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cmd/link: fix deferreturn detector #32477

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randall77 opened this issue Jun 7, 2019 · 4 comments
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cmd/link: fix deferreturn detector #32477

randall77 opened this issue Jun 7, 2019 · 4 comments
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@randall77
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The logic for detecting deferreturn calls is wrong.
We 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 having 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.

Update #6980
@randall77 randall77 self-assigned this Jun 7, 2019
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Change https://golang.org/cl/181258 mentions this issue: cmd/link: fix deferreturn detector

@randall77
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@gopherbot, please open a backport to 1.12.

@gopherbot gopherbot mentioned this issue Jun 7, 2019
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@gopherbot
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Backport issue(s) opened: #32484 (for 1.12).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases.

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Change https://golang.org/cl/181378 mentions this issue: Revert "Revert "cmd/compile,runtime: allocate defer records on the stack""

gopherbot pushed a commit that referenced this issue Jun 10, 2019
@randall77
Revert "Revert "cmd/compile,runtime: allocate defer records on the st…
8f296f5 
…ack""

This reverts CL 180761

Reason for revert: Reinstate the stack-allocated defer CL.

There was nothing wrong with the CL proper, but stack allocation of defers exposed two other issues.

Issue #32477: Fix has been submitted as CL 181258.
Issue #32498: Possible fix is CL 181377 (not submitted yet).

Change-Id: I32b3365d5026600069291b068bbba6cb15295eb3
Reviewed-on: https://go-review.googlesource.com/c/go/+/181378
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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