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Clean uncompressed kernel .bss section in the startup code before
the uncompressed kernel is executed. At this point of time initrd and
certificates have been already rescued. Uncompressed kernel .bss size
is known from vmlinux_info. It is also taken into consideration during
uncompressed kernel positioning by kaslr (so it is safe to clean it).
With that uncompressed kernel is starting with .bss section zeroed and
no .bss section usage restrictions apply. Which makes chkbss checks for
uncompressed kernel objects obsolete and they can be removed.
early_nobss.c is also not needed anymore. Parts of it which are still
relevant are moved to early.c. Kasan initialization code is now called
directly from head64 (early.c is instrumented and should not be
executed before kasan shadow memory is set up).
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The disabled_wait() function uses its argument as the PSW address when
it stops the CPU with a wait PSW that is disabled for interrupts.
The different callers sometimes use a specific number like 0xdeadbeef
to indicate a specific failure, the early boot code uses 0 and some
other calls sites use __builtin_return_address(0).
At the time a dump is created the current PSW and the registers of a
CPU are written to lowcore to make them avaiable to the dump analysis
tool. For a CPU stopped with disabled_wait the PSW and the registers
do not really make sense together, the PSW address does not point to
the function the registers belong to.
Simplify disabled_wait() by using _THIS_IP_ for the PSW address and
drop the argument to the function.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Kasan needs 1/8 of kernel virtual address space to be reserved as the
shadow area. And eventually it requires the shadow memory offset to be
known at compile time (passed to the compiler when full instrumentation
is enabled). Any value picked as the shadow area offset for 3-level
paging would eat up identity mapping on 4-level paging (with 1PB
shadow area size). So, the kernel sticks to 3-level paging when kasan
is enabled. 3TB border is picked as the shadow offset. The memory
layout is adjusted so, that physical memory border does not exceed
KASAN_SHADOW_START and vmemmap does not go below KASAN_SHADOW_END.
Due to the fact that on s390 paging is set up very late and to cover
more code with kasan instrumentation, temporary identity mapping and
final shadow memory are set up early. The shadow memory mapping is
later carried over to init_mm.pgd during paging_init.
For the needs of paging structures allocation and shadow memory
population a primitive allocator is used, which simply chops off
memory blocks from the end of the physical memory.
Kasan currenty doesn't track vmemmap and vmalloc areas.
Current memory layout (for 3-level paging, 2GB physical memory).
---[ Identity Mapping ]---
0x0000000000000000-0x0000000000100000
---[ Kernel Image Start ]---
0x0000000000100000-0x0000000002b00000
---[ Kernel Image End ]---
0x0000000002b00000-0x0000000080000000 2G <- physical memory border
0x0000000080000000-0x0000030000000000 3070G PUD I
---[ Kasan Shadow Start ]---
0x0000030000000000-0x0000030010000000 256M PMD RW X <- shadow for 2G memory
0x0000030010000000-0x0000037ff0000000 523776M PTE RO NX <- kasan zero ro page
0x0000037ff0000000-0x0000038000000000 256M PMD RW X <- shadow for 2G modules
---[ Kasan Shadow End ]---
0x0000038000000000-0x000003d100000000 324G PUD I
---[ vmemmap Area ]---
0x000003d100000000-0x000003e080000000
---[ vmalloc Area ]---
0x000003e080000000-0x000003ff80000000
---[ Modules Area ]---
0x000003ff80000000-0x0000040000000000 2G
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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To avoid multi-stage initrd rescue operation and to simplify
assumptions during early memory allocations move initrd at some final
safe destination as early as possible. This would also allow us to
drop .bss usage restrictions for some files.
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Move functions which may not access bss section to extra file. This
makes it easier to verify that all early functions which may not rely
on an initialized bss section are not accessing it.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Vasily Gorbik
Martin Schwidefsky
Heiko Carstens