pkg/bisect: Implement config bisection

Implement Linux kernel configuration bisection. Use bisected minimalistic
configuration in commit bisection. Utilizes config_bisect.pl script from Linux
kernel tree in bisection.

Modify syz-bisect to read in kernel.baseline_config. This is used as a "good"
configuration when bisection is run.

2 files changed, 64 insertions, 0 deletions

diff --git a/pkg/vcs/testdata/linux/config-bisect.pl b/pkg/vcs/testdata/linux/config-bisect.pl
new file mode 100755
index 000000000..5cecb8b6d
--- /dev/null
+++ b/pkg/vcs/testdata/linux/config-bisect.pl
@@ -0,0 +1,53 @@
+#!/bin/bash
+# Copyright 2020 syzkaller project authors. All rights reserved.
+# Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+# config-bisect.pl -l ctx.git.dir -r -b ctx.git.dir kernelBaselineConfig kernelConfig
+
+if [ "$3" == "-r" ]
+then
+    baseline=`cat $6`
+    outdir=$5
+    echo $baseline > $outdir/.config
+    exit 0
+fi
+
+# config-bisect.pl -l ctx.git.dir -b ctx.git.dir kernelBaselineConfig kernelConfig verdict
+baseline=`cat $5`
+
+# Test baseline file contains string CONFIG_FAILING -> fail
+if [ "$baseline" == "CONFIG_FAILING=y" ]
+then
+    exit 1
+fi
+
+# Generate end results which "reproduces" the crash
+if [ $baseline == "CONFIG_REPRODUCES_CRASH=y" ]
+then
+    echo "%%%%%%%% FAILED TO FIND SINGLE BAD CONFIG %%%%%%%%"
+    echo "Hmm, can't make any more changes without making good == bad?"
+    echo "Difference between good (+) and bad (-)"
+    echo "REPRODUCES_CRASH n -> y"
+    echo "-DISABLED_OPTION=n"
+    echo "+ONLY_IN_ORIGINAL_OPTION=y"
+    echo "See good and bad configs for details:"
+    echo "good: /mnt/work/config_bisect_evaluation/out/config_bisect/kernel.baseline_config.tmp"
+    echo "bad:  /mnt/work/config_bisect_evaluation/out/config_bisect/kernel.config.tmp"
+    echo "%%%%%%%% FAILED TO FIND SINGLE BAD CONFIG %%%%%%%%"
+    exit 2
+fi
+
+# Generate end result which doesn't "reproduce" the crash
+if [ $baseline == "CONFIG_NOT_REPRODUCE_CRASH=y" ]
+then
+    echo "%%%%%%%% FAILED TO FIND SINGLE BAD CONFIG %%%%%%%%"
+    echo "Hmm, can't make any more changes without making good == bad?"
+    echo "Difference between good (+) and bad (-)"
+    echo "NOT_REPRODUCE_CRASH n -> y"
+    echo "See good and bad configs for details:"
+    echo "good: /mnt/work/config_bisect_evaluation/out/config_bisect/kernel.baseline_config.tmp"
+    echo "bad:  /mnt/work/config_bisect_evaluation/out/config_bisect/kernel.config.tmp"
+    echo "%%%%%%%% FAILED TO FIND SINGLE BAD CONFIG %%%%%%%%"
+    exit 2
+fi
+
+
diff --git a/pkg/vcs/testdata/linux/merge_config.sh b/pkg/vcs/testdata/linux/merge_config.sh
new file mode 100755
index 000000000..1ab10d379
--- /dev/null
+++ b/pkg/vcs/testdata/linux/merge_config.sh
@@ -0,0 +1,11 @@
+#!/bin/bash
+# Copyright 2020 syzkaller project authors. All rights reserved.
+# Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+# merge_config.sh -m -O outdir baseline kernelAdditionsConfig
+OUTDIR=$3
+
+echo `cat $4` > $OUTDIR/.config
+echo `cat $5` >> $OUTDIR/.config
+
+exit 0