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zipl/boot: Integrate zlib compression to single volume DASD dumper

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Integrate zlib DFLTCC deflate compression to single volume dasd dumper
using the existing s390 extended dump format. Compression takes place
only if DFLTCC facility is available, otherwise dump is written
uncompressed as before.

First megabyte of memory is always written uncompressed and afterwards
this area is used for zlib workspace and for the compression output buffer.
The compression takes place in chunks of data of equal size (currently 1MB)
and the offset of each compressed chunk is stored in the dump segment
header. Since existing dump segment headers of 1 page size are used, we
need to limit the maximum size of compressed dump segments.
Chunk is written uncompressed in case of compression error or if
deflate compression only makes it bigger.

Thus every chunk of data is compressed separately and can be decompressed
independently. The main reason for that is to enable zgetdump to make fast
read seeks. Otherwise, zgetdump would need to decompress a big dump segment
in the worst case to extract a single piece of data.

Put compression related functions and structures to eckd2dump_zlib.c
and eckd2dump_zlib.h

Update zipl man page with the general information of zlib compression
support.

Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Mikhail Zaslonko
2022-12-02 10:42:45 +01:00
committed by Jan Höppner
parent 0dac47cb62
commit d53bfb9201
8 changed files with 354 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
include/boot/s390.h
View File

@@ -25,6 +25,7 @@
#define STACK_FRAME_OVERHEAD _AC(160, U)
/* Facilities */
#define DFLTCC_FACILITY _AC(151, U)
#define UNPACK_FACILITY _AC(161, U)
#ifndef __ASSEMBLER__

48
include/dump/s390_dump.h
View File

@@ -12,6 +12,7 @@
#include <stdint.h>
#include "boot/page.h"
#include "lib/zt_common.h"
/*
@@ -57,7 +58,9 @@ struct df_s390_hdr {
uint8_t mvdump; /* 0x05c */
uint16_t cpu_cnt; /* 0x05d */
uint16_t real_cpu_cnt; /* 0x05f */
uint8_t end_pad1[0x200 - 0x061]; /* 0x061 */
uint8_t zlib_version_s390; /* 0x061 */
uint32_t zlib_entry_size; /* 0x062 */
uint8_t end_pad1[0x200 - 0x066]; /* 0x066 */
uint64_t mvdump_sign; /* 0x200 */
uint64_t mvdump_zipl_time; /* 0x208 */
uint8_t end_pad2[0x800 - 0x210]; /* 0x210 */
@@ -79,10 +82,43 @@ struct df_s390_em {
* Dump segment header
*/
struct df_s390_dump_segm_hdr {
uint64_t start;
uint64_t len;
uint64_t stop_marker;
uint8_t reserved[0x1000 - 24];
} __packed;
union {
struct {
uint64_t start; /* 0x000 */
uint64_t len; /* 0x008 */
uint64_t stop_marker; /* 0x010 */
/* Size in blocks of compressed dump segment written to disk */
uint32_t size_on_disk; /* 0x018 */
uint8_t reserved_pad[0x30 - 0x1c]; /* 0x01c */
/*
* Number of compressed entries in this dump segment (up to
* 1011 entries)
*/
uint32_t entry_count; /* 0x030 */
/*
* Offsets in blocks to compressed entries written to disk
* from the start of the dump segment.
* High-order bit is set if the entry has been written
* uncompressed.
*/
uint32_t entry_offset[]; /* 0x034 */
} __packed;
uint8_t padding[PAGE_SIZE];
};
};
/* Data compression granularity (size of input data chunk for zlib deflate) */
#define DUMP_SEGM_ZLIB_ENTSIZE (1 * MIB)
/* Maximum number of compressed entries in one dump segment */
#define DUMP_SEGM_ZLIB_MAXENTS ((sizeof(struct df_s390_dump_segm_hdr) \
- offsetof(struct df_s390_dump_segm_hdr, entry_offset)) \
/ sizeof(uint32_t))
/*
* Maximum length of compressed dump segment considering the size of
* a single input chunk
*/
#define DUMP_SEGM_ZLIB_MAXLEN (DUMP_SEGM_ZLIB_MAXENTS * DUMP_SEGM_ZLIB_ENTSIZE)
/* Bitmask to mark uncompressed chunks */
#define DUMP_SEGM_ENTRY_UNCOMPRESSED 0x80000000
#endif /* S390_DUMP_H */