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Russ Cox 5ea69978fd runtime: make entersyscall/exitsyscall safe for stack splits
It is fundamentally unsafe to grow the stack once someone
has made a call to syscall.Syscall. That function takes 6 uintptr
arguments, but depending on the call some are pointers.
In fact, some might be pointers to stack values, and we don't know which.
That makes it impossible to copy the stack somewhere else.
Since we want to delete all the stack splitting code, relying only
on stack copying, make sure that Syscall never needs to split the stack.

The only thing Syscall does is:
        call entersyscall
        make the system call
        call exitsyscall

As long as we make sure that entersyscall and exitsyscall
can live in the nosplit region, they won't ask for more stack.

Do this by making entersyscall and exitsyscall set up the
stack guard so that any call to a function with a split check
will cause a crash. Then move non-essential slow-path
work onto the m stack using onM and mark the rest of the
work nosplit. The linker will verify that the chain of nosplits
fits in the total nosplit budget.

LGTM=iant
R=golang-codereviews, iant
CC=dvyukov, golang-codereviews, khr, r
https://golang.org/cl/140950043
2014-09-03 17:42:35 -04:00
api unicode: strconv: regexp: Upgrade to Unicode 7.0.0. 2014-08-18 20:26:10 +02:00
doc spec: Add link to rune literals from string literals when talking about escape sequences. 2014-09-03 10:44:33 -07:00
include cmd/ld: diagnose Go calling C 2014-08-31 22:49:14 -04:00
lib codereview: do not hit upload_complete on first patch 2014-08-06 16:12:24 -04:00
misc cmd/cgo, runtime: write cgo stub wrappers in Go, not C 2014-09-03 11:36:14 -04:00
src runtime: make entersyscall/exitsyscall safe for stack splits 2014-09-03 17:42:35 -04:00
test runtime: increase nosplit area to 192 2014-08-30 00:56:52 -04:00
.hgignore lib9: enable on Plan 9 2014-02-13 20:06:41 +01:00
.hgtags tag go1.3.1 2014-08-13 14:54:54 +10:00
AUTHORS A+C: David Leon Gil (individual CLA) 2014-09-02 12:22:57 -07:00
CONTRIBUTORS A+C: David Leon Gil (individual CLA) 2014-09-02 12:22:57 -07:00
favicon.ico godoc: update favicon 2012-10-11 17:02:36 +11:00
LICENSE doc: update licensing text one more time 2012-03-27 15:09:13 +11:00
PATENTS LICENSE: separate, change PATENTS text 2010-12-06 16:31:59 -05:00
README README: Fix installation instructions 2013-11-20 13:47:37 -08:00
robots.txt godoc: serve robots.txt raw 2011-02-19 05:46:20 +11:00

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