Re: spinlocks() are severely broken in 2.2.X and 2.4.X for modules

[Manfred Spraul]

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Andi Kleen wrote:
> 
> Here is a quick hack. The results are slightly off because of section
> padding though. It only works on object files or modules (vmlinux doesn't
> have any reloc records)
> 

$SPINSIZE = 14;

the .text.lock segment also contains semaphore & rwlock fixups.
Could you/Jeff send me a broken module?

If the wrong relocs really point into the wrong segment, then it should
be easy to find them: the number of relocs from .text into .text.lock
must be equal to the number of relocs from .text.lock back into .text.

[test attached]
	./mstest.sh `find -iname '*.o'`

As expected these number always match in my kernel tree
[gcc-2.95.3-0.20000517 + binutils 2.9.5.0.22-6 from redhat rawhide]

Are you absolutely sure that broken fixup cause the SMP problems? A
broken fixup within spinlock might cause hard crashes, continue as if
the spinlock was acquired???
--
	Manfred
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#!/bin/sh

checkfile() {
# params: $1=File Name
# echo -n "from .text.lock to .text"
x1=`objdump --reloc --section=.text.lock $1 | grep _PC32 | grep '\.text$' | wc -l`
# echo -n "from .text to .text..lock"
x2=`objdump --reloc --section=.text $1 | grep _PC32 | grep '\.text\.lock$' | wc -l`
# echo -n "from .text.lock to !.text"
y1=`objdump --reloc --section=.text.lock $1 | grep _PC32 | grep '\.text\..*$' | wc -l`
# echo -n "from .text.init to .lock"
y2=`objdump --reloc --section=.text.init $1 | grep _PC32 | grep '\.text\.lock$' | wc -l`
# echo -n "from .text.exit to .lock"
y3=`objdump --reloc --section=.text.exit $1 | grep _PC32 | grep '\.text\.lock$' | wc -l`
rx=$[x1-x2]
ry=$[y1-y2-y3]
#echo "$1	: .text $x1 -$x2 .text.init $y1 -$y2"
if [ 0 != $rx ]; then 
	echo "$1: mismatch for .text segment $x1 - $x2"
fi
if [ 0 != $ry ]; then
	echo "$1: mismatch for .text.init segment $y1 - $y2"
fi
}

for i in "$@";do
	checkfile $i
done

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