Fixes #7231.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/68250043

Currently an ECDHE handshake uses the client's curve preference. This
generally means that we use P-521. However, P-521's strength is
mismatched with the rest of the cipher suite in most cases and we have
a fast, constant-time implementation of P-256.

With this change, Go servers will use P-256 where the client supports
it although that can be overridden in the Config.

LGTM=bradfitz
R=bradfitz
CC=golang-codereviews
https://golang.org/cl/66060043

Record what's going on in case someone is debugging a failure there.
It's not Go's fault.

Fixes #7381.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/68200043

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/68380043

Credit goes to Dave Cheney for debugging the issue.

LGTM=dave, rsc
R=dave, rsc
CC=golang-codereviews
https://golang.org/cl/67820043

Revision c0e0467635ec (cmd/gc: return canonical Node* from temp)
exposed original nodes of temporaries, allowing callers to mutate
their types.

In walkcompare a temporary could be typed as ideal because of
this. Additionnally, assignment of a comparison result to
a custom boolean type was broken.

Fixes #7366.

LGTM=rsc
R=rsc, iant, khr
CC=golang-codereviews
https://golang.org/cl/66930044

Fixes the output of go env so that variables can be set
more accurately when using Plan 9's rc shell. Specifically,
GOPATH may have multiple components and the current
representation is plain wrong. In practice, we probably
ought to change os. Getenv to produce the right result, but
that requires considerably more thought.

LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews
https://golang.org/cl/66600043

LGTM=dave
R=golang-codereviews, dave
CC=golang-codereviews
https://golang.org/cl/66900044

Fatal must not be called from secondary goroutines.
Fixes #7401.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/67820047

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/68230045

With concurrent sweeping finc if modified by runfinq and queuefinalizer concurrently.
Fixes crashes like this one:
http://build.golang.org/log/6ad7b59ef2e93e3c9347eabfb4c4bd66df58fd5a
Fixes #7324.
Update #7396

LGTM=rsc
R=golang-codereviews, minux.ma, rsc
CC=golang-codereviews, khr
https://golang.org/cl/67980043

Reinforce the guarantee that MSpan_EnsureSwept actually ensures that the span is swept.
I have not observed crashes related to this, but I do not see why it can't crash as well.

LGTM=rsc
R=golang-codereviews
CC=golang-codereviews, khr, rsc
https://golang.org/cl/67990043

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/68020043

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/68060043

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/67830044

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/67910046

Note that current z-files for linux/amd64,386,arm are based on 3.2 kernel.

LGTM=iant
R=golang-codereviews, dave, bradfitz, gobot, iant
CC=golang-codereviews
https://golang.org/cl/59160044

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/68030043

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/68070043

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/68040044

runfinqv is already defined the same way on line 271.
There may also be something to fix in compiler/linker wrt diagnostics.
Fixes #7375.

LGTM=bradfitz
R=golang-codereviews, dave, bradfitz
CC=golang-codereviews
https://golang.org/cl/67850044

Update #7347

When runtime.panic is called the *Panic is malloced from the heap. This can lead to a gc cycle while panicing which can make a bad situation worse.

It appears to be possible to stack allocate the Panic and avoid malloc'ing during a panic.

Ref: https://groups.google.com/d/topic/golang-dev/OfxqpklGkh0/discussion

LGTM=minux.ma, dvyukov, rsc
R=r, minux.ma, gobot, rsc, dvyukov
CC=golang-codereviews
https://golang.org/cl/66830043

This lays the groundwork for making Go robust when the system's
calendar time jumps around. All input values to the runtimeTimer
struct now use the runtime clock as a common reference point.
This affects net.Conn.Set[Read|Write]Deadline(), time.Sleep(),
time.Timer, etc. Under normal conditions, behavior is unchanged.

Each platform and architecture's implementation of runtime·nanotime()
should be modified to use a monotonic system clock when possible.

Platforms/architectures modified and tested with monotonic clock:
  linux/x86     - clock_gettime(CLOCK_MONOTONIC)

Update #6007

LGTM=dvyukov, rsc
R=golang-codereviews, dvyukov, alex.brainman, stephen.gutekanst, dave, rsc, mikioh.mikioh
CC=golang-codereviews
https://golang.org/cl/53010043

LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews
https://golang.org/cl/64770043

Update #6963 Fixes pretty printing maps and updates
functions for interacting with $len(). goroutine $n bt
remains not working. Tested on gdb using python 2 and 3.
Fixes #7052
Update #6963
Fixes #6698

LGTM=rsc
R=golang-codereviews, josharian, rsc
CC=golang-codereviews
https://golang.org/cl/53590043

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/60640052

One defer was not removed in CL61150043.

LGTM=dvyukov
R=bradfitz, dvyukov
CC=golang-codereviews
https://golang.org/cl/64600044

After "runtime: combine small NoScan allocations" finalizers
for small objects run more non deterministically.
TestRaceFin episodically fails on my darwin/amd64.

LGTM=khr
R=golang-codereviews, khr, dave
CC=golang-codereviews
https://golang.org/cl/56970043

Also updates documentation.

LGTM=minux.ma
R=iant, bradfitz, nightlyone, minux.ma
CC=golang-codereviews
https://golang.org/cl/58660044

LGTM=iant
R=golang-codereviews, minux.ma, gobot, iant
CC=golang-codereviews
https://golang.org/cl/67170043

As per request from minux in CL 61520049, this CL consolidates
existing test cases for Unix-like systems into one file except
Linux-specific credential test.

LGTM=bradfitz
R=iant, minux.ma, bradfitz
CC=golang-codereviews
https://golang.org/cl/67800044

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/66990045

Fix build for 10.6 Darwin builders and OpenBSD builers.

LGTM=jsing
R=golang-codereviews, dave, jsing
CC=golang-codereviews
https://golang.org/cl/67710043

Fixes #7223.

LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews
https://golang.org/cl/63040043

Fix build for Dragonfly BSD.
Fixes #7318.
Fixes #7367.

LGTM=jsing, iant
R=jsing, iant, mikioh.mikioh
CC=golang-codereviews
https://golang.org/cl/64340043

LGTM=minux.ma, r
R=golang-codereviews, minux.ma, r
CC=golang-codereviews
https://golang.org/cl/67280043

Generated by addca.

R=gobot
CC=golang-codereviews
https://golang.org/cl/64100047

Fixes #7361.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/66910045

crypto/tls has two functions for creating a client connection: Dial,
which most users are expected to use, and Client, which is the
lower-level API.

Dial does what you expect: it gives you a secure connection to the host
that you specify and the majority of users of crypto/tls appear to work
fine with it.

Client gives more control but needs more care. Specifically, if it
wasn't given a server name in the tls.Config then it didn't check that
the server's certificates match any hostname - because it doesn't have
one to check against. It was assumed that users of the low-level API
call VerifyHostname on the certificate themselves if they didn't supply
a hostname.

A review of the uses of Client both within Google and in a couple of
external libraries has shown that nearly all of them got this wrong.

Thus, this change enforces that either a ServerName or
InsecureSkipVerify is given. This does not affect tls.Dial.

See discussion at https://groups.google.com/d/msg/golang-nuts/4vnt7NdLvVU/b1SJ4u0ikb0J.

Fixes #7342.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/67010043

Generated by addca.

R=gobot
CC=golang-codereviews
https://golang.org/cl/67010044