| commit | 8e5778ed70ec3d371615a663520a586745fb7bee | [log] [tgz] |
|---|---|---|
| author | Than McIntosh <thanm@google.com> | Thu Nov 05 14:19:47 2020 -0500 |
| committer | Than McIntosh <thanm@google.com> | Thu Nov 05 22:14:40 2020 +0000 |
| tree | 3c0e85b387456a7d0bbd37b86119c1dd7cb39a85 | |
| parent | 2822bae168fa5d7b14c87d2b2ee22cb85fc90cce [diff] |
cmd/link: report error if builtin referenced but not defined When the compiler refers to a runtime builtin, it emits an indexed symbol reference in the object file via predetermined/preassigned ID within the PkgIdxBuiltin pseudo-package. At link time when the loader encounters these references, it redirects them to the corresponding defined symbol in the runtime package. This redirection process currently assumes that if a runtime builtin is referenced, we'll always have a definition for it. This assumption holds in most cases, however for the builtins "runtime.racefuncenter" and "runtime.racefuncexit", we'll only see definitions if the runtime package we're linking against was built with "-race". In the bug in question, build passes "-gcflags=-race" during compilation of the main package, but doesn't pass "-race" directly to 'go build', and as a result the final link combines a race-instrumented main with a non-race runtime; this results in R_CALL relocations with zero-valued target symbols, resulting in a panic during stack checking. This patch changes the loader's resolve method to detect situations where we're asking for builtin "runtime.X", but the runtime package read in doesn't contain a definition for X. Fixes #42396. Change-Id: Iafd38bd3b0f7f462868d120ccd4d7d1b88b27436 Reviewed-on: https://go-review.googlesource.com/c/go/+/267881 Trust: Than McIntosh <thanm@google.com> Run-TryBot: Than McIntosh <thanm@google.com> Reviewed-by: Jeremy Faller <jeremy@golang.org> Reviewed-by: Cherry Zhang <cherryyz@google.com> TryBot-Result: Go Bot <gobot@golang.org>
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