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Russ Cox 03886707f9 runtime: fix handling of SPWRITE functions in traceback
It is valid to see SPWRITE functions at the top of a GC stack traceback,
in the case where they self-preempted during the stack growth check
and haven't actually modified SP in a traceback-unfriendly manner yet.
The current check is therefore too aggressive.

isAsyncSafePoint is taking care of not async-preempting SPWRITE functions
because it doesn't async-preempt any assembly functions at all.
But perhaps it will in the future.

To keep a check that SPWRITE assembly functions are not async-preempted,
add one in preemptPark. Then relax the check in traceback to avoid
triggering on self-preempted SPWRITE functions.

The long and short of this is that the assembly we corrected in x/crypto
issue #44269 was incredibly dodgy but not technically incompatible with
the Go runtime. After this change, the original x/crypto assembly no longer
causes GC traceback crashes during "GOGC=1 go test -count=1000".
But we'll still leave the corrected assembly.

This also means that we don't need to worry about diagnosing SPWRITE
assembly functions that may exist in the wild. They will be skipped for
async preemption and no harm no foul.

Fixes #44269, which was open pending some kind of check for
bad SPWRITE functions in the wild. (No longer needed.)

Change-Id: I6000197b62812bbd2cd92da28eab422634cf75a8
Reviewed-on: https://go-review.googlesource.com/c/go/+/317669
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
2021-05-12 15:23:09 +00:00
.github .github: add link to questions in ISSUE_TEMPLATE 2020-01-06 17:05:31 +00:00
api text/template/parse: rename DeferFuncCheck to SkipFuncCheck 2021-05-06 13:39:37 +00:00
doc doc/go1.17: fill in TODO for compress/lzw package 2021-05-07 21:01:09 +00:00
lib/time lib/time, time/tzdata: update tzdata to 2021a 2021-01-25 16:08:46 +00:00
misc runtime: rename walltime1 to walltime 2021-04-29 14:15:04 +00:00
src runtime: fix handling of SPWRITE functions in traceback 2021-05-12 15:23:09 +00:00
test cmd/compile: remove bit operations that modify memory directly 2021-05-08 03:27:59 +00:00
.gitattributes all: treat all files as binary, but check in .bat with CRLF 2020-06-08 15:31:43 +00:00
.gitignore internal/buildcfg: move build configuration out of cmd/internal/objabi 2021-04-16 19:20:53 +00:00
AUTHORS A+C: add Weixie Cui (individual CLA) 2021-04-30 16:27:50 +00:00
codereview.cfg codereview.cfg: add codereview.cfg for master branch 2021-02-19 18:44:53 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS CONTRIBUTORS: change my name 2021-05-06 16:28:56 +00:00
LICENSE doc: revert copyright date to 2009 2016-06-01 22:40:04 +00:00
PATENTS LICENSE: separate, change PATENTS text 2010-12-06 16:31:59 -05:00
README.md README: pull gopher image from website 2021-02-16 18:25:10 +00:00
SECURITY.md SECURITY.md: update go versions 2019-09-26 15:34:57 +00:00

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