From edd695b032ba3a90c3bb07d934500b2c390a61ff Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Sat, 26 Nov 2016 07:03:39 +0000 Subject: [PATCH] perf clang: Compile BPF script using builtin clang support After this patch, perf utilizes builtin clang support to build BPF script, no longer depend on external clang, but fallbacking to it if for some reason the builtin compiling framework fails. Test: $ type clang -bash: type: clang: not found $ cat ~/.perfconfig $ echo '#define LINUX_VERSION_CODE 0x040700' > ./test.c $ cat ./tools/perf/tests/bpf-script-example.c >> ./test.c $ ./perf record -v --dry-run -e ./test.c 2>&1 | grep builtin bpf: successfull builtin compilation $ Can't pass cflags so unable to include kernel headers now. Will be fixed by following commits. Committer notes: Make sure '-v' comes before the '-e ./test.c' in the command line otherwise the 'verbose' variable will not be set when the bpf event is parsed and thus the pr_debug indicating a 'successfull builtin compilation' will not be output, as the debug level (1) will be less than what 'verbose' has at that point (0). Signed-off-by: Wang Nan Tested-by: Arnaldo Carvalho de Melo Cc: Alexei Starovoitov Cc: He Kuang Cc: Jiri Olsa Cc: Joe Stringer Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/20161126070354.141764-16-wangnan0@huawei.com [ Spell check/reflow successfull pr_debug string ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/bpf-loader.c | 15 +++++++++++---- tools/perf/util/c++/clang-c.h | 26 ++++++++++++++++++++++++++ tools/perf/util/c++/clang.cpp | 29 +++++++++++++++++++++++++++++ 3 files changed, 66 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c index cf16b941..36c8611 100644 --- a/tools/perf/util/bpf-loader.c +++ b/tools/perf/util/bpf-loader.c @@ -14,11 +14,11 @@ #include "debug.h" #include "bpf-loader.h" #include "bpf-prologue.h" -#include "llvm-utils.h" #include "probe-event.h" #include "probe-finder.h" // for MAX_PROBES #include "parse-events.h" #include "llvm-utils.h" +#include "c++/clang-c.h" #define DEFINE_PRINT_FN(name, level) \ static int libbpf_##name(const char *fmt, ...) \ @@ -86,9 +86,16 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source) void *obj_buf; size_t obj_buf_sz; - err = llvm__compile_bpf(filename, &obj_buf, &obj_buf_sz); - if (err) - return ERR_PTR(-BPF_LOADER_ERRNO__COMPILE); + perf_clang__init(); + err = perf_clang__compile_bpf(filename, &obj_buf, &obj_buf_sz); + perf_clang__cleanup(); + if (err) { + pr_warning("bpf: builtin compilation failed: %d, try external compiler\n", err); + err = llvm__compile_bpf(filename, &obj_buf, &obj_buf_sz); + if (err) + return ERR_PTR(-BPF_LOADER_ERRNO__COMPILE); + } else + pr_debug("bpf: successfull builtin compilation\n"); obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, filename); if (!IS_ERR(obj) && llvm_param.dump_obj) diff --git a/tools/perf/util/c++/clang-c.h b/tools/perf/util/c++/clang-c.h index 22b3936..0eadd79 100644 --- a/tools/perf/util/c++/clang-c.h +++ b/tools/perf/util/c++/clang-c.h @@ -1,16 +1,42 @@ #ifndef PERF_UTIL_CLANG_C_H #define PERF_UTIL_CLANG_C_H +#include /* for size_t */ +#include /* for __maybe_unused */ + #ifdef __cplusplus extern "C" { #endif +#ifdef HAVE_LIBCLANGLLVM_SUPPORT extern void perf_clang__init(void); extern void perf_clang__cleanup(void); extern int test__clang_to_IR(void); extern int test__clang_to_obj(void); +extern int perf_clang__compile_bpf(const char *filename, + void **p_obj_buf, + size_t *p_obj_buf_sz); +#else + + +static inline void perf_clang__init(void) { } +static inline void perf_clang__cleanup(void) { } + +static inline int test__clang_to_IR(void) { return -1; } +static inline int test__clang_to_obj(void) { return -1;} + +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) +{ + return -ENOTSUP; +} + +#endif + #ifdef __cplusplus } #endif diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp index 2a1a75d..1e97415 100644 --- a/tools/perf/util/c++/clang.cpp +++ b/tools/perf/util/c++/clang.cpp @@ -163,4 +163,33 @@ void perf_clang__cleanup(void) perf::LLVMCtx.reset(nullptr); llvm::llvm_shutdown(); } + +int perf_clang__compile_bpf(const char *filename, + void **p_obj_buf, + size_t *p_obj_buf_sz) +{ + using namespace perf; + + if (!p_obj_buf || !p_obj_buf_sz) + return -EINVAL; + + llvm::opt::ArgStringList CFlags; + auto M = getModuleFromSource(std::move(CFlags), filename); + if (!M) + return -EINVAL; + auto O = getBPFObjectFromModule(&*M); + if (!O) + return -EINVAL; + + size_t size = O->size_in_bytes(); + void *buffer; + + buffer = malloc(size); + if (!buffer) + return -ENOMEM; + memcpy(buffer, O->data(), size); + *p_obj_buf = buffer; + *p_obj_buf_sz = size; + return 0; +} } -- 2.7.4