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