mmu_emu.rar_V2

/* ** 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/bootmem.h> #include <linux/bitops.h> #include <linux/module.h> #include <asm/setup.h> #include <asm/traps.h> #include <asm/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); printk (" pte=%lx [addr=%lx", val, (val & SUN3_PAGE_PGNUM_MASK) << PAGE_SHIFT); if (val & SUN3_PAGE_VALID) printk (" valid"); if (val & SUN3_PAGE_WRITEABLE) printk (" write"); if (val & SUN3_PAGE_SYSTEM) printk (" sys"); if (val & SUN3_PAGE_NOCACHE) printk (" nocache"); if (val & SUN3_PAGE_ACCESSED) printk (" accessed"); if (val & SUN3_PAGE_MODIFIED) printk (" modified"); switch (val & SUN3_PAGE_TYPE_MASK) { case SUN3_PAGE_TYPE_MEMORY: printk (" memory"); break; case SUN3_PAGE_TYPE_IO: printk (" io"); break; case SUN3_PAGE_TYPE_VME16: printk (" vme16"); break; case SUN3_PAGE_TYPE_VME32: printk (" vme32"); break; } printk ("]\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; } printk (" 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) { printk (" 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 printk("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++) { printk ("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