module.c

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/*
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 *
 *   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, version 2.
 *
 *   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, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 *
 * Based on i386 version, copyright (C) 2001 Rusty Russell.
 */

#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <asm/pgtable.h>
#include <asm/homecache.h>
#include <arch/opcode.h>

#ifdef MODULE_DEBUG
#define DEBUGP printk
#else
#define DEBUGP(fmt...)
#endif

/*
 * Allocate some address space in the range MEM_MODULE_START to
 * MEM_MODULE_END and populate it with memory.
 */
void *module_alloc(unsigned long size)
{
    struct page **pages;
    pgprot_t prot_rwx = __pgprot(_PAGE_KERNEL | _PAGE_KERNEL_EXEC);
    struct vm_struct *area;
    int i = 0;
    int npages;

    if (size == 0)
        return NULL;
    npages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
    pages = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
    if (pages == NULL)
        return NULL;
    for (; i < npages; ++i) {
        pages[i] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
        if (!pages[i])
            goto error;
    }

    area = __get_vm_area(size, VM_ALLOC, MEM_MODULE_START, MEM_MODULE_END);
    if (!area)
        goto error;
    area->nr_pages = npages;
    area->pages = pages;

    if (map_vm_area(area, prot_rwx, &pages)) {
        vunmap(area->addr);
        goto error;
    }

    return area->addr;

error:
    while (--i >= 0)
        __free_page(pages[i]);
    kfree(pages);
    return NULL;
}


/* Free memory returned from module_alloc */
void module_free(struct module *mod, void *module_region)
{
    vfree(module_region);

    /* Globally flush the L1 icache. */
    flush_remote(0, HV_FLUSH_EVICT_L1I, cpu_online_mask,
             0, 0, 0, NULL, NULL, 0);

    /*
     * FIXME: If module_region == mod->module_init, trim exception
     * table entries.
     */
}

#ifdef __tilegx__
/*
 * Validate that the high 16 bits of "value" is just the sign-extension of
 * the low 48 bits.
 */
static int validate_hw2_last(long value, struct module *me)
{
    if (((value << 16) >> 16) != value) {
        pr_warning("module %s: Out of range HW2_LAST value %#lx\n",
               me->name, value);
        return 0;
    }
    return 1;
}

/*
 * Validate that "value" isn't too big to hold in a JumpOff relocation.
 */
static int validate_jumpoff(long value)
{
    /* Determine size of jump offset. */
    int shift = __builtin_clzl(get_JumpOff_X1(create_JumpOff_X1(-1)));

    /* Check to see if it fits into the relocation slot. */
    long f = get_JumpOff_X1(create_JumpOff_X1(value));
    f = (f << shift) >> shift;

    return f == value;
}
#endif

int apply_relocate_add(Elf_Shdr *sechdrs,
               const char *strtab,
               unsigned int symindex,
               unsigned int relsec,
               struct module *me)
{
    unsigned int i;
    Elf_Rela *rel = (void *)sechdrs[relsec].sh_addr;
    Elf_Sym *sym;
    u64 *location;
    unsigned long value;

    DEBUGP("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.
         * Note that all undefined symbols have been resolved.
         */
        sym = (Elf_Sym *)sechdrs[symindex].sh_addr
            + ELF_R_SYM(rel[i].r_info);
        value = sym->st_value + rel[i].r_addend;

        switch (ELF_R_TYPE(rel[i].r_info)) {

#ifdef __LITTLE_ENDIAN
# define MUNGE(func) \
    (*location = ((*location & ~func(-1)) | func(value)))
#else
/*
 * Instructions are always little-endian, so when we read them as data,
 * we have to swap them around before and after modifying them.
 */
# define MUNGE(func) \
    (*location = swab64((swab64(*location) & ~func(-1)) | func(value)))
#endif

#ifndef __tilegx__
        case R_TILE_32:
            *(uint32_t *)location = value;
            break;
        case R_TILE_IMM16_X0_HA:
            value = (value + 0x8000) >> 16;
            /*FALLTHROUGH*/
        case R_TILE_IMM16_X0_LO:
            MUNGE(create_Imm16_X0);
            break;
        case R_TILE_IMM16_X1_HA:
            value = (value + 0x8000) >> 16;
            /*FALLTHROUGH*/
        case R_TILE_IMM16_X1_LO:
            MUNGE(create_Imm16_X1);
            break;
        case R_TILE_JOFFLONG_X1:
            value -= (unsigned long) location;  /* pc-relative */
            value = (long) value >> 3;     /* count by instrs */
            MUNGE(create_JOffLong_X1);
            break;
#else
        case R_TILEGX_64:
            *location = value;
            break;
        case R_TILEGX_IMM16_X0_HW2_LAST:
            if (!validate_hw2_last(value, me))
                return -ENOEXEC;
            value >>= 16;
            /*FALLTHROUGH*/
        case R_TILEGX_IMM16_X0_HW1:
            value >>= 16;
            /*FALLTHROUGH*/
        case R_TILEGX_IMM16_X0_HW0:
            MUNGE(create_Imm16_X0);
            break;
        case R_TILEGX_IMM16_X1_HW2_LAST:
            if (!validate_hw2_last(value, me))
                return -ENOEXEC;
            value >>= 16;
            /*FALLTHROUGH*/
        case R_TILEGX_IMM16_X1_HW1:
            value >>= 16;
            /*FALLTHROUGH*/
        case R_TILEGX_IMM16_X1_HW0:
            MUNGE(create_Imm16_X1);
            break;
        case R_TILEGX_JUMPOFF_X1:
            value -= (unsigned long) location;  /* pc-relative */
            value = (long) value >> 3;     /* count by instrs */
            if (!validate_jumpoff(value)) {
                pr_warning("module %s: Out of range jump to"
                       " %#llx at %#llx (%p)\n", me->name,
                       sym->st_value + rel[i].r_addend,
                       rel[i].r_offset, location);
                return -ENOEXEC;
            }
            MUNGE(create_JumpOff_X1);
            break;
#endif

#undef MUNGE

        default:
            pr_err("module %s: Unknown relocation: %d\n",
                   me->name, (int) ELF_R_TYPE(rel[i].r_info));
            return -ENOEXEC;
        }
    }
    return 0;
}