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Message-ID: <20161115040617.69788-28-wangnan0@huawei.com>
Date: Tue, 15 Nov 2016 04:06:10 +0000
From: Wang Nan <wangnan0@...wei.com>
To: <acme@...hat.com>, <ast@...com>
CC: <lizefan@...wei.com>, <hekuang@...wei.com>,
<linux-kernel@...r.kernel.org>, <pi3orama@....com>,
Wang Nan <wangnan0@...wei.com>, Jiri Olsa <jolsa@...nel.org>
Subject: [PATCH 27/34] perf clang jit: Collect the lowest address in maps section as map_base
During jitting, find the lowest address in maps section and store its
value to _map_base. Pass its value out through perf_clang__compile_bpf().
map_base is useful for jitted functions accessing BPF maps.
Signed-off-by: Wang Nan <wangnan0@...wei.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Alexei Starovoitov <ast@...com>
Cc: He Kuang <hekuang@...wei.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Zefan Li <lizefan@...wei.com>
Cc: pi3orama@....com
---
tools/perf/util/bpf-loader.c | 39 +++++++++++++++++++++++++++++++++++++--
tools/perf/util/c++/clang-c.h | 6 ++++--
tools/perf/util/c++/clang.cpp | 15 +++++++++++++--
tools/perf/util/c++/clang.h | 5 +++++
4 files changed, 59 insertions(+), 6 deletions(-)
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index e50045f..81c6fed 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -47,6 +47,10 @@ struct bpf_prog_priv {
int *type_mapping;
};
+struct bpf_obj_priv {
+ void *map_base;
+};
+
static bool libbpf_initialized;
struct bpf_object *
@@ -70,9 +74,20 @@ bpf__prepare_load_buffer(void *obj_buf, size_t obj_buf_sz, const char *name)
return obj;
}
+static void
+clear_obj_priv(struct bpf_object *obj __maybe_unused,
+ void *_priv)
+{
+ struct bpf_obj_priv *priv = _priv;
+
+ free(priv);
+}
+
struct bpf_object *bpf__prepare_load(const char *filename, bool source)
{
struct bpf_object *obj;
+ void *map_base = NULL;
+ int err;
if (!libbpf_initialized) {
libbpf_set_print(libbpf_warning,
@@ -82,14 +97,14 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source)
}
if (source) {
- int err;
void *obj_buf;
size_t obj_buf_sz;
jitted_funcs_map_t jitted_funcs_map;
perf_clang__init();
err = perf_clang__compile_bpf(filename, &obj_buf,
- &obj_buf_sz, &jitted_funcs_map);
+ &obj_buf_sz, &jitted_funcs_map,
+ &map_base);
perf_clang__cleanup();
if (err) {
pr_warning("bpf: builtin compiling failed: %d, try external compiler\n", err);
@@ -119,7 +134,27 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source)
return obj;
}
+ if (map_base) {
+ struct bpf_obj_priv *priv = calloc(sizeof(*priv), 1);
+
+ if (!priv) {
+ pr_debug("bpf: failed to alloc priv for object\n");
+ err = -ENOMEM;
+ goto errout;
+ }
+ priv->map_base = map_base;
+
+ err = bpf_object__set_priv(obj, priv, clear_obj_priv);
+ if (err) {
+ pr_debug("Failed to set priv for object '%s'\n", filename);
+ goto errout;
+ }
+ }
+
return obj;
+errout:
+ bpf_object__close(obj);
+ return ERR_PTR(err);
}
void bpf__clear(void)
diff --git a/tools/perf/util/c++/clang-c.h b/tools/perf/util/c++/clang-c.h
index 021b1ad..4cf651b 100644
--- a/tools/perf/util/c++/clang-c.h
+++ b/tools/perf/util/c++/clang-c.h
@@ -22,7 +22,8 @@ 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,
- jitted_funcs_map_t *p_funcs_map);
+ jitted_funcs_map_t *p_funcs_map,
+ void **p_map_base);
extern int
perf_clang__hook_jitted_func(jitted_funcs_map_t map, void *ctx, bool is_err);
@@ -40,7 +41,8 @@ static inline int
perf_clang__compile_bpf(const char *filename __maybe_unused,
void **p_obj_buf __maybe_unused,
size_t *p_obj_buf_sz __maybe_unused,
- jitted_funcs_map_t *p_funcs_map __maybe_unused)
+ jitted_funcs_map_t *p_funcs_map __maybe_unused,
+ void **p_map_base __maybe_unused)
{
return -ENOTSUP;
}
diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
index f2608f5..f8ea9bd 100644
--- a/tools/perf/util/c++/clang.cpp
+++ b/tools/perf/util/c++/clang.cpp
@@ -122,7 +122,7 @@ getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path)
return getModuleFromSource(std::move(CFlags), Path, VFS);
}
-PerfModule::PerfModule(std::unique_ptr<llvm::Module>&& M) : Module(std::move(M))
+PerfModule::PerfModule(std::unique_ptr<llvm::Module>&& M) : Module(std::move(M)), _map_base(NULL)
{
for (llvm::Function& F : *Module) {
if (F.getLinkage() != llvm::GlobalValue::ExternalLinkage)
@@ -247,6 +247,13 @@ int PerfModule::doJIT(void)
&JITMemoryManager,
std::move(Resolver));
+ void *map_base = NULL;
+ for (llvm::GlobalValue *map : Maps) {
+ JITSymbol sym = CompileLayer.findSymbol(map->getName().str(), true);
+ void *address = (void *)(intptr_t)sym.getAddress();
+ if (!map_base || address < map_base)
+ map_base = address;
+ }
for (Function *F : JITFunctions) {
JITSymbol sym = CompileLayer.findSymbol(F->getName().str(), true);
@@ -266,6 +273,7 @@ int PerfModule::doJIT(void)
<< hook << ", only one is used\n";
JITResult[hook] = func;
}
+ _map_base = map_base;
return 0;
}
@@ -389,7 +397,8 @@ void perf_clang__cleanup(void)
int perf_clang__compile_bpf(const char *_filename,
void **p_obj_buf,
size_t *p_obj_buf_sz,
- jitted_funcs_map_t *p_funcs_map)
+ jitted_funcs_map_t *p_funcs_map,
+ void **p_map_base)
{
using namespace perf;
@@ -422,6 +431,8 @@ int perf_clang__compile_bpf(const char *_filename,
if (p_funcs_map)
*p_funcs_map = (jitted_funcs_map_t)(M->copyJITResult());
+ if (p_map_base)
+ *p_map_base = M->getMapBase();
return 0;
}
diff --git a/tools/perf/util/c++/clang.h b/tools/perf/util/c++/clang.h
index df2eb8f..aacedc2 100644
--- a/tools/perf/util/c++/clang.h
+++ b/tools/perf/util/c++/clang.h
@@ -26,6 +26,7 @@ class PerfModule {
std::set<llvm::Function *> JITFunctions;
HookMap JITResult;
+ void *_map_base;
void prepareBPF(void);
void prepareJIT(void);
@@ -38,6 +39,10 @@ class PerfModule {
{
return new HookMap(JITResult);
}
+ inline void *getMapBase(void)
+ {
+ return _map_base;
+ }
PerfModule(std::unique_ptr<llvm::Module>&& M);
--
2.10.1
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