vma_map.c

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/*
 * Cell Broadband Engine OProfile Support
 *
 * (C) Copyright IBM Corporation 2006
 *
 * Author: Maynard Johnson <[email protected]>
 *
 * 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.
 */

/* The code in this source file is responsible for generating
 * vma-to-fileOffset maps for both overlay and non-overlay SPU
 * applications.
 */

#include <linux/mm.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <linux/elf.h>
#include <linux/slab.h>
#include "pr_util.h"


void vma_map_free(struct vma_to_fileoffset_map *map)
{
    while (map) {
        struct vma_to_fileoffset_map *next = map->next;
        kfree(map);
        map = next;
    }
}

unsigned int
vma_map_lookup(struct vma_to_fileoffset_map *map, unsigned int vma,
           const struct spu *aSpu, int *grd_val)
{
    /*
     * Default the offset to the physical address + a flag value.
     * Addresses of dynamically generated code can't be found in the vma
     * map.  For those addresses the flagged value will be sent on to
     * the user space tools so they can be reported rather than just
     * thrown away.
     */
    u32 offset = 0x10000000 + vma;
    u32 ovly_grd;

    for (; map; map = map->next) {
        if (vma < map->vma || vma >= map->vma + map->size)
            continue;

        if (map->guard_ptr) {
            ovly_grd = *(u32 *)(aSpu->local_store + map->guard_ptr);
            if (ovly_grd != map->guard_val)
                continue;
            *grd_val = ovly_grd;
        }
        offset = vma - map->vma + map->offset;
        break;
    }

    return offset;
}

static struct vma_to_fileoffset_map *
vma_map_add(struct vma_to_fileoffset_map *map, unsigned int vma,
        unsigned int size, unsigned int offset, unsigned int guard_ptr,
        unsigned int guard_val)
{
    struct vma_to_fileoffset_map *new =
        kzalloc(sizeof(struct vma_to_fileoffset_map), GFP_KERNEL);
    if (!new) {
        printk(KERN_ERR "SPU_PROF: %s, line %d: malloc failed\n",
               __func__, __LINE__);
        vma_map_free(map);
        return NULL;
    }

    new->next = map;
    new->vma = vma;
    new->size = size;
    new->offset = offset;
    new->guard_ptr = guard_ptr;
    new->guard_val = guard_val;

    return new;
}


/* Parse SPE ELF header and generate a list of vma_maps.
 * A pointer to the first vma_map in the generated list
 * of vma_maps is returned.  */
struct vma_to_fileoffset_map *create_vma_map(const struct spu *aSpu,
                         unsigned long __spu_elf_start)
{
    static const unsigned char expected[EI_PAD] = {
        [EI_MAG0] = ELFMAG0,
        [EI_MAG1] = ELFMAG1,
        [EI_MAG2] = ELFMAG2,
        [EI_MAG3] = ELFMAG3,
        [EI_CLASS] = ELFCLASS32,
        [EI_DATA] = ELFDATA2MSB,
        [EI_VERSION] = EV_CURRENT,
        [EI_OSABI] = ELFOSABI_NONE
    };

    int grd_val;
    struct vma_to_fileoffset_map *map = NULL;
    void __user *spu_elf_start = (void __user *)__spu_elf_start;
    struct spu_overlay_info ovly;
    unsigned int overlay_tbl_offset = -1;
    Elf32_Phdr __user *phdr_start;
    Elf32_Shdr __user *shdr_start;
    Elf32_Ehdr ehdr;
    Elf32_Phdr phdr;
    Elf32_Shdr shdr, shdr_str;
    Elf32_Sym sym;
    int i, j;
    char name[32];

    unsigned int ovly_table_sym = 0;
    unsigned int ovly_buf_table_sym = 0;
    unsigned int ovly_table_end_sym = 0;
    unsigned int ovly_buf_table_end_sym = 0;
    struct spu_overlay_info __user *ovly_table;
    unsigned int n_ovlys;

    /* Get and validate ELF header.  */

    if (copy_from_user(&ehdr, spu_elf_start, sizeof (ehdr)))
        goto fail;

    if (memcmp(ehdr.e_ident, expected, EI_PAD) != 0) {
        printk(KERN_ERR "SPU_PROF: "
               "%s, line %d: Unexpected e_ident parsing SPU ELF\n",
               __func__, __LINE__);
        goto fail;
    }
    if (ehdr.e_machine != EM_SPU) {
        printk(KERN_ERR "SPU_PROF: "
               "%s, line %d: Unexpected e_machine parsing SPU ELF\n",
               __func__,  __LINE__);
        goto fail;
    }
    if (ehdr.e_type != ET_EXEC) {
        printk(KERN_ERR "SPU_PROF: "
               "%s, line %d: Unexpected e_type parsing SPU ELF\n",
               __func__, __LINE__);
        goto fail;
    }
    phdr_start = spu_elf_start + ehdr.e_phoff;
    shdr_start = spu_elf_start + ehdr.e_shoff;

    /* Traverse program headers.  */
    for (i = 0; i < ehdr.e_phnum; i++) {
        if (copy_from_user(&phdr, phdr_start + i, sizeof(phdr)))
            goto fail;

        if (phdr.p_type != PT_LOAD)
            continue;
        if (phdr.p_flags & (1 << 27))
            continue;

        map = vma_map_add(map, phdr.p_vaddr, phdr.p_memsz,
                  phdr.p_offset, 0, 0);
        if (!map)
            goto fail;
    }

    pr_debug("SPU_PROF: Created non-overlay maps\n");
    /* Traverse section table and search for overlay-related symbols.  */
    for (i = 0; i < ehdr.e_shnum; i++) {
        if (copy_from_user(&shdr, shdr_start + i, sizeof(shdr)))
            goto fail;

        if (shdr.sh_type != SHT_SYMTAB)
            continue;
        if (shdr.sh_entsize != sizeof (sym))
            continue;

        if (copy_from_user(&shdr_str,
                   shdr_start + shdr.sh_link,
                   sizeof(shdr)))
            goto fail;

        if (shdr_str.sh_type != SHT_STRTAB)
            goto fail;

        for (j = 0; j < shdr.sh_size / sizeof (sym); j++) {
            if (copy_from_user(&sym, spu_elf_start +
                         shdr.sh_offset +
                         j * sizeof (sym),
                       sizeof (sym)))
                goto fail;

            if (copy_from_user(name, 
                       spu_elf_start + shdr_str.sh_offset +
                       sym.st_name,
                       20))
                goto fail;

            if (memcmp(name, "_ovly_table", 12) == 0)
                ovly_table_sym = sym.st_value;
            if (memcmp(name, "_ovly_buf_table", 16) == 0)
                ovly_buf_table_sym = sym.st_value;
            if (memcmp(name, "_ovly_table_end", 16) == 0)
                ovly_table_end_sym = sym.st_value;
            if (memcmp(name, "_ovly_buf_table_end", 20) == 0)
                ovly_buf_table_end_sym = sym.st_value;
        }
    }

    /* If we don't have overlays, we're done.  */
    if (ovly_table_sym == 0 || ovly_buf_table_sym == 0
        || ovly_table_end_sym == 0 || ovly_buf_table_end_sym == 0) {
        pr_debug("SPU_PROF: No overlay table found\n");
        goto out;
    } else {
        pr_debug("SPU_PROF: Overlay table found\n");
    }

    /* The _ovly_table symbol represents a table with one entry
     * per overlay section.  The _ovly_buf_table symbol represents
     * a table with one entry per overlay region.
     * The struct spu_overlay_info gives the structure of the _ovly_table
     * entries.  The structure of _ovly_table_buf is simply one
     * u32 word per entry.
     */
    overlay_tbl_offset = vma_map_lookup(map, ovly_table_sym,
                        aSpu, &grd_val);
    if (overlay_tbl_offset > 0x10000000) {
        printk(KERN_ERR "SPU_PROF: "
               "%s, line %d: Error finding SPU overlay table\n",
               __func__, __LINE__);
        goto fail;
    }
    ovly_table = spu_elf_start + overlay_tbl_offset;

    n_ovlys = (ovly_table_end_sym -
           ovly_table_sym) / sizeof (ovly);

    /* Traverse overlay table.  */
    for (i = 0; i < n_ovlys; i++) {
        if (copy_from_user(&ovly, ovly_table + i, sizeof (ovly)))
            goto fail;

        /* The ovly.vma/size/offset arguments are analogous to the same
         * arguments used above for non-overlay maps.  The final two
         * args are referred to as the guard pointer and the guard
         * value.
         * The guard pointer is an entry in the _ovly_buf_table,
         * computed using ovly.buf as the index into the table.  Since
         * ovly.buf values begin at '1' to reference the first (or 0th)
         * entry in the _ovly_buf_table, the computation subtracts 1
         * from ovly.buf.
         * The guard value is stored in the _ovly_buf_table entry and
         * is an index (starting at 1) back to the _ovly_table entry
         * that is pointing at this _ovly_buf_table entry.  So, for
         * example, for an overlay scenario with one overlay segment
         * and two overlay sections:
         *  - Section 1 points to the first entry of the
         *    _ovly_buf_table, which contains a guard value
         *    of '1', referencing the first (index=0) entry of
         *    _ovly_table.
         *  - Section 2 points to the second entry of the
         *    _ovly_buf_table, which contains a guard value
         *    of '2', referencing the second (index=1) entry of
         *    _ovly_table.
         */
        map = vma_map_add(map, ovly.vma, ovly.size, ovly.offset,
                  ovly_buf_table_sym + (ovly.buf-1) * 4, i+1);
        if (!map)
            goto fail;
    }
    goto out;

 fail:
    map = NULL;
 out:
    return map;
}