Re: [Qemu-devel] [PATCH v8 08/13] dump: add API to write dump header

[Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>]

On 01/28/2014 10:22 AM, qiaonuohan wrote:
> the functions are used to write header of kdump-compressed format to vmcore.
> Header of kdump-compressed format includes:
> 1. common header: DiskDumpHeader32 / DiskDumpHeader64
> 2. sub header: KdumpSubHeader32 / KdumpSubHeader64
> 3. extra information: only elf notes here
>
> Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> ---
>   dump.c                |  223 +++++++++++++++++++++++++++++++++++++++++++++++++
>   include/sysemu/dump.h |   96 +++++++++++++++++++++
>   2 files changed, 319 insertions(+), 0 deletions(-)
>
> diff --git a/dump.c b/dump.c
> index 3a1944e..4b2799f 100644
> --- a/dump.c
> +++ b/dump.c
> @@ -778,6 +778,229 @@ static int buf_write_note(const void *buf, size_t size, void *opaque)
>       return 0;
>   }
>
> +/* write common header, sub header and elf note to vmcore */
> +static int create_header32(DumpState *s)
> +{
> +    int ret = 0;
> +    DiskDumpHeader32 *dh = NULL;
> +    KdumpSubHeader32 *kh = NULL;
> +    size_t size;
> +    int endian = s->dump_info.d_endian;
> +    uint32_t block_size;
> +    uint32_t sub_hdr_size;
> +    uint32_t bitmap_blocks;
> +    uint32_t status = 0;
> +    uint64_t offset_note;
> +
> +    /* write common header, the version of kdump-compressed format is 6th */
> +    size = sizeof(DiskDumpHeader32);
> +    dh = g_malloc0(size);
> +
> +    strncpy(dh->signature, KDUMP_SIGNATURE, strlen(KDUMP_SIGNATURE));
> +    dh->header_version = cpu_convert_to_target32(6, endian);
> +    block_size = s->page_size;
> +    dh->block_size = cpu_convert_to_target32(block_size, endian);
> +    sub_hdr_size = sizeof(struct KdumpSubHeader32) + s->note_size;
> +    sub_hdr_size = DIV_ROUND_UP(sub_hdr_size, block_size);
> +    dh->sub_hdr_size = cpu_convert_to_target32(sub_hdr_size, endian);
> +    /* dh->max_mapnr may be truncated, full 64bit is in kh.max_mapnr_64 */
> +    dh->max_mapnr = cpu_convert_to_target32(MIN(s->max_mapnr, UINT_MAX),
> +                                            endian);
> +    dh->nr_cpus = cpu_convert_to_target32(s->nr_cpus, endian);
> +    bitmap_blocks = DIV_ROUND_UP(s->len_dump_bitmap, block_size) * 2;
> +    dh->bitmap_blocks = cpu_convert_to_target32(bitmap_blocks, endian);
> +    memcpy(&(dh->utsname.machine), "i686", 4);
> +

In my opinion, it's not a right thing to hardcode the architecture in
arch-independent module dump.c

you hardcode it here in create_header32 routine by

	memcpy(&(dh->utsname.machine), "i686", 4);

and in create_header64 routine by

	memcpy(&(dh->utsname.machine), "x86_64", 6);

Besides that you code actually can work on s390x arch. IMHO, target
arch should be coded here.

Maybe you could make use of this function: cpu_to_uname_machine.



> +    if (s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) {
> +        status |= DUMP_DH_COMPRESSED_ZLIB;
> +    }
> +#ifdef CONFIG_LZO
> +    if (s->flag_compress & DUMP_DH_COMPRESSED_LZO) {
> +        status |= DUMP_DH_COMPRESSED_LZO;
> +    }
> +#endif
> +#ifdef CONFIG_SNAPPY
> +    if (s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) {
> +        status |= DUMP_DH_COMPRESSED_SNAPPY;
> +    }
> +#endif
> +    dh->status = cpu_convert_to_target32(status, endian);
> +
> +    if (write_buffer(s->fd, 0, dh, size) < 0) {
> +        dump_error(s, "dump: failed to write disk dump header.\n");
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    /* write sub header */
> +    size = sizeof(KdumpSubHeader32);
> +    kh = g_malloc0(size);
> +
> +    /* 64bit max_mapnr_64 */
> +    kh->max_mapnr_64 = cpu_convert_to_target64(s->max_mapnr, endian);
> +    kh->phys_base = cpu_convert_to_target32(PHYS_BASE, endian);
> +    kh->dump_level = cpu_convert_to_target32(DUMP_LEVEL, endian);
> +
> +    offset_note = DISKDUMP_HEADER_BLOCKS * block_size + size;
> +    kh->offset_note = cpu_convert_to_target64(offset_note, endian);
> +    kh->note_size = cpu_convert_to_target32(s->note_size, endian);
> +
> +    if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
> +                     block_size, kh, size) < 0) {
> +        dump_error(s, "dump: failed to write kdump sub header.\n");
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    /* write note */
> +    s->note_buf = g_malloc0(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, offset_note, s->note_buf,
> +                     s->note_size) < 0) {
> +        dump_error(s, "dump: failed to write notes");
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    /* get offset of dump_bitmap */
> +    s->offset_dump_bitmap = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size) *
> +                             block_size;
> +
> +    /* get offset of page */
> +    s->offset_page = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size + bitmap_blocks) *
> +                     block_size;
> +
> +out:
> +    g_free(dh);
> +    g_free(kh);
> +    g_free(s->note_buf);
> +
> +    return ret;
> +}
> +
> +/* write common header, sub header and elf note to vmcore */
> +static int create_header64(DumpState *s)
> +{
> +    int ret = 0;
> +    DiskDumpHeader64 *dh = NULL;
> +    KdumpSubHeader64 *kh = NULL;
> +    size_t size;
> +    int endian = s->dump_info.d_endian;
> +    uint32_t block_size;
> +    uint32_t sub_hdr_size;
> +    uint32_t bitmap_blocks;
> +    uint32_t status = 0;
> +    uint64_t offset_note;
> +
> +    /* write common header, the version of kdump-compressed format is 6th */
> +    size = sizeof(DiskDumpHeader64);
> +    dh = g_malloc0(size);
> +
> +    strncpy(dh->signature, KDUMP_SIGNATURE, strlen(KDUMP_SIGNATURE));
> +    dh->header_version = cpu_convert_to_target32(6, endian);
> +    block_size = s->page_size;
> +    dh->block_size = cpu_convert_to_target32(block_size, endian);
> +    sub_hdr_size = sizeof(struct KdumpSubHeader64) + s->note_size;
> +    sub_hdr_size = DIV_ROUND_UP(sub_hdr_size, block_size);
> +    dh->sub_hdr_size = cpu_convert_to_target32(sub_hdr_size, endian);
> +    /* dh->max_mapnr may be truncated, full 64bit is in kh.max_mapnr_64 */
> +    dh->max_mapnr = cpu_convert_to_target32(MIN(s->max_mapnr, UINT_MAX),
> +                                            endian);
> +    dh->nr_cpus = cpu_convert_to_target32(s->nr_cpus, endian);
> +    bitmap_blocks = DIV_ROUND_UP(s->len_dump_bitmap, block_size) * 2;
> +    dh->bitmap_blocks = cpu_convert_to_target32(bitmap_blocks, endian);
> +    memcpy(&(dh->utsname.machine), "x86_64", 6);
dito

hardcoding the architecture should be fixed, IMHO (see above):

	memcpy(&(dh->utsname.machine), "x86_64", 6);

> +
> +    if (s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) {
> +        status |= DUMP_DH_COMPRESSED_ZLIB;
> +    }
> +#ifdef CONFIG_LZO
> +    if (s->flag_compress & DUMP_DH_COMPRESSED_LZO) {
> +        status |= DUMP_DH_COMPRESSED_LZO;
> +    }
> +#endif
> +#ifdef CONFIG_SNAPPY
> +    if (s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) {
> +        status |= DUMP_DH_COMPRESSED_SNAPPY;
> +    }
> +#endif
> +    dh->status = cpu_convert_to_target32(status, endian);
> +
> +    if (write_buffer(s->fd, 0, dh, size) < 0) {
> +        dump_error(s, "dump: failed to write disk dump header.\n");
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    /* write sub header */
> +    size = sizeof(KdumpSubHeader64);
> +    kh = g_malloc0(size);
> +
> +    /* 64bit max_mapnr_64 */
> +    kh->max_mapnr_64 = cpu_convert_to_target64(s->max_mapnr, endian);
> +    kh->phys_base = cpu_convert_to_target64(PHYS_BASE, endian);
> +    kh->dump_level = cpu_convert_to_target32(DUMP_LEVEL, endian);
> +
> +    offset_note = DISKDUMP_HEADER_BLOCKS * block_size + size;
> +    kh->offset_note = cpu_convert_to_target64(offset_note, endian);
> +    kh->note_size = cpu_convert_to_target64(s->note_size, endian);
> +
> +    if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
> +                     block_size, kh, size) < 0) {
> +        dump_error(s, "dump: failed to write kdump sub header.\n");
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    /* write note */
> +    s->note_buf = g_malloc0(s->note_size);
> +    s->note_buf_offset = 0;
> +
> +    /* use s->note_buf to store notes temporarily */
> +    if (write_elf64_notes(buf_write_note, s) < 0) {
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    if (write_buffer(s->fd, offset_note, s->note_buf,
> +                     s->note_size) < 0) {
> +        dump_error(s, "dump: failed to write notes");
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    /* get offset of dump_bitmap */
> +    s->offset_dump_bitmap = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size) *
> +                             block_size;
> +
> +    /* get offset of page */
> +    s->offset_page = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size + bitmap_blocks) *
> +                     block_size;
> +
> +out:
> +    g_free(dh);
> +    g_free(kh);
> +    g_free(s->note_buf);
> +
> +    return ret;
> +}
> +
> +static int write_dump_header(DumpState *s)
> +{
> +    if (s->dump_info.d_machine == EM_386) {
> +        return create_header32(s);
> +    } else {
> +        return create_header64(s);
> +    }
> +}
> +
>   static ram_addr_t get_start_block(DumpState *s)
>   {
>       GuestPhysBlock *block;
> diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
> index 995bf47..dfee238 100644
> --- a/include/sysemu/dump.h
> +++ b/include/sysemu/dump.h
> @@ -27,6 +27,19 @@
>   #define pfn_to_paddr(X, page_shift) \
>       (((unsigned long long)(X) + ARCH_PFN_OFFSET) << (page_shift))
>
> +/*
> + * flag for compressed format
> + */
> +#define DUMP_DH_COMPRESSED_ZLIB     (0x1)
> +#define DUMP_DH_COMPRESSED_LZO      (0x2)
> +#define DUMP_DH_COMPRESSED_SNAPPY   (0x4)
> +
> +#define KDUMP_SIGNATURE             "KDUMP   "
> +#define SIG_LEN                     (sizeof(KDUMP_SIGNATURE) - 1)
> +#define PHYS_BASE                   (0)
> +#define DUMP_LEVEL                  (1)
> +#define DISKDUMP_HEADER_BLOCKS      (1)
> +
>   typedef struct ArchDumpInfo {
>       int d_machine;  /* Architecture */
>       int d_endian;   /* ELFDATA2LSB or ELFDATA2MSB */
> @@ -44,6 +57,89 @@ typedef struct QEMU_PACKED MakedumpfileDataHeader {
>       int64_t buf_size;
>   } MakedumpfileDataHeader;
>
> +typedef struct QEMU_PACKED NewUtsname {
> +    char sysname[65];
> +    char nodename[65];
> +    char release[65];
> +    char version[65];
> +    char machine[65];
> +    char domainname[65];
> +} NewUtsname;
> +
> +typedef struct QEMU_PACKED DiskDumpHeader32 {
> +    char signature[SIG_LEN];        /* = "KDUMP   " */
> +    uint32_t header_version;        /* Dump header version */
> +    NewUtsname utsname;             /* copy of system_utsname */
> +    char timestamp[10];             /* Time stamp */
> +    uint32_t status;                /* Above flags */
> +    uint32_t block_size;            /* Size of a block in byte */
> +    uint32_t sub_hdr_size;          /* Size of arch dependent header in block */
> +    uint32_t bitmap_blocks;         /* Size of Memory bitmap in block */
> +    uint32_t max_mapnr;             /* = max_mapnr ,
> +                                       obsoleted in header_version 6 */
> +    uint32_t total_ram_blocks;      /* Number of blocks should be written */
> +    uint32_t device_blocks;         /* Number of total blocks in dump device */
> +    uint32_t written_blocks;        /* Number of written blocks */
> +    uint32_t current_cpu;           /* CPU# which handles dump */
> +    uint32_t nr_cpus;               /* Number of CPUs */
> +} DiskDumpHeader32;
> +
> +typedef struct QEMU_PACKED DiskDumpHeader64 {
> +    char signature[SIG_LEN];        /* = "KDUMP   " */
> +    uint32_t header_version;        /* Dump header version */
> +    NewUtsname utsname;             /* copy of system_utsname */
> +    char timestamp[22];             /* Time stamp */
> +    uint32_t status;                /* Above flags */
> +    uint32_t block_size;            /* Size of a block in byte */
> +    uint32_t sub_hdr_size;          /* Size of arch dependent header in block */
> +    uint32_t bitmap_blocks;         /* Size of Memory bitmap in block */
> +    uint32_t max_mapnr;             /* = max_mapnr,
> +                                       obsoleted in header_version 6 */
> +    uint32_t total_ram_blocks;      /* Number of blocks should be written */
> +    uint32_t device_blocks;         /* Number of total blocks in dump device */
> +    uint32_t written_blocks;        /* Number of written blocks */
> +    uint32_t current_cpu;           /* CPU# which handles dump */
> +    uint32_t nr_cpus;               /* Number of CPUs */
> +} DiskDumpHeader64;
> +
> +typedef struct QEMU_PACKED KdumpSubHeader32 {
> +    uint32_t phys_base;
> +    uint32_t dump_level;            /* header_version 1 and later */
> +    uint32_t split;                 /* header_version 2 and later */
> +    uint32_t start_pfn;             /* header_version 2 and later,
> +                                       obsoleted in header_version 6 */
> +    uint32_t end_pfn;               /* header_version 2 and later,
> +                                       obsoleted in header_version 6 */
> +    uint64_t offset_vmcoreinfo;     /* header_version 3 and later */
> +    uint32_t size_vmcoreinfo;       /* header_version 3 and later */
> +    uint64_t offset_note;           /* header_version 4 and later */
> +    uint32_t note_size;             /* header_version 4 and later */
> +    uint64_t offset_eraseinfo;      /* header_version 5 and later */
> +    uint32_t size_eraseinfo;        /* header_version 5 and later */
> +    uint64_t start_pfn_64;          /* header_version 6 and later */
> +    uint64_t end_pfn_64;            /* header_version 6 and later */
> +    uint64_t max_mapnr_64;          /* header_version 6 and later */
> +} KdumpSubHeader32;
> +
> +typedef struct QEMU_PACKED KdumpSubHeader64 {
> +    uint64_t phys_base;
> +    uint32_t dump_level;            /* header_version 1 and later */
> +    uint32_t split;                 /* header_version 2 and later */
> +    uint64_t start_pfn;             /* header_version 2 and later,
> +                                       obsoleted in header_version 6 */
> +    uint64_t end_pfn;               /* header_version 2 and later,
> +                                       obsoleted in header_version 6 */
> +    uint64_t offset_vmcoreinfo;     /* header_version 3 and later */
> +    uint64_t size_vmcoreinfo;       /* header_version 3 and later */
> +    uint64_t offset_note;           /* header_version 4 and later */
> +    uint64_t note_size;             /* header_version 4 and later */
> +    uint64_t offset_eraseinfo;      /* header_version 5 and later */
> +    uint64_t size_eraseinfo;        /* header_version 5 and later */
> +    uint64_t start_pfn_64;          /* header_version 6 and later */
> +    uint64_t end_pfn_64;            /* header_version 6 and later */
> +    uint64_t max_mapnr_64;          /* header_version 6 and later */
> +} KdumpSubHeader64;
> +
>   struct GuestPhysBlockList; /* memory_mapping.h */
>   int cpu_get_dump_info(ArchDumpInfo *info,
>                         const struct GuestPhysBlockList *guest_phys_blocks);
>