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cmd/link: fix deferreturn detector

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The logic for detecting deferreturn calls is wrong.

We used to look for a relocation whose symbol is runtime.deferreturn
and has an offset of 0. But on some architectures, the relocation
offset is not zero. These include arm (the offset is 0xebfffffe) and
s390x (the offset is 6).

This ends up setting the deferreturn offset at 0, so we end up using
the entry point live map instead of the deferreturn live map in a
frame which defers and then segfaults.

Instead, use the IsDirectCall helper to find calls.

Fixes #32477
Update #6980

Change-Id: Iecb530a7cf6eabd7233be7d0731ffa78873f3a54
Reviewed-on: https://go-review.googlesource.com/c/go/+/181258
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Keith Randall 2019-06-07 13:22:53 -04:00 • committed by Keith Randall
parent 4c84d87813
commit 9eb403159d
2 changed files with 72 additions and 1 deletions
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2
src/cmd/link/internal/ld/pcln.go
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@ -318,7 +318,7 @@ func (ctxt *Link) pclntab() {
// set the resumption point to PC_B.
lastWasmAddr = uint32(r.Add)
}
if r.Sym != nil && r.Sym.Name == "runtime.deferreturn" && r.Add == 0 {
if r.Type.IsDirectJump() && r.Sym != nil && r.Sym.Name == "runtime.deferreturn" {
if ctxt.Arch.Family == sys.Wasm {
deferreturn = lastWasmAddr
} else {