[PATCH v3 21/30] perf clang jit: Export functions for jitted code

[Wang Nan]

After this patch functions attached on perf hooks is allowed to invoke
external functions. Add a testcase for this feature.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
 tools/perf/tests/Build                |  2 +-
 tools/perf/tests/bpf-script-example.c |  4 ++++
 tools/perf/util/c++/clang-c.h         |  2 ++
 tools/perf/util/c++/clang-test.cpp    |  9 +++++++++
 tools/perf/util/c++/clang.cpp         | 17 ++++++++++++++++-
 5 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index 6676c2d..d6e6e00 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -49,7 +49,7 @@ $(OUTPUT)tests/llvm-src-base.c: tests/bpf-script-example.c tests/Build
 	$(call rule_mkdir)
 	$(Q)echo '#include <tests/llvm.h>' > $@
 	$(Q)echo 'const char test_llvm__bpf_base_prog[] =' >> $@
-	$(Q)sed -e 's/"/\\"/g' -e 's/\(.*\)/"\1\\n"/g' $< >> $@
+	$(Q)sed -e 's/\\/\\\\/g' -e 's/"/\\"/g' -e 's/\(.*\)/"\1\\n"/g' $< >> $@
 	$(Q)echo ';' >> $@
 
 $(OUTPUT)tests/llvm-src-kbuild.c: tests/bpf-script-test-kbuild.c tests/Build
diff --git a/tools/perf/tests/bpf-script-example.c b/tools/perf/tests/bpf-script-example.c
index 265036e..ccbc19c 100644
--- a/tools/perf/tests/bpf-script-example.c
+++ b/tools/perf/tests/bpf-script-example.c
@@ -48,9 +48,13 @@ char _license[] SEC("license") = "GPL";
 int _version SEC("version") = LINUX_VERSION_CODE;
 
 #ifdef TEST_PERF_HOOK
+extern int printf(const char *fmt, ...);
+extern void test__clang_callback(int x);
 SEC("perfhook:test")
 void hook_test(void)
 {
+	printf("Hello, hook_test\n");
+	test__clang_callback(1234);
 	return;
 }
 #endif
diff --git a/tools/perf/util/c++/clang-c.h b/tools/perf/util/c++/clang-c.h
index 5ebcb41..9f75e41 100644
--- a/tools/perf/util/c++/clang-c.h
+++ b/tools/perf/util/c++/clang-c.h
@@ -16,6 +16,8 @@ extern int test__clang_to_IR(void);
 extern int test__clang_to_obj(void);
 extern int test__clang_jit(void);
 
+extern void test__clang_callback(int x);
+
 extern int perf_clang__compile_bpf(const char *filename,
 				   void **p_obj_buf,
 				   size_t *p_obj_buf_sz);
diff --git a/tools/perf/util/c++/clang-test.cpp b/tools/perf/util/c++/clang-test.cpp
index 2b4aa8d..0bdb807 100644
--- a/tools/perf/util/c++/clang-test.cpp
+++ b/tools/perf/util/c++/clang-test.cpp
@@ -68,6 +68,13 @@ int test__clang_to_obj(void)
 	return 0;
 }
 
+static int callback_flag;
+
+void test__clang_callback(int x)
+{
+	callback_flag = x;
+}
+
 int test__clang_jit(void)
 {
 	perf_clang_scope _scope;
@@ -84,6 +91,8 @@ int test__clang_jit(void)
 		perf_hooks__set_hook(i.first.c_str(), i.second, NULL);
 
 	perf_hooks__invoke_test();
+	if (callback_flag != 1234)
+		return -1;
 	return 0;
 }
 
diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
index 03012b2..325fbe4 100644
--- a/tools/perf/util/c++/clang.cpp
+++ b/tools/perf/util/c++/clang.cpp
@@ -30,6 +30,8 @@
 #include "llvm/Target/TargetOptions.h"
 #include <memory>
 #include <vector>
+#include <set>
+#include <tuple>
 
 #include "clang.h"
 #include "clang-c.h"
@@ -194,6 +196,15 @@ PerfModule::toBPFObject(void)
 	return std::move(Buffer);
 }
 
+static std::map<const std::string, const void *> exported_funcs =
+{
+#define EXPORT(f) {#f, (const void *)&f}
+	EXPORT(test__clang_callback),
+	EXPORT(printf),
+	EXPORT(puts),
+#undef EXPORT
+};
+
 /*
  * Use a global memory manager so allocated code and data won't be released
  * when object destroy.
@@ -220,7 +231,11 @@ int PerfModule::doJIT(void)
 
 	auto Resolver = createLambdaResolver(
 			[](const std::string &Name) {
-				return RuntimeDyld::SymbolInfo(nullptr);
+				auto i = exported_funcs.find(Name);
+				if (i == exported_funcs.end())
+					return RuntimeDyld::SymbolInfo(nullptr);
+				return RuntimeDyld::SymbolInfo((uint64_t)(i->second),
+							       JITSymbolFlags::Exported);
 			},
 			[](const std::string &Name) {
 				return RuntimeDyld::SymbolInfo(nullptr);
-- 
2.10.1