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https://github.com/ibm-s390-linux/s390-tools.git
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800df6bef8
For the stage2 of zipl's boot loaders only 3 heap pages are available
[0x6000, 0x6000 + 0x3000]. Therefore, stage2 code needs to be very careful
when and for how long it allocates a heap page.
The heap OOM problem in stage2 was hidden until the commit 252be376
("zipl/boot: fix potential heap overflow in stage2"). Before this commit,
stage2 assumed that heap is 4 pages large which is apparently very wrong
but get_zeroed_page() still allowed allocating an extra 4th page by
overriding the memory segment following the heap area of stage2 (stage3
parameter area).
Try to avoid allocating a heap page and keeping it allocated over a long
period of time in the DASD dumpers. Free a heap page as soon as possible
if not required anymore.
And be extra careful with printf() because it always tries to allocate
a free heap page.
Fixes: 252be376 ("zipl/boot: fix potential heap overflow in stage2")
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
97 lines
2.0 KiB
C
97 lines
2.0 KiB
C
/*
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* zipl - zSeries Initial Program Loader tool
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*
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* Single-volume ECKD DASD dump tool
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*
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* Copyright IBM Corp. 2013, 2018
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*
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* s390-tools is free software; you can redistribute it and/or modify
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* it under the terms of the MIT license. See LICENSE for details.
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*/
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#include "lib/zt_common.h"
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#include "eckd2dump.h"
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#include "error.h"
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#include "stage2dump.h"
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/*
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* Magic number at start of dump record
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*/
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uint64_t __section(.stage2.head) magic = 0x5845434b44363401ULL; /* "XECKD64", version 1 */
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/*
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* ECKD parameter block passed by zipl
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*/
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struct eckd_dump_param {
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uint32_t blk_start;
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uint32_t blk_end;
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uint16_t blk_size;
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uint8_t num_heads;
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uint8_t bpt;
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char reserved[4];
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} __packed;
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/*
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* Get device characteristics from zipl parameter block
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*/
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void dt_device_parm_setup(void)
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{
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struct eckd_dump_param *parm = (void *) __stage2_desc;
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device.blk_start = parm->blk_start;
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device.blk_end = parm->blk_end;
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device.blk_size = parm->blk_size;
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device.num_heads = parm->num_heads;
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device.bpt = parm->bpt;
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device.sid = IPL_SC;
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}
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/*
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* Enable DASD device
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*/
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void dt_device_enable(void)
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{
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io_irq_enable();
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set_device(device.sid, ENABLED);
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stage2dump_eckd_init();
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}
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/*
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* Dump all memory to DASD partition
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*/
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void dt_dump_mem(void)
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{
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unsigned long blk, addr, end, page;
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struct df_s390_dump_segm_hdr *dump_segm;
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blk = device.blk_start;
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dump_segm = (void *)get_zeroed_page();
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/* Write dump header */
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writeblock(blk, __pa(dump_hdr), m2b(DF_S390_HDR_SIZE), 0);
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blk += m2b(DF_S390_HDR_SIZE);
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/* Write memory */
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addr = 0;
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total_dump_size = 0;
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end = dump_hdr->mem_size;
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while (addr < end) {
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addr = find_dump_segment(addr, end, 0, dump_segm);
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blk = write_dump_segment(blk, dump_segm);
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total_dump_size += dump_segm->len;
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if (dump_segm->stop_marker) {
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addr = end;
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break;
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}
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}
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free_page(__pa(dump_segm));
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progress_print(addr);
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/* Write end marker */
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page = get_zeroed_page();
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df_s390_em_page_init(page);
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writeblock(blk, page, 1, 0);
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free_page(page);
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}
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