[RFC PATCH v2 16/17] objtool: Add the --disas=<function-pattern> action

[Alexandre Chartre <alexandre.chartre@oracle.com>]

Add the --disas=<function-pattern> actions to disassemble the specified
functions. The function pattern can be a single function name (e.g.
--disas foo to disassemble the function with the name "foo"), or a shell
wildcard pattern (e.g. --disas foo* to disassemble all functions with a
name starting with "foo").

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
 tools/objtool/builtin-check.c           |  4 ++-
 tools/objtool/check.c                   | 35 ++++++++++++++-----------
 tools/objtool/disas.c                   | 28 ++++++++++++++++++++
 tools/objtool/include/objtool/builtin.h |  1 +
 tools/objtool/include/objtool/disas.h   |  2 ++
 5 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index c53d738e4fb0..49b37da28b90 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -73,6 +73,7 @@ static int parse_hacks(const struct option *opt, const char *str, int unset)
 
 static const struct option check_options[] = {
 	OPT_GROUP("Actions:"),
+	OPT_STRING_OPTARG('d',   "disas", &opts.disas, "function-pattern", "disassemble functions", "*"),
 	OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
 	OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
 	OPT_BOOLEAN('m', "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
@@ -159,7 +160,8 @@ static bool opts_valid(void)
 		return false;
 	}
 
-	if (opts.hack_jump_label	||
+	if (opts.disas			||
+	    opts.hack_jump_label	||
 	    opts.hack_noinstr		||
 	    opts.ibt			||
 	    opts.mcount			||
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index fecdf6f42358..c7a70d47f104 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2563,7 +2563,7 @@ static int decode_sections(struct objtool_file *file)
 	 * Must be before add_jump_destinations(), which depends on 'func'
 	 * being set for alternatives, to enable proper sibling call detection.
 	 */
-	if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr) {
+	if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr || opts.disas) {
 		ret = add_special_section_alts(file);
 		if (ret)
 			return ret;
@@ -4766,14 +4766,15 @@ int check(struct objtool_file *file)
 	int ret = 0, warnings = 0;
 
 	/*
-	 * If the verbose or backtrace option is used then we need a
-	 * disassembly context to disassemble instruction or function
-	 * on warning or backtrace.
+	 * Create a disassembly context if we might disassemble any
+	 * instruction or function.
 	 */
-	if (opts.verbose || opts.backtrace || opts.trace) {
+	if (opts.verbose || opts.backtrace || opts.trace || opts.disas) {
 		disas_ctx = disas_context_create(file);
-		if (!disas_ctx)
+		if (!disas_ctx) {
+			opts.disas = false;
 			opts.trace = false;
+		}
 		objtool_disas_ctx = disas_ctx;
 	}
 
@@ -4892,19 +4893,21 @@ int check(struct objtool_file *file)
 	}
 
 out:
-	if (!ret && !warnings)
-		return 0;
-
-	if (opts.werror && warnings)
-		ret = 1;
-
-	if (opts.verbose) {
+	if (ret || warnings) {
 		if (opts.werror && warnings)
-			WARN("%d warning(s) upgraded to errors", warnings);
-		print_args();
-		disas_warned_funcs(disas_ctx);
+			ret = 1;
+
+		if (opts.verbose) {
+			if (opts.werror && warnings)
+				WARN("%d warning(s) upgraded to errors", warnings);
+			print_args();
+			disas_warned_funcs(disas_ctx);
+		}
 	}
 
+	if (opts.disas)
+		disas_funcs(disas_ctx);
+
 	if (disas_ctx) {
 		disas_context_destroy(disas_ctx);
 		objtool_disas_ctx = NULL;
diff --git a/tools/objtool/disas.c b/tools/objtool/disas.c
index 376c7bedef47..97d506afdf45 100644
--- a/tools/objtool/disas.c
+++ b/tools/objtool/disas.c
@@ -3,6 +3,8 @@
  * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
  */
 
+#include <fnmatch.h>
+
 #include <objtool/arch.h>
 #include <objtool/check.h>
 #include <objtool/disas.h>
@@ -399,3 +401,29 @@ void disas_warned_funcs(struct disas_context *dctx)
 			disas_func(dctx, sym);
 	}
 }
+
+void disas_funcs(struct disas_context *dctx)
+{
+	bool disas_all = !strcmp(opts.disas, "*");
+	struct section *sec;
+	struct symbol *sym;
+
+	for_each_sec(dctx->file, sec) {
+
+		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+			continue;
+
+		sec_for_each_sym(sec, sym) {
+			/*
+			 * If the function had a warning and the verbose
+			 * option is used then the function was already
+			 * disassemble.
+			 */
+			if (opts.verbose && sym->warned)
+				continue;
+
+			if (disas_all || fnmatch(opts.disas, sym->name, 0) == 0)
+				disas_func(dctx, sym);
+		}
+	}
+}
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index b3c84b6fdc5f..e41f3802d397 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -26,6 +26,7 @@ struct opts {
 	bool uaccess;
 	int prefix;
 	bool cfi;
+	const char *disas;
 
 	/* options: */
 	bool backtrace;
diff --git a/tools/objtool/include/objtool/disas.h b/tools/objtool/include/objtool/disas.h
index 5db75d06f219..5d2149ffac33 100644
--- a/tools/objtool/include/objtool/disas.h
+++ b/tools/objtool/include/objtool/disas.h
@@ -14,6 +14,7 @@ struct disassemble_info;
 struct disas_context *disas_context_create(struct objtool_file *file);
 void disas_context_destroy(struct disas_context *dctx);
 void disas_warned_funcs(struct disas_context *dctx);
+void disas_funcs(struct disas_context *dctx);
 int disas_info_init(struct disassemble_info *dinfo,
 		    int arch, int mach32, int mach64,
 		    const char *options);
@@ -37,6 +38,7 @@ static inline struct disas_context *disas_context_create(struct objtool_file *fi
 
 static inline void disas_context_destroy(struct disas_context *dctx) {}
 static inline void disas_warned_funcs(struct disas_context *dctx) {}
+static inline void disas_funcs(struct disas_context *dctx) {}
 
 static inline int disas_info_init(struct disassemble_info *dinfo,
 				  int arch, int mach32, int mach64,
-- 
2.43.5