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dump: add API to write dump pages 

functions are used to write page to vmcore. vmcore is written page by page.
page desc is used to store the information of a page, including a page's size,
offset, compression format, etc.

Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
This commit is contained in:
qiaonuohan 2014-02-18 14:11:35 +08:00 committed by Luiz Capitulino
parent 64cfba6a47
commit d12f57ec66
2 changed files with 238 additions and 0 deletions
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231
dump.c
View File

@ -25,6 +25,14 @@
#include "qapi/error.h"
#include "qmp-commands.h"
#include <zlib.h>
#ifdef CONFIG_LZO
#include <lzo/lzo1x.h>
#endif
#ifdef CONFIG_SNAPPY
#include <snappy-c.h>
#endif
static uint16_t cpu_convert_to_target16(uint16_t val, int endian)
{
if (endian == ELFDATA2LSB) {
@ -1212,6 +1220,229 @@ static void free_data_cache(DataCache *data_cache)
g_free(data_cache->buf);
}
static size_t get_len_buf_out(size_t page_size, uint32_t flag_compress)
{
size_t len_buf_out_zlib, len_buf_out_lzo, len_buf_out_snappy;
size_t len_buf_out;
/* init buf_out */
len_buf_out_zlib = len_buf_out_lzo = len_buf_out_snappy = 0;
/* buf size for zlib */
len_buf_out_zlib = compressBound(page_size);
/* buf size for lzo */
#ifdef CONFIG_LZO
if (flag_compress & DUMP_DH_COMPRESSED_LZO) {
if (lzo_init() != LZO_E_OK) {
/* return 0 to indicate lzo is unavailable */
return 0;
}
}
/*
* LZO will expand incompressible data by a little amount. please check the
* following URL to see the expansion calculation:
* http://www.oberhumer.com/opensource/lzo/lzofaq.php
*/
len_buf_out_lzo = page_size + page_size / 16 + 64 + 3;
#endif
#ifdef CONFIG_SNAPPY
/* buf size for snappy */
len_buf_out_snappy = snappy_max_compressed_length(page_size);
#endif
/* get the biggest that can store all kinds of compressed page */
len_buf_out = MAX(len_buf_out_zlib,
MAX(len_buf_out_lzo, len_buf_out_snappy));
return len_buf_out;
}
/*
* check if the page is all 0
*/
static inline bool is_zero_page(const uint8_t *buf, size_t page_size)
{
return buffer_is_zero(buf, page_size);
}
static int write_dump_pages(DumpState *s)
{
int ret = 0;
DataCache page_desc, page_data;
size_t len_buf_out, size_out;
#ifdef CONFIG_LZO
lzo_bytep wrkmem = NULL;
#endif
uint8_t *buf_out = NULL;
off_t offset_desc, offset_data;
PageDescriptor pd, pd_zero;
uint8_t *buf;
int endian = s->dump_info.d_endian;
GuestPhysBlock *block_iter = NULL;
uint64_t pfn_iter;
/* get offset of page_desc and page_data in dump file */
offset_desc = s->offset_page;
offset_data = offset_desc + sizeof(PageDescriptor) * s->num_dumpable;
prepare_data_cache(&page_desc, s, offset_desc);
prepare_data_cache(&page_data, s, offset_data);
/* prepare buffer to store compressed data */
len_buf_out = get_len_buf_out(s->page_size, s->flag_compress);
if (len_buf_out == 0) {
dump_error(s, "dump: failed to get length of output buffer.\n");
goto out;
}
#ifdef CONFIG_LZO
wrkmem = g_malloc(LZO1X_1_MEM_COMPRESS);
#endif
buf_out = g_malloc(len_buf_out);
/*
* init zero page's page_desc and page_data, because every zero page
* uses the same page_data
*/
pd_zero.size = cpu_convert_to_target32(s->page_size, endian);
pd_zero.flags = cpu_convert_to_target32(0, endian);
pd_zero.offset = cpu_convert_to_target64(offset_data, endian);
pd_zero.page_flags = cpu_convert_to_target64(0, endian);
buf = g_malloc0(s->page_size);
ret = write_cache(&page_data, buf, s->page_size, false);
g_free(buf);
if (ret < 0) {
dump_error(s, "dump: failed to write page data(zero page).\n");
goto out;
}
offset_data += s->page_size;
/*
* dump memory to vmcore page by page. zero page will all be resided in the
* first page of page section
*/
while (get_next_page(&block_iter, &pfn_iter, &buf, s)) {
/* check zero page */
if (is_zero_page(buf, s->page_size)) {
ret = write_cache(&page_desc, &pd_zero, sizeof(PageDescriptor),
false);
if (ret < 0) {
dump_error(s, "dump: failed to write page desc.\n");
goto out;
}
} else {
/*
* not zero page, then:
* 1. compress the page
* 2. write the compressed page into the cache of page_data
* 3. get page desc of the compressed page and write it into the
* cache of page_desc
*
* only one compression format will be used here, for
* s->flag_compress is set. But when compression fails to work,
* we fall back to save in plaintext.
*/
size_out = len_buf_out;
if ((s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) &&
(compress2(buf_out, (uLongf *)&size_out, buf, s->page_size,
Z_BEST_SPEED) == Z_OK) && (size_out < s->page_size)) {
pd.flags = cpu_convert_to_target32(DUMP_DH_COMPRESSED_ZLIB,
endian);
pd.size = cpu_convert_to_target32(size_out, endian);
ret = write_cache(&page_data, buf_out, size_out, false);
if (ret < 0) {
dump_error(s, "dump: failed to write page data.\n");
goto out;
}
#ifdef CONFIG_LZO
} else if ((s->flag_compress & DUMP_DH_COMPRESSED_LZO) &&
(lzo1x_1_compress(buf, s->page_size, buf_out,
(lzo_uint *)&size_out, wrkmem) == LZO_E_OK) &&
(size_out < s->page_size)) {
pd.flags = cpu_convert_to_target32(DUMP_DH_COMPRESSED_LZO,
endian);
pd.size = cpu_convert_to_target32(size_out, endian);
ret = write_cache(&page_data, buf_out, size_out, false);
if (ret < 0) {
dump_error(s, "dump: failed to write page data.\n");
goto out;
}
#endif
#ifdef CONFIG_SNAPPY
} else if ((s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) &&
(snappy_compress((char *)buf, s->page_size,
(char *)buf_out, &size_out) == SNAPPY_OK) &&
(size_out < s->page_size)) {
pd.flags = cpu_convert_to_target32(
DUMP_DH_COMPRESSED_SNAPPY, endian);
pd.size = cpu_convert_to_target32(size_out, endian);
ret = write_cache(&page_data, buf_out, size_out, false);
if (ret < 0) {
dump_error(s, "dump: failed to write page data.\n");
goto out;
}
#endif
} else {
/*
* fall back to save in plaintext, size_out should be
* assigned to s->page_size
*/
pd.flags = cpu_convert_to_target32(0, endian);
size_out = s->page_size;
pd.size = cpu_convert_to_target32(size_out, endian);
ret = write_cache(&page_data, buf, s->page_size, false);
if (ret < 0) {
dump_error(s, "dump: failed to write page data.\n");
goto out;
}
}
/* get and write page desc here */
pd.page_flags = cpu_convert_to_target64(0, endian);
pd.offset = cpu_convert_to_target64(offset_data, endian);
offset_data += size_out;
ret = write_cache(&page_desc, &pd, sizeof(PageDescriptor), false);
if (ret < 0) {
dump_error(s, "dump: failed to write page desc.\n");
goto out;
}
}
}
ret = write_cache(&page_desc, NULL, 0, true);
if (ret < 0) {
dump_error(s, "dump: failed to sync cache for page_desc.\n");
goto out;
}
ret = write_cache(&page_data, NULL, 0, true);
if (ret < 0) {
dump_error(s, "dump: failed to sync cache for page_data.\n");
goto out;
}
out:
free_data_cache(&page_desc);
free_data_cache(&page_data);
#ifdef CONFIG_LZO
g_free(wrkmem);
#endif
g_free(buf_out);
return ret;
}
static ram_addr_t get_start_block(DumpState *s)
{
GuestPhysBlock *block;

7
include/sysemu/dump.h
View File

@ -151,6 +151,13 @@ typedef struct DataCache {
off_t offset; /* offset of the file */
} DataCache;
typedef struct QEMU_PACKED PageDescriptor {
uint64_t offset; /* the offset of the page data*/
uint32_t size; /* the size of this dump page */
uint32_t flags; /* flags */
uint64_t page_flags; /* page flags */
} PageDescriptor;
struct GuestPhysBlockList; /* memory_mapping.h */
int cpu_get_dump_info(ArchDumpInfo *info,
const struct GuestPhysBlockList *guest_phys_blocks);