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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/m68k/sun3/mmu_emu.c
downloadconfigs-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/m68k/sun3/mmu_emu.c')
-rw-r--r--arch/m68k/sun3/mmu_emu.c427
1 files changed, 427 insertions, 0 deletions
diff --git a/arch/m68k/sun3/mmu_emu.c b/arch/m68k/sun3/mmu_emu.c
new file mode 100644
index 00000000000..7a0e3a22068
--- /dev/null
+++ b/arch/m68k/sun3/mmu_emu.c
@@ -0,0 +1,427 @@
+/*
+** Tablewalk MMU emulator
+**
+** by Toshiyasu Morita
+**
+** Started 1/16/98 @ 2:22 am
+*/
+
+#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/system.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>
+
+extern void prom_reboot (char *) __attribute__ ((__noreturn__));
+
+#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 vmalloc_end;
+EXPORT_SYMBOL(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 */
+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 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(!vmalloc_end)
+ 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 intellegent... 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
+printk("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
+ printk ("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
+ printk ("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) {
+// printk ("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
+ printk ("seg:%d crp:%p ->", get_fs().seg, crp);
+ print_pte_vaddr (vaddr);
+ printk ("\n");
+#endif
+
+ return 1;
+}