[PATCH] i386: Add GLIBC_ABI_GNU_TLS version [BZ #33221]

[H.J. Lu]

On i386, programs and shared libraries with __thread usage may fail
silently at run-time against glibc without the TLS run-time fix for:

https://sourceware.org/bugzilla/show_bug.cgi?id=32996

Add GLIBC_ABI_GNU_TLS version to indicate that glibc has the working
GNU TLS run-time.  Linker can add the GLIBC_ABI_GNU_TLS version to
binaries which depend on the working TLS run-time so that such programs
and shared libraries will fail to load and run at run-time against
libc.so without the GLIBC_ABI_GNU_TLS version, instead of fail silently
at random.

This fixes BZ #33221.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
 sysdeps/i386/Makefile | 9 +++++++++
 sysdeps/i386/Versions | 5 +++++
 2 files changed, 14 insertions(+)

diff --git a/sysdeps/i386/Makefile b/sysdeps/i386/Makefile
index ee6470d78e..c0c017b899 100644
--- a/sysdeps/i386/Makefile
+++ b/sysdeps/i386/Makefile
@@ -60,6 +60,15 @@ $(objpfx)tst-ld-sse-use.out: ../sysdeps/i386/tst-ld-sse-use.sh $(objpfx)ld.so
 	@echo "Checking ld.so for SSE register use.  This will take a few seconds..."
 	$(BASH) $< $(objpfx) '$(NM)' '$(OBJDUMP)' '$(READELF)' > $@; \
 	$(evaluate-test)
+
+tests-special += $(objpfx)check-gnu-tls.out
+
+$(objpfx)check-gnu-tls.out: $(common-objpfx)libc.so
+	LC_ALL=C $(READELF) -V -W $< \
+		| sed -ne '/.gnu.version_d/, /.gnu.version_r/ p' \
+		| grep GLIBC_ABI_GNU_TLS > $@; \
+	$(evaluate-test)
+generated += check-gnu-tls.out
 else
 CFLAGS-.os += $(if $(filter rtld-%.os,$(@F)), $(rtld-CFLAGS))
 endif
diff --git a/sysdeps/i386/Versions b/sysdeps/i386/Versions
index 36e23b466a..9c84c8ef04 100644
--- a/sysdeps/i386/Versions
+++ b/sysdeps/i386/Versions
@@ -28,6 +28,11 @@ libc {
   GLIBC_2.13 {
     __fentry__;
   }
+  GLIBC_ABI_GNU_TLS {
+    # This symbol is used only for empty version map and will be removed
+    # by scripts/versions.awk.
+    __placeholder_only_for_empty_version_map;
+  }
 }
 libm {
   GLIBC_2.1 {
-- 
2.50.1