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1562 Commits

Author SHA1 Message Date
Austin Clements
bb6fb929d6 runtime: fix sanity check in stackBarrier
stackBarrier on amd64 sanity checks that it's unwinding the correct
entry in the stack barrier array. However, this check is wrong in two
ways that make it unlikely to catch anything, right or wrong:

1) It checks that savedLRPtr == SP, but, in fact, it should be that
   savedLRPtr+8 == SP because the RET that returned to stackBarrier
   popped the saved LR. However, we didn't notice this check was wrong
   because,

2) the sense of the conditional branch is also wrong.

Fix both of these.

Change-Id: I38ba1f652b0168b5b2c11b81637656241262af7c
Reviewed-on: https://go-review.googlesource.com/17039
Reviewed-by: Russ Cox <rsc@golang.org>
2015-12-03 03:53:35 +00:00
Shenghou Ma
08b80ca880 runtime: note interactions between GC and MemProfile
Change-Id: Icce28fc4937cc73c0712c054161222f034381c2f
Reviewed-on: https://go-review.googlesource.com/16876
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
2015-12-03 02:11:52 +00:00
Rahul Chaudhry
c091d4cd25 runtime: set TLSG_IS_VARIABLE for android/arm64.
On android, runtime.tls_g is a normal variable.
TLS offset is computed in x_cgo_inittls.

Change-Id: I18bc9a736d5fb2a89d0f798956c754e3c10d10e2
Reviewed-on: https://go-review.googlesource.com/17246
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-12-02 22:00:04 +00:00
Rahul Chaudhry
4480d6a927 runtime/cgo: define x_cgo_inittls() for android/arm64.
On android, runtime.tls_g is a normal variable.
TLS offset is computed in x_cgo_inittls.

Change-Id: I64cfd3543040776dcdf73cad8dba54fc6aaf6f35
Reviewed-on: https://go-review.googlesource.com/17245
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-12-02 21:59:52 +00:00
Michael Hudson-Doyle
f000523018 runtime: set r12 to sigpanic before jumping to it in sighandler
The ppc64le shared library ABI demands that r12 is set to a function's global
entrypoint before jumping to the global entrypoint. Not doing so means that
handling signals that usually panic actually crashes (and so, e.g. can't be
recovered). Fixes several failures of "cd test; go run run.go -linkshared".

Change-Id: Ia4d0da4c13efda68340d38c045a52b37c2f90796
Reviewed-on: https://go-review.googlesource.com/17280
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-12-01 04:51:35 +00:00
Michael Hudson-Doyle
fd2bc8681d runtime: fix conflict resolution in golang.org/cl/14207
Fixes testshared on arm64 and ppc64le.

Change-Id: Ie94bc0c85c7666fbb5ab6fc6d3dbb180407a9955
Reviewed-on: https://go-review.googlesource.com/17212
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2015-11-25 01:32:55 +00:00
Shenghou Ma
3583a44ed2 runtime: check that masks and shifts are correct aligned
We need a runtime check because the original issue is encountered
when running cross compiled windows program from linux. It's better
to give a meaningful crash message earlier than to segfault later.

The added test should not impose any measurable overhead to Go
programs.

For #12415.

Change-Id: Ib4a24ef560c09c0585b351d62eefd157b6b7f04c
Reviewed-on: https://go-review.googlesource.com/14207
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-25 00:46:57 +00:00
Austin Clements
ab9d5f38be runtime: make gcFlushBgCredit go:nowritebarrierrec
Write barriers in gcFlushBgCredit lead to very subtle bugs because it
executes after the getfull barrier. I tracked some bugs of this form
down before go:nowritebarrierrec was implemented. Ensure that they
don't reappear by making gcFlushBgCredit go:nowritebarrierrec.

Change-Id: Ia5ca2dc59e6268bce8d8b4c87055bd0f6e19bed2
Reviewed-on: https://go-review.googlesource.com/17052
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-24 19:37:03 +00:00
Austin Clements
e126f30a66 runtime: recursively disallow write barriers in sighandler
sighandler may run during STW, so write barriers are not allowed.

Change-Id: Icdf46be10ea296fd87e73ab56ebb718c5d3c97ac
Reviewed-on: https://go-review.googlesource.com/17007
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-24 19:36:55 +00:00
Elias Naur
a7383fc467 runtime: use a proper type, sigset, for m.sigmask
Replace the cross platform but unsafe [4]uintptr type with a OS
specific type, sigset. Most OSes already define sigset, and this
change defines a suitable sigset for the OSes that don't (darwin,
openbsd). The OSes that don't use m.sigmask (windows, plan9, nacl)
now defines sigset as the empty type, struct{}.

The gain is strongly typed access to m.sigmask, saving a dynamic
size sanity check and unsafe.Pointer casting. Also, some storage is
saved for each M, since [4]uinptr was conservative for most OSes.

The cost is that OSes that don't need m.sigmask has to define sigset.

completes ./all.bash with GOOS linux, on amd64
completes ./make.bash with GOOSes openbsd, android, plan9, windows,
darwin, solaris, netbsd, freebsd, dragonfly, all amd64.

With GOOS=nacl ./make.bash failed with a seemingly unrelated error.

[Replay of CL 16942 by Elias Naur.]

Change-Id: I98f144d626033ae5318576115ed635415ac71b2c
Reviewed-on: https://go-review.googlesource.com/17033
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
2015-11-24 17:16:47 +00:00
dvyukov
5526d95019 runtime/race: add tests for channels
These tests were failing on one of the versions of cl/9345
("runtime: simplify buffered channels").

Change-Id: I920ffcd28de428bcb7c2d5a300068644260e1017
Reviewed-on: https://go-review.googlesource.com/16416
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-24 17:00:43 +00:00
Ilya Tocar
b597e1ed54 runtime: speed up memclr with avx2 on amd64
Results are a bit noisy, but show good improvement (haswell)

name            old time/op    new time/op     delta
Memclr5-48        6.06ns ± 8%     5.65ns ± 8%    -6.81%  (p=0.000 n=20+20)
Memclr16-48       5.75ns ± 6%     5.71ns ± 6%      ~     (p=0.545 n=20+19)
Memclr64-48       6.54ns ± 5%     6.14ns ± 9%    -6.12%  (p=0.000 n=18+20)
Memclr256-48      10.1ns ±12%      9.9ns ±14%      ~     (p=0.285 n=20+19)
Memclr4096-48      104ns ± 8%       57ns ±15%   -44.98%  (p=0.000 n=20+20)
Memclr65536-48    2.45µs ± 5%     2.43µs ± 8%      ~     (p=0.665 n=16+20)
Memclr1M-48       58.7µs ±13%     56.4µs ±11%    -3.92%  (p=0.033 n=20+19)
Memclr4M-48        233µs ± 9%      234µs ± 9%      ~     (p=0.728 n=20+19)
Memclr8M-48        469µs ±11%      472µs ±16%      ~     (p=0.947 n=20+20)
Memclr16M-48       947µs ±10%      916µs ±10%      ~     (p=0.050 n=20+19)
Memclr64M-48      10.9ms ±10%      4.5ms ± 9%   -58.43%  (p=0.000 n=20+20)
GoMemclr5-48      3.80ns ±13%     3.38ns ± 6%   -11.02%  (p=0.000 n=20+20)
GoMemclr16-48     3.34ns ±15%     3.40ns ± 9%      ~     (p=0.351 n=20+20)
GoMemclr64-48     4.10ns ±15%     4.04ns ±10%      ~     (p=1.000 n=20+19)
GoMemclr256-48    7.75ns ±20%     7.88ns ± 9%      ~     (p=0.227 n=20+19)

name            old speed      new speed       delta
Memclr5-48       826MB/s ± 7%    886MB/s ± 8%    +7.32%  (p=0.000 n=20+20)
Memclr16-48     2.78GB/s ± 5%   2.81GB/s ± 6%      ~     (p=0.550 n=20+19)
Memclr64-48     9.79GB/s ± 5%  10.44GB/s ±10%    +6.64%  (p=0.000 n=18+20)
Memclr256-48    25.4GB/s ±14%   25.6GB/s ±12%      ~     (p=0.647 n=20+19)
Memclr4096-48   39.4GB/s ± 8%   72.0GB/s ±13%   +82.81%  (p=0.000 n=20+20)
Memclr65536-48  26.6GB/s ± 6%   27.0GB/s ± 9%      ~     (p=0.517 n=17+20)
Memclr1M-48     17.9GB/s ±12%   18.5GB/s ±11%      ~     (p=0.068 n=20+20)
Memclr4M-48     18.0GB/s ± 9%   17.8GB/s ±14%      ~     (p=0.547 n=20+20)
Memclr8M-48     17.9GB/s ±10%   17.8GB/s ±14%      ~     (p=0.947 n=20+20)
Memclr16M-48    17.8GB/s ± 9%   18.4GB/s ± 9%      ~     (p=0.050 n=20+19)
Memclr64M-48    6.19GB/s ±10%  14.87GB/s ± 9%  +140.11%  (p=0.000 n=20+20)
GoMemclr5-48    1.31GB/s ±10%   1.48GB/s ± 6%   +13.06%  (p=0.000 n=19+20)
GoMemclr16-48   4.81GB/s ±14%   4.71GB/s ± 8%      ~     (p=0.341 n=20+20)
GoMemclr64-48   15.7GB/s ±13%   15.8GB/s ±11%      ~     (p=0.967 n=20+19)

Change-Id: I393f3f20e2f31538d1b1dd70d6e5c201c106a095
Reviewed-on: https://go-review.googlesource.com/16773
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Klaus Post <klauspost@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
2015-11-24 16:49:30 +00:00
Dave Cheney
984004263d runtime: skip CallbackGC test in short mode on linux/arm
Fixes #11959
Fixes #12035

Skip the CallbackGC test on linux/arm. This test takes between 30 and 60
seconds to run by itself, and is run 4 times over the course of ./run.bash
(once during the runtime test, three times more later in the build).

Change-Id: I4e7d3046031cd8c08f39634bdd91da6e00054caf
Reviewed-on: https://go-review.googlesource.com/14485
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-24 16:48:32 +00:00
Alex Brainman
1cb53ce36b runtime: fix handling VirtualAlloc failure in sysUsed
Original code is mistakenly panics on VirtualAlloc failure - we want
it to go looking for smaller memory region that VirtualAlloc will
succeed to allocate. Also return immediately if VirtualAlloc succeeds.
See rsc comment on issue #12587 for details.

I still don't have a test for this. So I can only hope that this

Fixes #12587

Change-Id: I052068ec627fdcb466c94ae997ad112016f734b7
Reviewed-on: https://go-review.googlesource.com/17169
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-24 14:50:23 +00:00
Michael Hudson-Doyle
239273d963 runtime: mark {g,m,p}uintptr methods as nosplit
These are methods that are "obviously" going to get inlined -- until you build
with -l, when they can trigger a stack split at a bad time.

Fixes #11482

Change-Id: Ia065c385978a2e7fe9f587811991d088c4d68325
Reviewed-on: https://go-review.googlesource.com/17165
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-24 02:33:04 +00:00
Austin Clements
ecf388f3a4 runtime: take stack barrier lock during copystack
Commit bbd1a1c prevented SIGPROF from scanning stacks that were being
copied, but it didn't prevent a stack copy (specifically a stack
shrink) from happening while SIGPROF is scanning the stack. As a
result, a stack copy may adjust stack barriers while SIGPROF is in the
middle of scanning a stack, causing SIGPROF to panic when it detects
an inconsistent stack barrier.

Fix this by taking the stack barrier lock while adjusting the stack.
In addition to preventing SIGPROF from scanning this stack, this will
block until any in-progress SIGPROF is done scanning the stack.

For 1.5.2.

Fixes #13362.
Updates #12932.

Change-Id: I422219c363054410dfa56381f7b917e04690e5dd
Reviewed-on: https://go-review.googlesource.com/17191
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-24 01:50:52 +00:00
Alex Brainman
ab4c9298b8 runtime: do not call timeBeginPeriod on windows
Calling timeBeginPeriod changes Windows global timer resolution
from 15ms to 1ms. This used to improve Go runtime scheduler
performance, but not anymore. Thanks to @aclements, scheduler now
behaves the same way if we call timeBeginPeriod or not.

Remove call to timeBeginPeriod, since it is machine global
resource, and there are downsides of using low timer resolution.
See issue #8687 for details.

Fixes #8687

Change-Id: Ib7e41aa4a81861b62a900e0e62776c9ef19bfb73
Reviewed-on: https://go-review.googlesource.com/17164
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Yasuhiro MATSUMOTO <mattn.jp@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
2015-11-24 01:11:58 +00:00
Austin Clements
b890333998 runtime: clean up gcMarkDone
This improves the documentation comment on gcMarkDone, replaces a
recursive call with a simple goto, and disables preemption before
stopping the world in accordance with the documentation comment on
stopTheWorldWithSema.

Updates #13363, but, sadly, doesn't fix it.

Change-Id: I6cb2a5836b35685bf82f7b1ce7e48a7625906656
Reviewed-on: https://go-review.googlesource.com/17149
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-23 20:59:35 +00:00
Austin Clements
a7c09ad4fb runtime: improve stack barrier debugging
This improves stack barrier debugging messages in various ways:

1) Rather than printing only the remaining stack barriers (of which
   there may be none, which isn't very useful), print all of the G's
   stack barriers with a marker at the position the stack itself has
   unwound to and a marker at the problematic stack barrier (where
   applicable).

2) Rather than crashing if we encounter a stack barrier when there are
   no more stkbar entries, print the same debug message we would if we
   had encountered a stack barrier at an unexpected location.

Hopefully this will help with debugging #12528.

Change-Id: I2e6fe6a778e0d36dd8ef30afd4c33d5d94731262
Reviewed-on: https://go-review.googlesource.com/17147
Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-23 19:17:52 +00:00
Austin Clements
22e57c6655 runtime: make stack barrier locking more robust
The stack barrier locking functions use a simple cas lock because they
need to support trylock, but currently don't increment g.m.locks. This
is okay right now because they always run on the system stack or the
signal stack and are hence non-preemtible, but this could lead to
difficult-to-reproduce deadlocks if these conditions change in the
future.

Make these functions more robust by incrementing g.m.locks and making
them nosplit to enforce non-preemtibility.

Change-Id: I73d60a35bd2ad2d81c73aeb20dbd37665730eb1b
Reviewed-on: https://go-review.googlesource.com/17058
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ingo Oeser <nightlyone@googlemail.com>
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-23 19:13:15 +00:00
Austin Clements
624d798a41 runtime/pprof: disable TestStackBarrierProfiling on ppc64
This test depends on GODEBUG=gcstackbarrierall, which doesn't work on
ppc64.

Updates #13334.

Change-Id: Ie554117b783c4e999387f97dd660484488499d85
Reviewed-on: https://go-review.googlesource.com/17120
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-20 19:39:36 +00:00
Russ Cox
cb859021d1 runtime: fix new stack barrier check
During a crash showing goroutine stacks of all threads
(with GOTRACEBACK=crash), it can be that f == nil.

Only happens on Solaris; not sure why.

Change-Id: Iee2c394a0cf19fa0a24f6befbc70776b9e42d25a
Reviewed-on: https://go-review.googlesource.com/17110
Reviewed-by: Austin Clements <austin@google.com>
2015-11-20 19:08:21 +00:00
David Crawshaw
2fa64c4182 runtime/pprof: check if test can fork
(TestStackBarrierProfiling is failing on darwin/arm.)

Change-Id: I8006d6222ccafc213821e02105896440079caa37
Reviewed-on: https://go-review.googlesource.com/17091
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-20 17:52:33 +00:00
Shenghou Ma
35a5bd6431 runtime: make it possible to call syscall on solaris without g
The nosplit stack is now much bigger, so we can afford to allocate
libcall on stack.

Fix asmsysvicall6 to not update errno if g == nil.

These two fixes TestCgoCallbackGC on solaris, which used to stuck
in a loop.

Change-Id: Id1b13be992dae9f059aa3d47ffffd37785300933
Reviewed-on: https://go-review.googlesource.com/17076
Run-TryBot: Minux Ma <minux@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-20 08:11:35 +00:00
Russ Cox
3af29fb858 runtime: make asmcgocall work without a g
Solaris needs to make system calls without a g,
and Solaris uses asmcgocall to make system calls.
I know, I know.

I hope this makes CL 16915, fixing #12277, work on Solaris.

Change-Id: If988dfd37f418b302da9c7096f598e5113ecea87
Reviewed-on: https://go-review.googlesource.com/17072
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Run-TryBot: Russ Cox <rsc@golang.org>
2015-11-20 02:51:09 +00:00
Austin Clements
d2c81ad847 runtime: recursively disallow write barriers in sysmon
sysmon runs without a P. This means it can't interact with the garbage
collector, so write barriers not allowed in anything that sysmon does.

Fixes #10600.

Change-Id: I9de1283900dadee4f72e2ebfc8787123e382ae88
Reviewed-on: https://go-review.googlesource.com/17006
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-19 21:17:25 +00:00
Austin Clements
402e37d4a9 cmd/compile: special case nowritebarrierrec for allocm
allocm is a very unusual function: it is specifically designed to
allocate in contexts where m.p is nil by temporarily taking over a P.
Since allocm is used in many contexts where it would make sense to use
nowritebarrierrec, this commit teaches the nowritebarrierrec analysis
to stop at allocm.

Updates #10600.

Change-Id: I8499629461d4fe25712d861720dfe438df7ada9b
Reviewed-on: https://go-review.googlesource.com/17005
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-19 21:17:19 +00:00
Austin Clements
c84ae1c499 runtime: eliminate write barriers from mem_plan9.go
This replaces *memHdr with memHdrPtr.

Updates #10600.

Change-Id: I673aa2cd20f29abec8ab91ed7e783718c8479ce1
Reviewed-on: https://go-review.googlesource.com/17009
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David du Colombier <0intro@gmail.com>
2015-11-19 21:17:14 +00:00
Austin Clements
e9aef43d87 runtime: eliminate traceAllocBlock write barriers
This replaces *traceAllocBlock with traceAllocBlockPtr.

Updates #10600.

Change-Id: I94a20d90f04cca7c457b29062427748e315e4857
Reviewed-on: https://go-review.googlesource.com/17004
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
2015-11-19 21:17:09 +00:00
Austin Clements
b43b375c6c runtime: eliminate write barriers from gentraceback
gentraceback is used in many contexts where write barriers are
disallowed. This currently works because the only write barrier is in
assigning frame.argmap in setArgInfo and in practice frame is always
on the stack, so this write barrier is a no-op.

However, we can easily eliminate this write barrier, which will let us
statically disallow write barriers (using go:nowritebarrierrec
annotations) in many more situations. As a bonus, this makes the code
a little more idiomatic.

Updates #10600.

Change-Id: I45ba5cece83697ff79f8537ee6e43eadf1c18c6d
Reviewed-on: https://go-review.googlesource.com/17003
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
2015-11-19 21:17:04 +00:00
Russ Cox
8b1b81f463 cmd/compile: fix crash with -race on large expr containing string->[]byte conversion
The assumption is that there are no nested function calls in complex expressions.
For the most part that assumption is true. It wasn't for these calls inserted during walk.
Fix that.

I looked through all the calls to mkcall in walk and these were the only cases
that emitted calls, that could be part of larger expressions (like not delete),
and that were not already handled.

Fixes #12225.

Change-Id: Iad380683fe2e054d480e7ae4e8faf1078cdd744c
Reviewed-on: https://go-review.googlesource.com/17034
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-11-19 19:54:55 +00:00
Ian Lance Taylor
0e2c635788 cmd/cgo, runtime: exported Go functions can't return a Go pointer
Update #12416.

Change-Id: Iccbcb12709d1ca9bea87274f44f93cfcebadb070
Reviewed-on: https://go-review.googlesource.com/17048
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-11-19 18:28:39 +00:00
Austin Clements
9a7893550c runtime/pprof: test that stack barriers never appear in profile
This adds a test that runs CPU profiling with a high load of stack
barriers and stack barrier insertion/removal operations and checks
that both 1) the runtime doesn't crash and 2) stackBarrier itself
never appears in a profile. Prior to the fix for gentraceback starting
in the middle of stackBarrier, condition 2 often failed.

Change-Id: Ic28860448859029779844c4bf3bb28ca84611e2c
Reviewed-on: https://go-review.googlesource.com/17037
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-19 16:35:43 +00:00
Austin Clements
9c9d74aba7 runtime: prevent sigprof during all stack barrier ops
A sigprof during stack barrier insertion or removal can crash if it
detects an inconsistency between the stkbar array and the stack
itself. Currently we protect against this when scanning another G's
stack using stackLock, but we don't protect against it when unwinding
stack barriers for a recover or a memmove to the stack.

This commit cleans up and improves the stack locking code. It
abstracts out the lock and unlock operations. It uses the lock
consistently everywhere we perform stack operations, and pushes the
lock/unlock down closer to where the stack barrier operations happen
to make it more obvious what it's protecting. Finally, it modifies
sigprof so that instead of spinning until it acquires the lock, it
simply doesn't perform a traceback if it can't acquire it. This is
necessary to prevent self-deadlock.

Updates #11863, which introduced stackLock to fix some of these
issues, but didn't go far enough.

Updates #12528.

Change-Id: I9d1fa88ae3744d31ba91500c96c6988ce1a3a349
Reviewed-on: https://go-review.googlesource.com/17036
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-19 16:35:38 +00:00
Austin Clements
3a2fc06833 runtime: handle sigprof in stackBarrier
Currently, if a profiling signal happens in the middle of
stackBarrier, gentraceback may see inconsistencies between stkbar and
the barriers on the stack and it will certainly get the wrong return
PC for stackBarrier. In most cases, the return PC won't be a PC at all
and this will immediately abort the traceback (which is considered
okay for a sigprof), but if it happens to be a valid PC this may sent
gentraceback down a rabbit hole.

Fix this by detecting when the gentraceback starts in stackBarrier and
simulating the completion of the barrier to get the correct initial
frame.

Change-Id: Ib11f705ac9194925f63fe5dfbfc84013a38333e6
Reviewed-on: https://go-review.googlesource.com/17035
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-19 16:35:34 +00:00
Michael Hudson-Doyle
09d7de8d61 cmd/link, runtime: call addmoduledata when dynamically linking on linux/386
Change-Id: If1faa2bba28a4e9a8061693173797c4114a7d699
Reviewed-on: https://go-review.googlesource.com/16387
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-11-19 00:22:56 +00:00
Russ Cox
f8e6418637 runtime: fix bad signal stack when using cgo-created threads and async signals
Cgo-created threads transition between having associated Go g's and m's and not.
A signal arriving during the transition could think it was safe and appropriate to
run Go signal handlers when it was in fact not.
Avoid the race by masking all signals during the transition.

Fixes #12277.

Change-Id: Ie9711bc1d098391d58362492197a7e0f5b497d14
Reviewed-on: https://go-review.googlesource.com/16915
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-18 18:05:22 +00:00
Russ Cox
5af2be8604 Revert "runtime: use a proper type, sigset, for m.sigmask"
This reverts commit 7db77271e4.

Change-Id: I6d8855eb05ca331025dc49a5533c6da4d1fa4e84
Reviewed-on: https://go-review.googlesource.com/17030
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-18 17:18:20 +00:00
Michael Hudson-Doyle
6056cc5df6 runtime: handle volatility of CX when dynamically linking on linux/386
Mostly by avoiding CX entirely, sometimes by reloading it.

I also vetted the assembly in other packages, it's all fine.

Change-Id: I50059669aaaa04efa303cf22ac228f9d14d83db0
Reviewed-on: https://go-review.googlesource.com/16386
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-11-18 01:36:44 +00:00
Elias Naur
7db77271e4 runtime: use a proper type, sigset, for m.sigmask
Replace the cross platform but unsafe [4]uintptr type with a OS
specific type, sigset. Most OSes already define sigset, and this
change defines a suitable sigset for the OSes that don't (darwin,
openbsd). The OSes that don't use m.sigmask (windows, plan9, nacl)
now defines sigset as the empty type, struct{}.

The gain is strongly typed access to m.sigmask, saving a dynamic
size sanity check and unsafe.Pointer casting. Also, some storage is
saved for each M, since [4]uinptr was conservative for most OSes.

The cost is that OSes that don't need m.sigmask has to define sigset.

completes ./all.bash with GOOS linux, on amd64
completes ./make.bash with GOOSes openbsd, android, plan9, windows,
darwin, solaris, netbsd, freebsd, dragonfly, all amd64.

With GOOS=nacl ./make.bash failed with a seemingly unrelated error.

R=go1.7

Change-Id: Ib460379f063eb83d393e1c5efe7333a643c1595e
Reviewed-on: https://go-review.googlesource.com/16942
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-17 21:23:06 +00:00
Michael Hudson-Doyle
90e26f52c6 runtime, syscall: use int $0x80 to invoke syscalls on android/386
golang.org/cl/16796 broke android/386 by assuming behaviour specific to glibc's
dynamic linker. Copy bionic by using int $0x80 to invoke syscalls on
android/386 as the old alternative (CALL *runtime_vdso(SB)) cannot be compiled
without text relocations, which we want to get rid of on android.

Also remove "CALL *runtime_vdso(SB)" variant from the syscall package.

Change-Id: I6c01849f8dcbd073d000ddc8f13948a836b8b261
Reviewed-on: https://go-review.googlesource.com/16996
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
2015-11-17 20:22:47 +00:00
David Crawshaw
ce8f49f42f runtime: android/arm64 support
Not all tests passing yet, but a good chunk are.

Change-Id: I5daebaeabf3aecb380674ece8830a86751a8d139
Reviewed-on: https://go-review.googlesource.com/16458
Reviewed-by: Rahul Chaudhry <rahulchaudhry@google.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-11-17 16:28:18 +00:00
Austin Clements
f9357cdec1 runtime: check for updated arena_end overflow
Currently, if an allocation is large enough that arena_end + size
overflows (which is not hard to do on 32-bit), we go ahead and call
sysReserve with the impossible base and length and depend on this to
either directly fail because the kernel can't possibly fulfill the
requested mapping (causing mheap.sysAlloc to return nil) or to succeed
with a mapping at some other address which will then be rejected as
outside the arena.

In order to make this less subtle, less dependent on the kernel
getting all of this right, and to eliminate the hopeless system call,
add an explicit overflow check.

Updates #13143. This real issue has been fixed by 0de59c2, but this is
a belt-and-suspenders improvement on top of that. It was uncovered by
my symbolic modeling of that bug.

Change-Id: I85fa868a33286fdcc23cdd7cdf86b19abf1cb2d1
Reviewed-on: https://go-review.googlesource.com/16961
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-11-17 00:16:36 +00:00
Austin Clements
4d39bb6a3a runtime: make mcache.tiny a uintptr
mcache.tiny is in non-GC'd memory, but points to heap memory. As a
result, there may or may not be write barriers when writing to
mcache.tiny. Make it clearer that funny things are going on by making
mcache.tiny a uintptr instead of an unsafe.Pointer.

Change-Id: I732a5b7ea17162f196a9155154bbaff8d4d00eac
Reviewed-on: https://go-review.googlesource.com/16963
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-16 22:07:41 +00:00
Austin Clements
835c83b40d runtime: clear tiny alloc cache in mark term, not sweep term
The tiny alloc cache is maintained in a pointer from non-GC'd memory
(mcache) to heap memory and hence must be handled carefully.

Currently we clear the tiny alloc cache during sweep termination and,
if it is assigned to a non-nil value during concurrent marking, we
depend on a write barrier to keep the new value alive. However, while
the compiler currently always generates this write barrier, we're
treading on thin ice because write barriers may not happen for writes
to non-heap memory (e.g., typedmemmove). Without this lucky write
barrier, the GC may free a current tiny block while it's still
reachable by the tiny allocator, leading to later memory corruption.

Change this code so that, rather than depending on the write barrier,
we simply clear the tiny cache during mark termination when we're
clearing all of the other mcaches. If the current tiny block is
reachable from regular pointers, it will be retained; if it isn't
reachable from regular pointers, it may be freed, but that's okay
because there won't be any pointers in non-GC'd memory to it.

Change-Id: I8230980d8612c35c2997b9705641a1f9f865f879
Reviewed-on: https://go-review.googlesource.com/16962
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-16 22:07:37 +00:00
Ian Lance Taylor
be1ef46775 runtime: add optional expensive check for invalid cgo pointer passing
If you set GODEBUG=cgocheck=2 the runtime package will use the write
barrier to detect cases where a Go program writes a Go pointer into
non-Go memory.  In conjunction with the existing cgo checks, and the
not-yet-implemented cgo check for exported functions, this should
reliably detect all cases (that do not import the unsafe package) in
which a Go pointer is incorrectly shared with C code.  This check is
optional because it turns on the write barrier at all times, which is
known to be expensive.

Update #12416.

Change-Id: I549d8b2956daa76eac853928e9280e615d6365f4
Reviewed-on: https://go-review.googlesource.com/16899
Reviewed-by: Russ Cox <rsc@golang.org>
2015-11-16 18:39:06 +00:00
Austin Clements
0de59c27eb runtime: handle sysReserve returning a pointer below the arena
In mheap.sysAlloc, if an allocation at arena_used would exceed
arena_end (but wouldn't yet push us past arena_start+_MaxArean32), it
trie to extend the arena reservation by another 256 MB. It extends the
arena by calling sysReserve, which, on 32-bit, calls mmap without
MAP_FIXED, which means the address is just a hint and the kernel can
put the mapping wherever it wants. In particular, mmap may choose an
address below arena_start (the kernel also chose arena_start, so there
could be lots of space below it). Currently, we don't detect this case
and, if it happens, mheap.sysAlloc will corrupt arena_end and
arena_used then return the low pointer to mheap.grow, which will crash
when it attempts to index in to h_spans with an underflowed index.

Fix this by checking not only that that p+p_size isn't too high, but
that p isn't too low.

Fixes #13143.

Change-Id: I8d0f42bd1484460282a83c6f1a6f8f0df7fb2048
Reviewed-on: https://go-review.googlesource.com/16927
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-11-16 17:32:40 +00:00
Austin Clements
97dc591534 runtime: avoid stat underflow crash
If the area returned by sysReserve in mheap.sysAlloc is outside the
usable arena, we sysFree it. We pass a fake stat pointer to sysFree
because we haven't added the allocation to any stat at that point.
However, we pass a 0 stat, so sysFree panics when it decrements the
stat because the fake stat underflows.

Fix this by setting the fake stat to the allocation size.

Updates #13143 (this is a prerequisite to fixing that bug).

Change-Id: I61a6c9be19ac1c95863cf6a8435e19790c8bfc9a
Reviewed-on: https://go-review.googlesource.com/16926
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-11-16 17:32:29 +00:00
Michael Hudson-Doyle
7af0839e11 cmd/go, runtime: always use position-independent code to invoke vsyscall helper on linux/386
golang.org/cl/16346 changed the runtime on linux/386 to invoke the vsyscall
helper via a PIC sequence (CALL 0x10(GS)) when dynamically linking. But it's
actually quite easy to make that code sequence work all the time, so do that,
and remove the ugly machinery that passed the buildmode from the go tool to the
assembly.

This means enlarging m.tls so that we can safely access 0x10(GS) (GS is set to
&m.tls + 4, so 0x10(GS) accesses m_tls[5]).

Change-Id: I1345c34029b149cb5f25320bf19a3cdd73a056fa
Reviewed-on: https://go-review.googlesource.com/16796
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-11-15 06:42:19 +00:00
Ian Lance Taylor
52393ad036 runtime: remove go:nosplit comment from reflect.typelinks
A nosplit comment was added to reflect.typelinks accidentally in
https://golang.org/cl/98510044.  There is only one caller of
reflect.typelinks, reflect.typesByString, and that function is not
nosplit.  There is no reason for reflect.typelinks to be nosplit.

Change-Id: I0fd3cc66fafcd92643e38e53fa586d6b2f868a0a
Reviewed-on: https://go-review.googlesource.com/16932
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
2015-11-15 05:49:48 +00:00