source: src/linux/ar531x/linux-2.6.23/arch/mips/kernel/module.c @ 12400

/*
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that 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
 *
 *  Copyright (C) 2001 Rusty Russell.
 *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
 *  Copyright (C) 2005 Thiemo Seufer
 */

#undef DEBUG

#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <asm/pgtable.h>        /* MODULE_START */

struct mips_hi16 {
        struct mips_hi16 *next;
        Elf_Addr *addr;
        Elf_Addr value;
};

static struct mips_hi16 *mips_hi16_list;

static LIST_HEAD(dbe_list);
static DEFINE_SPINLOCK(dbe_lock);

static void *alloc_phys(unsigned long size)
{
        unsigned order;
        struct page *page;
        struct page *p;

        size = PAGE_ALIGN(size);
        order = get_order(size);

        page = alloc_pages(
                GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN | __GFP_THISNODE,
                order);
        if (!page)
                return 0;

        split_page(page, order);

        for (p = page + (size >> PAGE_SHIFT); p < page + (1 << order); ++p)
                __free_page(p);

        return page_address(page);
}

static void free_phys(void *ptr, unsigned long size)
{
        struct page *page;
        struct page *end;

        page = virt_to_page(ptr);
        end = page + (PAGE_ALIGN(size) >> PAGE_SHIFT);

        for (; page < end; ++page)
                __free_pages(page, 0);
}

void *module_alloc(unsigned long size)
{
#ifdef MODULE_START
        struct vm_struct *area;

        size = PAGE_ALIGN(size);
        if (!size)
                return NULL;

        area = __get_vm_area(size, VM_ALLOC, MODULE_START, MODULE_END);
        if (!area)
                return NULL;

        return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL);
#else
        unsigned addr;
        void *ptr;

        size = PAGE_ALIGN(size);
        if (size == 0)
                return NULL;

        ptr = alloc_phys(size);
        if (ptr)
                return ptr;

        /* try to allocate contiguos chunk of memory not spanning 256Mb
           range, so all jump instructions can work */
        addr = VMALLOC_START;
        while (addr < VMALLOC_END) {
                unsigned end = ALIGN(addr + 1, 1u << 28);

                if (addr + size <= end) {
                        struct vm_struct *area
                                = __get_vm_area(size, VM_ALLOC, addr, end);

                        if (area)
                                return __vmalloc_area(
                                        area, GFP_KERNEL, PAGE_KERNEL);
                }
                addr = end;
        }
        return NULL;
#endif
}

static inline int is_phys(void *ptr)
{
        unsigned addr = (unsigned) ptr;
        return addr && (addr < VMALLOC_START || addr > VMALLOC_END);
}

/* Free memory returned from module_alloc */
void module_free(struct module *mod, void *module_region)
{
        if (is_phys(module_region)) {
                if (mod->module_init == module_region)
                        free_phys(module_region, mod->init_size);
                else if (mod->module_core == module_region)
                        free_phys(module_region, mod->core_size);
                else
                    BUG();
                return;
        }

        vfree(module_region);
        /* FIXME: If module_region == mod->init_region, trim exception
           table entries. */
}

int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
                              char *secstrings, struct module *mod)
{
        return 0;
}

/* Get the potential trampolines size required of the init and
   non-init sections */
static unsigned get_plt_size(const Elf32_Ehdr *hdr,
                             const Elf32_Shdr *sechdrs,
                             const char *secstrings,
                             unsigned symindex,
                             int is_init)
{
        unsigned long ret = 0;
        unsigned i, j;
        Elf_Sym *syms;

        /* Everything marked ALLOC (this includes the exported symbols) */
        for (i = 1; i < hdr->e_shnum; ++i) {
                unsigned int info = sechdrs[i].sh_info;

                if (sechdrs[i].sh_type != SHT_REL
                    && sechdrs[i].sh_type != SHT_RELA)
                        continue;

                /* 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 it's called *.init*, and we're not init, we're
                   not interested */
                if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0)
                    != is_init)
                        continue;

                syms = (Elf_Sym *) sechdrs[symindex].sh_addr;
                if (sechdrs[i].sh_type == SHT_REL) {
                        Elf_Mips_Rel *rel = (void *) sechdrs[i].sh_addr;
                        unsigned size = sechdrs[i].sh_size / sizeof(*rel);

                        for (j = 0; j < size; ++j) {
                                Elf_Sym *sym;

                                if (ELF_MIPS_R_TYPE(rel[j]) != R_MIPS_26)
                                        continue;
                                sym = syms + ELF_MIPS_R_SYM(rel[j]);
                                if (!is_init && sym->st_shndx != SHN_UNDEF)
                                        continue;

                                ret += sizeof(unsigned[4]);
                        }
                } else {
                        Elf_Mips_Rela *rela = (void *) sechdrs[i].sh_addr;
                        unsigned size = sechdrs[i].sh_size / sizeof(*rela);

                        for (j = 0; j < size; ++j) {
                                Elf_Sym *sym;

                                if (ELF_MIPS_R_TYPE(rela[j]) != R_MIPS_26)
                                        continue;
                                sym = syms + ELF_MIPS_R_SYM(rela[j]);
                                if (!is_init && sym->st_shndx != SHN_UNDEF)
                                        continue;

                                ret += sizeof(unsigned[4]);
                        }
                }

        }

        return ret;
}

int module_relayout(Elf32_Ehdr *hdr,
                    Elf32_Shdr *sechdrs,
                    char *secstrings,
                    unsigned symindex,
                    struct module *me)
{
        unsigned core_plt_size = get_plt_size(
            hdr, sechdrs, secstrings, symindex, 0);
        unsigned init_plt_size = get_plt_size(
            hdr, sechdrs, secstrings, symindex, 1);

        if (core_plt_size > 0)
                me->core_size = PAGE_ALIGN(me->core_size);
        me->arch.core_plt_offset = me->core_size;
        me->core_size = me->core_size + core_plt_size;

        me->arch.init_plt_offset = me->init_size;
        me->init_size = me->init_size + init_plt_size;

        return 0;
}

static int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)
{
        return 0;
}

static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)
{
        *location += v;

        return 0;
}

static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
{
        *location = v;

        return 0;
}

static Elf_Addr add_plt_entry_to(unsigned *plt_offset,
                                 void *start, unsigned size, Elf_Addr v)
{
        unsigned *tramp = start + *plt_offset;
        if (*plt_offset == size) return 0;

        *plt_offset += sizeof(unsigned[4]);

        /* adjust carry for addiu */
        if (v & 0x00008000) 
                v += 0x10000;
        
        tramp[0] = 0x3c190000 | (v >> 16);      /* lui t9, hi16 */
        tramp[1] = 0x27390000 | (v & 0xffff);   /* addiu t9, t9, lo16 */
        tramp[2] = 0x03200008;                  /* jr t9 */
        tramp[3] = 0x00000000;                  /* nop */
        
        return (Elf_Addr) tramp;
}

static Elf_Addr add_plt_entry(struct module *me, void *location, Elf_Addr v)
{
        if (location >= me->module_core
            && location < me->module_core + me->core_size) {
                return add_plt_entry_to(&me->arch.core_plt_offset,
                                        me->module_core, me->core_size, v);
        } else if (location > me->module_init
                   && location < me->module_init + me->init_size) {
                return add_plt_entry_to(&me->arch.init_plt_offset,
                                        me->module_init, me->init_size, v);
        } else {
                printk(KERN_ERR "module %s: "
                       "relocation to unknown segment %u\n",
                       me->name, v);
        }
        return 0;
}

static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v)
{
        if (v % 4) {
                printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
                return -ENOEXEC;
        }

        if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
                v = add_plt_entry(me, location,
                                  v + ((*location & 0x03ffffff) << 2));
                if (v == 0) {
                printk(KERN_ERR
                       "module %s: relocation overflow\n",
                       me->name);
                return -ENOEXEC;
        }
                *location = (*location & ~0x03ffffff) |
                            ((v >> 2) & 0x03ffffff);
                return 0;
        }

        *location = (*location & ~0x03ffffff) |
                    ((*location + (v >> 2)) & 0x03ffffff);

        return 0;
}

static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)
{
        if (v % 4) {
                printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
                return -ENOEXEC;
        }

        if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
                v = add_plt_entry(me, location, v);
                if (v == 0) {
                printk(KERN_ERR
                       "module %s: relocation overflow\n",
                       me->name);
                return -ENOEXEC;
        }
        }

        *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);

        return 0;
}

static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_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 = (Elf_Addr *)location;
        n->value = v;
        n->next = mips_hi16_list;
        mips_hi16_list = n;

        return 0;
}

static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
{
        *location = (*location & 0xffff0000) |
                    ((((long long) v + 0x8000LL) >> 16) & 0xffff);

        return 0;
}

static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
{
        unsigned long insnlo = *location;
        Elf_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)
                                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 apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
{
        *location = (*location & 0xffff0000) | (v & 0xffff);

        return 0;
}

static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
{
        *(Elf_Addr *)location = v;

        return 0;
}

static int apply_r_mips_higher_rela(struct module *me, u32 *location,
                                    Elf_Addr v)
{
        *location = (*location & 0xffff0000) |
                    ((((long long) v + 0x80008000LL) >> 32) & 0xffff);

        return 0;
}

static int apply_r_mips_highest_rela(struct module *me, u32 *location,
                                     Elf_Addr v)
{
        *location = (*location & 0xffff0000) |
                    ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);

        return 0;
}

static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
                                Elf_Addr v) = {
        [R_MIPS_NONE]           = apply_r_mips_none,
        [R_MIPS_32]             = apply_r_mips_32_rel,
        [R_MIPS_26]             = apply_r_mips_26_rel,
        [R_MIPS_HI16]           = apply_r_mips_hi16_rel,
        [R_MIPS_LO16]           = apply_r_mips_lo16_rel
};

static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
                                Elf_Addr v) = {
        [R_MIPS_NONE]           = apply_r_mips_none,
        [R_MIPS_32]             = apply_r_mips_32_rela,
        [R_MIPS_26]             = apply_r_mips_26_rela,
        [R_MIPS_HI16]           = apply_r_mips_hi16_rela,
        [R_MIPS_LO16]           = apply_r_mips_lo16_rela,
        [R_MIPS_64]             = apply_r_mips_64_rela,
        [R_MIPS_HIGHER]         = apply_r_mips_higher_rela,
        [R_MIPS_HIGHEST]        = apply_r_mips_highest_rela
};

int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
                   unsigned int symindex, unsigned int relsec,
                   struct module *me)
{
        Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr;
        Elf_Sym *sym;
        u32 *location;
        unsigned int i;
        Elf_Addr v;
        int res;

        pr_debug("Applying relocate section %u to %u\n", relsec,
               sechdrs[relsec].sh_info);

        for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
                /* 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 = (Elf_Sym *)sechdrs[symindex].sh_addr
                        + ELF_MIPS_R_SYM(rel[i]);
                if (!sym->st_value) {
                        /* Ignore unresolved weak symbol */
                        if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
                                continue;
                        printk(KERN_WARNING "%s: Unknown symbol %s\n",
                               me->name, strtab + sym->st_name);
                        return -ENOENT;
                }

                v = sym->st_value;

                res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
                if (res)
                        return res;
        }

        return 0;
}

int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
                       unsigned int symindex, unsigned int relsec,
                       struct module *me)
{
        Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
        Elf_Sym *sym;
        u32 *location;
        unsigned int i;
        Elf_Addr v;
        int res;

        pr_debug("Applying relocate section %u to %u\n", relsec,
               sechdrs[relsec].sh_info);

        for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
                /* 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 = (Elf_Sym *)sechdrs[symindex].sh_addr
                        + ELF_MIPS_R_SYM(rel[i]);
                if (!sym->st_value) {
                        /* Ignore unresolved weak symbol */
                        if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
                                continue;
                        printk(KERN_WARNING "%s: Unknown symbol %s\n",
                               me->name, strtab + sym->st_name);
                        return -ENOENT;
                }

                v = sym->st_value + rel[i].r_addend;

                res = reloc_handlers_rela[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
                if (res)
                        return res;
        }

        return 0;
}

/* Given an address, look for it in the module exception tables. */
const struct exception_table_entry *search_module_dbetables(unsigned long addr)
{
        unsigned long flags;
        const struct exception_table_entry *e = NULL;
        struct mod_arch_specific *dbe;

        spin_lock_irqsave(&dbe_lock, flags);
        list_for_each_entry(dbe, &dbe_list, dbe_list) {
                e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
                if (e)
                        break;
        }
        spin_unlock_irqrestore(&dbe_lock, flags);

        /* Now, if we found one, we are running inside it now, hence
           we cannot unload the module, hence no refcnt needed. */
        return e;
}

/* Put in dbe list if neccessary. */
int module_finalize(const Elf_Ehdr *hdr,
                    const Elf_Shdr *sechdrs,
                    struct module *me)
{
        const Elf_Shdr *s;
        char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

        INIT_LIST_HEAD(&me->arch.dbe_list);
        for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
                if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
                        continue;
                me->arch.dbe_start = (void *)s->sh_addr;
                me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
                spin_lock_irq(&dbe_lock);
                list_add(&me->arch.dbe_list, &dbe_list);
                spin_unlock_irq(&dbe_lock);
        }

        if (me->arch.core_plt_offset < me->core_size
            && PAGE_ALIGN(me->arch.core_plt_offset) == me->arch.core_plt_offset
            && is_phys(me->module_core)) {
                free_phys(me->module_core + me->arch.core_plt_offset,
                          me->core_size - me->arch.core_plt_offset);
                me->core_size = me->arch.core_plt_offset;
        }
        return 0;
}

void module_arch_cleanup(struct module *mod)
{
        spin_lock_irq(&dbe_lock);
        list_del(&mod->arch.dbe_list);
        spin_unlock_irq(&dbe_lock);
}