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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>
54 lines
1.2 KiB
C
54 lines
1.2 KiB
C
/*
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* zipl - zSeries Initial Program Loader tool
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*
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* Common ECKD dump I/O functions
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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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#ifndef ECKD2DUMP_H
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#define ECKD2DUMP_H
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#include "cio.h"
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#include "stage2dump.h"
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struct eckd_device {
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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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struct subchannel_id sid;
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uint16_t devno;
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};
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extern struct eckd_device device;
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extern unsigned long eckd_blk_max;
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/*
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* Convert memory size to number of blocks
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*/
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static inline unsigned long m2b(unsigned long mem)
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{
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return mem / device.blk_size;
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}
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/*
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* Convert number of blocks to memory size
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*/
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static inline unsigned long b2m(unsigned long blk)
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{
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return blk * device.blk_size;
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}
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void stage2dump_eckd_init();
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void writeblock(unsigned long blk, unsigned long addr, unsigned long blk_count,
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unsigned long zero_page);
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void readblock(unsigned long blk, unsigned long addr, unsigned long blk_count);
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unsigned long write_dump_segment(unsigned long blk,
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struct df_s390_dump_segm_hdr *segm);
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#endif /* ECKD2DUMP_H */
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