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Date: Mon, 20 Aug 2018 13:15:44 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: Clark Williams <williams@...hat.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Alexei Starovoitov <ast@...com>,
Daniel Borkmann <daniel@...earbox.net>,
Jiri Olsa <jolsa@...nel.org>, Martin KaFai Lau <kafai@...com>,
Namhyung Kim <namhyung@...nel.org>,
Wang Nan <wangnan0@...wei.com>, Yonghong Song <yhs@...com>
Subject: [PATCH 03/21] perf llvm: Allow passing options to llc in addition to clang
From: Arnaldo Carvalho de Melo <acme@...hat.com>
The newly added 'llvm.opts' variable allows passing options directly to
llc, like needed to get sane DWARF in BPF ELF debug sections:
With:
[root@...enth perf]# cat ~/.perfconfig
[llvm]
dump-obj = true
clang-opt = -g
[root@...enth perf]#
We get:
[root@...enth perf]# perf trace -e tools/perf/examples/bpf/hello.c cat /etc/passwd > /dev/null
LLVM: dumping tools/perf/examples/bpf/hello.o
0.000 __bpf_stdout__:Hello, world
0.015 __bpf_stdout__:Hello, world
0.187 __bpf_stdout__:Hello, world
[root@...enth perf]# pahole tools/perf/examples/bpf/hello.o
struct clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c) {
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 0 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 4 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 8 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 12 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 16 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 20 4 */
clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566e.org clang version 8.0.0 (http://llvm.org/git/clang.git 8587270a739ee30c926a76d5657e65e85b560f6e) (http://llvm.org/git/llvm.git 0566eefef9c3777bd780ec4cbb9efa764633b76c); /* 24 4 */
/* size: 28, cachelines: 1, members: 7 */
/* last cacheline: 28 bytes */
};
[root@...enth perf]#
Adding these options to be passed to llvm's llc:
[root@...enth perf]# cat ~/.perfconfig
[llvm]
dump-obj = true
clang-opt = -g
opts = -mattr=dwarfris
[root@...enth perf]#
We get sane output:
[root@...enth perf]# perf trace -e tools/perf/examples/bpf/hello.c cat /etc/passwd > /dev/null
LLVM: dumping tools/perf/examples/bpf/hello.o
0.000 __bpf_stdout__:Hello, world
0.015 __bpf_stdout__:Hello, world
0.185 __bpf_stdout__:Hello, world
[root@...enth perf]# pahole tools/perf/examples/bpf/hello.o
struct bpf_map {
unsigned int type; /* 0 4 */
unsigned int key_size; /* 4 4 */
unsigned int value_size; /* 8 4 */
unsigned int max_entries; /* 12 4 */
unsigned int map_flags; /* 16 4 */
unsigned int inner_map_idx; /* 20 4 */
unsigned int numa_node; /* 24 4 */
/* size: 28, cachelines: 1, members: 7 */
/* last cacheline: 28 bytes */
};
[root@...enth perf]#
Cc: Alexei Starovoitov <ast@...com>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Martin KaFai Lau <kafai@...com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Wang Nan <wangnan0@...wei.com>,
Cc: Yonghong Song <yhs@...com>
Link: https://lkml.kernel.org/n/tip-0lrwmrip4dru1651rm8xa7tq@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
tools/perf/util/llvm-utils.c | 31 +++++++++++++++++++++++++++++--
tools/perf/util/llvm-utils.h | 9 +++++++++
2 files changed, 38 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/llvm-utils.c b/tools/perf/util/llvm-utils.c
index 5e94857dfca2..19262f98cd4e 100644
--- a/tools/perf/util/llvm-utils.c
+++ b/tools/perf/util/llvm-utils.c
@@ -22,12 +22,14 @@
"$CLANG_OPTIONS $KERNEL_INC_OPTIONS $PERF_BPF_INC_OPTIONS " \
"-Wno-unused-value -Wno-pointer-sign " \
"-working-directory $WORKING_DIR " \
- "-c \"$CLANG_SOURCE\" -target bpf -O2 -o -"
+ "-c \"$CLANG_SOURCE\" -target bpf $CLANG_EMIT_LLVM -O2 -o - $LLVM_OPTIONS_PIPE"
struct llvm_param llvm_param = {
.clang_path = "clang",
+ .llc_path = "llc",
.clang_bpf_cmd_template = CLANG_BPF_CMD_DEFAULT_TEMPLATE,
.clang_opt = NULL,
+ .opts = NULL,
.kbuild_dir = NULL,
.kbuild_opts = NULL,
.user_set_param = false,
@@ -51,6 +53,8 @@ int perf_llvm_config(const char *var, const char *value)
llvm_param.kbuild_opts = strdup(value);
else if (!strcmp(var, "dump-obj"))
llvm_param.dump_obj = !!perf_config_bool(var, value);
+ else if (!strcmp(var, "opts"))
+ llvm_param.opts = strdup(value);
else {
pr_debug("Invalid LLVM config option: %s\n", value);
return -1;
@@ -430,11 +434,13 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
unsigned int kernel_version;
char linux_version_code_str[64];
const char *clang_opt = llvm_param.clang_opt;
- char clang_path[PATH_MAX], abspath[PATH_MAX], nr_cpus_avail_str[64];
+ char clang_path[PATH_MAX], llc_path[PATH_MAX], abspath[PATH_MAX], nr_cpus_avail_str[64];
char serr[STRERR_BUFSIZE];
char *kbuild_dir = NULL, *kbuild_include_opts = NULL,
*perf_bpf_include_opts = NULL;
const char *template = llvm_param.clang_bpf_cmd_template;
+ char *pipe_template = NULL;
+ const char *opts = llvm_param.opts;
char *command_echo = NULL, *command_out;
char *perf_include_dir = system_path(PERF_INCLUDE_DIR);
@@ -484,6 +490,26 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
force_set_env("PERF_BPF_INC_OPTIONS", perf_bpf_include_opts);
force_set_env("WORKING_DIR", kbuild_dir ? : ".");
+ if (opts) {
+ err = search_program(llvm_param.llc_path, "llc", llc_path);
+ if (err) {
+ pr_err("ERROR:\tunable to find llc.\n"
+ "Hint:\tTry to install latest clang/llvm to support BPF. Check your $PATH\n"
+ " \tand 'llc-path' option in [llvm] section of ~/.perfconfig.\n");
+ version_notice();
+ goto errout;
+ }
+
+ if (asprintf(&pipe_template, "%s -emit-llvm | %s -march=bpf %s -filetype=obj -o -",
+ template, llc_path, opts) < 0) {
+ pr_err("ERROR:\tnot enough memory to setup command line\n");
+ goto errout;
+ }
+
+ template = pipe_template;
+
+ }
+
/*
* Since we may reset clang's working dir, path of source file
* should be transferred into absolute path, except we want
@@ -535,6 +561,7 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
free(obj_buf);
free(perf_bpf_include_opts);
free(perf_include_dir);
+ free(pipe_template);
if (p_obj_buf)
*p_obj_buf = NULL;
if (p_obj_buf_sz)
diff --git a/tools/perf/util/llvm-utils.h b/tools/perf/util/llvm-utils.h
index d3ad8deb5db4..bf3f3f4c4fe2 100644
--- a/tools/perf/util/llvm-utils.h
+++ b/tools/perf/util/llvm-utils.h
@@ -11,6 +11,8 @@
struct llvm_param {
/* Path of clang executable */
const char *clang_path;
+ /* Path of llc executable */
+ const char *llc_path;
/*
* Template of clang bpf compiling. 5 env variables
* can be used:
@@ -23,6 +25,13 @@ struct llvm_param {
const char *clang_bpf_cmd_template;
/* Will be filled in $CLANG_OPTIONS */
const char *clang_opt;
+ /*
+ * If present it'll add -emit-llvm to $CLANG_OPTIONS to pipe
+ * the clang output to llc, useful for new llvm options not
+ * yet selectable via 'clang -mllvm option', such as -mattr=dwarfris
+ * in clang 6.0/llvm 7
+ */
+ const char *opts;
/* Where to find kbuild system */
const char *kbuild_dir;
/*
--
2.14.4
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