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doc/oops-tracing: add Code: decode info

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Add info that the Code: bytes line contains <xy> or (wxyz) in some
architecture oops reports and what that means.

Add a script by Andi Kleen that reads the Code: line from an Oops report
file and generates assembly code from the hex bytes.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Randy Dunlap 2007-07-15 23:41:15 -07:00 committed by Linus Torvalds
parent 213dd266d4
commit dcecc6c700
2 changed files with 65 additions and 0 deletions
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14
Documentation/oops-tracing.txt
View file

@ -86,6 +86,20 @@ stuff are the values reported by the Oops - you can just cut-and-paste
and do a replace of spaces to "\x" - that's what I do, as I'm too lazy
to write a program to automate this all).
Alternatively, you can use the shell script in scripts/decodecode.
Its usage is: decodecode < oops.txt
The hex bytes that follow "Code:" may (in some architectures) have a series
of bytes that precede the current instruction pointer as well as bytes at and
following the current instruction pointer. In some cases, one instruction
byte or word is surrounded by <> or (), as in "<86>" or "(f00d)". These
<> or () markings indicate the current instruction pointer. Example from
i386, split into multiple lines for readability:
Code: f9 0f 8d f9 00 00 00 8d 42 0c e8 dd 26 11 c7 a1 60 ea 2b f9 8b 50 08 a1
64 ea 2b f9 8d 34 82 8b 1e 85 db 74 6d 8b 15 60 ea 2b f9 <8b> 43 04 39 42 54
7e 04 40 89 42 54 8b 43 04 3b 05 00 f6 52 c0
Finally, if you want to see where the code comes from, you can do
cd /usr/src/linux

51
scripts/decodecode Normal file
View file

@ -0,0 +1,51 @@
#!/bin/sh
# Disassemble the Code: line in Linux oopses
# usage: decodecode < oops.file
#
# options: set env. variable AFLAGS=options to pass options to "as";
# e.g., to decode an i386 oops on an x86_64 system, use:
# AFLAGS=--32 decodecode < 386.oops
T=`mktemp`
code=
while read i ; do
case "$i" in
*Code:*)
code=$i
;;
esac
done
if [ -z "$code" ]; then
exit
fi
echo $code
code=`echo $code | sed -e 's/.*Code: //'`
marker=`expr index "$code" "\<"`
if [ $marker -eq 0 ]; then
marker=`expr index "$code" "\("`
fi
if [ $marker -ne 0 ]; then
beforemark=`echo "$code" | cut -c-$((${marker} - 1))`
echo -n " .byte 0x" > $T.s
echo $beforemark | sed -e 's/ /,0x/g' >> $T.s
as $AFLAGS -o $T.o $T.s
objdump -S $T.o
rm $T.o $T.s
# and fix code at-and-after marker
code=`echo "$code" | cut -c$((${marker} + 1))-`
fi
code=`echo $code | sed -e 's/ [<(]/ /;s/[>)] / /;s/ /,0x/g'`
echo -n " .byte 0x" > $T.s
echo $code >> $T.s
as $AFLAGS -o $T.o $T.s
objdump -S $T.o
rm $T.o $T.s