dashboard/app, syz-ci: bisection support

This adds bulk of support for bisection to dashboard/app and syz-ci:
- APIs to send bisection jobs and accept results
- syz-ci logic to execute bisection jobs
- formatting of emails with results
- showing of results on dashboard

Some difficulties we have to overcome:
- since linux is frequently build/boot broken, lots of bisections are inconclusive,
  need to present such results too
- git bisect is poorly suitable for automation, have to resort to output parsing (is output stable?)
- git bisect turns out to fail (exit with non-0 status) when bisection is inconclusive
  (multiple potential cause commits)
- older syzkaller revisions can't be built with newer (broken) kernel header, e.g.:
  ebtables.h:197:19: error: invalid conversion from ‘void*’ to ‘ebt_entry_target*’
- newer compilers produce more warnings and break old syzkaller builds, e.g.:
  kvm.S.h:6:12: error: ‘kvm_asm64_vm86’ defined but not used [-Werror=unused-const-variable=]
- figuring relevant emails to CC from a commit is non-trivial:
  besides commit author, there can be some emails in commit tags, or not,
  which tags to use is an interesting question (some may include irrelevant emails)
  we can also run get_maintainers.pl on the commit, but this can produce too wide
  list if commit touches lots of files, it can also produce too small list,
  and then we need to resort to blame
- for inconclusive bisection we probably don't need to include emails referenced
  in the commits (there can be too many of these commits)
- need to be careful to exclude own syzbot email from commit CC list,
  now syzbot emails are referenced in some commits (Reported-by/Tested-by/etc)
  (can cause some kind of infinite recursion)
- lots of commits reference stable mailing list,
  we should not include it in CC because it's referenced for backports rather then bug reports
- since we add new Bug entity fields which we use in queries,
  whole datastore need to be upgrades to add the new field to index
- we must not discard the crash that was used for bisection
  (treat it as a reported crash)
- bisection results need 2 forms of reports:
  one when we add bisection results to already reported bug
  another when we report a bug first time with bisection results
- when reporting a bug with bisection results we need to use the crash
  that was used for bisection
- some fraction of bisections will probably fail with various errors
  and we will need some mechanism to retry bisection after the root cause is resolved
  this is not implemented yet
- linux-next is problematic for 2 reasons:
  fix bisection can't possibly run on linux-next as commits are not reachable from HEAD
  lots of commits are missing in linux-next (even in linux-next-history)
  e.g. we have some c63e9e91a254a52 which is now missing in linux-next/linux-next-history
- older kernels can't be build with fresh gcc/binutils/perl/make/glibc
  for now we have to stop at v3.9 (this only requires switching gcc several times along the way)
- kernels past v4.11 do not build with gcc 7 and 8 (undefined reference to `____ilog2_NaN')
- v4.1 and back have only compiler-gcc5.h
- v3.17 and back have only compiler-gcc4.h
- v3.6 and back do not have make olddefconfig
- compat socket calls can't be bisected past "x86/entry/syscalls: Wire up 32-bit
  direct socket calls" (v4.10) because of
  https://syzkaller.appspot.com/bug?id=b5b150e322d5f48c869bcf1528cdbee08d1421cb
- v2.6.28 and below does not work with modern make:
  *** mixed implicit and normal rules: deprecated syntax
- v3.8 build fails:
  Can't use 'defined(@array)' (Maybe you should just omit the defined()?) at kernel/timeconst.pl line 373.
  kernel/Makefile:134: recipe for target 'kernel/timeconst.h' failed
- make 3.81 works for v2.6.28.
  3.81 almost works with current HEAD, you need to run make twice because first run spuriously fails with:
- v2.6.28 with gcc-4.9.4 broken with:
  include/linux/kvm.h:240:9: error: duplicate member ‘padding’
- but even defconfig fails:
  VDSO    arch/x86/vdso/vdso.so.dbg
  gcc: error: elf_x86_64: No such file or directory
  gcc: error: unrecognized command line option ‘-m’
  It seems that we also need old binutils.
- for v3.8 and below we need perl-5.14.4.
  Unfortunately this or any manually built perl doesn't work for later kernels:
  Can't locate strict.pm in @INC
- kernels starting from 4.14 and older are boot broken:
  https://lkml.org/lkml/2018/9/7/648
- kernels older than 4.12 are broken during netdev setup
  (fixed by commit 675c8da049fd6556eb2d6cdd745fe812752f07a8)

Update #501

1 files changed, 40 insertions, 8 deletions

diff --git a/dashboard/dashapi/dashapi.go b/dashboard/dashapi/dashapi.go
index ffc72d79a..006ed1ce7 100644
--- a/dashboard/dashapi/dashapi.go
+++ b/dashboard/dashapi/dashapi.go
@@ -72,11 +72,13 @@ type Build struct {
 }
 
 type Commit struct {
-	Hash   string
-	Title  string
-	Author string
-	BugIDs []string // ID's extracted from Reported-by tags
-	Date   time.Time
+	Hash       string
+	Title      string
+	Author     string
+	AuthorName string
+	CC         []string
+	BugIDs     []string // ID's extracted from Reported-by tags
+	Date       time.Time
 }
 
 func (dash *Dashboard) UploadBuild(build *Build) error {
@@ -124,9 +126,11 @@ type JobPollReq struct {
 
 type JobPollResp struct {
 	ID              string
+	Type            JobType
 	Manager         string
 	KernelRepo      string
 	KernelBranch    string
+	KernelCommit    string
 	KernelConfig    []byte
 	SyzkallerCommit string
 	Patch           []byte
@@ -139,11 +143,27 @@ type JobDoneReq struct {
 	ID          string
 	Build       Build
 	Error       []byte
+	Log         []byte // bisection log
 	CrashTitle  string
 	CrashLog    []byte
 	CrashReport []byte
+	// Bisection results:
+	// If there is 0 commits:
+	//  - still happens on HEAD for fix bisection
+	//  - already happened on the oldest release
+	// If there is 1 commits: bisection result (cause or fix).
+	// If there are more than 1: suspected commits due to skips (broken build/boot).
+	Commits []Commit
 }
 
+type JobType int
+
+const (
+	JobTestPatch JobType = iota
+	JobBisectCause
+	JobBisectFix
+)
+
 func (dash *Dashboard) JobPoll(managers []string) (*JobPollResp, error) {
 	req := &JobPollReq{Managers: managers}
 	resp := new(JobPollResp)
@@ -299,6 +319,16 @@ type BugReport struct {
 	ErrorLink      string
 	ErrorTruncated bool // full Error text is too large and was truncated
 	PatchLink      string
+	BisectCause    *BisectResult
+	BisectFix      *BisectResult
+}
+
+type BisectResult struct {
+	Commit          *Commit   // for conclusive bisection
+	Commits         []*Commit // for inconclusive bisection
+	LogLink         string
+	CrashLogLink    string
+	CrashReportLink string
 }
 
 type BugUpdate struct {
@@ -458,9 +488,11 @@ const (
 )
 
 const (
-	ReportNew       ReportType = iota // First report for this bug in the reporting stage.
-	ReportRepro                       // Found repro for an already reported bug.
-	ReportTestPatch                   // Patch testing result.
+	ReportNew         ReportType = iota // First report for this bug in the reporting stage.
+	ReportRepro                         // Found repro for an already reported bug.
+	ReportTestPatch                     // Patch testing result.
+	ReportBisectCause                   // Cause bisection result for an already reported bug.
+	ReportBisectFix                     // Fix bisection result for an already reported bug.
 )
 
 func (dash *Dashboard) Query(method string, req, reply interface{}) error {