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go/misc
Cherry Zhang 7799756a50 cmd/link: fix GC data reading from shared library (attempt 2)
When linking against a Go shared library, when a global variable
in the main module has a type defined in the shared library, the
linker needs to pull the GC data from the shared library to build
the GC program for the global variable. Currently, this fails
silently, as the shared library file is closed too early and the
read failed (with no error check), causing a zero GC map emitted
for the variable, which in turn causes the runtime to treat the
variable as pointerless.

For now, fix this by keeping the file open. In the future we may
want to use mmap to read from the shared library instead.

Also add error checking. And fix a (mostly harmless) mistake in
size caluculation.

Also remove an erroneous condition for ARM64. ARM64 used to have
a special case to get the addend from the relocation on the
gcdata field. That was removed, but the new code accidentally
returned 0 unconditionally. It's no longer necessary to have any
special case, since the addend is now applied directly to the
gcdata field on ARM64, like on all the other platforms.

Fixes #39927.

This is the second attempt of CL 240462. And this reverts
CL 240616.

Change-Id: I01c82422b9f67e872d833336885935bc509bc91b
Reviewed-on: https://go-review.googlesource.com/c/go/+/240621
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
2020-07-01 14:41:56 +00:00
..
android misc/android: fix a typo in README 2019-05-17 06:01:17 +00:00
arm
cgo cmd/link: fix GC data reading from shared library (attempt 2) 2020-07-01 14:41:56 +00:00
chrome/gophertool misc/chrome/gophertool: replace deprecated tabs.getSelected method 2019-11-18 18:14:37 +00:00
ios all: remove scattered remnants of darwin/arm 2020-04-08 18:35:49 +00:00
linkcheck
reboot misc: remove use of relative directories in overlayDir functions 2019-11-25 16:26:15 +00:00
swig
trace cmd/trace: update to use WebComponents V0 polyfill 2020-02-20 19:12:11 +00:00
wasm syscall/js: prepare IDs for the preset objects 2020-05-12 15:01:56 +00:00
editors
go.mod misc: add go.mod file 2019-02-27 17:47:31 +00:00