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runtime: fix crash during VDSO calls on arm

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As discussed in #32912, a crash occurs when go runtime calls a VDSO function (say
__vdso_clock_gettime) and a signal arrives to that thread.
Since VDSO functions temporarily destroy the G register (R10),
Go functions asynchronously executed in that thread (i.e. Go's signal
handler) can try to load data from the destroyed G, which causes
segmentation fault.

To fix the issue a guard is inserted in front of sigtrampgo, so that the control escapes from
signal handlers without touching G in case the signal occurred in the VDSO context.
The test case included in the patch is take from discussion in a relevant thread on github:
https://github.com/golang/go/issues/32912#issuecomment-517874531.
This patch not only fixes the issue on AArch64 but also that on 32bit ARM.

Fixes #32912

Change-Id: I657472e54b7aa3c617fabc5019ce63aa4105624a
GitHub-Last-Rev: 28ce42c4a0
GitHub-Pull-Request: golang/go#34030
Reviewed-on: https://go-review.googlesource.com/c/go/+/192937
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Yuichi Nishiwaki 2019-09-11 02:26:02 +00:00 • committed by Ian Lance Taylor
parent 8ef6d6a8f2
commit 904f046e2b
4 changed files with 86 additions and 6 deletions
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9
src/runtime/crash_test.go
View file

@ -143,6 +143,15 @@ func buildTestProg(t *testing.T, binary string, flags ...string) (string, error)
return exe, nil
}
func TestVDSO(t *testing.T) {
t.Parallel()
output := runTestProg(t, "testprog", "SignalInVDSO")
want := "success\n"
if output != want {
t.Fatalf("output:\n%s\n\nwanted:\n%s", output, want);
}
}
var (
staleRuntimeOnce sync.Once // guards init of staleRuntimeErr
staleRuntimeErr error