unix/linux: update glibc to 2.39

Change-Id: I5c2b996180073ca10f1b7c86201a19eaf0557e43
GitHub-Last-Rev: a092f56
GitHub-Pull-Request: #195
Reviewed-on: https://go-review.googlesource.com/c/sys/+/585136
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

unix/linux/Dockerfile

@@ -17,8 +17,8 @@ WORKDIR /git
 RUN git config --global advice.detachedHead false
 # Linux Kernel: Released 12 May 2024
 RUN git clone --branch v6.9 --depth 1 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
-# GNU C library: Released 1 Feb 2023
-RUN git clone --branch release/2.37/master --depth 1 https://sourceware.org/git/glibc.git
+# GNU C library: Released 31 Jan 2024
+RUN git clone --branch release/2.39/master --depth 1 https://sourceware.org/git/glibc.git
 
 # Get Go
 ENV GOLANG_VERSION 1.21.0

unix/linux/mkall.go

@@ -417,6 +417,20 @@ func (t *target) makeHeaders() error {
 	} else {
 		glibcArgs = append(glibcArgs, "--enable-kernel="+MinKernel)
 	}
+
+	// CET is not supported on x86 but glibc 2.39 enables it by default, it was later reverted.
+	// See https://sourceware.org/git/?p=glibc.git;a=commit;h=25f1e16ef03a6a8fb1701c4647d46c564480d88c
+	if t.LinuxArch == "x86" {
+		glibcArgs = append(glibcArgs, "--enable-cet=no")
+	}
+
+	// glibc 2.38 requires libmvec to be disabled explicitly in aarch64
+	// since the installed compiler does not have SVE ACLE.
+	// See https://sourceware.org/pipermail/libc-alpha/2023-May/147829.html
+	if t.LinuxArch == "arm64" {
+		glibcArgs = append(glibcArgs, "--disable-mathvec")
+	}
+
 	glibcConf := t.makeCommand(confScript, glibcArgs...)
 
 	glibcConf.Dir = buildDir