tools build: Check if gettid() is available before providing helper

Laura reported that the perf build failed in fedora when we got a glibc
that provides gettid(), which I reproduced using fedora rawhide with the
glibc-devel-2.29.9000-26.fc31.x86_64 package.

Add a feature check to avoid providing a gettid() helper in such
systems.

On a fedora rawhide system with this patch applied we now get:

  [root@7a5f55352234 perf]# grep gettid /tmp/build/perf/FEATURE-DUMP
  feature-gettid=1
  [root@7a5f55352234 perf]# cat /tmp/build/perf/feature/test-gettid.make.output
  [root@7a5f55352234 perf]# ldd /tmp/build/perf/feature/test-gettid.bin
          linux-vdso.so.1 (0x00007ffc6b1f6000)
          libc.so.6 => /lib64/libc.so.6 (0x00007f04e0a74000)
          /lib64/ld-linux-x86-64.so.2 (0x00007f04e0c47000)
  [root@7a5f55352234 perf]# nm /tmp/build/perf/feature/test-gettid.bin | grep -w gettid
                   U gettid@@GLIBC_2.30
  [root@7a5f55352234 perf]#

While on a fedora:29 system:

  [acme@quaco perf]$ grep gettid /tmp/build/perf/FEATURE-DUMP
  feature-gettid=0
  [acme@quaco perf]$ cat /tmp/build/perf/feature/test-gettid.make.output
  test-gettid.c: In function ‘main’:
  test-gettid.c:8:9: error: implicit declaration of function ‘gettid’; did you mean ‘getgid’? [-Werror=implicit-function-declaration]
    return gettid();
           ^~~~~~
           getgid
  cc1: all warnings being treated as errors
  [acme@quaco perf]$

Reported-by: Laura Abbott <labbott@redhat.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lkml.kernel.org/n/tip-yfy3ch53agmklwu9o7rlgf9c@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 21 insertions, 0 deletions

diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index 3b24231c58a2..50377cc2f5f9 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -36,6 +36,7 @@ FEATURE_TESTS_BASIC :=                  \
         fortify-source                  \
         sync-compare-and-swap           \
         get_current_dir_name            \
+        gettid				\
         glibc                           \
         gtk2                            \
         gtk2-infobar                    \
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 4b8244ee65ce..523ee42db0c8 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -54,6 +54,7 @@ FILES=                                          \
          test-get_cpuid.bin                     \
          test-sdt.bin                           \
          test-cxx.bin                           \
+         test-gettid.bin			\
          test-jvmti.bin				\
          test-jvmti-cmlr.bin			\
          test-sched_getcpu.bin			\
@@ -267,6 +268,9 @@ $(OUTPUT)test-sdt.bin:
 $(OUTPUT)test-cxx.bin:
 	$(BUILDXX) -std=gnu++11
 
+$(OUTPUT)test-gettid.bin:
+	$(BUILD)
+
 $(OUTPUT)test-jvmti.bin:
 	$(BUILD)
 
diff --git a/tools/build/feature/test-all.c b/tools/build/feature/test-all.c
index a59c53705093..3b3d5d72124a 100644
--- a/tools/build/feature/test-all.c
+++ b/tools/build/feature/test-all.c
@@ -38,6 +38,10 @@
 # include "test-get_current_dir_name.c"
 #undef main
 
+#define main main_test_gettid
+# include "test-gettid.c"
+#undef main
+
 #define main main_test_glibc
 # include "test-glibc.c"
 #undef main
@@ -195,6 +199,7 @@ int main(int argc, char *argv[])
 	main_test_libelf();
 	main_test_libelf_mmap();
 	main_test_get_current_dir_name();
+	main_test_gettid();
 	main_test_glibc();
 	main_test_dwarf();
 	main_test_dwarf_getlocations();
diff --git a/tools/build/feature/test-gettid.c b/tools/build/feature/test-gettid.c
new file mode 100644
index 000000000000..ef24e42d3f1b
--- /dev/null
+++ b/tools/build/feature/test-gettid.c
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2019, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
+#define _GNU_SOURCE
+#include <unistd.h>
+
+int main(void)
+{
+	return gettid();
+}
+
+#undef _GNU_SOURCE