[RFC PATCH v6 25/32] perf tools: Add 'bpf.' config section to perf default config

[Wang Nan <wangnan0@huawei.com>]

perf_bpf_config() is added to parse 'bpf' section in perf config file.
Following is an example:

 [bpf]
   clang-path = /llvm/bin/x86_64-linux-clang"
   llc-path = /llvm/bin/x86_64-linux-llc"
   clang-opt = "-nostdinc -isystem /llvm/lib/clang/include -I/kernel/arch/x86/include ..."
   llc-opt = ""

Error messages are updated to hint user about these options.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/util/bpf-loader.c | 24 +++++++++++++++++++++++-
 tools/perf/util/bpf-loader.h |  1 +
 tools/perf/util/config.c     |  3 +++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index e5c03e9..f33fd47 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -8,6 +8,7 @@
 #include <bpf/libbpf.h>
 #include "perf.h"
 #include "debug.h"
+#include "util.h"
 #include "bpf-loader.h"
 
 #define DEFINE_PRINT_FN(name, level) \
@@ -39,6 +40,25 @@ struct bpf_param bpf_param = {
 	.llc_opt = "",
 };
 
+int perf_bpf_config(const char *var, const char *value)
+{
+	if (prefixcmp(var, "bpf."))
+		return 0;
+	var += sizeof("bpf.") - 1;
+
+	if (!strcmp(var, "clang-path"))
+		bpf_param.clang_path = strdup(value);
+	else if (!strcmp(var, "llc-path"))
+		bpf_param.llc_path = strdup(value);
+	else if (!strcmp(var, "clang-opt"))
+		bpf_param.clang_opt = strdup(value);
+	else if (!strcmp(var, "llc-opt"))
+		bpf_param.llc_opt = strdup(value);
+	else
+		return -1;
+	return 0;
+}
+
 static int search_program(const char *def, const char *name,
 			  char *output)
 {
@@ -111,7 +131,8 @@ static int bpf__compile(const char *filename, void **p_obj_buf,
 	if (err) {
 		err = -ENOENT;
 		pr_err("Error:\tunable to find clang or llc in $PATH\n");
-		pr_err("Hint:\tTry install LLVM with BPF backend.\n");
+		pr_err("Hint:\tTry install LLVM with BPF backend,\n");
+		pr_err("     \tthen setup [bpf.clang-path] and [bpf.llc-path] in ~/.perfconfig\n");
 		goto out;
 	}
 
@@ -175,6 +196,7 @@ static int bpf__compile(const char *filename, void **p_obj_buf,
 		err = -EINVAL;
 		pr_err("Error:\tsomething went wrong when compiling %s\n",
 		       filename);
+		pr_err("Hint:\tTry to set correct [bpf.clang-opt] and [bpf.llc-opt] in ~/.perfconfig\n");
 		pr_err("Hint:\tTry manually run following command and check:\n");
 		pr_err("  # " CMD_FMT "\n\n",
 		       clang_path, bpf_param.clang_opt, filename,
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index 5fd015c..edc211e 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -15,6 +15,7 @@ struct bpf_param {
 	const char *llc_opt;
 };
 extern struct bpf_param bpf_param;
+extern int perf_bpf_config(const char *var, const char *value);
 
 #ifdef HAVE_LIBBPF_SUPPORT
 int bpf__prepare_load(const char *filename, bool source);
diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
index e18f653..def2b59 100644
--- a/tools/perf/util/config.c
+++ b/tools/perf/util/config.c
@@ -12,6 +12,7 @@
 #include "cache.h"
 #include "exec_cmd.h"
 #include "util/hist.h"  /* perf_hist_config */
+#include "util/bpf-loader.h"  /* perf_bpf_config */
 
 #define MAXNAME (256)
 
@@ -408,6 +409,8 @@ int perf_default_config(const char *var, const char *value,
 	if (!prefixcmp(var, "call-graph."))
 		return perf_callchain_config(var, value);
 
+	if (!prefixcmp(var, "bpf."))
+		return perf_bpf_config(var, value);
 	/* Add other config variables here. */
 	return 0;
 }
-- 
1.8.3.4