[PATCH] tools/perf: Fix bpf-script-test-prologue test compile issue with clang

[Athira Rajeev <atrajeev@linux.vnet.ibm.com>]

While running perf test for bpf, observed that "BPF prologue
generation" test case fails to compile with clang. Logs below
from powerpc:

<stdin>:33:2: error: use of undeclared identifier 'fmode_t'
        fmode_t f_mode = (fmode_t)_f_mode;
        ^
<stdin>:37:6: error: use of undeclared identifier 'f_mode'; did you mean '_f_mode'?
        if (f_mode & FMODE_WRITE)
            ^~~~~~
            _f_mode
<stdin>:30:60: note: '_f_mode' declared here
int bpf_func__null_lseek(void *ctx, int err, unsigned long _f_mode,
                                                           ^
2 errors generated.

The test code tests/bpf-script-test-prologue.c uses fmode_t.
And the error above is for "fmode_t" which is defined in
include/linux/types.h as part of kernel build directory:
"/lib/modules/<kernel_version>/build" that comes from
kernel devel [ soft link to /usr/src/<kernel_version> ].
Clang picks this header file from "-working-directory" build
option that specifies this build folder.

But the 'commit 14e4b9f4289a ("perf trace: Raw augmented
syscalls fix libbpf 1.0+ compatibility")', changed the
include directory to use: "/usr/include".  Post this change,
types.h from /usr/include/ is getting picked upwhich doesn’t
contain definition of "fmode_t" and hence fails to compile.

Compilation command before this commit:
/usr/bin/clang -D__KERNEL__ -D__NR_CPUS__=72 -DLINUX_VERSION_CODE=0x50e00 -xc  -I/root/lib/perf/include/bpf -nostdinc -I./arch/powerpc/include -I./arch/powerpc/include/generated  -I./include -I./arch/powerpc/include/uapi -I./arch/powerpc/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/compiler-version.h -include ./include/linux/kconfig.h  -Wno-unused-value -Wno-pointer-sign -working-directory /lib/modules/<ver>/build -c - -target bpf  -g -O2 -o -

Compilation command after this commit:
/usr/bin/clang -D__KERNEL__ -D__NR_CPUS__=72 -DLINUX_VERSION_CODE=0x50e00 -xc  -I/usr/include/ -nostdinc -I./arch/powerpc/include -I./arch/powerpc/include/generated  -I./include -I./arch/powerpc/include/uapi -I./arch/powerpc/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/compiler-version.h -include ./include/linux/kconfig.h  -Wno-unused-value -Wno-pointer-sign -working-directory /lib/modules/<ver>/build -c - -target bpf  -g -O2 -o -

The difference is addition of -I/usr/include/  in the first line
which is causing the error. Fix this by adding typedef for "fmode_t"
in the testcase to solve the compile issue.

Fixes: 14e4b9f4289a ("perf trace: Raw augmented syscalls fix libbpf 1.0+ compatibility")
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
---
 tools/perf/tests/bpf-script-test-prologue.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/tests/bpf-script-test-prologue.c b/tools/perf/tests/bpf-script-test-prologue.c
index bd83d364cf30..91778b5c6125 100644
--- a/tools/perf/tests/bpf-script-test-prologue.c
+++ b/tools/perf/tests/bpf-script-test-prologue.c
@@ -20,6 +20,8 @@
 # undef if
 #endif
 
+typedef unsigned int __bitwise fmode_t;
+
 #define FMODE_READ		0x1
 #define FMODE_WRITE		0x2
 
-- 
2.31.1