation. */
349
-			flags &= ~FAULT_FLAG_ALLOW_RETRY;
350310 			flags |= FAULT_FLAG_TRIED;
351311 			goto retry;
352312 		}
353313 	}
354314 
355
-	up_read(&mm->mmap_sem);
315
+	mmap_read_unlock(mm);
356316 
357317 	/*
358318 	 * Handle the "normal" case first - VM_FAULT_MAJOR
....@@ -394,7 +354,7 @@
394354 			SEGV_ACCERR : SEGV_MAPERR;
395355 	}
396356 
397
-	__do_user_fault(tsk, addr, fsr, sig, code, regs);
357
+	__do_user_fault(addr, fsr, sig, code, regs);
398358 	return 0;
399359 
400360 no_context:
....@@ -433,14 +393,12 @@
433393 {
434394 	unsigned int index;
435395 	pgd_t *pgd, *pgd_k;
396
+	p4d_t *p4d, *p4d_k;
436397 	pud_t *pud, *pud_k;
437398 	pmd_t *pmd, *pmd_k;
438399 
439400 	if (addr < TASK_SIZE)
440401 		return do_page_fault(addr, fsr, regs);
441
-
442
-	if (interrupts_enabled(regs))
443
-		local_irq_enable();
444402 
445403 	if (user_mode(regs))
446404 		goto bad_area;
....@@ -450,13 +408,16 @@
450408 	pgd = cpu_get_pgd() + index;
451409 	pgd_k = init_mm.pgd + index;
452410 
453
-	if (pgd_none(*pgd_k))
454
-		goto bad_area;
455
-	if (!pgd_present(*pgd))
456
-		set_pgd(pgd, *pgd_k);
411
+	p4d = p4d_offset(pgd, addr);
412
+	p4d_k = p4d_offset(pgd_k, addr);
457413 
458
-	pud = pud_offset(pgd, addr);
459
-	pud_k = pud_offset(pgd_k, addr);
414
+	if (p4d_none(*p4d_k))
415
+		goto bad_area;
416
+	if (!p4d_present(*p4d))
417
+		set_p4d(p4d, *p4d_k);
418
+
419
+	pud = pud_offset(p4d, addr);
420
+	pud_k = pud_offset(p4d_k, addr);
460421 
461422 	if (pud_none(*pud_k))
462423 		goto bad_area;
....@@ -509,9 +470,6 @@
509470 static int
510471 do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
511472 {
512
-	if (interrupts_enabled(regs))
513
-		local_irq_enable();
514
-
515473 	do_bad_area(addr, fsr, regs);
516474 	return 0;
517475 }
....@@ -560,21 +518,17 @@
560518 do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
561519 {
562520 	const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
563
-	struct siginfo info;
564521 
565522 	if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
566523 		return;
567524 
525
+	pr_alert("8<--- cut here ---\n");
568526 	pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n",
569527 		inf->name, fsr, addr);
570
-	show_pte(current->mm, addr);
528
+	show_pte(KERN_ALERT, current->mm, addr);
571529 
572
-	clear_siginfo(&info);
573
-	info.si_signo = inf->sig;
574
-	info.si_errno = 0;
575
-	info.si_code  = inf->code;
576
-	info.si_addr  = (void __user *)addr;
577
-	arm_notify_die("", regs, &info, fsr, 0);
530
+	arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
531
+		       fsr, 0);
578532 }
579533 
580534 void __init
....@@ -594,7 +548,6 @@
594548 do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
595549 {
596550 	const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
597
-	struct siginfo info;
598551 
599552 	if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
600553 		return;
....@@ -602,12 +555,8 @@
602555 	pr_alert("Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
603556 		inf->name, ifsr, addr);
604557 
605
-	clear_siginfo(&info);
606
-	info.si_signo = inf->sig;
607
-	info.si_errno = 0;
608
-	info.si_code  = inf->code;
609
-	info.si_addr  = (void __user *)addr;
610
-	arm_notify_die("", regs, &info, ifsr, 0);
558
+	arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
559
+		       ifsr, 0);
611560 }
612561 
613562 /*