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coredump.c

/*
 * SPU core dump code
 *
 * (C) Copyright 2006 IBM Corp.
 *
 * Author: Dwayne Grant McConnell <decimal@us.ibm.com>
 *
 * 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/list.h>
#include <linux/module.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%.16lx", 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 = current->signal->rlim[RLIMIT_CORE].rlim_cur;
      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;
}

/*
 * 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.
 */
static struct spu_context *coredump_next_context(int *fd)
{
      struct fdtable *fdt = files_fdtable(current->files);
      struct file *file;
      struct spu_context *ctx = NULL;

      for (; *fd < fdt->max_fds; (*fd)++) {
            if (!FD_ISSET(*fd, fdt->open_fds))
                  continue;

            file = fcheck(*fd);

            if (!file || file->f_op != &spufs_context_fops)
                  continue;

            ctx = SPUFS_I(file->f_dentry->d_inode)->i_ctx;
            if (ctx->flags & SPU_CREATE_NOSCHED)
                  continue;

            break;
      }

      return 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;
}

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