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[S390] Initialize __LC_THREAD_INFO early.

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"lockdep: Fix backtraces" reveales a bug in early setup code: when
lockdep tries to save a stack backtrace before setup_arch has been
called the lowcore pointer for the current thread info pointer isn't
initialized yet.
However our save stack backtrace code relies on it. If the pointer
isn't initialized the saved backtrace will have zero entries.
lockdep however relies (correctly) on the fact that that cannot
happen.
A write access to some random memory region is the result.

Fix this by initializing the thread info pointer early.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2009-09-11 10:28:58 +02:00 committed by Martin Schwidefsky
parent 50aa98bad0
commit 0c88ee5b75
2 changed files with 2 additions and 0 deletions
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1
arch/s390/kernel/head31.S
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@ -24,6 +24,7 @@ startup_continue:
# Setup stack
#
l %r15,.Linittu-.LPG1(%r13)
st %r15,__LC_THREAD_INFO # cache thread info in lowcore
mvc __LC_CURRENT(4),__TI_task(%r15)
ahi %r15,1<<(PAGE_SHIFT+THREAD_ORDER) # init_task_union+THREAD_SIZE
st %r15,__LC_KERNEL_STACK # set end of kernel stack

1
arch/s390/kernel/head64.S
View file

@ -92,6 +92,7 @@ startup_continue:
# Setup stack
#
larl %r15,init_thread_union
stg %r15,__LC_THREAD_INFO # cache thread info in lowcore
lg %r14,__TI_task(%r15) # cache current in lowcore
stg %r14,__LC_CURRENT
aghi %r15,1<<(PAGE_SHIFT+THREAD_ORDER) # init_task_union + THREAD_SIZE