perf tools: Introduce weak alternative to sched_getcpu()

Which is just a wrapper for sys_getcpu and is not present in at least
musl libc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-kblef7svmhr0g93kkx78envg@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 14 insertions, 4 deletions

diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c
index fde772db1d5c..f0dcd0ee0afa 100644
--- a/tools/perf/util/cloexec.c
+++ b/tools/perf/util/cloexec.c
@@ -4,18 +4,24 @@
 #include "cloexec.h"
 #include "asm/bug.h"
 #include "debug.h"
+#include <unistd.h>
+#include <asm/unistd.h>
+#include <sys/syscall.h>
 
 static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
 
-#ifdef __GLIBC_PREREQ
-#if !__GLIBC_PREREQ(2, 6)
 int __weak sched_getcpu(void)
 {
+#ifdef __NR_getcpu
+        unsigned cpu;
+        int err = syscall(__NR_getcpu, &cpu, NULL, NULL);
+        if (!err)
+                return cpu;
+#else
         errno = ENOSYS;
+#endif
         return -1;
 }
-#endif
-#endif
 
 static int perf_flag_probe(void)
 {
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 2370cfb902b2..d8d41ef8da57 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -361,4 +361,8 @@ void print_binary(unsigned char *data, size_t len,
                   size_t bytes_per_line, print_binary_t printer,
                   void *extra);
 
+#ifndef __GLIBC__
+extern int sched_getcpu(void);
+#endif
+
 #endif /* GIT_COMPAT_UTIL_H */