perf machine: Record if a arch has a single user/kernel address space

Some architectures have a single address space for kernel and user
addresses, which makes it possible to determine if an address is in
kernel space or user space. Some don't, e.g.: sparc.

Cache that info in perf_env so that, for instance, code needing to
fallback failed symbol lookups at the kernel space in single address
space arches can lookup at userspace.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: stable@vger.kernel.org # 4.19
Link: http://lkml.kernel.org/r/20181106210712.12098-2-adrian.hunter@intel.com
[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/common.c

@@ -200,3 +200,13 @@ int perf_env__lookup_objdump(struct perf_env *env, const char **path)
 
 	return perf_env__lookup_binutils_path(env, "objdump", path);
 }
+
+/*
+ * Some architectures have a single address space for kernel and user addresses,
+ * which makes it possible to determine if an address is in kernel space or user
+ * space.
+ */
+bool perf_env__single_address_space(struct perf_env *env)
+{
+	return strcmp(perf_env__arch(env), "sparc");
+}

tools/perf/arch/common.h

@@ -5,5 +5,6 @@
 #include "../util/env.h"
 
 int perf_env__lookup_objdump(struct perf_env *env, const char **path);
+bool perf_env__single_address_space(struct perf_env *env);
 
 #endif /* ARCH_PERF_COMMON_H */

tools/perf/util/machine.h

@@ -42,6 +42,7 @@ struct machine {
 	u16		  id_hdr_size;
 	bool		  comm_exec;
 	bool		  kptr_restrict_warned;
+	bool		  single_address_space;
 	char		  *root_dir;
 	char		  *mmap_name;
 	struct threads    threads[THREADS__TABLE_SIZE];

tools/perf/util/session.c

@@ -24,6 +24,7 @@
 #include "thread.h"
 #include "thread-stack.h"
 #include "stat.h"
+#include "arch/common.h"
 
 static int perf_session__deliver_event(struct perf_session *session,
 				       union perf_event *event,
@@ -150,6 +151,9 @@ struct perf_session *perf_session__new(struct perf_data *data,
 		session->machines.host.env = &perf_env;
 	}
 
+	session->machines.host.single_address_space =
+		perf_env__single_address_space(session->machines.host.env);
+
 	if (!data || perf_data__is_write(data)) {
 		/*
 		 * In O_RDONLY mode this will be performed when reading the