Re: [Qemu-devel] [PATCH v5 5/9] dump: add API to write dump header

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, Jul 09, 2013 at 03:30:10PM +0800, Qiao Nuohan wrote:
> +/* write common header, sub header and elf note to vmcore */
> +static int create_header32(DumpState *s)
> +{
> +    int ret = 0;
> +    DiskDumpHeader32 *dh;
> +    KdumpSubHeader32 *kh;
> +    size_t size;
> +
> +    /* write common header, the version of kdump-compressed format is 5th */
> +    size = sizeof(DiskDumpHeader32);
> +    dh = g_malloc0(size);
> +
> +    strncpy(dh->signature, KDUMP_SIGNATURE, strlen(KDUMP_SIGNATURE));
> +    dh->header_version = 5;
> +    dh->block_size = s->page_size;
> +    dh->sub_hdr_size = sizeof(struct KdumpSubHeader32) + s->note_size;
> +    dh->sub_hdr_size = divideup(dh->sub_hdr_size, dh->block_size);
> +    dh->max_mapnr = s->max_mapnr;
> +    dh->nr_cpus = s->nr_cpus;
> +    dh->bitmap_blocks = divideup(s->len_dump_bitmap, s->page_size);
> +    memcpy(&(dh->utsname.machine), "i686", 4);
> +
> +    if (write_buffer(s->fd, s->flag_flatten, 0, dh, size) < 0) {
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    /* write sub header */
> +    size = sizeof(KdumpSubHeader32);
> +    kh = g_malloc0(size);
> +
> +    kh->phys_base = PHYS_BASE;
> +    kh->dump_level = DUMP_LEVEL;
> +
> +    kh->offset_note = DISKDUMP_HEADER_BLOCKS * dh->block_size + size;
> +    kh->note_size = s->note_size;
> +
> +    if (write_buffer(s->fd, s->flag_flatten, dh->block_size, kh, size) < 0) {
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    /* write note */
> +    s->note_buf = g_malloc(s->note_size);
> +    s->note_buf_offset = 0;
> +
> +    /* use s->note_buf to store notes temporarily */
> +    if (write_elf32_notes(buf_write_note, s) < 0) {
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    if (write_buffer(s->fd, s->flag_flatten, kh->offset_note, s->note_buf,
> +                     s->note_size) < 0) {
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    /* get offset of dump_bitmap */
> +    s->offset_dump_bitmap = (DISKDUMP_HEADER_BLOCKS + dh->sub_hdr_size) *
> +                             dh->block_size;
> +
> +    /* get offset of page */
> +    s->offset_page = (DISKDUMP_HEADER_BLOCKS + dh->sub_hdr_size +
> +                      dh->bitmap_blocks) * dh->block_size;
> +
> +out:
> +    g_free(dh);
> +    g_free(kh);
> +    g_free(s->note_buf);

These variables must be initialized to NULL so that an early goto out
does not access uninitialized memory.

> +
> +    return ret;
> +}
> +
> +/* write common header, sub header and elf note to vmcore */
> +static int create_header64(DumpState *s)
> +{
> +    int ret = 0;
> +    DiskDumpHeader64 *dh;
> +    KdumpSubHeader64 *kh;

Same here.

> diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
> index 81cbaa8..54ae4e5 100644
> --- a/include/sysemu/dump.h
> +++ b/include/sysemu/dump.h
> @@ -20,6 +20,14 @@
>  #define VERSION_FLAT_HEADER         (1)    /* version of flattened format */
>  #define END_FLAG_FLAT_HEADER        (-1)
>  
> +#define KDUMP_SIGNATURE             "KDUMP   "
> +#define SIG_LEN                     (sizeof(KDUMP_SIGNATURE) - 1)
> +#define PHYS_BASE                   (0)
> +#define DUMP_LEVEL                  (1)
> +#define DISKDUMP_HEADER_BLOCKS      (1)
> +
> +#define divideup(x, y)              (((x) + ((y) - 1)) / (y))

Please use QEMU's DIV_ROUND_UP().