2 ** Tablewalk MMU emulator
6 ** Started 1/16/98 @ 2:22 am
9 #include <linux/mman.h>
11 #include <linux/kernel.h>
12 #include <linux/ptrace.h>
13 #include <linux/delay.h>
14 #include <linux/bootmem.h>
15 #include <linux/bitops.h>
16 #include <linux/module.h>
18 #include <asm/setup.h>
19 #include <asm/traps.h>
20 #include <asm/uaccess.h>
22 #include <asm/pgtable.h>
23 #include <asm/sun3mmu.h>
24 #include <asm/segment.h>
25 #include <asm/oplib.h>
26 #include <asm/mmu_context.h>
31 #define DEBUG_PROM_MAPS
37 #define CONTEXTS_NUM 8
38 #define SEGMAPS_PER_CONTEXT_NUM 2048
39 #define PAGES_PER_SEGMENT 16
41 #define PMEG_MASK 0xFF
47 unsigned long m68k_vmalloc_end
;
48 EXPORT_SYMBOL(m68k_vmalloc_end
);
50 unsigned long pmeg_vaddr
[PMEGS_NUM
];
51 unsigned char pmeg_alloc
[PMEGS_NUM
];
52 unsigned char pmeg_ctx
[PMEGS_NUM
];
54 /* pointers to the mm structs for each task in each
55 context. 0xffffffff is a marker for kernel context */
56 static struct mm_struct
*ctx_alloc
[CONTEXTS_NUM
] = {
57 [0] = (struct mm_struct
*)0xffffffff
60 /* has this context been mmdrop'd? */
61 static unsigned char ctx_avail
= CONTEXTS_NUM
-1;
63 /* array of pages to be marked off for the rom when we do mem_init later */
64 /* 256 pages lets the rom take up to 2mb of physical ram.. I really
65 hope it never wants mote than that. */
66 unsigned long rom_pages
[256];
68 /* Print a PTE value in symbolic form. For debugging. */
69 void print_pte (pte_t pte
)
72 /* Verbose version. */
73 unsigned long val
= pte_val (pte
);
74 printk (" pte=%lx [addr=%lx",
75 val
, (val
& SUN3_PAGE_PGNUM_MASK
) << PAGE_SHIFT
);
76 if (val
& SUN3_PAGE_VALID
) printk (" valid");
77 if (val
& SUN3_PAGE_WRITEABLE
) printk (" write");
78 if (val
& SUN3_PAGE_SYSTEM
) printk (" sys");
79 if (val
& SUN3_PAGE_NOCACHE
) printk (" nocache");
80 if (val
& SUN3_PAGE_ACCESSED
) printk (" accessed");
81 if (val
& SUN3_PAGE_MODIFIED
) printk (" modified");
82 switch (val
& SUN3_PAGE_TYPE_MASK
) {
83 case SUN3_PAGE_TYPE_MEMORY
: printk (" memory"); break;
84 case SUN3_PAGE_TYPE_IO
: printk (" io"); break;
85 case SUN3_PAGE_TYPE_VME16
: printk (" vme16"); break;
86 case SUN3_PAGE_TYPE_VME32
: printk (" vme32"); break;
90 /* Terse version. More likely to fit on a line. */
91 unsigned long val
= pte_val (pte
);
94 flags
[0] = (val
& SUN3_PAGE_VALID
) ? 'v' : '-';
95 flags
[1] = (val
& SUN3_PAGE_WRITEABLE
) ? 'w' : '-';
96 flags
[2] = (val
& SUN3_PAGE_SYSTEM
) ? 's' : '-';
97 flags
[3] = (val
& SUN3_PAGE_NOCACHE
) ? 'x' : '-';
98 flags
[4] = (val
& SUN3_PAGE_ACCESSED
) ? 'a' : '-';
99 flags
[5] = (val
& SUN3_PAGE_MODIFIED
) ? 'm' : '-';
102 switch (val
& SUN3_PAGE_TYPE_MASK
) {
103 case SUN3_PAGE_TYPE_MEMORY
: type
= "memory"; break;
104 case SUN3_PAGE_TYPE_IO
: type
= "io" ; break;
105 case SUN3_PAGE_TYPE_VME16
: type
= "vme16" ; break;
106 case SUN3_PAGE_TYPE_VME32
: type
= "vme32" ; break;
107 default: type
= "unknown?"; break;
110 printk (" pte=%08lx [%07lx %s %s]\n",
111 val
, (val
& SUN3_PAGE_PGNUM_MASK
) << PAGE_SHIFT
, flags
, type
);
115 /* Print the PTE value for a given virtual address. For debugging. */
116 void print_pte_vaddr (unsigned long vaddr
)
118 printk (" vaddr=%lx [%02lx]", vaddr
, sun3_get_segmap (vaddr
));
119 print_pte (__pte (sun3_get_pte (vaddr
)));
123 * Initialise the MMU emulator.
125 void mmu_emu_init(unsigned long bootmem_end
)
127 unsigned long seg
, num
;
130 memset(rom_pages
, 0, sizeof(rom_pages
));
131 memset(pmeg_vaddr
, 0, sizeof(pmeg_vaddr
));
132 memset(pmeg_alloc
, 0, sizeof(pmeg_alloc
));
133 memset(pmeg_ctx
, 0, sizeof(pmeg_ctx
));
135 /* pmeg align the end of bootmem, adding another pmeg,
136 * later bootmem allocations will likely need it */
137 bootmem_end
= (bootmem_end
+ (2 * SUN3_PMEG_SIZE
)) & ~SUN3_PMEG_MASK
;
139 /* mark all of the pmegs used thus far as reserved */
140 for (i
=0; i
< __pa(bootmem_end
) / SUN3_PMEG_SIZE
; ++i
)
144 /* I'm thinking that most of the top pmeg's are going to be
145 used for something, and we probably shouldn't risk it */
146 for(num
= 0xf0; num
<= 0xff; num
++)
149 /* liberate all existing mappings in the rest of kernel space */
150 for(seg
= bootmem_end
; seg
< 0x0f800000; seg
+= SUN3_PMEG_SIZE
) {
151 i
= sun3_get_segmap(seg
);
156 print_pte_vaddr (seg
);
158 sun3_put_segmap(seg
, SUN3_INVALID_PMEG
);
163 for (num
=0, seg
=0x0F800000; seg
<0x10000000; seg
+=16*PAGE_SIZE
) {
164 if (sun3_get_segmap (seg
) != SUN3_INVALID_PMEG
) {
165 #ifdef DEBUG_PROM_MAPS
166 for(i
= 0; i
< 16; i
++) {
168 print_pte_vaddr (seg
+ (i
*PAGE_SIZE
));
172 // the lowest mapping here is the end of our
174 if (!m68k_vmalloc_end
)
175 m68k_vmalloc_end
= seg
;
177 // mark the segmap alloc'd, and reserve any
178 // of the first 0xbff pages the hardware is
179 // already using... does any sun3 support > 24mb?
180 pmeg_alloc
[sun3_get_segmap(seg
)] = 2;
187 /* blank everything below the kernel, and we've got the base
188 mapping to start all the contexts off with... */
189 for(seg
= 0; seg
< PAGE_OFFSET
; seg
+= SUN3_PMEG_SIZE
)
190 sun3_put_segmap(seg
, SUN3_INVALID_PMEG
);
192 set_fs(MAKE_MM_SEG(3));
193 for(seg
= 0; seg
< 0x10000000; seg
+= SUN3_PMEG_SIZE
) {
194 i
= sun3_get_segmap(seg
);
195 for(j
= 1; j
< CONTEXTS_NUM
; j
++)
196 (*(romvec
->pv_setctxt
))(j
, (void *)seg
, i
);
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 */
207 void clear_context(unsigned long context
)
209 unsigned char oldctx
;
213 if(!ctx_alloc
[context
])
214 panic("clear_context: context not allocated\n");
216 ctx_alloc
[context
]->context
= SUN3_INVALID_CONTEXT
;
217 ctx_alloc
[context
] = (struct mm_struct
*)0;
221 oldctx
= sun3_get_context();
223 sun3_put_context(context
);
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
);
234 sun3_put_context(oldctx
);
237 /* gets an empty context. if full, kills the next context listed to
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 */
243 unsigned long get_free_context(struct mm_struct
*mm
)
245 unsigned long new = 1;
246 static unsigned char next_to_die
= 1;
249 /* kill someone to get our context */
252 next_to_die
= (next_to_die
+ 1) & 0x7;
256 while(new < CONTEXTS_NUM
) {
262 // check to make sure one was really free...
263 if(new == CONTEXTS_NUM
)
264 panic("get_free_context: failed to find free context");
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.
278 //todo: better allocation scheme? but is extra complexity worthwhile?
279 //todo: only clear old entries if necessary? how to tell?
281 inline void mmu_emu_map_pmeg (int context
, int vaddr
)
283 static unsigned char curr_pmeg
= 128;
286 /* Round address to PMEG boundary. */
287 vaddr
&= ~SUN3_PMEG_MASK
;
289 /* Find a spare one. */
290 while (pmeg_alloc
[curr_pmeg
] == 2)
295 printk("mmu_emu_map_pmeg: pmeg %x to context %d vaddr %x\n",
296 curr_pmeg
, context
, vaddr
);
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
);
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 */
312 for(i
= 0; i
< CONTEXTS_NUM
; i
++) {
314 sun3_put_segmap (vaddr
, curr_pmeg
);
316 sun3_put_context(context
);
317 pmeg_alloc
[curr_pmeg
] = 2;
318 pmeg_ctx
[curr_pmeg
] = 0;
322 pmeg_alloc
[curr_pmeg
] = 1;
323 pmeg_ctx
[curr_pmeg
] = context
;
324 sun3_put_segmap (vaddr
, curr_pmeg
);
327 pmeg_vaddr
[curr_pmeg
] = vaddr
;
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
);
333 /* Consider a different one next time. */
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.
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> ?
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.
353 int mmu_emu_handle_fault (unsigned long vaddr
, int read_flag
, int kernel_fault
)
355 unsigned long segment
, offset
;
356 unsigned char context
;
360 if(current
->mm
== NULL
) {
361 crp
= swapper_pg_dir
;
364 context
= current
->mm
->context
;
366 crp
= swapper_pg_dir
;
368 crp
= current
->mm
->pgd
;
372 printk ("mmu_emu_handle_fault: vaddr=%lx type=%s crp=%p\n",
373 vaddr
, read_flag
? "read" : "write", crp
);
376 segment
= (vaddr
>> SUN3_PMEG_SIZE_BITS
) & 0x7FF;
377 offset
= (vaddr
>> SUN3_PTE_SIZE_BITS
) & 0xF;
380 printk ("mmu_emu_handle_fault: segment=%lx offset=%lx\n", segment
, offset
);
383 pte
= (pte_t
*) pgd_val (*(crp
+ segment
));
385 //todo: next line should check for valid pmd properly.
387 // printk ("mmu_emu_handle_fault: invalid pmd\n");
391 pte
= (pte_t
*) __va ((unsigned long)(pte
+ offset
));
393 /* Make sure this is a valid page */
394 if (!(pte_val (*pte
) & SUN3_PAGE_VALID
))
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
);
401 /* Write the pte value to hardware MMU */
402 sun3_put_pte (vaddr
&PAGE_MASK
, pte_val (*pte
));
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
410 if (pte_val (*pte
) & SUN3_PAGE_WRITEABLE
)
411 pte_val (*pte
) |= (SUN3_PAGE_ACCESSED
412 | SUN3_PAGE_MODIFIED
);
414 return 0; /* Write-protect error. */
416 pte_val (*pte
) |= SUN3_PAGE_ACCESSED
;
419 printk ("seg:%d crp:%p ->", get_fs().seg
, crp
);
420 print_pte_vaddr (vaddr
);