dump: add API to write dump pages (d12f57ec) · Commits · SUMMER2020 / students / proj-2021291

dump.c

+231 −0

Original line number	Diff line number	Diff line
		@@ -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;

include/sysemu/dump.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -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);