module.c

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/*
 *  Kernel module help for s390.
 *
 *  S390 version
 *    Copyright IBM Corp. 2002, 2003
 *    Author(s): Arnd Bergmann ([email protected])
 *       Martin Schwidefsky ([email protected])
 *
 *  based on i386 version
 *    Copyright (C) 2001 Rusty Russell.
 *
 *  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
 */
#include <linux/module.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/moduleloader.h>
#include <linux/bug.h>

#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt , ...)
#endif

#ifndef CONFIG_64BIT
#define PLT_ENTRY_SIZE 12
#else /* CONFIG_64BIT */
#define PLT_ENTRY_SIZE 20
#endif /* CONFIG_64BIT */

#ifdef CONFIG_64BIT
void *module_alloc(unsigned long size)
{
    if (PAGE_ALIGN(size) > MODULES_LEN)
        return NULL;
    return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
                    GFP_KERNEL, PAGE_KERNEL, -1,
                    __builtin_return_address(0));
}
#endif

/* Free memory returned from module_alloc */
void module_free(struct module *mod, void *module_region)
{
    if (mod) {
        vfree(mod->arch.syminfo);
        mod->arch.syminfo = NULL;
    }
    vfree(module_region);
}

static void
check_rela(Elf_Rela *rela, struct module *me)
{
    struct mod_arch_syminfo *info;

    info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
    switch (ELF_R_TYPE (rela->r_info)) {
    case R_390_GOT12:   /* 12 bit GOT offset.  */
    case R_390_GOT16:   /* 16 bit GOT offset.  */
    case R_390_GOT20:   /* 20 bit GOT offset.  */
    case R_390_GOT32:   /* 32 bit GOT offset.  */
    case R_390_GOT64:   /* 64 bit GOT offset.  */
    case R_390_GOTENT:  /* 32 bit PC rel. to GOT entry shifted by 1. */
    case R_390_GOTPLT12:    /* 12 bit offset to jump slot.  */
    case R_390_GOTPLT16:    /* 16 bit offset to jump slot.  */
    case R_390_GOTPLT20:    /* 20 bit offset to jump slot.  */
    case R_390_GOTPLT32:    /* 32 bit offset to jump slot.  */
    case R_390_GOTPLT64:    /* 64 bit offset to jump slot.  */
    case R_390_GOTPLTENT:   /* 32 bit rel. offset to jump slot >> 1. */
        if (info->got_offset == -1UL) {
            info->got_offset = me->arch.got_size;
            me->arch.got_size += sizeof(void*);
        }
        break;
    case R_390_PLT16DBL:    /* 16 bit PC rel. PLT shifted by 1.  */
    case R_390_PLT32DBL:    /* 32 bit PC rel. PLT shifted by 1.  */
    case R_390_PLT32:   /* 32 bit PC relative PLT address.  */
    case R_390_PLT64:   /* 64 bit PC relative PLT address.  */
    case R_390_PLTOFF16:    /* 16 bit offset from GOT to PLT. */
    case R_390_PLTOFF32:    /* 32 bit offset from GOT to PLT. */
    case R_390_PLTOFF64:    /* 16 bit offset from GOT to PLT. */
        if (info->plt_offset == -1UL) {
            info->plt_offset = me->arch.plt_size;
            me->arch.plt_size += PLT_ENTRY_SIZE;
        }
        break;
    case R_390_COPY:
    case R_390_GLOB_DAT:
    case R_390_JMP_SLOT:
    case R_390_RELATIVE:
        /* Only needed if we want to support loading of 
           modules linked with -shared. */
        break;
    }
}

/*
 * Account for GOT and PLT relocations. We can't add sections for
 * got and plt but we can increase the core module size.
 */
int
module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
              char *secstrings, struct module *me)
{
    Elf_Shdr *symtab;
    Elf_Sym *symbols;
    Elf_Rela *rela;
    char *strings;
    int nrela, i, j;

    /* Find symbol table and string table. */
    symtab = NULL;
    for (i = 0; i < hdr->e_shnum; i++)
        switch (sechdrs[i].sh_type) {
        case SHT_SYMTAB:
            symtab = sechdrs + i;
            break;
        }
    if (!symtab) {
        printk(KERN_ERR "module %s: no symbol table\n", me->name);
        return -ENOEXEC;
    }

    /* Allocate one syminfo structure per symbol. */
    me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
    me->arch.syminfo = vmalloc(me->arch.nsyms *
                   sizeof(struct mod_arch_syminfo));
    if (!me->arch.syminfo)
        return -ENOMEM;
    symbols = (void *) hdr + symtab->sh_offset;
    strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
    for (i = 0; i < me->arch.nsyms; i++) {
        if (symbols[i].st_shndx == SHN_UNDEF &&
            strcmp(strings + symbols[i].st_name,
               "_GLOBAL_OFFSET_TABLE_") == 0)
            /* "Define" it as absolute. */
            symbols[i].st_shndx = SHN_ABS;
        me->arch.syminfo[i].got_offset = -1UL;
        me->arch.syminfo[i].plt_offset = -1UL;
        me->arch.syminfo[i].got_initialized = 0;
        me->arch.syminfo[i].plt_initialized = 0;
    }

    /* Search for got/plt relocations. */
    me->arch.got_size = me->arch.plt_size = 0;
    for (i = 0; i < hdr->e_shnum; i++) {
        if (sechdrs[i].sh_type != SHT_RELA)
            continue;
        nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
        rela = (void *) hdr + sechdrs[i].sh_offset;
        for (j = 0; j < nrela; j++)
            check_rela(rela + j, me);
    }

    /* Increase core size by size of got & plt and set start
       offsets for got and plt. */
    me->core_size = ALIGN(me->core_size, 4);
    me->arch.got_offset = me->core_size;
    me->core_size += me->arch.got_size;
    me->arch.plt_offset = me->core_size;
    me->core_size += me->arch.plt_size;
    return 0;
}

static int
apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, 
       struct module *me)
{
    struct mod_arch_syminfo *info;
    Elf_Addr loc, val;
    int r_type, r_sym;

    /* This is where to make the change */
    loc = base + rela->r_offset;
    /* This is the symbol it is referring to.  Note that all
       undefined symbols have been resolved.  */
    r_sym = ELF_R_SYM(rela->r_info);
    r_type = ELF_R_TYPE(rela->r_info);
    info = me->arch.syminfo + r_sym;
    val = symtab[r_sym].st_value;

    switch (r_type) {
    case R_390_8:       /* Direct 8 bit.   */
    case R_390_12:      /* Direct 12 bit.  */
    case R_390_16:      /* Direct 16 bit.  */
    case R_390_20:      /* Direct 20 bit.  */
    case R_390_32:      /* Direct 32 bit.  */
    case R_390_64:      /* Direct 64 bit.  */
        val += rela->r_addend;
        if (r_type == R_390_8)
            *(unsigned char *) loc = val;
        else if (r_type == R_390_12)
            *(unsigned short *) loc = (val & 0xfff) |
                (*(unsigned short *) loc & 0xf000);
        else if (r_type == R_390_16)
            *(unsigned short *) loc = val;
        else if (r_type == R_390_20)
            *(unsigned int *) loc =
                (*(unsigned int *) loc & 0xf00000ff) |
                (val & 0xfff) << 16 | (val & 0xff000) >> 4;
        else if (r_type == R_390_32)
            *(unsigned int *) loc = val;
        else if (r_type == R_390_64)
            *(unsigned long *) loc = val;
        break;
    case R_390_PC16:    /* PC relative 16 bit.  */
    case R_390_PC16DBL: /* PC relative 16 bit shifted by 1.  */
    case R_390_PC32DBL: /* PC relative 32 bit shifted by 1.  */
    case R_390_PC32:    /* PC relative 32 bit.  */
    case R_390_PC64:    /* PC relative 64 bit.  */
        val += rela->r_addend - loc;
        if (r_type == R_390_PC16)
            *(unsigned short *) loc = val;
        else if (r_type == R_390_PC16DBL)
            *(unsigned short *) loc = val >> 1;
        else if (r_type == R_390_PC32DBL)
            *(unsigned int *) loc = val >> 1;
        else if (r_type == R_390_PC32)
            *(unsigned int *) loc = val;
        else if (r_type == R_390_PC64)
            *(unsigned long *) loc = val;
        break;
    case R_390_GOT12:   /* 12 bit GOT offset.  */
    case R_390_GOT16:   /* 16 bit GOT offset.  */
    case R_390_GOT20:   /* 20 bit GOT offset.  */
    case R_390_GOT32:   /* 32 bit GOT offset.  */
    case R_390_GOT64:   /* 64 bit GOT offset.  */
    case R_390_GOTENT:  /* 32 bit PC rel. to GOT entry shifted by 1. */
    case R_390_GOTPLT12:    /* 12 bit offset to jump slot.  */
    case R_390_GOTPLT20:    /* 20 bit offset to jump slot.  */
    case R_390_GOTPLT16:    /* 16 bit offset to jump slot.  */
    case R_390_GOTPLT32:    /* 32 bit offset to jump slot.  */
    case R_390_GOTPLT64:    /* 64 bit offset to jump slot.  */
    case R_390_GOTPLTENT:   /* 32 bit rel. offset to jump slot >> 1. */
        if (info->got_initialized == 0) {
            Elf_Addr *gotent;

            gotent = me->module_core + me->arch.got_offset +
                info->got_offset;
            *gotent = val;
            info->got_initialized = 1;
        }
        val = info->got_offset + rela->r_addend;
        if (r_type == R_390_GOT12 ||
            r_type == R_390_GOTPLT12)
            *(unsigned short *) loc = (val & 0xfff) |
                (*(unsigned short *) loc & 0xf000);
        else if (r_type == R_390_GOT16 ||
             r_type == R_390_GOTPLT16)
            *(unsigned short *) loc = val;
        else if (r_type == R_390_GOT20 ||
             r_type == R_390_GOTPLT20)
            *(unsigned int *) loc =
                (*(unsigned int *) loc & 0xf00000ff) |
                (val & 0xfff) << 16 | (val & 0xff000) >> 4;
        else if (r_type == R_390_GOT32 ||
             r_type == R_390_GOTPLT32)
            *(unsigned int *) loc = val;
        else if (r_type == R_390_GOTENT ||
             r_type == R_390_GOTPLTENT)
            *(unsigned int *) loc =
                (val + (Elf_Addr) me->module_core - loc) >> 1;
        else if (r_type == R_390_GOT64 ||
             r_type == R_390_GOTPLT64)
            *(unsigned long *) loc = val;
        break;
    case R_390_PLT16DBL:    /* 16 bit PC rel. PLT shifted by 1.  */
    case R_390_PLT32DBL:    /* 32 bit PC rel. PLT shifted by 1.  */
    case R_390_PLT32:   /* 32 bit PC relative PLT address.  */
    case R_390_PLT64:   /* 64 bit PC relative PLT address.  */
    case R_390_PLTOFF16:    /* 16 bit offset from GOT to PLT. */
    case R_390_PLTOFF32:    /* 32 bit offset from GOT to PLT. */
    case R_390_PLTOFF64:    /* 16 bit offset from GOT to PLT. */
        if (info->plt_initialized == 0) {
            unsigned int *ip;
            ip = me->module_core + me->arch.plt_offset +
                info->plt_offset;
#ifndef CONFIG_64BIT
            ip[0] = 0x0d105810; /* basr 1,0; l 1,6(1); br 1 */
            ip[1] = 0x100607f1;
            ip[2] = val;
#else /* CONFIG_64BIT */
            ip[0] = 0x0d10e310; /* basr 1,0; lg 1,10(1); br 1 */
            ip[1] = 0x100a0004;
            ip[2] = 0x07f10000;
            ip[3] = (unsigned int) (val >> 32);
            ip[4] = (unsigned int) val;
#endif /* CONFIG_64BIT */
            info->plt_initialized = 1;
        }
        if (r_type == R_390_PLTOFF16 ||
            r_type == R_390_PLTOFF32 ||
            r_type == R_390_PLTOFF64)
            val = me->arch.plt_offset - me->arch.got_offset +
                info->plt_offset + rela->r_addend;
        else {
            if (!((r_type == R_390_PLT16DBL &&
                   val - loc + 0xffffUL < 0x1ffffeUL) ||
                  (r_type == R_390_PLT32DBL &&
                   val - loc + 0xffffffffULL < 0x1fffffffeULL)))
                val = (Elf_Addr) me->module_core +
                    me->arch.plt_offset +
                    info->plt_offset;
            val += rela->r_addend - loc;
        }
        if (r_type == R_390_PLT16DBL)
            *(unsigned short *) loc = val >> 1;
        else if (r_type == R_390_PLTOFF16)
            *(unsigned short *) loc = val;
        else if (r_type == R_390_PLT32DBL)
            *(unsigned int *) loc = val >> 1;
        else if (r_type == R_390_PLT32 ||
             r_type == R_390_PLTOFF32)
            *(unsigned int *) loc = val;
        else if (r_type == R_390_PLT64 ||
             r_type == R_390_PLTOFF64)
            *(unsigned long *) loc = val;
        break;
    case R_390_GOTOFF16:    /* 16 bit offset to GOT.  */
    case R_390_GOTOFF32:    /* 32 bit offset to GOT.  */
    case R_390_GOTOFF64:    /* 64 bit offset to GOT. */
        val = val + rela->r_addend -
            ((Elf_Addr) me->module_core + me->arch.got_offset);
        if (r_type == R_390_GOTOFF16)
            *(unsigned short *) loc = val;
        else if (r_type == R_390_GOTOFF32)
            *(unsigned int *) loc = val;
        else if (r_type == R_390_GOTOFF64)
            *(unsigned long *) loc = val;
        break;
    case R_390_GOTPC:   /* 32 bit PC relative offset to GOT. */
    case R_390_GOTPCDBL:    /* 32 bit PC rel. off. to GOT shifted by 1. */
        val = (Elf_Addr) me->module_core + me->arch.got_offset +
            rela->r_addend - loc;
        if (r_type == R_390_GOTPC)
            *(unsigned int *) loc = val;
        else if (r_type == R_390_GOTPCDBL)
            *(unsigned int *) loc = val >> 1;
        break;
    case R_390_COPY:
    case R_390_GLOB_DAT:    /* Create GOT entry.  */
    case R_390_JMP_SLOT:    /* Create PLT entry.  */
    case R_390_RELATIVE:    /* Adjust by program base.  */
        /* Only needed if we want to support loading of 
           modules linked with -shared. */
        break;
    default:
        printk(KERN_ERR "module %s: Unknown relocation: %u\n",
               me->name, r_type);
        return -ENOEXEC;
    }
    return 0;
}

int
apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
           unsigned int symindex, unsigned int relsec,
           struct module *me)
{
    Elf_Addr base;
    Elf_Sym *symtab;
    Elf_Rela *rela;
    unsigned long i, n;
    int rc;

    DEBUGP("Applying relocate section %u to %u\n",
           relsec, sechdrs[relsec].sh_info);
    base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
    symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
    rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
    n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);

    for (i = 0; i < n; i++, rela++) {
        rc = apply_rela(rela, base, symtab, me);
        if (rc)
            return rc;
    }
    return 0;
}

int module_finalize(const Elf_Ehdr *hdr,
            const Elf_Shdr *sechdrs,
            struct module *me)
{
    vfree(me->arch.syminfo);
    me->arch.syminfo = NULL;
    return 0;
}