objtool: Add the --disas=<function-pattern> action

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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://patch.msgid.link/20251121095340.464045-18-alexandre.chartre@oracle.com

1 files changed, 21 insertions, 17 deletions

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4ebadf94f8af..9cd9f9d4f656 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2611,7 +2611,7 @@ 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 (validate_branch_enabled() || opts.noinstr || opts.hack_jump_label) {
+	if (validate_branch_enabled() || opts.noinstr || opts.hack_jump_label || opts.disas) {
 		if (add_special_section_alts(file))
 			return -1;
 	}
@@ -4915,14 +4915,15 @@ 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;
 	}
 
@@ -5054,20 +5055,20 @@ int check(struct objtool_file *file)
 	}
 
 out:
-	if (!ret && !warnings) {
-		free_insns(file);
-		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);
-		disas_warned_funcs(disas_ctx);
+			ret = 1;
+
+		if (opts.verbose) {
+			if (opts.werror && warnings)
+				WARN("%d warning(s) upgraded to errors", warnings);
+			disas_warned_funcs(disas_ctx);
+		}
 	}
 
+	if (opts.disas)
+		disas_funcs(disas_ctx);
+
 	if (disas_ctx) {
 		disas_context_destroy(disas_ctx);
 		objtool_disas_ctx = NULL;
@@ -5075,6 +5076,9 @@ out:
 
 	free_insns(file);
 
+	if (!ret && !warnings)
+		return 0;
+
 	if (opts.backup && make_backup())
 		return 1;