[PATCH] selftests/rseq: Fix build with undefined __weak

[Mark Brown]

Commit 3bcbc20942db ("selftests/rseq: Play nice with binaries statically
linked against glibc 2.35+") which is now in Linus' tree introduced uses
of __weak but did nothing to ensure that a definition is provided for it
resulting in build failures for the rseq tests:

rseq.c:41:1: error: unknown type name '__weak'
__weak ptrdiff_t __rseq_offset;
^
rseq.c:41:17: error: expected ';' after top level declarator
__weak ptrdiff_t __rseq_offset;
                ^
                ;
rseq.c:42:1: error: unknown type name '__weak'
__weak unsigned int __rseq_size;
^
rseq.c:43:1: error: unknown type name '__weak'
__weak unsigned int __rseq_flags;

Fix this by using the definition from tools/include compiler.h.

Fixes: 3bcbc20942db ("selftests/rseq: Play nice with binaries statically linked against glibc 2.35+")
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
It'd be good if the KVM testing could include builds of the rseq
selftests, the KVM tests pull in code from rseq but not the build system
which has resulted in multiple failures like this.
---
 tools/testing/selftests/rseq/Makefile | 4 +++-
 tools/testing/selftests/rseq/rseq.c   | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/rseq/Makefile b/tools/testing/selftests/rseq/Makefile
index b357ba24af06..7a957c7d459a 100644
--- a/tools/testing/selftests/rseq/Makefile
+++ b/tools/testing/selftests/rseq/Makefile
@@ -4,8 +4,10 @@ ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
 CLANG_FLAGS += -no-integrated-as
 endif
 
+top_srcdir = ../../../..
+
 CFLAGS += -O2 -Wall -g -I./ $(KHDR_INCLUDES) -L$(OUTPUT) -Wl,-rpath=./ \
-	  $(CLANG_FLAGS)
+	  $(CLANG_FLAGS) -I$(top_srcdir)/tools/include
 LDLIBS += -lpthread -ldl
 
 # Own dependencies because we only want to build against 1st prerequisite, but
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index a723da253244..96e812bdf8a4 100644
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -31,6 +31,8 @@
 #include <sys/auxv.h>
 #include <linux/auxvec.h>
 
+#include <linux/compiler.h>
+
 #include "../kselftest.h"
 #include "rseq.h"
 

---
base-commit: 5d0c230f1de8c7515b6567d9afba1f196fb4e2f4
change-id: 20230804-kselftest-rseq-build-9d537942b1de

Best regards,
-- 
Mark Brown <broonie@xxxxxxxxxx>