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
// SPDX-License-Identifier: GPL-2.0
/*
** Tablewalk MMU emulator
**
** by Toshiyasu Morita
**
** Started 1/16/98 @ 2:22 am
*/

#include <linux/init.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/delay.h>
#include <linux/memblock.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/sched/mm.h>

#include <asm/setup.h>
#include <asm/traps.h>
#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/sun3mmu.h>
#include <asm/segment.h>
#include <asm/oplib.h>
#include <asm/mmu_context.h>
#include <asm/dvma.h>


#undef DEBUG_MMU_EMU
#define DEBUG_PROM_MAPS

/*
** Defines
*/

#define CONTEXTS_NUM		8
#define SEGMAPS_PER_CONTEXT_NUM 2048
#define PAGES_PER_SEGMENT	16
#define PMEGS_NUM		256
#define PMEG_MASK		0xFF

/*
** Globals
*/

unsigned long m68k_vmalloc_end;
EXPORT_SYMBOL(m68k_vmalloc_end);

unsigned long pmeg_vaddr[PMEGS_NUM];
unsigned char pmeg_alloc[PMEGS_NUM];
unsigned char pmeg_ctx[PMEGS_NUM];

/* pointers to the mm structs for each task in each
   context. 0xffffffff is a marker for kernel context */
static struct mm_struct *ctx_alloc[CONTEXTS_NUM] = {
    [0] = (struct mm_struct *)0xffffffff
};

/* has this context been mmdrop'd? */
static unsigned char ctx_avail = CONTEXTS_NUM-1;

/* array of pages to be marked off for the rom when we do mem_init later */
/* 256 pages lets the rom take up to 2mb of physical ram..  I really
   hope it never wants mote than that. */
unsigned long rom_pages[256];

/* Print a PTE value in symbolic form. For debugging. */
void print_pte (pte_t pte)
{
#if 0
	/* Verbose version. */
	unsigned long val = pte_val (pte);
	pr_cont(" pte=%lx [addr=%lx",
		val, (val & SUN3_PAGE_PGNUM_MASK) << PAGE_SHIFT);
	if (val & SUN3_PAGE_VALID)	pr_cont(" valid");
	if (val & SUN3_PAGE_WRITEABLE)	pr_cont(" write");
	if (val & SUN3_PAGE_SYSTEM)	pr_cont(" sys");
	if (val & SUN3_PAGE_NOCACHE)	pr_cont(" nocache");
	if (val & SUN3_PAGE_ACCESSED)	pr_cont(" accessed");
	if (val & SUN3_PAGE_MODIFIED)	pr_cont(" modified");
	switch (val & SUN3_PAGE_TYPE_MASK) {
		case SUN3_PAGE_TYPE_MEMORY: pr_cont(" memory"); break;
		case SUN3_PAGE_TYPE_IO:     pr_cont(" io");     break;
		case SUN3_PAGE_TYPE_VME16:  pr_cont(" vme16");  break;
		case SUN3_PAGE_TYPE_VME32:  pr_cont(" vme32");  break;
	}
	pr_cont("]\n");
#else
	/* Terse version. More likely to fit on a line. */
	unsigned long val = pte_val (pte);
	char flags[7], *type;

	flags[0] = (val & SUN3_PAGE_VALID)     ? 'v' : '-';
	flags[1] = (val & SUN3_PAGE_WRITEABLE) ? 'w' : '-';
	flags[2] = (val & SUN3_PAGE_SYSTEM)    ? 's' : '-';
	flags[3] = (val & SUN3_PAGE_NOCACHE)   ? 'x' : '-';
	flags[4] = (val & SUN3_PAGE_ACCESSED)  ? 'a' : '-';
	flags[5] = (val & SUN3_PAGE_MODIFIED)  ? 'm' : '-';
	flags[6] = '\0';

	switch (val & SUN3_PAGE_TYPE_MASK) {
		case SUN3_PAGE_TYPE_MEMORY: type = "memory"; break;
		case SUN3_PAGE_TYPE_IO:     type = "io"    ; break;
		case SUN3_PAGE_TYPE_VME16:  type = "vme16" ; break;
		case SUN3_PAGE_TYPE_VME32:  type = "vme32" ; break;
		default: type = "unknown?"; break;
	}

	pr_cont(" pte=%08lx [%07lx %s %s]\n",
		val, (val & SUN3_PAGE_PGNUM_MASK) << PAGE_SHIFT, flags, type);
#endif
}

/* Print the PTE value for a given virtual address. For debugging. */
void print_pte_vaddr (unsigned long vaddr)
{
	pr_cont(" vaddr=%lx [%02lx]", vaddr, sun3_get_segmap (vaddr));
	print_pte (__pte (sun3_get_pte (vaddr)));
}

/*
 * Initialise the MMU emulator.
 */
void __init mmu_emu_init(unsigned long bootmem_end)
{
	unsigned long seg, num;
	int i,j;

	memset(rom_pages, 0, sizeof(rom_pages));
	memset(pmeg_vaddr, 0, sizeof(pmeg_vaddr));
	memset(pmeg_alloc, 0, sizeof(pmeg_alloc));
	memset(pmeg_ctx, 0, sizeof(pmeg_ctx));

	/* pmeg align the end of bootmem, adding another pmeg,
	 * later bootmem allocations will likely need it */
	bootmem_end = (bootmem_end + (2 * SUN3_PMEG_SIZE)) & ~SUN3_PMEG_MASK;

	/* mark all of the pmegs used thus far as reserved */
	for (i=0; i < __pa(bootmem_end) / SUN3_PMEG_SIZE ; ++i)
		pmeg_alloc[i] = 2;


	/* I'm thinking that most of the top pmeg's are going to be
	   used for something, and we probably shouldn't risk it */
	for(num = 0xf0; num <= 0xff; num++)
		pmeg_alloc[num] = 2;

	/* liberate all existing mappings in the rest of kernel space */
	for(seg = bootmem_end; seg < 0x0f800000; seg += SUN3_PMEG_SIZE) {
		i = sun3_get_segmap(seg);

		if(!pmeg_alloc[i]) {
#ifdef DEBUG_MMU_EMU
			pr_info("freed:");
			print_pte_vaddr (seg);
#endif
			sun3_put_segmap(seg, SUN3_INVALID_PMEG);
		}
	}

	j = 0;
	for (num=0, seg=0x0F800000; seg<0x10000000; seg+=16*PAGE_SIZE) {
		if (sun3_get_segmap (seg) != SUN3_INVALID_PMEG) {
#ifdef DEBUG_PROM_MAPS
			for(i = 0; i < 16; i++) {
				pr_info("mapped:");
				print_pte_vaddr (seg + (i*PAGE_SIZE));
				break;
			}
#endif
			// the lowest mapping here is the end of our
			// vmalloc region
			if (!m68k_vmalloc_end)
				m68k_vmalloc_end = seg;

			// mark the segmap alloc'd, and reserve any
			// of the first 0xbff pages the hardware is
			// already using...  does any sun3 support > 24mb?
			pmeg_alloc[sun3_get_segmap(seg)] = 2;
		}
	}

	dvma_init();


	/* blank everything below the kernel, and we've got the base
	   mapping to start all the contexts off with... */
	for(seg = 0; seg < PAGE_OFFSET; seg += SUN3_PMEG_SIZE)
		sun3_put_segmap(seg, SUN3_INVALID_PMEG);

	set_fs(MAKE_MM_SEG(3));
	for(seg = 0; seg < 0x10000000; seg += SUN3_PMEG_SIZE) {
		i = sun3_get_segmap(seg);
		for(j = 1; j < CONTEXTS_NUM; j++)
			(*(romvec->pv_setctxt))(j, (void *)seg, i);
	}
	set_fs(KERNEL_DS);

}

/* erase the mappings for a dead context.  Uses the pg_dir for hints
   as the pmeg tables proved somewhat unreliable, and unmapping all of
   TASK_SIZE was much slower and no more stable. */
/* todo: find a better way to keep track of the pmegs used by a
   context for when they're cleared */
void clear_context(unsigned long context)
{
     unsigned char oldctx;
     unsigned long i;

     if(context) {
	     if(!ctx_alloc[context])
		     panic("clear_context: context not allocated\n");

	     ctx_alloc[context]->context = SUN3_INVALID_CONTEXT;
	     ctx_alloc[context] = (struct mm_struct *)0;
	     ctx_avail++;
     }

     oldctx = sun3_get_context();

     sun3_put_context(context);

     for(i = 0; i < SUN3_INVALID_PMEG; i++) {
	     if((pmeg_ctx[i] == context) && (pmeg_alloc[i] == 1)) {
		     sun3_put_segmap(pmeg_vaddr[i], SUN3_INVALID_PMEG);
		     pmeg_ctx[i] = 0;
		     pmeg_alloc[i] = 0;
		     pmeg_vaddr[i] = 0;
	     }
     }

     sun3_put_context(oldctx);
}

/* gets an empty context.  if full, kills the next context listed to
   die first */
/* This context invalidation scheme is, well, totally arbitrary, I'm
   sure it could be much more intelligent...  but it gets the job done
   for now without much overhead in making it's decision. */
/* todo: come up with optimized scheme for flushing contexts */
unsigned long get_free_context(struct mm_struct *mm)
{
	unsigned long new = 1;
	static unsigned char next_to_die = 1;

	if(!ctx_avail) {
		/* kill someone to get our context */
		new = next_to_die;
		clear_context(new);
		next_to_die = (next_to_die + 1) & 0x7;
		if(!next_to_die)
			next_to_die++;
	} else {
		while(new < CONTEXTS_NUM) {
			if(ctx_alloc[new])
				new++;
			else
				break;
		}
		// check to make sure one was really free...
		if(new == CONTEXTS_NUM)
			panic("get_free_context: failed to find free context");
	}

	ctx_alloc[new] = mm;
	ctx_avail--;

	return new;
}

/*
 * Dynamically select a `spare' PMEG and use it to map virtual `vaddr' in
 * `context'. Maintain internal PMEG management structures. This doesn't
 * actually map the physical address, but does clear the old mappings.
 */
//todo: better allocation scheme? but is extra complexity worthwhile?
//todo: only clear old entries if necessary? how to tell?

inline void mmu_emu_map_pmeg (int context, int vaddr)
{
	static unsigned char curr_pmeg = 128;
	int i;

	/* Round address to PMEG boundary. */
	vaddr &= ~SUN3_PMEG_MASK;

	/* Find a spare one. */
	while (pmeg_alloc[curr_pmeg] == 2)
		++curr_pmeg;


#ifdef DEBUG_MMU_EMU
	pr_info("mmu_emu_map_pmeg: pmeg %x to context %d vaddr %x\n",
		curr_pmeg, context, vaddr);
#endif

	/* Invalidate old mapping for the pmeg, if any */
	if (pmeg_alloc[curr_pmeg] == 1) {
		sun3_put_context(pmeg_ctx[curr_pmeg]);
		sun3_put_segmap (pmeg_vaddr[curr_pmeg], SUN3_INVALID_PMEG);
		sun3_put_context(context);
	}

	/* Update PMEG management structures. */
	// don't take pmeg's away from the kernel...
	if(vaddr >= PAGE_OFFSET) {
		/* map kernel pmegs into all contexts */
		unsigned char i;

		for(i = 0; i < CONTEXTS_NUM; i++) {
			sun3_put_context(i);
			sun3_put_segmap (vaddr, curr_pmeg);
		}
		sun3_put_context(context);
		pmeg_alloc[curr_pmeg] = 2;
		pmeg_ctx[curr_pmeg] = 0;

	}
	else {
		pmeg_alloc[curr_pmeg] = 1;
		pmeg_ctx[curr_pmeg] = context;
		sun3_put_segmap (vaddr, curr_pmeg);

	}
	pmeg_vaddr[curr_pmeg] = vaddr;

	/* Set hardware mapping and clear the old PTE entries. */
	for (i=0; i<SUN3_PMEG_SIZE; i+=SUN3_PTE_SIZE)
		sun3_put_pte (vaddr + i, SUN3_PAGE_SYSTEM);

	/* Consider a different one next time. */
	++curr_pmeg;
}

/*
 * Handle a pagefault at virtual address `vaddr'; check if there should be a
 * page there (specifically, whether the software pagetables indicate that
 * there is). This is necessary due to the limited size of the second-level
 * Sun3 hardware pagetables (256 groups of 16 pages). If there should be a
 * mapping present, we select a `spare' PMEG and use it to create a mapping.
 * `read_flag' is nonzero for a read fault; zero for a write. Returns nonzero
 * if we successfully handled the fault.
 */
//todo: should we bump minor pagefault counter? if so, here or in caller?
//todo: possibly inline this into bus_error030 in <asm/buserror.h> ?

// kernel_fault is set when a kernel page couldn't be demand mapped,
// and forces another try using the kernel page table.  basically a
// hack so that vmalloc would work correctly.

int mmu_emu_handle_fault (unsigned long vaddr, int read_flag, int kernel_fault)
{
	unsigned long segment, offset;
	unsigned char context;
	pte_t *pte;
	pgd_t * crp;

	if(current->mm == NULL) {
		crp = swapper_pg_dir;
		context = 0;
	} else {
		context = current->mm->context;
		if(kernel_fault)
			crp = swapper_pg_dir;
		else
			crp = current->mm->pgd;
	}

#ifdef DEBUG_MMU_EMU
	pr_info("mmu_emu_handle_fault: vaddr=%lx type=%s crp=%p\n",
		vaddr, read_flag ? "read" : "write", crp);
#endif

	segment = (vaddr >> SUN3_PMEG_SIZE_BITS) & 0x7FF;
	offset  = (vaddr >> SUN3_PTE_SIZE_BITS) & 0xF;

#ifdef DEBUG_MMU_EMU
	pr_info("mmu_emu_handle_fault: segment=%lx offset=%lx\n", segment,
		offset);
#endif

	pte = (pte_t *) pgd_val (*(crp + segment));

//todo: next line should check for valid pmd properly.
	if (!pte) {
//                pr_info("mmu_emu_handle_fault: invalid pmd\n");
                return 0;
        }

	pte = (pte_t *) __va ((unsigned long)(pte + offset));

	/* Make sure this is a valid page */
	if (!(pte_val (*pte) & SUN3_PAGE_VALID))
		return 0;

	/* Make sure there's a pmeg allocated for the page */
	if (sun3_get_segmap (vaddr&~SUN3_PMEG_MASK) == SUN3_INVALID_PMEG)
		mmu_emu_map_pmeg (context, vaddr);

	/* Write the pte value to hardware MMU */
	sun3_put_pte (vaddr&PAGE_MASK, pte_val (*pte));

	/* Update software copy of the pte value */
// I'm not sure this is necessary. If this is required, we ought to simply
// copy this out when we reuse the PMEG or at some other convenient time.
// Doing it here is fairly meaningless, anyway, as we only know about the
// first access to a given page. --m
	if (!read_flag) {
		if (pte_val (*pte) & SUN3_PAGE_WRITEABLE)
			pte_val (*pte) |= (SUN3_PAGE_ACCESSED
					   | SUN3_PAGE_MODIFIED);
		else
			return 0;	/* Write-protect error. */
	} else
		pte_val (*pte) |= SUN3_PAGE_ACCESSED;

#ifdef DEBUG_MMU_EMU
	pr_info("seg:%ld crp:%p ->", get_fs().seg, crp);
	print_pte_vaddr (vaddr);
	pr_cont("\n");
#endif

	return 1;
}