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authorBorislav Petkov <bp@suse.de>2020-10-13 16:48:14 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 18:38:26 -0700
commitd72e720a19393eb611a112e4c5c377785dbd645d (patch)
tree31ad47809ba5c596890c043b8332bd9f5a59122e /scripts/decodecode
parent33c5bb375ea4128b6e72b3ee260b74b59c295957 (diff)
downloadlwn-d72e720a19393eb611a112e4c5c377785dbd645d.tar.gz
lwn-d72e720a19393eb611a112e4c5c377785dbd645d.zip
scripts/decodecode: add the capability to supply the program counter
So that comparing with objdump output from vmlinux can ease pinpointing where the trapping instruction actually is. An example is better than a thousand words: $ PC=0xffffffff8329a927 ./scripts/decodecode < ~/tmp/syz/gfs2.splat [ 477.379104][T23917] Code: 48 83 ec 28 48 89 3c 24 48 89 54 24 08 e8 c1 b4 4a fe 48 8d bb 00 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 97 05 00 00 48 8b 9b 00 01 00 00 48 85 db 0f 84 All code ======== ffffffff8329a8fd: 48 83 ec 28 sub $0x28,%rsp ffffffff8329a901: 48 89 3c 24 mov %rdi,(%rsp) ffffffff8329a905: 48 89 54 24 08 mov %rdx,0x8(%rsp) ffffffff8329a90a: e8 c1 b4 4a fe callq 0xffffffff81745dd0 ffffffff8329a90f: 48 8d bb 00 01 00 00 lea 0x100(%rbx),%rdi ffffffff8329a916: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax ffffffff8329a91d: fc ff df ffffffff8329a920: 48 89 fa mov %rdi,%rdx ffffffff8329a923: 48 c1 ea 03 shr $0x3,%rdx ffffffff8329a927:* 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction ffffffff8329a92b: 0f 85 97 05 00 00 jne 0xffffffff8329aec8 ffffffff8329a931: 48 8b 9b 00 01 00 00 mov 0x100(%rbx),%rbx ffffffff8329a938: 48 85 db test %rbx,%rbx ffffffff8329a93b: 0f .byte 0xf ffffffff8329a93c: 84 .byte 0x84 Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Marc Zyngier <maz@misterjones.org> Cc: Will Deacon <will@kernel.org> Cc: Rabin Vincent <rabin@rab.in> Link: https://lkml.kernel.org/r/20200930111416.GF6810@zn.tnic Link: https://lkml.kernel.org/r/20200929113238.GC21110@zn.tnic Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'scripts/decodecode')
-rwxr-xr-xscripts/decodecode29
1 files changed, 22 insertions, 7 deletions
diff --git a/scripts/decodecode b/scripts/decodecode
index fbdb325cdf4f..31d884e35f2f 100755
--- a/scripts/decodecode
+++ b/scripts/decodecode
@@ -6,6 +6,7 @@
# 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
+# PC=hex - the PC (program counter) the oops points to
cleanup() {
rm -f $T $T.s $T.o $T.oo $T.aa $T.dis
@@ -67,15 +68,19 @@ if [ -z "$ARCH" ]; then
esac
fi
+# Params: (tmp_file, pc_sub)
disas() {
- ${CROSS_COMPILE}as $AFLAGS -o $1.o $1.s > /dev/null 2>&1
+ t=$1
+ pc_sub=$2
+
+ ${CROSS_COMPILE}as $AFLAGS -o $t.o $t.s > /dev/null 2>&1
if [ "$ARCH" = "arm" ]; then
if [ $width -eq 2 ]; then
OBJDUMPFLAGS="-M force-thumb"
fi
- ${CROSS_COMPILE}strip $1.o
+ ${CROSS_COMPILE}strip $t.o
fi
if [ "$ARCH" = "arm64" ]; then
@@ -83,11 +88,18 @@ disas() {
type=inst
fi
- ${CROSS_COMPILE}strip $1.o
+ ${CROSS_COMPILE}strip $t.o
fi
- ${CROSS_COMPILE}objdump $OBJDUMPFLAGS -S $1.o | \
- grep -v "/tmp\|Disassembly\|\.text\|^$" > $1.dis 2>&1
+ if [ $pc_sub -ne 0 ]; then
+ if [ $PC ]; then
+ adj_vma=$(( $PC - $pc_sub ))
+ OBJDUMPFLAGS="$OBJDUMPFLAGS --adjust-vma=$adj_vma"
+ fi
+ fi
+
+ ${CROSS_COMPILE}objdump $OBJDUMPFLAGS -S $t.o | \
+ grep -v "/tmp\|Disassembly\|\.text\|^$" > $t.dis 2>&1
}
marker=`expr index "$code" "\<"`
@@ -95,14 +107,17 @@ if [ $marker -eq 0 ]; then
marker=`expr index "$code" "\("`
fi
+
touch $T.oo
if [ $marker -ne 0 ]; then
+ # 2 opcode bytes and a single space
+ pc_sub=$(( $marker / 3 ))
echo All code >> $T.oo
echo ======== >> $T.oo
beforemark=`echo "$code"`
echo -n " .$type 0x" > $T.s
echo $beforemark | sed -e 's/ /,0x/g; s/[<>()]//g' >> $T.s
- disas $T
+ disas $T $pc_sub
cat $T.dis >> $T.oo
rm -f $T.o $T.s $T.dis
@@ -114,7 +129,7 @@ echo =========================================== >> $T.aa
code=`echo $code | sed -e 's/ [<(]/ /;s/[>)] / /;s/ /,0x/g; s/[>)]$//'`
echo -n " .$type 0x" > $T.s
echo $code >> $T.s
-disas $T
+disas $T 0
cat $T.dis >> $T.aa
# (lines of whole $T.oo) - (lines of $T.aa, i.e. "Code starting") + 3,