coredump.c

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/*
 * SPU core dump code
 *
 * (C) Copyright 2006 IBM Corp.
 *
 * Author: Dwayne Grant McConnell <[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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/elf.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/fs.h>
#include <linux/gfp.h>
#include <linux/list.h>
#include <linux/syscalls.h>

#include <asm/uaccess.h>

#include "spufs.h"

static ssize_t do_coredump_read(int num, struct spu_context *ctx, void *buffer,
                size_t size, loff_t *off)
{
    u64 data;
    int ret;

    if (spufs_coredump_read[num].read)
        return spufs_coredump_read[num].read(ctx, buffer, size, off);

    data = spufs_coredump_read[num].get(ctx);
    ret = snprintf(buffer, size, "0x%.16llx", data);
    if (ret >= size)
        return size;
    return ++ret; /* count trailing NULL */
}

/*
 * These are the only things you should do on a core-file: use only these
 * functions to write out all the necessary info.
 */
static int spufs_dump_write(struct file *file, const void *addr, int nr, loff_t *foffset)
{
    unsigned long limit = rlimit(RLIMIT_CORE);
    ssize_t written;

    if (*foffset + nr > limit)
        return -EIO;

    written = file->f_op->write(file, addr, nr, &file->f_pos);
    *foffset += written;

    if (written != nr)
        return -EIO;

    return 0;
}

static int spufs_dump_align(struct file *file, char *buf, loff_t new_off,
                loff_t *foffset)
{
    int rc, size;

    size = min((loff_t)PAGE_SIZE, new_off - *foffset);
    memset(buf, 0, size);

    rc = 0;
    while (rc == 0 && new_off > *foffset) {
        size = min((loff_t)PAGE_SIZE, new_off - *foffset);
        rc = spufs_dump_write(file, buf, size, foffset);
    }

    return rc;
}

static int spufs_ctx_note_size(struct spu_context *ctx, int dfd)
{
    int i, sz, total = 0;
    char *name;
    char fullname[80];

    for (i = 0; spufs_coredump_read[i].name != NULL; i++) {
        name = spufs_coredump_read[i].name;
        sz = spufs_coredump_read[i].size;

        sprintf(fullname, "SPU/%d/%s", dfd, name);

        total += sizeof(struct elf_note);
        total += roundup(strlen(fullname) + 1, 4);
        total += roundup(sz, 4);
    }

    return total;
}

static int match_context(const void *v, struct file *file, unsigned fd)
{
    struct spu_context *ctx;
    if (file->f_op != &spufs_context_fops)
        return 0;
    ctx = SPUFS_I(file->f_dentry->d_inode)->i_ctx;
    if (ctx->flags & SPU_CREATE_NOSCHED)
        return 0;
    return fd + 1;
}

/*
 * The additional architecture-specific notes for Cell are various
 * context files in the spu context.
 *
 * This function iterates over all open file descriptors and sees
 * if they are a directory in spufs.  In that case we use spufs
 * internal functionality to dump them without needing to actually
 * open the files.
 */
/*
 * descriptor table is not shared, so files can't change or go away.
 */
static struct spu_context *coredump_next_context(int *fd)
{
    struct file *file;
    int n = iterate_fd(current->files, *fd, match_context, NULL);
    if (!n)
        return NULL;
    *fd = n - 1;
    file = fcheck(*fd);
    return SPUFS_I(file->f_dentry->d_inode)->i_ctx;
}

int spufs_coredump_extra_notes_size(void)
{
    struct spu_context *ctx;
    int size = 0, rc, fd;

    fd = 0;
    while ((ctx = coredump_next_context(&fd)) != NULL) {
        rc = spu_acquire_saved(ctx);
        if (rc)
            break;
        rc = spufs_ctx_note_size(ctx, fd);
        spu_release_saved(ctx);
        if (rc < 0)
            break;

        size += rc;

        /* start searching the next fd next time */
        fd++;
    }

    return size;
}

static int spufs_arch_write_note(struct spu_context *ctx, int i,
                  struct file *file, int dfd, loff_t *foffset)
{
    loff_t pos = 0;
    int sz, rc, nread, total = 0;
    const int bufsz = PAGE_SIZE;
    char *name;
    char fullname[80], *buf;
    struct elf_note en;

    buf = (void *)get_zeroed_page(GFP_KERNEL);
    if (!buf)
        return -ENOMEM;

    name = spufs_coredump_read[i].name;
    sz = spufs_coredump_read[i].size;

    sprintf(fullname, "SPU/%d/%s", dfd, name);
    en.n_namesz = strlen(fullname) + 1;
    en.n_descsz = sz;
    en.n_type = NT_SPU;

    rc = spufs_dump_write(file, &en, sizeof(en), foffset);
    if (rc)
        goto out;

    rc = spufs_dump_write(file, fullname, en.n_namesz, foffset);
    if (rc)
        goto out;

    rc = spufs_dump_align(file, buf, roundup(*foffset, 4), foffset);
    if (rc)
        goto out;

    do {
        nread = do_coredump_read(i, ctx, buf, bufsz, &pos);
        if (nread > 0) {
            rc = spufs_dump_write(file, buf, nread, foffset);
            if (rc)
                goto out;
            total += nread;
        }
    } while (nread == bufsz && total < sz);

    if (nread < 0) {
        rc = nread;
        goto out;
    }

    rc = spufs_dump_align(file, buf, roundup(*foffset - total + sz, 4),
                  foffset);

out:
    free_page((unsigned long)buf);
    return rc;
}

int spufs_coredump_extra_notes_write(struct file *file, loff_t *foffset)
{
    struct spu_context *ctx;
    int fd, j, rc;

    fd = 0;
    while ((ctx = coredump_next_context(&fd)) != NULL) {
        rc = spu_acquire_saved(ctx);
        if (rc)
            return rc;

        for (j = 0; spufs_coredump_read[j].name != NULL; j++) {
            rc = spufs_arch_write_note(ctx, j, file, fd, foffset);
            if (rc) {
                spu_release_saved(ctx);
                return rc;
            }
        }

        spu_release_saved(ctx);

        /* start searching the next fd next time */
        fd++;
    }

    return 0;
}