[dev.simd] all: merge master (88cf0c5) into dev.simd

Merge List:

+ 2025-07-11 88cf0c5d55 cmd/link: do size fixups after symbol references are loaded
+ 2025-07-10 7a38975a48 os: trivial comment fix
+ 2025-07-10 aa5de9ebb5 synctest: fix comments for time.Now() in synctests
+ 2025-07-10 63ec70d4e1 crypto/cipher: Fix comment punctuation
+ 2025-07-09 8131635e5a runtime: run TestSignalDuringExec in its own process group
+ 2025-07-09 67c1704444 crypto/tls: empty server_name conf. ext. from server
+ 2025-07-08 54c9d77630 cmd/go: disable support for multiple vcs in one module
+ 2025-07-08 fca43a8436 internal: make struct comment match struct name
+ 2025-07-08 bb917bb030 cmd/compile: document that nosplit directive is unsafe
+ 2025-07-08 a5bda585d5 cmd/compile: run fmt on ssa
+ 2025-07-07 86b5ba7310 internal/trace: only test for sync preemption if async preemption is off
+ 2025-07-07 ef46e1b164 cmd/internal/doc: fix GOROOT skew and path joining bugs
+ 2025-07-07 75b43f9a97 runtime: make traceStack testable and add a benchmark
+ 2025-07-07 20978f46fd crypto/rsa: remove another forgotten note to future self
+ 2025-07-07 33fb4819f5 cmd/compile/internal/ssa: skip EndSequence entries in TestStmtLines
+ 2025-07-07 a995269a93 sort: clarify Less doc
+ 2025-07-03 6c3b5a2798 runtime: correct vdsoSP on S390X
+ 2025-07-03 dd687c3860 hash: document that Clone may only return ErrUnsupported or a nil error
+ 2025-07-02 b325151453 cmd/cgo/internal/testsanitizers: skip asan tests when FIPS140 mode is on
+ 2025-07-02 15d9fe43d6 testing/synctest: explicitly state Run will be removed in Go 1.26
+ 2025-07-01 de646d94f7 cmd/go/internal/modindex: apply changes in CL 502615 to modindex package
+ 2025-07-01 2f653a5a9e crypto/tls: ensure the ECDSA curve matches the signature algorithm
+ 2025-07-01 6e95fd96cc crypto/ecdsa: fix crypto/x509 godoc links
+ 2025-07-01 7755a05209 Revert "crypto/internal/fips140/subtle: add assembly implementation of xorBytes for arm"
+ 2025-07-01 d168ad18e1 slices: update TestIssue68488 to avoid false positives
+ 2025-07-01 27ad1f5013 internal/abi: fix comment on NonEmptyInterface
+ 2025-06-30 86fca3dcb6 encoding/json/jsontext: use bytes.Buffer.AvailableBuffer
+ 2025-06-30 6bd9944c9a encoding/json/v2: avoid escaping jsonopts.Struct
+ 2025-06-30 e46d586edd cmd/compile/internal/escape: add debug hash for literal allocation optimizations
+ 2025-06-30 479b51ee1f cmd/compile/internal/escape: stop disabling literal allocation optimizations when coverage is enabled
+ 2025-06-30 8002d283e8 crypto/tls: update bogo version
+ 2025-06-30 fdd7713fe5 internal/goexperiment: fix godoc formatting

Change-Id: I074e6c75778890930975925c016004aabca2b9d1

10 files changed, 118 insertions, 10 deletions

diff --git a/src/runtime/export_test.go b/src/runtime/export_test.go
index b3bb5d2c58..81542deb59 100644
--- a/src/runtime/export_test.go
+++ b/src/runtime/export_test.go
@@ -1919,3 +1919,13 @@ const (
 	BubbleAssocCurrentBubble = bubbleAssocCurrentBubble
 	BubbleAssocOtherBubble   = bubbleAssocOtherBubble
 )
+
+type TraceStackTable traceStackTable
+
+func (t *TraceStackTable) Reset() {
+	t.tab.reset()
+}
+
+func TraceStack(gp *G, tab *TraceStackTable) {
+	traceStack(0, gp, (*traceStackTable)(tab))
+}
diff --git a/src/runtime/metrics/doc.go b/src/runtime/metrics/doc.go
index 32fc436e1a..a1902bc6d7 100644
--- a/src/runtime/metrics/doc.go
+++ b/src/runtime/metrics/doc.go
@@ -230,6 +230,11 @@ Below is the full list of supported metrics, ordered lexicographically.
 	/gc/stack/starting-size:bytes
 		The stack size of new goroutines.
 
+	/godebug/non-default-behavior/allowmultiplevcs:events
+		The number of non-default behaviors executed by the cmd/go
+		package due to a non-default GODEBUG=allowmultiplevcs=...
+		setting.
+
 	/godebug/non-default-behavior/asynctimerchan:events
 		The number of non-default behaviors executed by the time package
 		due to a non-default GODEBUG=asynctimerchan=... setting.
diff --git a/src/runtime/runtime-gdb_test.go b/src/runtime/runtime-gdb_test.go
index 19ad29c127..47c1fe5851 100644
--- a/src/runtime/runtime-gdb_test.go
+++ b/src/runtime/runtime-gdb_test.go
@@ -78,6 +78,9 @@ func checkGdbVersion(t *testing.T) {
 	if major < 10 {
 		t.Skipf("skipping: gdb version %d.%d too old", major, minor)
 	}
+	if major < 12 || (major == 12 && minor < 1) {
+		t.Logf("gdb version <12.1 is known to crash due to a SIGWINCH recieved in non-interactive mode; if you see a crash, some test may be sending SIGWINCH to the whole process group. See go.dev/issue/58932.")
+	}
 	t.Logf("gdb version %d.%d", major, minor)
 }
 
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index 8c6ef2b4fc..866c46a83d 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -981,6 +981,9 @@ func pcvalue(f funcInfo, off uint32, targetpc uintptr, strict bool) (int32, uint
 	// matches the cached contents.
 	const debugCheckCache = false
 
+	// If true, skip checking the cache entirely.
+	const skipCache = false
+
 	if off == 0 {
 		return -1, 0
 	}
@@ -991,7 +994,7 @@ func pcvalue(f funcInfo, off uint32, targetpc uintptr, strict bool) (int32, uint
 	var checkVal int32
 	var checkPC uintptr
 	ck := pcvalueCacheKey(targetpc)
-	{
+	if !skipCache {
 		mp := acquirem()
 		cache := &mp.pcvalueCache
 		// The cache can be used by the signal handler on this M. Avoid
diff --git a/src/runtime/sys_linux_s390x.s b/src/runtime/sys_linux_s390x.s
index 2f9d4beda8..a3472a4508 100644
--- a/src/runtime/sys_linux_s390x.s
+++ b/src/runtime/sys_linux_s390x.s
@@ -226,7 +226,7 @@ TEXT runtime·walltime(SB),NOSPLIT,$32-12
 	MOVD	R4, 24(R15)
 
 	MOVD	R14, R8 		// Backup return address
-	MOVD	$sec+0(FP), R4 	// return parameter caller
+	MOVD	$ret-8(FP), R4 	// caller's SP
 
 	MOVD	R8, m_vdsoPC(R6)
 	MOVD	R4, m_vdsoSP(R6)
@@ -312,7 +312,7 @@ TEXT runtime·nanotime1(SB),NOSPLIT,$32-8
 	MOVD	R4, 24(R15)
 
 	MOVD	R14, R8			// Backup return address
-	MOVD	$ret+0(FP), R4	// caller's SP
+	MOVD	$ret-8(FP), R4	// caller's SP
 
 	MOVD	R8, m_vdsoPC(R6)
 	MOVD	R4, m_vdsoSP(R6)
diff --git a/src/runtime/testdata/testprognet/signalexec.go b/src/runtime/testdata/testprognet/signalexec.go
index 62ebce7176..7e7591e8f7 100644
--- a/src/runtime/testdata/testprognet/signalexec.go
+++ b/src/runtime/testdata/testprognet/signalexec.go
@@ -13,9 +13,11 @@ package main
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"os/exec"
 	"os/signal"
+	"runtime"
 	"sync"
 	"syscall"
 	"time"
@@ -23,10 +25,51 @@ import (
 
 func init() {
 	register("SignalDuringExec", SignalDuringExec)
+	register("SignalDuringExecPgrp", SignalDuringExecPgrp)
 	register("Nop", Nop)
 }
 
 func SignalDuringExec() {
+	// Re-launch ourselves in a new process group.
+	cmd := exec.Command(os.Args[0], "SignalDuringExecPgrp")
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Setpgid: true,
+	}
+
+	// Start the new process with an extra pipe. It will
+	// exit if the pipe is closed.
+	rp, wp, err := os.Pipe()
+	if err != nil {
+		fmt.Printf("Failed to create pipe: %v", err)
+		return
+	}
+	cmd.ExtraFiles = []*os.File{rp}
+
+	// Run the command.
+	if err := cmd.Run(); err != nil {
+		fmt.Printf("Run failed: %v", err)
+	}
+
+	// We don't actually need to write to the pipe, it just
+	// needs to get closed, which will happen on process
+	// exit.
+	runtime.KeepAlive(wp)
+}
+
+func SignalDuringExecPgrp() {
+	// Grab fd 3 which is a pipe we need to read on.
+	f := os.NewFile(3, "pipe")
+	go func() {
+		// Nothing will ever get written to the pipe, so we'll
+		// just block on it. If it closes, ReadAll will return
+		// one way or another, at which point we'll exit.
+		io.ReadAll(f)
+		os.Exit(1)
+	}()
+
+	// This is just for SignalDuringExec.
 	pgrp := syscall.Getpgrp()
 
 	const tries = 10
diff --git a/src/runtime/trace.go b/src/runtime/trace.go
index b92e7b4e8e..0d71ad445c 100644
--- a/src/runtime/trace.go
+++ b/src/runtime/trace.go
@@ -396,7 +396,7 @@ func traceAdvance(stopTrace bool) {
 				ug.status = readgstatus(s.g) &^ _Gscan
 				ug.waitreason = s.g.waitreason
 				ug.inMarkAssist = s.g.inMarkAssist
-				ug.stackID = traceStack(0, gp, gen)
+				ug.stackID = traceStack(0, gp, &trace.stackTab[gen%2])
 			}
 			resumeG(s)
 			casgstatus(me, _Gwaiting, _Grunning)
diff --git a/src/runtime/traceevent.go b/src/runtime/traceevent.go
index 9d1a93d3f9..263847be2e 100644
--- a/src/runtime/traceevent.go
+++ b/src/runtime/traceevent.go
@@ -56,7 +56,7 @@ func (e traceEventWriter) event(ev tracev2.EventType, args ...traceArg) {
 // It then returns a traceArg representing that stack which may be
 // passed to write.
 func (tl traceLocker) stack(skip int) traceArg {
-	return traceArg(traceStack(skip, nil, tl.gen))
+	return traceArg(traceStack(skip, nil, &trace.stackTab[tl.gen%2]))
 }
 
 // startPC takes a start PC for a goroutine and produces a unique
diff --git a/src/runtime/tracestack.go b/src/runtime/tracestack.go
index 2ee68c85f0..76d6b05048 100644
--- a/src/runtime/tracestack.go
+++ b/src/runtime/tracestack.go
@@ -28,10 +28,8 @@ const (
 // skip controls the number of leaf frames to omit in order to hide tracer internals
 // from stack traces, see CL 5523.
 //
-// Avoid calling this function directly. gen needs to be the current generation
-// that this stack trace is being written out for, which needs to be synchronized with
-// generations moving forward. Prefer traceEventWriter.stack.
-func traceStack(skip int, gp *g, gen uintptr) uint64 {
+// Avoid calling this function directly. Prefer traceEventWriter.stack.
+func traceStack(skip int, gp *g, tab *traceStackTable) uint64 {
 	var pcBuf [tracev2.MaxFramesPerStack]uintptr
 
 	// Figure out gp and mp for the backtrace.
@@ -134,7 +132,7 @@ func traceStack(skip int, gp *g, gen uintptr) uint64 {
 	if nstk > 0 && gp.goid == 1 {
 		nstk-- // skip runtime.main
 	}
-	id := trace.stackTab[gen%2].put(pcBuf[:nstk])
+	id := tab.put(pcBuf[:nstk])
 	return id
 }
 
diff --git a/src/runtime/tracestack_test.go b/src/runtime/tracestack_test.go
new file mode 100644
index 0000000000..eaf4d906e3
--- /dev/null
+++ b/src/runtime/tracestack_test.go
@@ -0,0 +1,46 @@
+// Copyright 2025 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	"runtime"
+	"strconv"
+	"testing"
+)
+
+func BenchmarkTraceStack(b *testing.B) {
+	for _, stackDepth := range []int{1, 10, 100} {
+		b.Run("stackDepth="+strconv.Itoa(stackDepth), func(b *testing.B) {
+			benchmarkTraceStack(b, stackDepth)
+		})
+	}
+}
+
+func benchmarkTraceStack(b *testing.B, stackDepth int) {
+	var tab runtime.TraceStackTable
+	defer tab.Reset()
+
+	wait := make(chan struct{})
+	ready := make(chan struct{})
+	done := make(chan struct{})
+	var gp *runtime.G
+	go func() {
+		gp = runtime.Getg()
+		useStackAndCall(stackDepth, func() {
+			ready <- struct{}{}
+			<-wait
+		})
+		done <- struct{}{}
+	}()
+	<-ready
+
+	for b.Loop() {
+		runtime.TraceStack(gp, &tab)
+	}
+
+	// Clean up.
+	wait <- struct{}{}
+	<-done
+}