Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
/*
 * arch/sh/mm/tlb-flush_64.c
 *
 * Copyright (C) 2000, 2001  Paolo Alberelli
 * Copyright (C) 2003  Richard Curnow (/proc/tlb, bug fixes)
 * Copyright (C) 2003 - 2009 Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/signal.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/perf_event.h>
#include <linux/interrupt.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/tlb.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/mmu_context.h>

extern void die(const char *,struct pt_regs *,long);

#define PFLAG(val,flag)   (( (val) & (flag) ) ? #flag : "" )
#define PPROT(flag) PFLAG(pgprot_val(prot),flag)

static inline void print_prots(pgprot_t prot)
{
	printk("prot is 0x%08lx\n",pgprot_val(prot));

	printk("%s %s %s %s %s\n",PPROT(_PAGE_SHARED),PPROT(_PAGE_READ),
	       PPROT(_PAGE_EXECUTE),PPROT(_PAGE_WRITE),PPROT(_PAGE_USER));
}

static inline void print_vma(struct vm_area_struct *vma)
{
	printk("vma start 0x%08lx\n", vma->vm_start);
	printk("vma end   0x%08lx\n", vma->vm_end);

	print_prots(vma->vm_page_prot);
	printk("vm_flags 0x%08lx\n", vma->vm_flags);
}

static inline void print_task(struct task_struct *tsk)
{
	printk("Task pid %d\n", task_pid_nr(tsk));
}

static pte_t *lookup_pte(struct mm_struct *mm, unsigned long address)
{
	pgd_t *dir;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	pte_t entry;

	dir = pgd_offset(mm, address);
	if (pgd_none(*dir))
		return NULL;

	pud = pud_offset(dir, address);
	if (pud_none(*pud))
		return NULL;

	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd))
		return NULL;

	pte = pte_offset_kernel(pmd, address);
	entry = *pte;
	if (pte_none(entry) || !pte_present(entry))
		return NULL;

	return pte;
}

/*
 * This routine handles page faults.  It determines the address,
 * and the problem, and then passes it off to one of the appropriate
 * routines.
 */
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
			      unsigned long textaccess, unsigned long address)
{
	struct task_struct *tsk;
	struct mm_struct *mm;
	struct vm_area_struct * vma;
	const struct exception_table_entry *fixup;
	pte_t *pte;
	int fault;

	/* SIM
	 * Note this is now called with interrupts still disabled
	 * This is to cope with being called for a missing IO port
	 * address with interrupts disabled. This should be fixed as
	 * soon as we have a better 'fast path' miss handler.
	 *
	 * Plus take care how you try and debug this stuff.
	 * For example, writing debug data to a port which you
	 * have just faulted on is not going to work.
	 */

	tsk = current;
	mm = tsk->mm;

	/* Not an IO address, so reenable interrupts */
	local_irq_enable();

	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);

	/*
	 * If we're in an interrupt or have no user
	 * context, we must not take the fault..
	 */
	if (in_atomic() || !mm)
		goto no_context;

	/* TLB misses upon some cache flushes get done under cli() */
	down_read(&mm->mmap_sem);

	vma = find_vma(mm, address);

	if (!vma) {
#ifdef DEBUG_FAULT
		print_task(tsk);
		printk("%s:%d fault, address is 0x%08x PC %016Lx textaccess %d writeaccess %d\n",
		       __func__, __LINE__,
		       address,regs->pc,textaccess,writeaccess);
		show_regs(regs);
#endif
		goto bad_area;
	}
	if (vma->vm_start <= address) {
		goto good_area;
	}

	if (!(vma->vm_flags & VM_GROWSDOWN)) {
#ifdef DEBUG_FAULT
		print_task(tsk);
		printk("%s:%d fault, address is 0x%08x PC %016Lx textaccess %d writeaccess %d\n",
		       __func__, __LINE__,
		       address,regs->pc,textaccess,writeaccess);
		show_regs(regs);

		print_vma(vma);
#endif
		goto bad_area;
	}
	if (expand_stack(vma, address)) {
#ifdef DEBUG_FAULT
		print_task(tsk);
		printk("%s:%d fault, address is 0x%08x PC %016Lx textaccess %d writeaccess %d\n",
		       __func__, __LINE__,
		       address,regs->pc,textaccess,writeaccess);
		show_regs(regs);
#endif
		goto bad_area;
	}
/*
 * Ok, we have a good vm_area for this memory access, so
 * we can handle it..
 */
good_area:
	if (textaccess) {
		if (!(vma->vm_flags & VM_EXEC))
			goto bad_area;
	} else {
		if (writeaccess) {
			if (!(vma->vm_flags & VM_WRITE))
				goto bad_area;
		} else {
			if (!(vma->vm_flags & VM_READ))
				goto bad_area;
		}
	}

	/*
	 * If for any reason at all we couldn't handle the fault,
	 * make sure we exit gracefully rather than endlessly redo
	 * the fault.
	 */
survive:
	fault = handle_mm_fault(mm, vma, address, writeaccess ? FAULT_FLAG_WRITE : 0);
	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGBUS)
			goto do_sigbus;
		BUG();
	}

	if (fault & VM_FAULT_MAJOR) {
		tsk->maj_flt++;
		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
				     regs, address);
	} else {
		tsk->min_flt++;
		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
				     regs, address);
	}

	/* If we get here, the page fault has been handled.  Do the TLB refill
	   now from the newly-setup PTE, to avoid having to fault again right
	   away on the same instruction. */
	pte = lookup_pte (mm, address);
	if (!pte) {
		/* From empirical evidence, we can get here, due to
		   !pte_present(pte).  (e.g. if a swap-in occurs, and the page
		   is swapped back out again before the process that wanted it
		   gets rescheduled?) */
		goto no_pte;
	}

	__do_tlb_refill(address, textaccess, pte);

no_pte:

	up_read(&mm->mmap_sem);
	return;

/*
 * Something tried to access memory that isn't in our memory map..
 * Fix it, but check if it's kernel or user first..
 */
bad_area:
#ifdef DEBUG_FAULT
	printk("fault:bad area\n");
#endif
	up_read(&mm->mmap_sem);

	if (user_mode(regs)) {
		static int count=0;
		siginfo_t info;
		if (count < 4) {
			/* This is really to help debug faults when starting
			 * usermode, so only need a few */
			count++;
			printk("user mode bad_area address=%08lx pid=%d (%s) pc=%08lx\n",
				address, task_pid_nr(current), current->comm,
				(unsigned long) regs->pc);
#if 0
			show_regs(regs);
#endif
		}
		if (is_global_init(tsk)) {
			panic("INIT had user mode bad_area\n");
		}
		tsk->thread.address = address;
		tsk->thread.error_code = writeaccess;
		info.si_signo = SIGSEGV;
		info.si_errno = 0;
		info.si_addr = (void *) address;
		force_sig_info(SIGSEGV, &info, tsk);
		return;
	}

no_context:
#ifdef DEBUG_FAULT
	printk("fault:No context\n");
#endif
	/* Are we prepared to handle this kernel fault?  */
	fixup = search_exception_tables(regs->pc);
	if (fixup) {
		regs->pc = fixup->fixup;
		return;
	}

/*
 * Oops. The kernel tried to access some bad page. We'll have to
 * terminate things with extreme prejudice.
 *
 */
	if (address < PAGE_SIZE)
		printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
	else
		printk(KERN_ALERT "Unable to handle kernel paging request");
	printk(" at virtual address %08lx\n", address);
	printk(KERN_ALERT "pc = %08Lx%08Lx\n", regs->pc >> 32, regs->pc & 0xffffffff);
	die("Oops", regs, writeaccess);
	do_exit(SIGKILL);

/*
 * We ran out of memory, or some other thing happened to us that made
 * us unable to handle the page fault gracefully.
 */
out_of_memory:
	if (is_global_init(current)) {
		panic("INIT out of memory\n");
		yield();
		goto survive;
	}
	printk("fault:Out of memory\n");
	up_read(&mm->mmap_sem);
	if (is_global_init(current)) {
		yield();
		down_read(&mm->mmap_sem);
		goto survive;
	}
	printk("VM: killing process %s\n", tsk->comm);
	if (user_mode(regs))
		do_group_exit(SIGKILL);
	goto no_context;

do_sigbus:
	printk("fault:Do sigbus\n");
	up_read(&mm->mmap_sem);

	/*
	 * Send a sigbus, regardless of whether we were in kernel
	 * or user mode.
	 */
	tsk->thread.address = address;
	tsk->thread.error_code = writeaccess;
	tsk->thread.trap_no = 14;
	force_sig(SIGBUS, tsk);

	/* Kernel mode? Handle exceptions or die */
	if (!user_mode(regs))
		goto no_context;
}

void local_flush_tlb_one(unsigned long asid, unsigned long page)
{
	unsigned long long match, pteh=0, lpage;
	unsigned long tlb;

	/*
	 * Sign-extend based on neff.
	 */
	lpage = neff_sign_extend(page);
	match = (asid << PTEH_ASID_SHIFT) | PTEH_VALID;
	match |= lpage;

	for_each_itlb_entry(tlb) {
		asm volatile ("getcfg	%1, 0, %0"
			      : "=r" (pteh)
			      : "r" (tlb) );

		if (pteh == match) {
			__flush_tlb_slot(tlb);
			break;
		}
	}

	for_each_dtlb_entry(tlb) {
		asm volatile ("getcfg	%1, 0, %0"
			      : "=r" (pteh)
			      : "r" (tlb) );

		if (pteh == match) {
			__flush_tlb_slot(tlb);
			break;
		}

	}
}

void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
	unsigned long flags;

	if (vma->vm_mm) {
		page &= PAGE_MASK;
		local_irq_save(flags);
		local_flush_tlb_one(get_asid(), page);
		local_irq_restore(flags);
	}
}

void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
			   unsigned long end)
{
	unsigned long flags;
	unsigned long long match, pteh=0, pteh_epn, pteh_low;
	unsigned long tlb;
	unsigned int cpu = smp_processor_id();
	struct mm_struct *mm;

	mm = vma->vm_mm;
	if (cpu_context(cpu, mm) == NO_CONTEXT)
		return;

	local_irq_save(flags);

	start &= PAGE_MASK;
	end &= PAGE_MASK;

	match = (cpu_asid(cpu, mm) << PTEH_ASID_SHIFT) | PTEH_VALID;

	/* Flush ITLB */
	for_each_itlb_entry(tlb) {
		asm volatile ("getcfg	%1, 0, %0"
			      : "=r" (pteh)
			      : "r" (tlb) );

		pteh_epn = pteh & PAGE_MASK;
		pteh_low = pteh & ~PAGE_MASK;

		if (pteh_low == match && pteh_epn >= start && pteh_epn <= end)
			__flush_tlb_slot(tlb);
	}

	/* Flush DTLB */
	for_each_dtlb_entry(tlb) {
		asm volatile ("getcfg	%1, 0, %0"
			      : "=r" (pteh)
			      : "r" (tlb) );

		pteh_epn = pteh & PAGE_MASK;
		pteh_low = pteh & ~PAGE_MASK;

		if (pteh_low == match && pteh_epn >= start && pteh_epn <= end)
			__flush_tlb_slot(tlb);
	}

	local_irq_restore(flags);
}

void local_flush_tlb_mm(struct mm_struct *mm)
{
	unsigned long flags;
	unsigned int cpu = smp_processor_id();

	if (cpu_context(cpu, mm) == NO_CONTEXT)
		return;

	local_irq_save(flags);

	cpu_context(cpu, mm) = NO_CONTEXT;
	if (mm == current->mm)
		activate_context(mm, cpu);

	local_irq_restore(flags);
}

void local_flush_tlb_all(void)
{
	/* Invalidate all, including shared pages, excluding fixed TLBs */
	unsigned long flags, tlb;

	local_irq_save(flags);

	/* Flush each ITLB entry */
	for_each_itlb_entry(tlb)
		__flush_tlb_slot(tlb);

	/* Flush each DTLB entry */
	for_each_dtlb_entry(tlb)
		__flush_tlb_slot(tlb);

	local_irq_restore(flags);
}

void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
        /* FIXME: Optimize this later.. */
        flush_tlb_all();
}

void __update_tlb(struct vm_area_struct *vma, unsigned long address, pte_t pte)
{
}