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1// SPDX-License-Identifier: GPL-2.0
2/*
3** Tablewalk MMU emulator
4**
5** by Toshiyasu Morita
6**
7** Started 1/16/98 @ 2:22 am
8*/
9
10#include <linux/init.h>
11#include <linux/mman.h>
12#include <linux/mm.h>
13#include <linux/kernel.h>
14#include <linux/ptrace.h>
15#include <linux/delay.h>
16#include <linux/memblock.h>
17#include <linux/bitops.h>
18#include <linux/module.h>
19#include <linux/sched/mm.h>
20
21#include <asm/setup.h>
22#include <asm/traps.h>
23#include <linux/uaccess.h>
24#include <asm/page.h>
25#include <asm/sun3mmu.h>
26#include <asm/oplib.h>
27#include <asm/mmu_context.h>
28#include <asm/dvma.h>
29
30
31#undef DEBUG_MMU_EMU
32#define DEBUG_PROM_MAPS
33
34/*
35** Defines
36*/
37
38#define CONTEXTS_NUM 8
39#define SEGMAPS_PER_CONTEXT_NUM 2048
40#define PAGES_PER_SEGMENT 16
41#define PMEGS_NUM 256
42#define PMEG_MASK 0xFF
43
44/*
45** Globals
46*/
47
48unsigned long m68k_vmalloc_end;
49EXPORT_SYMBOL(m68k_vmalloc_end);
50
51unsigned long pmeg_vaddr[PMEGS_NUM];
52unsigned char pmeg_alloc[PMEGS_NUM];
53unsigned char pmeg_ctx[PMEGS_NUM];
54
55/* pointers to the mm structs for each task in each
56 context. 0xffffffff is a marker for kernel context */
57static struct mm_struct *ctx_alloc[CONTEXTS_NUM] = {
58 [0] = (struct mm_struct *)0xffffffff
59};
60
61/* has this context been mmdrop'd? */
62static unsigned char ctx_avail = CONTEXTS_NUM-1;
63
64/* array of pages to be marked off for the rom when we do mem_init later */
65/* 256 pages lets the rom take up to 2mb of physical ram.. I really
66 hope it never wants mote than that. */
67unsigned long rom_pages[256];
68
69/* Print a PTE value in symbolic form. For debugging. */
70void print_pte (pte_t pte)
71{
72#if 0
73 /* Verbose version. */
74 unsigned long val = pte_val (pte);
75 pr_cont(" pte=%lx [addr=%lx",
76 val, (val & SUN3_PAGE_PGNUM_MASK) << PAGE_SHIFT);
77 if (val & SUN3_PAGE_VALID) pr_cont(" valid");
78 if (val & SUN3_PAGE_WRITEABLE) pr_cont(" write");
79 if (val & SUN3_PAGE_SYSTEM) pr_cont(" sys");
80 if (val & SUN3_PAGE_NOCACHE) pr_cont(" nocache");
81 if (val & SUN3_PAGE_ACCESSED) pr_cont(" accessed");
82 if (val & SUN3_PAGE_MODIFIED) pr_cont(" modified");
83 switch (val & SUN3_PAGE_TYPE_MASK) {
84 case SUN3_PAGE_TYPE_MEMORY: pr_cont(" memory"); break;
85 case SUN3_PAGE_TYPE_IO: pr_cont(" io"); break;
86 case SUN3_PAGE_TYPE_VME16: pr_cont(" vme16"); break;
87 case SUN3_PAGE_TYPE_VME32: pr_cont(" vme32"); break;
88 }
89 pr_cont("]\n");
90#else
91 /* Terse version. More likely to fit on a line. */
92 unsigned long val = pte_val (pte);
93 char flags[7], *type;
94
95 flags[0] = (val & SUN3_PAGE_VALID) ? 'v' : '-';
96 flags[1] = (val & SUN3_PAGE_WRITEABLE) ? 'w' : '-';
97 flags[2] = (val & SUN3_PAGE_SYSTEM) ? 's' : '-';
98 flags[3] = (val & SUN3_PAGE_NOCACHE) ? 'x' : '-';
99 flags[4] = (val & SUN3_PAGE_ACCESSED) ? 'a' : '-';
100 flags[5] = (val & SUN3_PAGE_MODIFIED) ? 'm' : '-';
101 flags[6] = '\0';
102
103 switch (val & SUN3_PAGE_TYPE_MASK) {
104 case SUN3_PAGE_TYPE_MEMORY: type = "memory"; break;
105 case SUN3_PAGE_TYPE_IO: type = "io" ; break;
106 case SUN3_PAGE_TYPE_VME16: type = "vme16" ; break;
107 case SUN3_PAGE_TYPE_VME32: type = "vme32" ; break;
108 default: type = "unknown?"; break;
109 }
110
111 pr_cont(" pte=%08lx [%07lx %s %s]\n",
112 val, (val & SUN3_PAGE_PGNUM_MASK) << PAGE_SHIFT, flags, type);
113#endif
114}
115
116/* Print the PTE value for a given virtual address. For debugging. */
117void print_pte_vaddr (unsigned long vaddr)
118{
119 pr_cont(" vaddr=%lx [%02lx]", vaddr, sun3_get_segmap (vaddr));
120 print_pte (__pte (sun3_get_pte (vaddr)));
121}
122
123/*
124 * Initialise the MMU emulator.
125 */
126void __init mmu_emu_init(unsigned long bootmem_end)
127{
128 unsigned long seg, num;
129 int i,j;
130
131 memset(rom_pages, 0, sizeof(rom_pages));
132 memset(pmeg_vaddr, 0, sizeof(pmeg_vaddr));
133 memset(pmeg_alloc, 0, sizeof(pmeg_alloc));
134 memset(pmeg_ctx, 0, sizeof(pmeg_ctx));
135
136 /* pmeg align the end of bootmem, adding another pmeg,
137 * later bootmem allocations will likely need it */
138 bootmem_end = (bootmem_end + (2 * SUN3_PMEG_SIZE)) & ~SUN3_PMEG_MASK;
139
140 /* mark all of the pmegs used thus far as reserved */
141 for (i=0; i < __pa(bootmem_end) / SUN3_PMEG_SIZE ; ++i)
142 pmeg_alloc[i] = 2;
143
144
145 /* I'm thinking that most of the top pmeg's are going to be
146 used for something, and we probably shouldn't risk it */
147 for(num = 0xf0; num <= 0xff; num++)
148 pmeg_alloc[num] = 2;
149
150 /* liberate all existing mappings in the rest of kernel space */
151 for(seg = bootmem_end; seg < 0x0f800000; seg += SUN3_PMEG_SIZE) {
152 i = sun3_get_segmap(seg);
153
154 if(!pmeg_alloc[i]) {
155#ifdef DEBUG_MMU_EMU
156 pr_info("freed:");
157 print_pte_vaddr (seg);
158#endif
159 sun3_put_segmap(seg, SUN3_INVALID_PMEG);
160 }
161 }
162
163 j = 0;
164 for (num=0, seg=0x0F800000; seg<0x10000000; seg+=16*PAGE_SIZE) {
165 if (sun3_get_segmap (seg) != SUN3_INVALID_PMEG) {
166#ifdef DEBUG_PROM_MAPS
167 for(i = 0; i < 16; i++) {
168 pr_info("mapped:");
169 print_pte_vaddr (seg + (i*PAGE_SIZE));
170 break;
171 }
172#endif
173 // the lowest mapping here is the end of our
174 // vmalloc region
175 if (!m68k_vmalloc_end)
176 m68k_vmalloc_end = seg;
177
178 // mark the segmap alloc'd, and reserve any
179 // of the first 0xbff pages the hardware is
180 // already using... does any sun3 support > 24mb?
181 pmeg_alloc[sun3_get_segmap(seg)] = 2;
182 }
183 }
184
185 dvma_init();
186
187
188 /* blank everything below the kernel, and we've got the base
189 mapping to start all the contexts off with... */
190 for(seg = 0; seg < PAGE_OFFSET; seg += SUN3_PMEG_SIZE)
191 sun3_put_segmap(seg, SUN3_INVALID_PMEG);
192
193 set_fc(3);
194 for(seg = 0; seg < 0x10000000; seg += SUN3_PMEG_SIZE) {
195 i = sun3_get_segmap(seg);
196 for(j = 1; j < CONTEXTS_NUM; j++)
197 (*(romvec->pv_setctxt))(j, (void *)seg, i);
198 }
199 set_fc(USER_DATA);
200}
201
202/* erase the mappings for a dead context. Uses the pg_dir for hints
203 as the pmeg tables proved somewhat unreliable, and unmapping all of
204 TASK_SIZE was much slower and no more stable. */
205/* todo: find a better way to keep track of the pmegs used by a
206 context for when they're cleared */
207void clear_context(unsigned long context)
208{
209 unsigned char oldctx;
210 unsigned long i;
211
212 if(context) {
213 if(!ctx_alloc[context])
214 panic("%s: context not allocated\n", __func__);
215
216 ctx_alloc[context]->context = SUN3_INVALID_CONTEXT;
217 ctx_alloc[context] = (struct mm_struct *)0;
218 ctx_avail++;
219 }
220
221 oldctx = sun3_get_context();
222
223 sun3_put_context(context);
224
225 for(i = 0; i < SUN3_INVALID_PMEG; i++) {
226 if((pmeg_ctx[i] == context) && (pmeg_alloc[i] == 1)) {
227 sun3_put_segmap(pmeg_vaddr[i], SUN3_INVALID_PMEG);
228 pmeg_ctx[i] = 0;
229 pmeg_alloc[i] = 0;
230 pmeg_vaddr[i] = 0;
231 }
232 }
233
234 sun3_put_context(oldctx);
235}
236
237/* gets an empty context. if full, kills the next context listed to
238 die first */
239/* This context invalidation scheme is, well, totally arbitrary, I'm
240 sure it could be much more intelligent... but it gets the job done
241 for now without much overhead in making it's decision. */
242/* todo: come up with optimized scheme for flushing contexts */
243unsigned long get_free_context(struct mm_struct *mm)
244{
245 unsigned long new = 1;
246 static unsigned char next_to_die = 1;
247
248 if(!ctx_avail) {
249 /* kill someone to get our context */
250 new = next_to_die;
251 clear_context(new);
252 next_to_die = (next_to_die + 1) & 0x7;
253 if(!next_to_die)
254 next_to_die++;
255 } else {
256 while(new < CONTEXTS_NUM) {
257 if(ctx_alloc[new])
258 new++;
259 else
260 break;
261 }
262 // check to make sure one was really free...
263 if(new == CONTEXTS_NUM)
264 panic("%s: failed to find free context", __func__);
265 }
266
267 ctx_alloc[new] = mm;
268 ctx_avail--;
269
270 return new;
271}
272
273/*
274 * Dynamically select a `spare' PMEG and use it to map virtual `vaddr' in
275 * `context'. Maintain internal PMEG management structures. This doesn't
276 * actually map the physical address, but does clear the old mappings.
277 */
278//todo: better allocation scheme? but is extra complexity worthwhile?
279//todo: only clear old entries if necessary? how to tell?
280
281inline void mmu_emu_map_pmeg (int context, int vaddr)
282{
283 static unsigned char curr_pmeg = 128;
284 int i;
285
286 /* Round address to PMEG boundary. */
287 vaddr &= ~SUN3_PMEG_MASK;
288
289 /* Find a spare one. */
290 while (pmeg_alloc[curr_pmeg] == 2)
291 ++curr_pmeg;
292
293
294#ifdef DEBUG_MMU_EMU
295 pr_info("mmu_emu_map_pmeg: pmeg %x to context %d vaddr %x\n",
296 curr_pmeg, context, vaddr);
297#endif
298
299 /* Invalidate old mapping for the pmeg, if any */
300 if (pmeg_alloc[curr_pmeg] == 1) {
301 sun3_put_context(pmeg_ctx[curr_pmeg]);
302 sun3_put_segmap (pmeg_vaddr[curr_pmeg], SUN3_INVALID_PMEG);
303 sun3_put_context(context);
304 }
305
306 /* Update PMEG management structures. */
307 // don't take pmeg's away from the kernel...
308 if(vaddr >= PAGE_OFFSET) {
309 /* map kernel pmegs into all contexts */
310 unsigned char i;
311
312 for(i = 0; i < CONTEXTS_NUM; i++) {
313 sun3_put_context(i);
314 sun3_put_segmap (vaddr, curr_pmeg);
315 }
316 sun3_put_context(context);
317 pmeg_alloc[curr_pmeg] = 2;
318 pmeg_ctx[curr_pmeg] = 0;
319
320 }
321 else {
322 pmeg_alloc[curr_pmeg] = 1;
323 pmeg_ctx[curr_pmeg] = context;
324 sun3_put_segmap (vaddr, curr_pmeg);
325
326 }
327 pmeg_vaddr[curr_pmeg] = vaddr;
328
329 /* Set hardware mapping and clear the old PTE entries. */
330 for (i=0; i<SUN3_PMEG_SIZE; i+=SUN3_PTE_SIZE)
331 sun3_put_pte (vaddr + i, SUN3_PAGE_SYSTEM);
332
333 /* Consider a different one next time. */
334 ++curr_pmeg;
335}
336
337/*
338 * Handle a pagefault at virtual address `vaddr'; check if there should be a
339 * page there (specifically, whether the software pagetables indicate that
340 * there is). This is necessary due to the limited size of the second-level
341 * Sun3 hardware pagetables (256 groups of 16 pages). If there should be a
342 * mapping present, we select a `spare' PMEG and use it to create a mapping.
343 * `read_flag' is nonzero for a read fault; zero for a write. Returns nonzero
344 * if we successfully handled the fault.
345 */
346//todo: should we bump minor pagefault counter? if so, here or in caller?
347//todo: possibly inline this into bus_error030 in <asm/buserror.h> ?
348
349// kernel_fault is set when a kernel page couldn't be demand mapped,
350// and forces another try using the kernel page table. basically a
351// hack so that vmalloc would work correctly.
352
353int mmu_emu_handle_fault (unsigned long vaddr, int read_flag, int kernel_fault)
354{
355 unsigned long segment, offset;
356 unsigned char context;
357 pte_t *pte;
358 pgd_t * crp;
359
360 if(current->mm == NULL) {
361 crp = swapper_pg_dir;
362 context = 0;
363 } else {
364 context = current->mm->context;
365 if(kernel_fault)
366 crp = swapper_pg_dir;
367 else
368 crp = current->mm->pgd;
369 }
370
371#ifdef DEBUG_MMU_EMU
372 pr_info("%s: vaddr=%lx type=%s crp=%p\n", __func__, vaddr,
373 read_flag ? "read" : "write", crp);
374#endif
375
376 segment = (vaddr >> SUN3_PMEG_SIZE_BITS) & 0x7FF;
377 offset = (vaddr >> SUN3_PTE_SIZE_BITS) & 0xF;
378
379#ifdef DEBUG_MMU_EMU
380 pr_info("%s: segment=%lx offset=%lx\n", __func__, segment, offset);
381#endif
382
383 pte = (pte_t *) pgd_val (*(crp + segment));
384
385//todo: next line should check for valid pmd properly.
386 if (!pte) {
387// pr_info("mmu_emu_handle_fault: invalid pmd\n");
388 return 0;
389 }
390
391 pte = (pte_t *) __va ((unsigned long)(pte + offset));
392
393 /* Make sure this is a valid page */
394 if (!(pte_val (*pte) & SUN3_PAGE_VALID))
395 return 0;
396
397 /* Make sure there's a pmeg allocated for the page */
398 if (sun3_get_segmap (vaddr&~SUN3_PMEG_MASK) == SUN3_INVALID_PMEG)
399 mmu_emu_map_pmeg (context, vaddr);
400
401 /* Write the pte value to hardware MMU */
402 sun3_put_pte (vaddr&PAGE_MASK, pte_val (*pte));
403
404 /* Update software copy of the pte value */
405// I'm not sure this is necessary. If this is required, we ought to simply
406// copy this out when we reuse the PMEG or at some other convenient time.
407// Doing it here is fairly meaningless, anyway, as we only know about the
408// first access to a given page. --m
409 if (!read_flag) {
410 if (pte_val (*pte) & SUN3_PAGE_WRITEABLE)
411 pte_val (*pte) |= (SUN3_PAGE_ACCESSED
412 | SUN3_PAGE_MODIFIED);
413 else
414 return 0; /* Write-protect error. */
415 } else
416 pte_val (*pte) |= SUN3_PAGE_ACCESSED;
417
418#ifdef DEBUG_MMU_EMU
419 pr_info("seg:%ld crp:%p ->", get_fs().seg, crp);
420 print_pte_vaddr (vaddr);
421 pr_cont("\n");
422#endif
423
424 return 1;
425}
1// SPDX-License-Identifier: GPL-2.0
2/*
3** Tablewalk MMU emulator
4**
5** by Toshiyasu Morita
6**
7** Started 1/16/98 @ 2:22 am
8*/
9
10#include <linux/init.h>
11#include <linux/mman.h>
12#include <linux/mm.h>
13#include <linux/kernel.h>
14#include <linux/ptrace.h>
15#include <linux/delay.h>
16#include <linux/bootmem.h>
17#include <linux/bitops.h>
18#include <linux/module.h>
19#include <linux/sched/mm.h>
20
21#include <asm/setup.h>
22#include <asm/traps.h>
23#include <linux/uaccess.h>
24#include <asm/page.h>
25#include <asm/pgtable.h>
26#include <asm/sun3mmu.h>
27#include <asm/segment.h>
28#include <asm/oplib.h>
29#include <asm/mmu_context.h>
30#include <asm/dvma.h>
31
32
33#undef DEBUG_MMU_EMU
34#define DEBUG_PROM_MAPS
35
36/*
37** Defines
38*/
39
40#define CONTEXTS_NUM 8
41#define SEGMAPS_PER_CONTEXT_NUM 2048
42#define PAGES_PER_SEGMENT 16
43#define PMEGS_NUM 256
44#define PMEG_MASK 0xFF
45
46/*
47** Globals
48*/
49
50unsigned long m68k_vmalloc_end;
51EXPORT_SYMBOL(m68k_vmalloc_end);
52
53unsigned long pmeg_vaddr[PMEGS_NUM];
54unsigned char pmeg_alloc[PMEGS_NUM];
55unsigned char pmeg_ctx[PMEGS_NUM];
56
57/* pointers to the mm structs for each task in each
58 context. 0xffffffff is a marker for kernel context */
59static struct mm_struct *ctx_alloc[CONTEXTS_NUM] = {
60 [0] = (struct mm_struct *)0xffffffff
61};
62
63/* has this context been mmdrop'd? */
64static unsigned char ctx_avail = CONTEXTS_NUM-1;
65
66/* array of pages to be marked off for the rom when we do mem_init later */
67/* 256 pages lets the rom take up to 2mb of physical ram.. I really
68 hope it never wants mote than that. */
69unsigned long rom_pages[256];
70
71/* Print a PTE value in symbolic form. For debugging. */
72void print_pte (pte_t pte)
73{
74#if 0
75 /* Verbose version. */
76 unsigned long val = pte_val (pte);
77 pr_cont(" pte=%lx [addr=%lx",
78 val, (val & SUN3_PAGE_PGNUM_MASK) << PAGE_SHIFT);
79 if (val & SUN3_PAGE_VALID) pr_cont(" valid");
80 if (val & SUN3_PAGE_WRITEABLE) pr_cont(" write");
81 if (val & SUN3_PAGE_SYSTEM) pr_cont(" sys");
82 if (val & SUN3_PAGE_NOCACHE) pr_cont(" nocache");
83 if (val & SUN3_PAGE_ACCESSED) pr_cont(" accessed");
84 if (val & SUN3_PAGE_MODIFIED) pr_cont(" modified");
85 switch (val & SUN3_PAGE_TYPE_MASK) {
86 case SUN3_PAGE_TYPE_MEMORY: pr_cont(" memory"); break;
87 case SUN3_PAGE_TYPE_IO: pr_cont(" io"); break;
88 case SUN3_PAGE_TYPE_VME16: pr_cont(" vme16"); break;
89 case SUN3_PAGE_TYPE_VME32: pr_cont(" vme32"); break;
90 }
91 pr_cont("]\n");
92#else
93 /* Terse version. More likely to fit on a line. */
94 unsigned long val = pte_val (pte);
95 char flags[7], *type;
96
97 flags[0] = (val & SUN3_PAGE_VALID) ? 'v' : '-';
98 flags[1] = (val & SUN3_PAGE_WRITEABLE) ? 'w' : '-';
99 flags[2] = (val & SUN3_PAGE_SYSTEM) ? 's' : '-';
100 flags[3] = (val & SUN3_PAGE_NOCACHE) ? 'x' : '-';
101 flags[4] = (val & SUN3_PAGE_ACCESSED) ? 'a' : '-';
102 flags[5] = (val & SUN3_PAGE_MODIFIED) ? 'm' : '-';
103 flags[6] = '\0';
104
105 switch (val & SUN3_PAGE_TYPE_MASK) {
106 case SUN3_PAGE_TYPE_MEMORY: type = "memory"; break;
107 case SUN3_PAGE_TYPE_IO: type = "io" ; break;
108 case SUN3_PAGE_TYPE_VME16: type = "vme16" ; break;
109 case SUN3_PAGE_TYPE_VME32: type = "vme32" ; break;
110 default: type = "unknown?"; break;
111 }
112
113 pr_cont(" pte=%08lx [%07lx %s %s]\n",
114 val, (val & SUN3_PAGE_PGNUM_MASK) << PAGE_SHIFT, flags, type);
115#endif
116}
117
118/* Print the PTE value for a given virtual address. For debugging. */
119void print_pte_vaddr (unsigned long vaddr)
120{
121 pr_cont(" vaddr=%lx [%02lx]", vaddr, sun3_get_segmap (vaddr));
122 print_pte (__pte (sun3_get_pte (vaddr)));
123}
124
125/*
126 * Initialise the MMU emulator.
127 */
128void __init mmu_emu_init(unsigned long bootmem_end)
129{
130 unsigned long seg, num;
131 int i,j;
132
133 memset(rom_pages, 0, sizeof(rom_pages));
134 memset(pmeg_vaddr, 0, sizeof(pmeg_vaddr));
135 memset(pmeg_alloc, 0, sizeof(pmeg_alloc));
136 memset(pmeg_ctx, 0, sizeof(pmeg_ctx));
137
138 /* pmeg align the end of bootmem, adding another pmeg,
139 * later bootmem allocations will likely need it */
140 bootmem_end = (bootmem_end + (2 * SUN3_PMEG_SIZE)) & ~SUN3_PMEG_MASK;
141
142 /* mark all of the pmegs used thus far as reserved */
143 for (i=0; i < __pa(bootmem_end) / SUN3_PMEG_SIZE ; ++i)
144 pmeg_alloc[i] = 2;
145
146
147 /* I'm thinking that most of the top pmeg's are going to be
148 used for something, and we probably shouldn't risk it */
149 for(num = 0xf0; num <= 0xff; num++)
150 pmeg_alloc[num] = 2;
151
152 /* liberate all existing mappings in the rest of kernel space */
153 for(seg = bootmem_end; seg < 0x0f800000; seg += SUN3_PMEG_SIZE) {
154 i = sun3_get_segmap(seg);
155
156 if(!pmeg_alloc[i]) {
157#ifdef DEBUG_MMU_EMU
158 pr_info("freed:");
159 print_pte_vaddr (seg);
160#endif
161 sun3_put_segmap(seg, SUN3_INVALID_PMEG);
162 }
163 }
164
165 j = 0;
166 for (num=0, seg=0x0F800000; seg<0x10000000; seg+=16*PAGE_SIZE) {
167 if (sun3_get_segmap (seg) != SUN3_INVALID_PMEG) {
168#ifdef DEBUG_PROM_MAPS
169 for(i = 0; i < 16; i++) {
170 pr_info("mapped:");
171 print_pte_vaddr (seg + (i*PAGE_SIZE));
172 break;
173 }
174#endif
175 // the lowest mapping here is the end of our
176 // vmalloc region
177 if (!m68k_vmalloc_end)
178 m68k_vmalloc_end = seg;
179
180 // mark the segmap alloc'd, and reserve any
181 // of the first 0xbff pages the hardware is
182 // already using... does any sun3 support > 24mb?
183 pmeg_alloc[sun3_get_segmap(seg)] = 2;
184 }
185 }
186
187 dvma_init();
188
189
190 /* blank everything below the kernel, and we've got the base
191 mapping to start all the contexts off with... */
192 for(seg = 0; seg < PAGE_OFFSET; seg += SUN3_PMEG_SIZE)
193 sun3_put_segmap(seg, SUN3_INVALID_PMEG);
194
195 set_fs(MAKE_MM_SEG(3));
196 for(seg = 0; seg < 0x10000000; seg += SUN3_PMEG_SIZE) {
197 i = sun3_get_segmap(seg);
198 for(j = 1; j < CONTEXTS_NUM; j++)
199 (*(romvec->pv_setctxt))(j, (void *)seg, i);
200 }
201 set_fs(KERNEL_DS);
202
203}
204
205/* erase the mappings for a dead context. Uses the pg_dir for hints
206 as the pmeg tables proved somewhat unreliable, and unmapping all of
207 TASK_SIZE was much slower and no more stable. */
208/* todo: find a better way to keep track of the pmegs used by a
209 context for when they're cleared */
210void clear_context(unsigned long context)
211{
212 unsigned char oldctx;
213 unsigned long i;
214
215 if(context) {
216 if(!ctx_alloc[context])
217 panic("clear_context: context not allocated\n");
218
219 ctx_alloc[context]->context = SUN3_INVALID_CONTEXT;
220 ctx_alloc[context] = (struct mm_struct *)0;
221 ctx_avail++;
222 }
223
224 oldctx = sun3_get_context();
225
226 sun3_put_context(context);
227
228 for(i = 0; i < SUN3_INVALID_PMEG; i++) {
229 if((pmeg_ctx[i] == context) && (pmeg_alloc[i] == 1)) {
230 sun3_put_segmap(pmeg_vaddr[i], SUN3_INVALID_PMEG);
231 pmeg_ctx[i] = 0;
232 pmeg_alloc[i] = 0;
233 pmeg_vaddr[i] = 0;
234 }
235 }
236
237 sun3_put_context(oldctx);
238}
239
240/* gets an empty context. if full, kills the next context listed to
241 die first */
242/* This context invalidation scheme is, well, totally arbitrary, I'm
243 sure it could be much more intelligent... but it gets the job done
244 for now without much overhead in making it's decision. */
245/* todo: come up with optimized scheme for flushing contexts */
246unsigned long get_free_context(struct mm_struct *mm)
247{
248 unsigned long new = 1;
249 static unsigned char next_to_die = 1;
250
251 if(!ctx_avail) {
252 /* kill someone to get our context */
253 new = next_to_die;
254 clear_context(new);
255 next_to_die = (next_to_die + 1) & 0x7;
256 if(!next_to_die)
257 next_to_die++;
258 } else {
259 while(new < CONTEXTS_NUM) {
260 if(ctx_alloc[new])
261 new++;
262 else
263 break;
264 }
265 // check to make sure one was really free...
266 if(new == CONTEXTS_NUM)
267 panic("get_free_context: failed to find free context");
268 }
269
270 ctx_alloc[new] = mm;
271 ctx_avail--;
272
273 return new;
274}
275
276/*
277 * Dynamically select a `spare' PMEG and use it to map virtual `vaddr' in
278 * `context'. Maintain internal PMEG management structures. This doesn't
279 * actually map the physical address, but does clear the old mappings.
280 */
281//todo: better allocation scheme? but is extra complexity worthwhile?
282//todo: only clear old entries if necessary? how to tell?
283
284inline void mmu_emu_map_pmeg (int context, int vaddr)
285{
286 static unsigned char curr_pmeg = 128;
287 int i;
288
289 /* Round address to PMEG boundary. */
290 vaddr &= ~SUN3_PMEG_MASK;
291
292 /* Find a spare one. */
293 while (pmeg_alloc[curr_pmeg] == 2)
294 ++curr_pmeg;
295
296
297#ifdef DEBUG_MMU_EMU
298 pr_info("mmu_emu_map_pmeg: pmeg %x to context %d vaddr %x\n",
299 curr_pmeg, context, vaddr);
300#endif
301
302 /* Invalidate old mapping for the pmeg, if any */
303 if (pmeg_alloc[curr_pmeg] == 1) {
304 sun3_put_context(pmeg_ctx[curr_pmeg]);
305 sun3_put_segmap (pmeg_vaddr[curr_pmeg], SUN3_INVALID_PMEG);
306 sun3_put_context(context);
307 }
308
309 /* Update PMEG management structures. */
310 // don't take pmeg's away from the kernel...
311 if(vaddr >= PAGE_OFFSET) {
312 /* map kernel pmegs into all contexts */
313 unsigned char i;
314
315 for(i = 0; i < CONTEXTS_NUM; i++) {
316 sun3_put_context(i);
317 sun3_put_segmap (vaddr, curr_pmeg);
318 }
319 sun3_put_context(context);
320 pmeg_alloc[curr_pmeg] = 2;
321 pmeg_ctx[curr_pmeg] = 0;
322
323 }
324 else {
325 pmeg_alloc[curr_pmeg] = 1;
326 pmeg_ctx[curr_pmeg] = context;
327 sun3_put_segmap (vaddr, curr_pmeg);
328
329 }
330 pmeg_vaddr[curr_pmeg] = vaddr;
331
332 /* Set hardware mapping and clear the old PTE entries. */
333 for (i=0; i<SUN3_PMEG_SIZE; i+=SUN3_PTE_SIZE)
334 sun3_put_pte (vaddr + i, SUN3_PAGE_SYSTEM);
335
336 /* Consider a different one next time. */
337 ++curr_pmeg;
338}
339
340/*
341 * Handle a pagefault at virtual address `vaddr'; check if there should be a
342 * page there (specifically, whether the software pagetables indicate that
343 * there is). This is necessary due to the limited size of the second-level
344 * Sun3 hardware pagetables (256 groups of 16 pages). If there should be a
345 * mapping present, we select a `spare' PMEG and use it to create a mapping.
346 * `read_flag' is nonzero for a read fault; zero for a write. Returns nonzero
347 * if we successfully handled the fault.
348 */
349//todo: should we bump minor pagefault counter? if so, here or in caller?
350//todo: possibly inline this into bus_error030 in <asm/buserror.h> ?
351
352// kernel_fault is set when a kernel page couldn't be demand mapped,
353// and forces another try using the kernel page table. basically a
354// hack so that vmalloc would work correctly.
355
356int mmu_emu_handle_fault (unsigned long vaddr, int read_flag, int kernel_fault)
357{
358 unsigned long segment, offset;
359 unsigned char context;
360 pte_t *pte;
361 pgd_t * crp;
362
363 if(current->mm == NULL) {
364 crp = swapper_pg_dir;
365 context = 0;
366 } else {
367 context = current->mm->context;
368 if(kernel_fault)
369 crp = swapper_pg_dir;
370 else
371 crp = current->mm->pgd;
372 }
373
374#ifdef DEBUG_MMU_EMU
375 pr_info("mmu_emu_handle_fault: vaddr=%lx type=%s crp=%p\n",
376 vaddr, read_flag ? "read" : "write", crp);
377#endif
378
379 segment = (vaddr >> SUN3_PMEG_SIZE_BITS) & 0x7FF;
380 offset = (vaddr >> SUN3_PTE_SIZE_BITS) & 0xF;
381
382#ifdef DEBUG_MMU_EMU
383 pr_info("mmu_emu_handle_fault: segment=%lx offset=%lx\n", segment,
384 offset);
385#endif
386
387 pte = (pte_t *) pgd_val (*(crp + segment));
388
389//todo: next line should check for valid pmd properly.
390 if (!pte) {
391// pr_info("mmu_emu_handle_fault: invalid pmd\n");
392 return 0;
393 }
394
395 pte = (pte_t *) __va ((unsigned long)(pte + offset));
396
397 /* Make sure this is a valid page */
398 if (!(pte_val (*pte) & SUN3_PAGE_VALID))
399 return 0;
400
401 /* Make sure there's a pmeg allocated for the page */
402 if (sun3_get_segmap (vaddr&~SUN3_PMEG_MASK) == SUN3_INVALID_PMEG)
403 mmu_emu_map_pmeg (context, vaddr);
404
405 /* Write the pte value to hardware MMU */
406 sun3_put_pte (vaddr&PAGE_MASK, pte_val (*pte));
407
408 /* Update software copy of the pte value */
409// I'm not sure this is necessary. If this is required, we ought to simply
410// copy this out when we reuse the PMEG or at some other convenient time.
411// Doing it here is fairly meaningless, anyway, as we only know about the
412// first access to a given page. --m
413 if (!read_flag) {
414 if (pte_val (*pte) & SUN3_PAGE_WRITEABLE)
415 pte_val (*pte) |= (SUN3_PAGE_ACCESSED
416 | SUN3_PAGE_MODIFIED);
417 else
418 return 0; /* Write-protect error. */
419 } else
420 pte_val (*pte) |= SUN3_PAGE_ACCESSED;
421
422#ifdef DEBUG_MMU_EMU
423 pr_info("seg:%ld crp:%p ->", get_fs().seg, crp);
424 print_pte_vaddr (vaddr);
425 pr_cont("\n");
426#endif
427
428 return 1;
429}