It matters whether we are calling a function that would
return a 32-bit or 64-bit -1 on error. A few sites were wrong
and this key detail was omitted from syscall/syscallX docs.

Change-Id: I48a421b6cc4d2d2b5e58f790cc947e3cb2f98940
Reviewed-on: https://go-review.googlesource.com/c/go/+/180841
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

This removes the special case for finding assembly references to Go
symbols in runtime and runtime/internal/atomic. These are no longer
necessary because we've now marked all symbols in these packages that
must be accessible from assembly in other packages.

Fixes #31230.

Change-Id: I70c90b70e13b922a6669f3d46c53347f98d6fc3f
Reviewed-on: https://go-review.googlesource.com/c/go/+/179863
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

This marks all Go symbols called from assembly in other packages with
"go:linkname" directives to ensure they get ABI wrappers.

Now that we have this go:linkname convention, this also removes the
abi0Syms definition in the runtime, which was used to give morestackc
an ABI0 wrapper. Instead, we now just mark morestackc with a
go:linkname directive.

This was tested with buildall.bash in the default configuration, with
-race, and with -gcflags=all=-d=ssa/intrinsics/off. Since I couldn't
test cgo on non-Linux configurations, I manually grepped for runtime
symbols in runtime/cgo.

Updates #31230.

Change-Id: I6c8aa56be2ca6802dfa2bf159e49c411b9071bf1
Reviewed-on: https://go-review.googlesource.com/c/go/+/179862
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

The //go:linkname directive can be used to make a symbol accessible to
another package (when it wouldn't normally be). Sometimes you want to
do this without actually changing the symbol's object file symbol
name; for example, in gccgo this makes unexported symbols non-static,
and in gc this provides ABI0 wrappers for Go symbols so they can be
called from assembly in other packages. Currently, this results in
stutter like

   //go:linkname entersyscall runtime.entersyscall

This CL makes the second argument to go:linkname optional for the case
where the intent is simply to expose the symbol rather than to rename
it in the object file.

Updates #31230.

Change-Id: Id06d9c4b2ec3d8e27f9b8a0d65212ab8048d734f
Reviewed-on: https://go-review.googlesource.com/c/go/+/179861
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Calling a Go symbol from assembly in another package currently results
in a link failure because the Go symbol is defined as ABIInternal, but
the assembly call is from ABI0. In general this is okay because you
shouldn't do this anyway, but there are special cases where this is
necessary, especially between the runtime and packages closely tied to
the runtime in std.

Currently, we address this for runtime symbols with a hack in cmd/go
that knows to scan related packages when building the symabis file for
the runtime and runtime/internal/atomic. However, in addition to being
a messy solution in the first place, this hack causes races in cmd/go
that are difficult to work around.

We considered creating dummy references from assembly in the runtime
to these symbols, just to make sure they get ABI0 wrappers. However,
there are a fairly large number of these symbols on some platforms,
and it can vary significantly depending on build flags (e.g., race
mode), so even this solution is fairly unpalatable.

This CL addresses this by providing a way to mark symbols in Go code
that should be made available to assembly in other packages. Rather
than introduce a new pragma, we lightly expand the meaning of
"//go:linkname", since that pragma already generally indicates that
you're making the symbol available in a way it wasn't before. This
also dovetails nicely with the behavior of go:linkname in gccgo, which
makes unexported symbols available to other packages.

Follow-up CLs will make use of this and then remove the hack from
cmd/go.

Updates #31230.

Change-Id: I23060c97280626581f025c5c01fb8d24bb4c5159
Reviewed-on: https://go-review.googlesource.com/c/go/+/179860
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

The z/Architecture does not guarantee that a load following a store
will not be reordered with that store, unless they access the same
address. Therefore if we want to ensure the sequential consistency
of atomic loads and stores we need to perform serialization
operations after atomic stores.

We do not need to serialize in the runtime when using StoreRel[ease]
and LoadAcq[uire]. The z/Architecture already provides sufficient
ordering guarantees for these operations.

name              old time/op  new time/op  delta
AtomicLoad64-16   0.51ns ± 0%  0.51ns ± 0%     ~     (all equal)
AtomicStore64-16  0.51ns ± 0%  0.60ns ± 9%  +16.47%  (p=0.000 n=17+20)
AtomicLoad-16     0.51ns ± 0%  0.51ns ± 0%     ~     (all equal)
AtomicStore-16    0.51ns ± 0%  0.60ns ± 9%  +16.50%  (p=0.000 n=18+20)

Fixes #32428.

Change-Id: I88d19a4010c46070e4fff4b41587efe4c628d4d9
Reviewed-on: https://go-review.googlesource.com/c/go/+/180439
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Tool refactoring smallStacks into smallFrames helpfully
"corrected" the capitalization in a string, this undoes
the help.

This is necessary to ensure correct (re)building when the
flag is used to research stack-marking GC latency bugs.

Updates #27732.

Change-Id: Ib7c8d4a36c9e4f9612559be68bd481f9d9cc69f1
Reviewed-on: https://go-review.googlesource.com/c/go/+/180958
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

This is a follow up CL of CL 180877:
It will skip test create user namespaces under 3 conditions:

1. sysctl file is missing
2. file reads nothing
3. user don't have permission to create namespaces

Change-Id: I25f00a6b67213bf98d654972388637789978e1fe
Reviewed-on: https://go-review.googlesource.com/c/go/+/180937
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

Shrinks the size of things that can be stack allocated from
10M to 128k for declared variables and from 64k to 16k for
implicit allocations (new(T), &T{}, etc).

Usage: "go build -gcflags -smallframes hello.go"

An earlier GOEXPERIMENT version of this caused only one
problem, when a gc-should-detect-oversize-stack test no
longer had an oversized stack to detect.  The change was
converted to a flag to make it easier to access (for
diagnosing "long" GC-related single-thread pauses) and to
remove interference with the test.

Includes test to verify behavior.

Updates #27732.

Change-Id: I1255d484331e77185e07c78389a8b594041204c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/180817
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The original test (CL 166460) didn't check the existence of
/proc/sys/kernel/unprivileged_userns_clone and continue the test
if the file doesn't exist.

Fixes #32459

Change-Id: Iab4938252fcaded32b61e17edf68f966c2565582
Reviewed-on: https://go-review.googlesource.com/c/go/+/180877
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

Change-Id: Ie00494f098bd2bce9bfd1b18dbf9543cf46faad6
Reviewed-on: https://go-review.googlesource.com/c/go/+/180840
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I6940a4c747f2da871263afa6a4e3386395d5cf54
Reviewed-on: https://go-review.googlesource.com/c/go/+/180839
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

If the test fails, conf.teardown wouldn't be.
It doesn't look like it matters much, but clean up anyway.

Change-Id: I45c18095abfd49422975d061be20cbd971a98f8f
Reviewed-on: https://go-review.googlesource.com/c/go/+/180780
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

At least one libc call we make
(res_search, which calls _mdns_query and then mdns_item_call)
pushes a 64 kB stack frame onto the stack.
Then it faults on the guard page.

Use the default system stack size, under the assumption
that the C code being called is compatible with that stack size.

For #31705.

Change-Id: I1b0bfc2e54043c49f0709255988ef920ce30ee82
Reviewed-on: https://go-review.googlesource.com/c/go/+/180779
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #32167

Change-Id: If1277789ac96363430045e73e49d008bdae9be79
GitHub-Last-Rev: 71c9435c8417b19faaf66dc2e08740d7a9c22e3b
GitHub-Pull-Request: golang/go#32171
Reviewed-on: https://go-review.googlesource.com/c/go/+/178397
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #32427

Change-Id: I4b863bd3836067dcc2eb3a9c3a7169656763d003
Reviewed-on: https://go-review.googlesource.com/c/go/+/180438Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

This reverts commit fff4f599.

Reason for revert: Seems to still have issues around GC.

Fixes #32452

Change-Id: Ibe7af629f9ad6a3d5312acd7b066123f484da7f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/180761
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Change-Id: Ibe514058770bd5342e1f344c5b8a9ab1427d5dfe
Reviewed-on: https://go-review.googlesource.com/c/go/+/180297
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

It was rolled back.

Change-Id: I8372bb7e11bab7be242f4af7093a73d2fa093067
Reviewed-on: https://go-review.googlesource.com/c/go/+/180760Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The additions were generated using golang.org/x/build/cmd/relnote.

Change-Id: Ie7322f7d01a2dd4a7bca89b9ef9c1ce93bc2671a
Reviewed-on: https://go-review.googlesource.com/c/go/+/180778Reviewed-by: Bryan C. Mills <bcmills@google.com>

Windows does not have atomic renames; instead, it produces one of a
handful of errors in case a read races with a rename.

CL 180219 added a utility function that retries those errors in most
cases; this change updates the locations that use renameio for writes
to also use the new renameio.ReadFile function for reads.

It remains possible for a renameio.ReadFile to fail with a spurious
ERROR_FILE_NOT_FOUND, but with retries in place for the other errors
(and practical limits on write concurrency) such failures are unlikely
in practice.

Fixes #32188

Change-Id: I78c81051cc871325c1e3229e696b921b0fcd865a
Reviewed-on: https://go-review.googlesource.com/c/go/+/180517
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

ReadFile is a drop-in replacement for ioutil.ReadFile that works
around Windows filesystem flakiness under load.

A followup CL will replace uses of ioutil.ReadFile in cmd/go with this
function.

Updates #32188

Change-Id: I232ba893b132bdc84cd7b0edde436165a69e1aa8
Reviewed-on: https://go-review.googlesource.com/c/go/+/180219
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Updates #31093

Change-Id: I7962aaca0b012de01768b7b42dc2283d5845eeea
Reviewed-on: https://go-review.googlesource.com/c/go/+/180377
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

Roll back CL 159258 and CL 168337. Those changes broke existing
code. I can't see any way to keep existing code working while also
producing good error messages for types like C.ulong (such as the ones
already tested for in misc/cgo/errors).

This is not an exact roll back because parts of the code have changed
since those CLs.

Updates #29878
Fixes #31093

Change-Id: I56fe76c167ff0ab381ed273b9ca4b952402e1434
Reviewed-on: https://go-review.googlesource.com/c/go/+/180357
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

Roll back CL 161738. That fix changed StripPrefix behavior in the
general case, not just in the situation where where stripping the
prefix from path resulted in the empty string, causing issue #31622.

That kind of change to StripPrefix behavior is not backwards compatible,
and there can be a smaller, more targeted fix for the original issue.

Fixes #31622
Updates #30165

Change-Id: Ie2fcfe6787a32e44f71d564d8f9c9d580fc6f704
Reviewed-on: https://go-review.googlesource.com/c/go/+/180498
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

GOSUMDB and GONOSUMDB are described in detail by
'go help module-auth'. So, this change mentions the two
variables and says to see 'go help module-auth'.

This also adds GONOPROXY to 'go help environment'.

Fixes #32292 and updates #32056.

Change-Id: I2eae0f906a3fbfcb88ad5c8fb4870917d0d7bbcd
Reviewed-on: https://go-review.googlesource.com/c/go/+/179219Reviewed-by: Russ Cox <rsc@golang.org>

When a defer is executed at most once in a function body,
we can allocate the defer record for it on the stack instead
of on the heap.

This should make defers like this (which are very common) faster.

This optimization applies to 363 out of the 370 static defer sites
in the cmd/go binary.

name     old time/op  new time/op  delta
Defer-4  52.2ns ± 5%  36.2ns ± 3%  -30.70%  (p=0.000 n=10+10)

Fixes #6980
Update #14939

Change-Id: I697109dd7aeef9e97a9eeba2ef65ff53d3ee1004
Reviewed-on: https://go-review.googlesource.com/c/go/+/171758
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Some <h3>s were missing ids due to which the anchor links
weren't getting generated.

Fixes #32415

Change-Id: Ica21425c1a7c49735231c1de96b6c77dd594ce64
Reviewed-on: https://go-review.googlesource.com/c/go/+/180397Reviewed-by: Ian Lance Taylor <iant@golang.org>

The example in example_test.go requires that the whole file be
displayed; the addition of ExampleAs meant that only the body of the
package example function was shown, rather than the surrounding context.

This change moves ExampleAs to the file wrap_test.go file, restoring the
package example to its former glory.

Update #31716

Change-Id: Id0ea77bc06023b239a63c1d6a7c8b3c1dae91ce9
Reviewed-on: https://go-review.googlesource.com/c/go/+/179737Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
Reviewed-by: Jean de Klerk <deklerk@google.com>
Run-TryBot: Benny Siegert <bsiegert@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #32386

Change-Id: I29ad4113b02264336eebe7865895f07ef386f450
Reviewed-on: https://go-review.googlesource.com/c/go/+/180177
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

ARM64's R19-R29 and F8-F15 are callee saved registers, which
should be saved in the beginning of sigtramp, and restored at
the end.

fixes #31827

Change-Id: I622e03f1a13fec969d3a11b6a303a8a492e02bcd
Reviewed-on: https://go-review.googlesource.com/c/go/+/177045
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Normally, reflect.makeFuncStub records the context value at a known
point in the stack frame, so that the runtime can get the argument map
for reflect.makeFuncStub from that known location.

This doesn't work for defers or goroutines that haven't started yet,
because they haven't allocated a frame or run an instruction yet. The
argument map must be extracted from the context value. We already do
this for defers (the non-nil ctxt arg to getArgInfo), we just need to
do it for unstarted goroutines as well.

When we traceback a goroutine, remember the context value from
g.sched.  Use it for the first frame we find.

(We never need it for deeper frames, because we normally don't stop at
 the start of reflect.makeFuncStub, as it is nosplit. With this CL we
 could allow makeFuncStub to no longer be nosplit.)

Fixes #25897

Change-Id: I427abf332a741a80728cdc0b8412aa8f37e7c418
Reviewed-on: https://go-review.googlesource.com/c/go/+/180258Reviewed-by: Cherry Zhang <cherryyz@google.com>

Fixes #31857

Change-Id: Ic4afe1262d863112db97794edc1ade20f6926d64
Reviewed-on: https://go-review.googlesource.com/c/go/+/180197Reviewed-by: Jay Conrod <jayconrod@google.com>

When adding coverage counters to a block, the block's statement list is
mutated. CL 77150 removed the part where the mutated list is assigned
back to its parent node; this was confusing ast.Walk, which would then
lose its place and stop walking the current block, dropping counters in
the process.

This change has addCounters make a copy of the list before mutating
it, so that the original list doesn't change under Walk's feet.

Fix #32200

Change-Id: Ia3b67d8cee860ceb7caf8748cb7a80ff9c6276e0
Reviewed-on: https://go-review.googlesource.com/c/go/+/179581Reviewed-by: Rob Pike <r@golang.org>

As js.TypedArray no longer exists, the comment should be updated.

Change-Id: Idd1087c8007afc90307fdd965f28d3be8d8cd73e
Reviewed-on: https://go-review.googlesource.com/c/go/+/180097Reviewed-by: Richard Musiol <neelance@gmail.com>

Change-Id: Ie9fef7767f3263ef7daed8415ab2f59c5377a3cb
GitHub-Last-Rev: a4d13b7452f0fe060cb7575acfc200e3353fdde0
GitHub-Pull-Request: golang/go#32385
Reviewed-on: https://go-review.googlesource.com/c/go/+/180037Reviewed-by: Agniva De Sarker <agniva.quicksilver@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

In module mode, 'go get' should not consider build constraints when
loading packages in order to modify the module graph. With this
change, 'go get' considers all build tags to be true except for
"ignore" and malformed build constraint expressions.

When 'go get' builds packages, it still applies build constraints for
the target platform.

Fixes #32345

Change-Id: I6dceae6f10a5185870537de730b36292271ad124
Reviewed-on: https://go-review.googlesource.com/c/go/+/179898Reviewed-by: Bryan C. Mills <bcmills@google.com>

We need to make sure that there's no possible faulting
instruction between a VarDef and that variable being
fully initialized. If there was, then anything scanning
the stack during the handling of that fault will see
a live but uninitialized variable on the stack.

If we have:

  NilCheck p
  VarDef x
  x = *p

We can't rewrite that to

  VarDef x
  NilCheck p
  x = *p

Particularly, even though *p faults on p==nil, we still
have to do the explicit nil check before the VarDef.

Fixes #32288

Change-Id: Ib8b88e6a5af3bf6f238ff5491ac86f53f3cf9fc9
Reviewed-on: https://go-review.googlesource.com/c/go/+/179239
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

Some runtime functions, like getcallerpc/sp, don't have Go or
assembly implementations and have to be intrinsified. Make sure
they are, even if intrinsics are disabled.

This makes "go build -gcflags=all=-d=ssa/intrinsics/off hello.go"
work.

Change-Id: I77caaed7715d3ca7ffef68a3cdc9357f095c6b9f
Reviewed-on: https://go-review.googlesource.com/c/go/+/179897
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Previously, we used the passed-in statVers as the basis for tag search,
but it is not always valid.
Instead, use info.Name, which (by precondition) must be valid.

Updates #32161
Updates #27171

Change-Id: Iaecb5043bdf2fefd26fbe3f8e3714b07d22f580f
Reviewed-on: https://go-review.googlesource.com/c/go/+/179857
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>