1 files changed, 1295 insertions, 0 deletions

diff --git a/arch/mips/kernel/vpe.c b/arch/mips/kernel/vpe.c
new file mode 100644
index 000000000000..6bf42ba08f09
--- /dev/null
+++ b/arch/mips/kernel/vpe.c
@@ -0,0 +1,1295 @@
+/*
+ * Copyright (C) 2004, 2005 MIPS Technologies, Inc.  All rights reserved.
+ *
+ *  This program is free software; you can distribute it and/or modify it
+ *  under the terms of the GNU General Public License (Version 2) as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ */
+
+/*
+ * VPE support module
+ *
+ * Provides support for loading a MIPS SP program on VPE1.
+ * The SP enviroment is rather simple, no tlb's.  It needs to be relocatable
+ * (or partially linked). You should initialise your stack in the startup
+ * code. This loader looks for the symbol __start and sets up
+ * execution to resume from there. The MIPS SDE kit contains suitable examples.
+ *
+ * To load and run, simply cat a SP 'program file' to /dev/vpe1.
+ * i.e cat spapp >/dev/vpe1.
+ *
+ * You'll need to have the following device files.
+ * mknod /dev/vpe0 c 63 0
+ * mknod /dev/vpe1 c 63 1
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <asm/uaccess.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/vmalloc.h>
+#include <linux/elf.h>
+#include <linux/seq_file.h>
+#include <linux/syscalls.h>
+#include <linux/moduleloader.h>
+#include <linux/interrupt.h>
+#include <linux/poll.h>
+#include <linux/bootmem.h>
+#include <asm/mipsregs.h>
+#include <asm/cacheflush.h>
+#include <asm/atomic.h>
+#include <asm/cpu.h>
+#include <asm/processor.h>
+#include <asm/system.h>
+
+typedef void *vpe_handle;
+
+// defined here because the kernel module loader doesn't have
+// anything to do with it.
+#define SHN_MIPS_SCOMMON 0xff03
+
+#ifndef ARCH_SHF_SMALL
+#define ARCH_SHF_SMALL 0
+#endif
+
+/* If this is set, the section belongs in the init part of the module */
+#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))
+
+// temp number,
+#define VPE_MAJOR 63
+
+static char module_name[] = "vpe";
+static int major = 0;
+
+/* grab the likely amount of memory we will need. */
+#ifdef CONFIG_MIPS_VPE_LOADER_TOM
+#define P_SIZE (2 * 1024 * 1024)
+#else
+/* add an overhead to the max kmalloc size for non-striped symbols/etc */
+#define P_SIZE (256 * 1024)
+#endif
+
+#define MAX_VPES 16
+
+enum vpe_state {
+        VPE_STATE_UNUSED = 0,
+        VPE_STATE_INUSE,
+        VPE_STATE_RUNNING
+};
+
+enum tc_state {
+        TC_STATE_UNUSED = 0,
+        TC_STATE_INUSE,
+        TC_STATE_RUNNING,
+        TC_STATE_DYNAMIC
+};
+
+struct vpe;
+typedef struct tc {
+        enum tc_state state;
+        int index;
+
+        /* parent VPE */
+        struct vpe *pvpe;
+
+        /* The list of TC's with this VPE */
+        struct list_head tc;
+
+        /* The global list of tc's */
+        struct list_head list;
+} tc_t;
+
+typedef struct vpe {
+        enum vpe_state state;
+
+        /* (device) minor associated with this vpe */
+        int minor;
+
+        /* elfloader stuff */
+        void *load_addr;
+        u32 len;
+        char *pbuffer;
+        u32 plen;
+
+        unsigned long __start;
+
+        /* tc's associated with this vpe */
+        struct list_head tc;
+
+        /* The list of vpe's */
+        struct list_head list;
+
+        /* shared symbol address */
+        void *shared_ptr;
+} vpe_t;
+
+struct vpecontrol_ {
+        /* Virtual processing elements */
+        struct list_head vpe_list;
+
+        /* Thread contexts */
+        struct list_head tc_list;
+} vpecontrol;
+
+static void release_progmem(void *ptr);
+static void dump_vpe(vpe_t * v);
+extern void save_gp_address(unsigned int secbase, unsigned int rel);
+
+/* get the vpe associated with this minor */
+struct vpe *get_vpe(int minor)
+{
+        struct vpe *v;
+
+        list_for_each_entry(v, &vpecontrol.vpe_list, list) {
+                if (v->minor == minor)
+                        return v;
+        }
+
+        printk(KERN_DEBUG "VPE: get_vpe minor %d not found\n", minor);
+        return NULL;
+}
+
+/* get the vpe associated with this minor */
+struct tc *get_tc(int index)
+{
+        struct tc *t;
+
+        list_for_each_entry(t, &vpecontrol.tc_list, list) {
+                if (t->index == index)
+                        return t;
+        }
+
+        printk(KERN_DEBUG "VPE: get_tc index %d not found\n", index);
+
+        return NULL;
+}
+
+struct tc *get_tc_unused(void)
+{
+        struct tc *t;
+
+        list_for_each_entry(t, &vpecontrol.tc_list, list) {
+                if (t->state == TC_STATE_UNUSED)
+                        return t;
+        }
+
+        printk(KERN_DEBUG "VPE: All TC's are in use\n");
+
+        return NULL;
+}
+
+/* allocate a vpe and associate it with this minor (or index) */
+struct vpe *alloc_vpe(int minor)
+{
+        struct vpe *v;
+
+        if ((v = kmalloc(sizeof(struct vpe), GFP_KERNEL)) == NULL) {
+                printk(KERN_WARNING "VPE: alloc_vpe no mem\n");
+                return NULL;
+        }
+
+        memset(v, 0, sizeof(struct vpe));
+
+        INIT_LIST_HEAD(&v->tc);
+        list_add_tail(&v->list, &vpecontrol.vpe_list);
+
+        v->minor = minor;
+        return v;
+}
+
+/* allocate a tc. At startup only tc0 is running, all other can be halted. */
+struct tc *alloc_tc(int index)
+{
+        struct tc *t;
+
+        if ((t = kmalloc(sizeof(struct tc), GFP_KERNEL)) == NULL) {
+                printk(KERN_WARNING "VPE: alloc_tc no mem\n");
+                return NULL;
+        }
+
+        memset(t, 0, sizeof(struct tc));
+
+        INIT_LIST_HEAD(&t->tc);
+        list_add_tail(&t->list, &vpecontrol.tc_list);
+
+        t->index = index;
+
+        return t;
+}
+
+/* clean up and free everything */
+void release_vpe(struct vpe *v)
+{
+        list_del(&v->list);
+        if (v->load_addr)
+                release_progmem(v);
+        kfree(v);
+}
+
+void dump_mtregs(void)
+{
+        unsigned long val;
+
+        val = read_c0_config3();
+        printk("config3 0x%lx MT %ld\n", val,
+               (val & CONFIG3_MT) >> CONFIG3_MT_SHIFT);
+
+        val = read_c0_mvpconf0();
+        printk("mvpconf0 0x%lx, PVPE %ld PTC %ld M %ld\n", val,
+               (val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT,
+               val & MVPCONF0_PTC, (val & MVPCONF0_M) >> MVPCONF0_M_SHIFT);
+
+        val = read_c0_mvpcontrol();
+        printk("MVPControl 0x%lx, STLB %ld VPC %ld EVP %ld\n", val,
+               (val & MVPCONTROL_STLB) >> MVPCONTROL_STLB_SHIFT,
+               (val & MVPCONTROL_VPC) >> MVPCONTROL_VPC_SHIFT,
+               (val & MVPCONTROL_EVP));
+
+        val = read_c0_vpeconf0();
+        printk("VPEConf0 0x%lx MVP %ld\n", val,
+               (val & VPECONF0_MVP) >> VPECONF0_MVP_SHIFT);
+}
+
+/* Find some VPE program space  */
+static void *alloc_progmem(u32 len)
+{
+#ifdef CONFIG_MIPS_VPE_LOADER_TOM
+        /* this means you must tell linux to use less memory than you physically have */
+        return (void *)((max_pfn * PAGE_SIZE) + KSEG0);
+#else
+        // simple grab some mem for now
+        return kmalloc(len, GFP_KERNEL);
+#endif
+}
+
+static void release_progmem(void *ptr)
+{
+#ifndef CONFIG_MIPS_VPE_LOADER_TOM
+        kfree(ptr);
+#endif
+}
+
+/* Update size with this section: return offset. */
+static long get_offset(unsigned long *size, Elf_Shdr * sechdr)
+{
+        long ret;
+
+        ret = ALIGN(*size, sechdr->sh_addralign ? : 1);
+        *size = ret + sechdr->sh_size;
+        return ret;
+}
+
+/* Lay out the SHF_ALLOC sections in a way not dissimilar to how ld
+   might -- code, read-only data, read-write data, small data.  Tally
+   sizes, and place the offsets into sh_entsize fields: high bit means it
+   belongs in init. */
+static void layout_sections(struct module *mod, const Elf_Ehdr * hdr,
+                            Elf_Shdr * sechdrs, const char *secstrings)
+{
+        static unsigned long const masks[][2] = {
+                /* NOTE: all executable code must be the first section
+                 * in this array; otherwise modify the text_size
+                 * finder in the two loops below */
+                {SHF_EXECINSTR | SHF_ALLOC, ARCH_SHF_SMALL},
+                {SHF_ALLOC, SHF_WRITE | ARCH_SHF_SMALL},
+                {SHF_WRITE | SHF_ALLOC, ARCH_SHF_SMALL},
+                {ARCH_SHF_SMALL | SHF_ALLOC, 0}
+        };
+        unsigned int m, i;
+
+        for (i = 0; i < hdr->e_shnum; i++)
+                sechdrs[i].sh_entsize = ~0UL;
+
+        for (m = 0; m < ARRAY_SIZE(masks); ++m) {
+                for (i = 0; i < hdr->e_shnum; ++i) {
+                        Elf_Shdr *s = &sechdrs[i];
+
+                        //  || strncmp(secstrings + s->sh_name, ".init", 5) == 0)
+                        if ((s->sh_flags & masks[m][0]) != masks[m][0]
+                            || (s->sh_flags & masks[m][1])
+                            || s->sh_entsize != ~0UL)
+                                continue;
+                        s->sh_entsize = get_offset(&mod->core_size, s);
+                }
+
+                if (m == 0)
+                        mod->core_text_size = mod->core_size;
+
+        }
+}
+
+
+/* from module-elf32.c, but subverted a little */
+
+struct mips_hi16 {
+        struct mips_hi16 *next;
+        Elf32_Addr *addr;
+        Elf32_Addr value;
+};
+
+static struct mips_hi16 *mips_hi16_list;
+static unsigned int gp_offs, gp_addr;
+
+static int apply_r_mips_none(struct module *me, uint32_t *location,
+                             Elf32_Addr v)
+{
+        return 0;
+}
+
+static int apply_r_mips_gprel16(struct module *me, uint32_t *location,
+                                Elf32_Addr v)
+{
+        int rel;
+
+        if( !(*location & 0xffff) ) {
+                rel = (int)v - gp_addr;
+        }
+        else {
+                /* .sbss + gp(relative) + offset */
+                /* kludge! */
+                rel =  (int)(short)((int)v + gp_offs +
+                                    (int)(short)(*location & 0xffff) - gp_addr);
+        }
+
+        if( (rel > 32768) || (rel < -32768) ) {
+                printk(KERN_ERR
+                       "apply_r_mips_gprel16: relative address out of range 0x%x %d\n",
+                       rel, rel);
+                return -ENOEXEC;
+        }
+
+        *location = (*location & 0xffff0000) | (rel & 0xffff);
+
+        return 0;
+}
+
+static int apply_r_mips_pc16(struct module *me, uint32_t *location,
+                             Elf32_Addr v)
+{
+        int rel;
+        rel = (((unsigned int)v - (unsigned int)location));
+        rel >>= 2;              // because the offset is in _instructions_ not bytes.
+        rel -= 1;               // and one instruction less due to the branch delay slot.
+
+        if( (rel > 32768) || (rel < -32768) ) {
+                printk(KERN_ERR
+                       "apply_r_mips_pc16: relative address out of range 0x%x\n", rel);
+                return -ENOEXEC;
+        }
+
+        *location = (*location & 0xffff0000) | (rel & 0xffff);
+
+        return 0;
+}
+
+static int apply_r_mips_32(struct module *me, uint32_t *location,
+                           Elf32_Addr v)
+{
+        *location += v;
+
+        return 0;
+}
+
+static int apply_r_mips_26(struct module *me, uint32_t *location,
+                           Elf32_Addr v)
+{
+        if (v % 4) {
+                printk(KERN_ERR "module %s: dangerous relocation mod4\n", me->name);
+                return -ENOEXEC;
+        }
+
+/* Not desperately convinced this is a good check of an overflow condition
+   anyway. But it gets in the way of handling undefined weak symbols which
+   we want to set to zero.
+   if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
+   printk(KERN_ERR
+   "module %s: relocation overflow\n",
+   me->name);
+   return -ENOEXEC;
+   }
+*/
+
+        *location = (*location & ~0x03ffffff) |
+                ((*location + (v >> 2)) & 0x03ffffff);
+        return 0;
+}
+
+static int apply_r_mips_hi16(struct module *me, uint32_t *location,
+                             Elf32_Addr v)
+{
+        struct mips_hi16 *n;
+
+        /*
+         * We cannot relocate this one now because we don't know the value of
+         * the carry we need to add.  Save the information, and let LO16 do the
+         * actual relocation.
+         */
+        n = kmalloc(sizeof *n, GFP_KERNEL);
+        if (!n)
+                return -ENOMEM;
+
+        n->addr = location;
+        n->value = v;
+        n->next = mips_hi16_list;
+        mips_hi16_list = n;
+
+        return 0;
+}
+
+static int apply_r_mips_lo16(struct module *me, uint32_t *location,
+                             Elf32_Addr v)
+{
+        unsigned long insnlo = *location;
+        Elf32_Addr val, vallo;
+
+        /* Sign extend the addend we extract from the lo insn.  */
+        vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
+
+        if (mips_hi16_list != NULL) {
+                struct mips_hi16 *l;
+
+                l = mips_hi16_list;
+                while (l != NULL) {
+                        struct mips_hi16 *next;
+                        unsigned long insn;
+
+                        /*
+                         * The value for the HI16 had best be the same.
+                         */
+                        if (v != l->value) {
+                                printk("%d != %d\n", v, l->value);
+                                goto out_danger;
+                        }
+
+
+                        /*
+                         * Do the HI16 relocation.  Note that we actually don't
+                         * need to know anything about the LO16 itself, except
+                         * where to find the low 16 bits of the addend needed
+                         * by the LO16.
+                         */
+                        insn = *l->addr;
+                        val = ((insn & 0xffff) << 16) + vallo;
+                        val += v;
+
+                        /*
+                         * Account for the sign extension that will happen in
+                         * the low bits.
+                         */
+                        val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;
+
+                        insn = (insn & ~0xffff) | val;
+                        *l->addr = insn;
+
+                        next = l->next;
+                        kfree(l);
+                        l = next;
+                }
+
+                mips_hi16_list = NULL;
+        }
+
+        /*
+         * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
+         */
+        val = v + vallo;
+        insnlo = (insnlo & ~0xffff) | (val & 0xffff);
+        *location = insnlo;
+
+        return 0;
+
+out_danger:
+        printk(KERN_ERR "module %s: dangerous " "relocation\n", me->name);
+
+        return -ENOEXEC;
+}
+
+static int (*reloc_handlers[]) (struct module *me, uint32_t *location,
+                                Elf32_Addr v) = {
+        [R_MIPS_NONE]   = apply_r_mips_none,
+        [R_MIPS_32]     = apply_r_mips_32,
+        [R_MIPS_26]     = apply_r_mips_26,
+        [R_MIPS_HI16]   = apply_r_mips_hi16,
+        [R_MIPS_LO16]   = apply_r_mips_lo16,
+        [R_MIPS_GPREL16] = apply_r_mips_gprel16,
+        [R_MIPS_PC16] = apply_r_mips_pc16
+};
+
+
+int apply_relocations(Elf32_Shdr *sechdrs,
+                      const char *strtab,
+                      unsigned int symindex,
+                      unsigned int relsec,
+                      struct module *me)
+{
+        Elf32_Rel *rel = (void *) sechdrs[relsec].sh_addr;
+        Elf32_Sym *sym;
+        uint32_t *location;
+        unsigned int i;
+        Elf32_Addr v;
+        int res;
+
+        for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
+                Elf32_Word r_info = rel[i].r_info;
+
+                /* This is where to make the change */
+                location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+                        + rel[i].r_offset;
+                /* This is the symbol it is referring to */
+                sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
+                        + ELF32_R_SYM(r_info);
+
+                if (!sym->st_value) {
+                        printk(KERN_DEBUG "%s: undefined weak symbol %s\n",
+                               me->name, strtab + sym->st_name);
+                        /* just print the warning, dont barf */
+                }
+
+                v = sym->st_value;
+
+                res = reloc_handlers[ELF32_R_TYPE(r_info)](me, location, v);
+                if( res ) {
+                        printk(KERN_DEBUG
+                               "relocation error 0x%x sym refer <%s> value 0x%x "
+                               "type 0x%x r_info 0x%x\n",
+                               (unsigned int)location, strtab + sym->st_name, v,
+                               r_info, ELF32_R_TYPE(r_info));
+                }
+
+                if (res)
+                        return res;
+        }
+
+        return 0;
+}
+
+void save_gp_address(unsigned int secbase, unsigned int rel)
+{
+        gp_addr = secbase + rel;
+        gp_offs = gp_addr - (secbase & 0xffff0000);
+}
+/* end module-elf32.c */
+
+
+
+/* Change all symbols so that sh_value encodes the pointer directly. */
+static int simplify_symbols(Elf_Shdr * sechdrs,
+                            unsigned int symindex,
+                            const char *strtab,
+                            const char *secstrings,
+                            unsigned int nsecs, struct module *mod)
+{
+        Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
+        unsigned long secbase, bssbase = 0;
+        unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);
+        int ret = 0, size;
+
+        /* find the .bss section for COMMON symbols */
+        for (i = 0; i < nsecs; i++) {
+                if (strncmp(secstrings + sechdrs[i].sh_name, ".bss", 4) == 0)
+                        bssbase = sechdrs[i].sh_addr;
+        }
+
+        for (i = 1; i < n; i++) {
+                switch (sym[i].st_shndx) {
+                case SHN_COMMON:
+                        /* Allocate space for the symbol in the .bss section. st_value is currently size.
+                           We want it to have the address of the symbol. */
+
+                        size = sym[i].st_value;
+                        sym[i].st_value = bssbase;
+
+                        bssbase += size;
+                        break;
+
+                case SHN_ABS:
+                        /* Don't need to do anything */
+                        break;
+
+                case SHN_UNDEF:
+                        /* ret = -ENOENT; */
+                        break;
+
+                case SHN_MIPS_SCOMMON:
+
+                        printk(KERN_DEBUG
+                               "simplify_symbols: ignoring SHN_MIPS_SCOMMON symbol <%s> st_shndx %d\n",
+                               strtab + sym[i].st_name, sym[i].st_shndx);
+
+                        // .sbss section
+                        break;
+
+                default:
+                        secbase = sechdrs[sym[i].st_shndx].sh_addr;
+
+                        if (strncmp(strtab + sym[i].st_name, "_gp", 3) == 0) {
+                                save_gp_address(secbase, sym[i].st_value);
+                        }
+
+                        sym[i].st_value += secbase;
+                        break;
+                }
+
+        }
+
+        return ret;
+}
+
+#ifdef DEBUG_ELFLOADER
+static void dump_elfsymbols(Elf_Shdr * sechdrs, unsigned int symindex,
+                            const char *strtab, struct module *mod)
+{
+        Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
+        unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);
+
+        printk(KERN_DEBUG "dump_elfsymbols: n %d\n", n);
+        for (i = 1; i < n; i++) {
+                printk(KERN_DEBUG " i %d name <%s> 0x%x\n", i,
+                       strtab + sym[i].st_name, sym[i].st_value);
+        }
+}
+#endif
+
+static void dump_tc(struct tc *t)
+{
+        printk(KERN_WARNING "VPE: TC index %d TCStatus 0x%lx halt 0x%lx\n",
+               t->index, read_tc_c0_tcstatus(), read_tc_c0_tchalt());
+        printk(KERN_WARNING "VPE: tcrestart 0x%lx\n", read_tc_c0_tcrestart());
+}
+
+static void dump_tclist(void)
+{
+        struct tc *t;
+
+        list_for_each_entry(t, &vpecontrol.tc_list, list) {
+                dump_tc(t);
+        }
+}
+
+/* We are prepared so configure and start the VPE... */
+int vpe_run(vpe_t * v)
+{
+        unsigned long val;
+        struct tc *t;
+
+        /* check we are the Master VPE */
+        val = read_c0_vpeconf0();
+        if (!(val & VPECONF0_MVP)) {
+                printk(KERN_WARNING
+                       "VPE: only Master VPE's are allowed to configure MT\n");
+                return -1;
+        }
+
+        /* disable MT (using dvpe) */
+        dvpe();
+
+        /* Put MVPE's into 'configuration state' */
+        write_c0_mvpcontrol(read_c0_mvpcontrol() | MVPCONTROL_VPC);
+
+        if (!list_empty(&v->tc)) {
+                if ((t = list_entry(v->tc.next, struct tc, tc)) == NULL) {
+                        printk(KERN_WARNING "VPE: TC %d is already in use.\n",
+                               t->index);
+                        return -ENOEXEC;
+                }
+        } else {
+                printk(KERN_WARNING "VPE: No TC's associated with VPE %d\n",
+                       v->minor);
+                return -ENOEXEC;
+        }
+
+        settc(t->index);
+
+        val = read_vpe_c0_vpeconf0();
+
+        /* should check it is halted, and not activated */
+        if ((read_tc_c0_tcstatus() & TCSTATUS_A) || !(read_tc_c0_tchalt() & TCHALT_H)) {
+                printk(KERN_WARNING "VPE: TC %d is already doing something!\n",
+                       t->index);
+
+                dump_tclist();
+                return -ENOEXEC;
+        }
+
+        /* Write the address we want it to start running from in the TCPC register. */
+        write_tc_c0_tcrestart((unsigned long)v->__start);
+
+        /* write the sivc_info address to tccontext */
+        write_tc_c0_tccontext((unsigned long)0);
+
+        /* Set up the XTC bit in vpeconf0 to point at our tc */
+        write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() | (t->index << VPECONF0_XTC_SHIFT));
+
+        /* mark the TC as activated, not interrupt exempt and not dynamically allocatable */
+        val = read_tc_c0_tcstatus();
+        val = (val & ~(TCSTATUS_DA | TCSTATUS_IXMT)) | TCSTATUS_A;
+        write_tc_c0_tcstatus(val);
+
+        write_tc_c0_tchalt(read_tc_c0_tchalt() & ~TCHALT_H);
+
+        /* set up VPE1 */
+        write_vpe_c0_vpecontrol(read_vpe_c0_vpecontrol() & ~VPECONTROL_TE);     // no multiple TC's
+        write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() | VPECONF0_VPA);   // enable this VPE
+
+        /*
+         * The sde-kit passes 'memsize' to __start in $a3, so set something
+         * here...
+         * Or set $a3 (register 7) to zero and define DFLT_STACK_SIZE and
+         * DFLT_HEAP_SIZE when you compile your program
+         */
+
+        mttgpr(7, 0);
+
+        /* set config to be the same as vpe0, particularly kseg0 coherency alg */
+        write_vpe_c0_config(read_c0_config());
+
+        /* clear out any left overs from a previous program */
+        write_vpe_c0_cause(0);
+
+        /* take system out of configuration state */
+        write_c0_mvpcontrol(read_c0_mvpcontrol() & ~MVPCONTROL_VPC);
+
+        /* clear interrupts enabled IE, ERL, EXL, and KSU from c0 status */
+        write_vpe_c0_status(read_vpe_c0_status() & ~(ST0_ERL | ST0_KSU | ST0_IE | ST0_EXL));
+
+        /* set it running */
+        evpe(EVPE_ENABLE);
+
+        return 0;
+}
+
+static unsigned long find_vpe_symbols(vpe_t * v, Elf_Shdr * sechdrs,
+                                      unsigned int symindex, const char *strtab,
+                                      struct module *mod)
+{
+        Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
+        unsigned int i, n = sechdrs[symindex].sh_size / sizeof(Elf_Sym);
+
+        for (i = 1; i < n; i++) {
+                if (strcmp(strtab + sym[i].st_name, "__start") == 0) {
+                        v->__start = sym[i].st_value;
+                }
+
+                if (strcmp(strtab + sym[i].st_name, "vpe_shared") == 0) {
+                        v->shared_ptr = (void *)sym[i].st_value;
+                }
+        }
+
+        return 0;
+}
+
+/* Allocates a VPE with some program code space(the load address), copies the contents
+   of the program (p)buffer performing relocatations/etc, free's it when finished.
+*/
+int vpe_elfload(vpe_t * v)
+{
+        Elf_Ehdr *hdr;
+        Elf_Shdr *sechdrs;
+        long err = 0;
+        char *secstrings, *strtab = NULL;
+        unsigned int len, i, symindex = 0, strindex = 0;
+
+        struct module mod;      // so we can re-use the relocations code
+
+        memset(&mod, 0, sizeof(struct module));
+        strcpy(mod.name, "VPE dummy prog module");
+
+        hdr = (Elf_Ehdr *) v->pbuffer;
+        len = v->plen;
+
+        /* Sanity checks against insmoding binaries or wrong arch,
+           weird elf version */
+        if (memcmp(hdr->e_ident, ELFMAG, 4) != 0
+            || hdr->e_type != ET_REL || !elf_check_arch(hdr)
+            || hdr->e_shentsize != sizeof(*sechdrs)) {
+                printk(KERN_WARNING
+                       "VPE program, wrong arch or weird elf version\n");
+
+                return -ENOEXEC;
+        }
+
+        if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr)) {
+                printk(KERN_ERR "VPE program length %u truncated\n", len);
+                return -ENOEXEC;
+        }
+
+        /* Convenience variables */
+        sechdrs = (void *)hdr + hdr->e_shoff;
+        secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+        sechdrs[0].sh_addr = 0;
+
+        /* And these should exist, but gcc whinges if we don't init them */
+        symindex = strindex = 0;
+
+        for (i = 1; i < hdr->e_shnum; i++) {
+
+                if (sechdrs[i].sh_type != SHT_NOBITS
+                    && len < sechdrs[i].sh_offset + sechdrs[i].sh_size) {
+                        printk(KERN_ERR "VPE program length %u truncated\n",
+                               len);
+                        return -ENOEXEC;
+                }
+
+                /* Mark all sections sh_addr with their address in the
+                   temporary image. */
+                sechdrs[i].sh_addr = (size_t) hdr + sechdrs[i].sh_offset;
+
+                /* Internal symbols and strings. */
+                if (sechdrs[i].sh_type == SHT_SYMTAB) {
+                        symindex = i;
+                        strindex = sechdrs[i].sh_link;
+                        strtab = (char *)hdr + sechdrs[strindex].sh_offset;
+                }
+        }
+
+        layout_sections(&mod, hdr, sechdrs, secstrings);
+
+        v->load_addr = alloc_progmem(mod.core_size);
+        memset(v->load_addr, 0, mod.core_size);
+
+        printk("VPE elf_loader: loading to %p\n", v->load_addr);
+
+        for (i = 0; i < hdr->e_shnum; i++) {
+                void *dest;
+
+                if (!(sechdrs[i].sh_flags & SHF_ALLOC))
+                        continue;
+
+                dest = v->load_addr + sechdrs[i].sh_entsize;
+
+                if (sechdrs[i].sh_type != SHT_NOBITS)
+                        memcpy(dest, (void *)sechdrs[i].sh_addr,
+                               sechdrs[i].sh_size);
+                /* Update sh_addr to point to copy in image. */
+                sechdrs[i].sh_addr = (unsigned long)dest;
+        }
+
+        /* Fix up syms, so that st_value is a pointer to location. */
+        err =
+                simplify_symbols(sechdrs, symindex, strtab, secstrings,
+                                 hdr->e_shnum, &mod);
+        if (err < 0) {
+                printk(KERN_WARNING "VPE: unable to simplify symbols\n");
+                goto cleanup;
+        }
+
+        /* Now do relocations. */
+        for (i = 1; i < hdr->e_shnum; i++) {
+                const char *strtab = (char *)sechdrs[strindex].sh_addr;
+                unsigned int info = sechdrs[i].sh_info;
+
+                /* Not a valid relocation section? */
+                if (info >= hdr->e_shnum)
+                        continue;
+
+                /* Don't bother with non-allocated sections */
+                if (!(sechdrs[info].sh_flags & SHF_ALLOC))
+                        continue;
+
+                if (sechdrs[i].sh_type == SHT_REL)
+                        err =
+                                apply_relocations(sechdrs, strtab, symindex, i, &mod);
+                else if (sechdrs[i].sh_type == SHT_RELA)
+                        err = apply_relocate_add(sechdrs, strtab, symindex, i,
+                                                 &mod);
+                if (err < 0) {
+                        printk(KERN_WARNING
+                               "vpe_elfload: error in relocations err %ld\n",
+                               err);
+                        goto cleanup;
+                }
+        }
+
+        /* make sure it's physically written out */
+        flush_icache_range((unsigned long)v->load_addr,
+                           (unsigned long)v->load_addr + v->len);
+
+        if ((find_vpe_symbols(v, sechdrs, symindex, strtab, &mod)) < 0) {
+
+                printk(KERN_WARNING
+                       "VPE: program doesn't contain __start or vpe_shared symbols\n");
+                err = -ENOEXEC;
+        }
+
+        printk(" elf loaded\n");
+
+cleanup:
+        return err;
+}
+
+static void dump_vpe(vpe_t * v)
+{
+        struct tc *t;
+
+        printk(KERN_DEBUG "VPEControl 0x%lx\n", read_vpe_c0_vpecontrol());
+        printk(KERN_DEBUG "VPEConf0 0x%lx\n", read_vpe_c0_vpeconf0());
+
+        list_for_each_entry(t, &vpecontrol.tc_list, list) {
+                dump_tc(t);
+        }
+}
+
+/* checks for VPE is unused and gets ready to load program       */
+static int vpe_open(struct inode *inode, struct file *filp)
+{
+        int minor;
+        vpe_t *v;
+
+        /* assume only 1 device at the mo. */
+        if ((minor = MINOR(inode->i_rdev)) != 1) {
+                printk(KERN_WARNING "VPE: only vpe1 is supported\n");
+                return -ENODEV;
+        }
+
+        if ((v = get_vpe(minor)) == NULL) {
+                printk(KERN_WARNING "VPE: unable to get vpe\n");
+                return -ENODEV;
+        }
+
+        if (v->state != VPE_STATE_UNUSED) {
+                unsigned long tmp;
+                struct tc *t;
+
+                printk(KERN_WARNING "VPE: device %d already in use\n", minor);
+
+                dvpe();
+                dump_vpe(v);
+
+                printk(KERN_WARNING "VPE: re-initialising %d\n", minor);
+
+                release_progmem(v->load_addr);
+
+                t = get_tc(minor);
+                settc(minor);
+                tmp = read_tc_c0_tcstatus();
+
+                /* mark not allocated and not dynamically allocatable */
+                tmp &= ~(TCSTATUS_A | TCSTATUS_DA);
+                tmp |= TCSTATUS_IXMT;   /* interrupt exempt */
+                write_tc_c0_tcstatus(tmp);
+
+                write_tc_c0_tchalt(TCHALT_H);
+
+        }
+
+        // allocate it so when we get write ops we know it's expected.
+        v->state = VPE_STATE_INUSE;
+
+        /* this of-course trashes what was there before... */
+        v->pbuffer = vmalloc(P_SIZE);
+        v->plen = P_SIZE;
+        v->load_addr = NULL;
+        v->len = 0;
+
+        return 0;
+}
+
+static int vpe_release(struct inode *inode, struct file *filp)
+{
+        int minor, ret = 0;
+        vpe_t *v;
+        Elf_Ehdr *hdr;
+
+        minor = MINOR(inode->i_rdev);
+        if ((v = get_vpe(minor)) == NULL)
+                return -ENODEV;
+
+        // simple case of fire and forget, so tell the VPE to run...
+
+        hdr = (Elf_Ehdr *) v->pbuffer;
+        if (memcmp(hdr->e_ident, ELFMAG, 4) == 0) {
+                if (vpe_elfload(v) >= 0)
+                        vpe_run(v);
+                else {
+                        printk(KERN_WARNING "VPE: ELF load failed.\n");
+                        ret = -ENOEXEC;
+                }
+        } else {
+                printk(KERN_WARNING "VPE: only elf files are supported\n");
+                ret = -ENOEXEC;
+        }
+
+        // cleanup any temp buffers
+        if (v->pbuffer)
+                vfree(v->pbuffer);
+        v->plen = 0;
+        return ret;
+}
+
+static ssize_t vpe_write(struct file *file, const char __user * buffer,
+                         size_t count, loff_t * ppos)
+{
+        int minor;
+        size_t ret = count;
+        vpe_t *v;
+
+        minor = MINOR(file->f_dentry->d_inode->i_rdev);
+        if ((v = get_vpe(minor)) == NULL)
+                return -ENODEV;
+
+        if (v->pbuffer == NULL) {
+                printk(KERN_ERR "vpe_write: no pbuffer\n");
+                return -ENOMEM;
+        }
+
+        if ((count + v->len) > v->plen) {
+                printk(KERN_WARNING
+                       "VPE Loader: elf size too big. Perhaps strip uneeded symbols\n");
+                return -ENOMEM;
+        }
+
+        count -= copy_from_user(v->pbuffer + v->len, buffer, count);
+        if (!count) {
+                printk("vpe_write: copy_to_user failed\n");
+                return -EFAULT;
+        }
+
+        v->len += count;
+        return ret;
+}
+
+static struct file_operations vpe_fops = {
+        .owner = THIS_MODULE,
+        .open = vpe_open,
+        .release = vpe_release,
+        .write = vpe_write
+};
+
+/* module wrapper entry points */
+/* give me a vpe */
+vpe_handle vpe_alloc(void)
+{
+        int i;
+        struct vpe *v;
+
+        /* find a vpe */
+        for (i = 1; i < MAX_VPES; i++) {
+                if ((v = get_vpe(i)) != NULL) {
+                        v->state = VPE_STATE_INUSE;
+                        return v;
+                }
+        }
+        return NULL;
+}
+
+EXPORT_SYMBOL(vpe_alloc);
+
+/* start running from here */
+int vpe_start(vpe_handle vpe, unsigned long start)
+{
+        struct vpe *v = vpe;
+
+        v->__start = start;
+        return vpe_run(v);
+}
+
+EXPORT_SYMBOL(vpe_start);
+
+/* halt it for now */
+int vpe_stop(vpe_handle vpe)
+{
+        struct vpe *v = vpe;
+        struct tc *t;
+        unsigned int evpe_flags;
+
+        evpe_flags = dvpe();
+
+        if ((t = list_entry(v->tc.next, struct tc, tc)) != NULL) {
+
+                settc(t->index);
+                write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() & ~VPECONF0_VPA);
+        }
+
+        evpe(evpe_flags);
+
+        return 0;
+}
+
+EXPORT_SYMBOL(vpe_stop);
+
+/* I've done with it thank you */
+int vpe_free(vpe_handle vpe)
+{
+        struct vpe *v = vpe;
+        struct tc *t;
+        unsigned int evpe_flags;
+
+        if ((t = list_entry(v->tc.next, struct tc, tc)) == NULL) {
+                return -ENOEXEC;
+        }
+
+        evpe_flags = dvpe();
+
+        /* Put MVPE's into 'configuration state' */
+        write_c0_mvpcontrol(read_c0_mvpcontrol() | MVPCONTROL_VPC);
+
+        settc(t->index);
+        write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() & ~VPECONF0_VPA);
+
+        /* mark the TC unallocated and halt'ed */
+        write_tc_c0_tcstatus(read_tc_c0_tcstatus() & ~TCSTATUS_A);
+        write_tc_c0_tchalt(TCHALT_H);
+
+        v->state = VPE_STATE_UNUSED;
+
+        write_c0_mvpcontrol(read_c0_mvpcontrol() & ~MVPCONTROL_VPC);
+        evpe(evpe_flags);
+
+        return 0;
+}
+
+EXPORT_SYMBOL(vpe_free);
+
+void *vpe_get_shared(int index)
+{
+        struct vpe *v;
+
+        if ((v = get_vpe(index)) == NULL) {
+                printk(KERN_WARNING "vpe: invalid vpe index %d\n", index);
+                return NULL;
+        }
+
+        return v->shared_ptr;
+}
+
+EXPORT_SYMBOL(vpe_get_shared);
+
+static int __init vpe_module_init(void)
+{
+        struct vpe *v = NULL;
+        struct tc *t;
+        unsigned long val;
+        int i;
+
+        if (!cpu_has_mipsmt) {
+                printk("VPE loader: not a MIPS MT capable processor\n");
+                return -ENODEV;
+        }
+
+        if ((major = register_chrdev(VPE_MAJOR, module_name, &vpe_fops) < 0)) {
+                printk("VPE loader: unable to register character device\n");
+                return -EBUSY;
+        }
+
+        if (major == 0)
+                major = VPE_MAJOR;
+
+        dmt();
+        dvpe();
+
+        /* Put MVPE's into 'configuration state' */
+        write_c0_mvpcontrol(read_c0_mvpcontrol() | MVPCONTROL_VPC);
+
+        /* dump_mtregs(); */
+
+        INIT_LIST_HEAD(&vpecontrol.vpe_list);
+        INIT_LIST_HEAD(&vpecontrol.tc_list);
+
+        val = read_c0_mvpconf0();
+        for (i = 0; i < ((val & MVPCONF0_PTC) + 1); i++) {
+                t = alloc_tc(i);
+
+                /* VPE's */
+                if (i < ((val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) + 1) {
+                        settc(i);
+
+                        if ((v = alloc_vpe(i)) == NULL) {
+                                printk(KERN_WARNING "VPE: unable to allocate VPE\n");
+                                return -ENODEV;
+                        }
+
+                        list_add(&t->tc, &v->tc);       /* add the tc to the list of this vpe's tc's. */
+
+                        /* deactivate all but vpe0 */
+                        if (i != 0) {
+                                unsigned long tmp = read_vpe_c0_vpeconf0();
+
+                                tmp &= ~VPECONF0_VPA;
+
+                                /* master VPE */
+                                tmp |= VPECONF0_MVP;
+                                write_vpe_c0_vpeconf0(tmp);
+                        }
+
+                        /* disable multi-threading with TC's */
+                        write_vpe_c0_vpecontrol(read_vpe_c0_vpecontrol() & ~VPECONTROL_TE);
+
+                        if (i != 0) {
+                                write_vpe_c0_status((read_c0_status() &
+                                                     ~(ST0_IM | ST0_IE | ST0_KSU))
+                                                    | ST0_CU0);
+
+                                /* set config to be the same as vpe0, particularly kseg0 coherency alg */
+                                write_vpe_c0_config(read_c0_config());
+                        }
+
+                }
+
+                /* TC's */
+                t->pvpe = v;    /* set the parent vpe */
+
+                if (i != 0) {
+                        unsigned long tmp;
+
+                        /* tc 0 will of course be running.... */
+                        if (i == 0)
+                                t->state = TC_STATE_RUNNING;
+
+                        settc(i);
+
+                        /* bind a TC to each VPE, May as well put all excess TC's
+                           on the last VPE */
+                        if (i >= (((val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) + 1))
+                                write_tc_c0_tcbind(read_tc_c0_tcbind() |
+                                                   ((val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT));
+                        else
+                                write_tc_c0_tcbind(read_tc_c0_tcbind() | i);
+
+                        tmp = read_tc_c0_tcstatus();
+
+                        /* mark not allocated and not dynamically allocatable */
+                        tmp &= ~(TCSTATUS_A | TCSTATUS_DA);
+                        tmp |= TCSTATUS_IXMT;   /* interrupt exempt */
+                        write_tc_c0_tcstatus(tmp);
+
+                        write_tc_c0_tchalt(TCHALT_H);
+                }
+        }
+
+        /* release config state */
+        write_c0_mvpcontrol(read_c0_mvpcontrol() & ~MVPCONTROL_VPC);
+
+        return 0;
+}
+
+static void __exit vpe_module_exit(void)
+{
+        struct vpe *v, *n;
+
+        list_for_each_entry_safe(v, n, &vpecontrol.vpe_list, list) {
+                if (v->state != VPE_STATE_UNUSED) {
+                        release_vpe(v);
+                }
+        }
+
+        unregister_chrdev(major, module_name);
+}
+
+module_init(vpe_module_init);
+module_exit(vpe_module_exit);
+MODULE_DESCRIPTION("MIPS VPE Loader");
+MODULE_AUTHOR("Elizabeth Clarke, MIPS Technologies, Inc");
+MODULE_LICENSE("GPL");