Alexander Egorenkov 802c7db50e zfcpdump: fix hsa release for V!=R kernel ...

Since V!=R kernel introduction, HSA memory can be
contained in/spread over more than one ELF LOAD segment of
/proc/vmcore simultaneously. Therefore, the old HSA release logic is no
longer valid because it assumes that HSA memory is fully contained in
exactly one ELF LOAD segment of /proc/vmcore. This resulted in zfcpdump
releasing HSA memory too soon and by that making parts of /proc/vmcore
which cover HSA memory unreadable by user space. To correct this
problem on V!=R kernel, we need first to find all ELF LOAD segments
containing HSA memory, write those /proc/vmcore parts first and only then
release HSA memory. The new HSA release logic must be able to handle
both V!=R and V==R kernels to be backwards compatible.

====================
Tests of V!=R kernel
====================

Output of test run (KASLR on)
=============================

Writing dump:

TRACE: Read: /sys/kernel/debug/zcore/hsa:
TRACE: '2ffff000'

TRACE: ELF LOAD segment: p_offset=0x0000000000009000 p_filesz=0x0000000001cb0000 p_paddr=0x00000002f1e30000 p_vaddr=0x000002c609044000
TRACE: ELF LOAD segment: p_offset=0x0000000001cb9000 p_filesz=0x0000000040000000 p_paddr=0x0000000000000000 p_vaddr=0x000001bd00000000
TRACE: ELF LOAD segment: p_offset=0x0000000041cb9000 p_filesz=0x0000000300000000 p_paddr=0x0000000100000000 p_vaddr=0x000001be00000000

TRACE: Write copy table entry 0: off=0x0000000001cb9000 size=0x000000002ffff000 hsa=1
TRACE: Write copy table entry 1: off=0x0000000000001000 size=0x0000000001cb8000 hsa=0
TRACE: Release HSA memory
TRACE: Write copy table entry 2: off=0x0000000031cb8000 size=0x0000000310001000 hsa=0
TRACE: Write copy table entry 3: off=0x0000000000000000 size=0x0000000000001000 hsa=0

Dump successful

Output of test run (KASLR off)
==============================

Writing dump:

TRACE: Read: /sys/kernel/debug/zcore/hsa:
TRACE: '2ffff000'

TRACE: ELF LOAD segment: p_offset=0x0000000000009000 p_filesz=0x0000000001cb0000 p_paddr=0x0000000000c21000 p_vaddr=0x000003ffe0000000
TRACE: ELF LOAD segment: p_offset=0x0000000001cb9000 p_filesz=0x0000000040000000 p_paddr=0x0000000000000000 p_vaddr=0x000002f200000000
TRACE: ELF LOAD segment: p_offset=0x0000000041cb9000 p_filesz=0x0000000300000000 p_paddr=0x0000000100000000 p_vaddr=0x000002f300000000

TRACE: Write copy table entry 0: off=0x0000000000009000 size=0x0000000001cb0000 hsa=1
TRACE: Write copy table entry 1: off=0x0000000001cb9000 size=0x000000002ffff000 hsa=1
TRACE: Write copy table entry 2: off=0x0000000000001000 size=0x0000000000008000 hsa=0
TRACE: Release HSA memory
TRACE: Write copy table entry 3: off=0x0000000031cb8000 size=0x0000000310001000 hsa=0
TRACE: Write copy table entry 4: off=0x0000000000000000 size=0x0000000000001000 hsa=0

Dump successful

====================
Tests of V==R kernel
====================

Output of test run (KASLR on)
=============================

Writing dump:

TRACE: Read: /sys/kernel/debug/zcore/hsa:
TRACE: '2ffff000'

TRACE: ELF LOAD segment: p_offset=0x0000000000009000 p_filesz=0x0000000000000000 p_paddr=0x0000000000000000 p_vaddr=0x0000000000000000
TRACE: ELF LOAD segment: p_offset=0x0000000000009000 p_filesz=0x0000000040000000 p_paddr=0x0000000000000000 p_vaddr=0x0000000000000000
TRACE: ELF LOAD segment: p_offset=0x0000000040009000 p_filesz=0x0000000300000000 p_paddr=0x0000000100000000 p_vaddr=0x0000000100000000

TRACE: Write copy table entry 0: off=0x0000000000009000 size=0x000000002ffff000 hsa=1
TRACE: Write copy table entry 1: off=0x0000000000001000 size=0x0000000000008000 hsa=0
TRACE: Release HSA memory
TRACE: Write copy table entry 2: off=0x0000000030008000 size=0x0000000310001000 hsa=0
TRACE: Write copy table entry 3: off=0x0000000000000000 size=0x0000000000001000 hsa=0

Dump successful

Output of test run (KASLR off)
==============================

Writing dump:

TRACE: Read: /sys/kernel/debug/zcore/hsa:
TRACE: '2ffff000'

TRACE: ELF LOAD segment: p_offset=0x0000000000009000 p_filesz=0x0000000000000000 p_paddr=0x0000000000000000 p_vaddr=0x0000000000000000
TRACE: ELF LOAD segment: p_offset=0x0000000000009000 p_filesz=0x0000000040000000 p_paddr=0x0000000000000000 p_vaddr=0x0000000000000000
TRACE: ELF LOAD segment: p_offset=0x0000000040009000 p_filesz=0x0000000300000000 p_paddr=0x0000000100000000 p_vaddr=0x0000000100000000

TRACE: Write copy table entry 0: off=0x0000000000009000 size=0x000000002ffff000 hsa=1
TRACE: Write copy table entry 1: off=0x0000000000001000 size=0x0000000000008000 hsa=0
TRACE: Release HSA memory
TRACE: Write copy table entry 2: off=0x0000000030008000 size=0x0000000310001000 hsa=0
TRACE: Write copy table entry 3: off=0x0000000000000000 size=0x0000000000001000 hsa=0

Dump successful

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

2024-05-27 16:49:54 +02:00

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