The following commit has been merged into the objtool/core branch of tip:
Commit-ID: 9b580accac003767a461bf52d738ad1ab4e8ccfa
Gitweb: https://git.kernel.org/tip/9b580accac003767a461bf52d738ad1ab4e8ccfa
Author: Alexandre Chartre <alexandre.chartre@oracle.com>
AuthorDate: Fri, 21 Nov 2025 10:53:24 +01:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 21 Nov 2025 15:30:11 +01:00
objtool: Add functions to better name alternatives
Add the disas_alt_name() and disas_alt_type_name() to provide a
name and a type name for an alternative. This will be used to
better name alternatives when tracing their execution.
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/20251121095340.464045-15-alexandre.chartre@oracle.com
---
tools/objtool/disas.c | 72 ++++++++++++++++++++++++++-
tools/objtool/include/objtool/disas.h | 12 ++++-
2 files changed, 84 insertions(+)
diff --git a/tools/objtool/disas.c b/tools/objtool/disas.c
index 0ca6e6c..b53be24 100644
--- a/tools/objtool/disas.c
+++ b/tools/objtool/disas.c
@@ -3,6 +3,8 @@
* Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
*/
+#define _GNU_SOURCE
+
#include <objtool/arch.h>
#include <objtool/check.h>
#include <objtool/disas.h>
@@ -451,6 +453,76 @@ size_t disas_insn(struct disas_context *dctx, struct instruction *insn)
}
/*
+ * Provide a name for the type of alternatives present at the
+ * specified instruction.
+ *
+ * An instruction can have alternatives with different types, for
+ * example alternative instructions and an exception table. In that
+ * case the name for the alternative instructions type is used.
+ *
+ * Return NULL if the instruction as no alternative.
+ */
+const char *disas_alt_type_name(struct instruction *insn)
+{
+ struct alternative *alt;
+ const char *name;
+
+ name = NULL;
+ for (alt = insn->alts; alt; alt = alt->next) {
+ if (alt->type == ALT_TYPE_INSTRUCTIONS) {
+ name = "alternative";
+ break;
+ }
+
+ switch (alt->type) {
+ case ALT_TYPE_EX_TABLE:
+ name = "ex_table";
+ break;
+ case ALT_TYPE_JUMP_TABLE:
+ name = "jump_table";
+ break;
+ default:
+ name = "unknown";
+ break;
+ }
+ }
+
+ return name;
+}
+
+/*
+ * Provide a name for an alternative.
+ */
+char *disas_alt_name(struct alternative *alt)
+{
+ char *str = NULL;
+
+ switch (alt->type) {
+
+ case ALT_TYPE_EX_TABLE:
+ str = strdup("EXCEPTION");
+ break;
+
+ case ALT_TYPE_JUMP_TABLE:
+ str = strdup("JUMP");
+ break;
+
+ case ALT_TYPE_INSTRUCTIONS:
+ /*
+ * This is a non-default group alternative. Create a unique
+ * name using the offset of the first original and alternative
+ * instructions.
+ */
+ asprintf(&str, "ALTERNATIVE %lx.%lx",
+ alt->insn->alt_group->orig_group->first_insn->offset,
+ alt->insn->alt_group->first_insn->offset);
+ break;
+ }
+
+ return str;
+}
+
+/*
* Disassemble a function.
*/
static void disas_func(struct disas_context *dctx, struct symbol *func)
diff --git a/tools/objtool/include/objtool/disas.h b/tools/objtool/include/objtool/disas.h
index 5db75d0..8959d4c 100644
--- a/tools/objtool/include/objtool/disas.h
+++ b/tools/objtool/include/objtool/disas.h
@@ -6,6 +6,7 @@
#ifndef _DISAS_H
#define _DISAS_H
+struct alternative;
struct disas_context;
struct disassemble_info;
@@ -24,6 +25,8 @@ void disas_print_info(FILE *stream, struct instruction *insn, int depth,
void disas_print_insn(FILE *stream, struct disas_context *dctx,
struct instruction *insn, int depth,
const char *format, ...);
+char *disas_alt_name(struct alternative *alt);
+const char *disas_alt_type_name(struct instruction *insn);
#else /* DISAS */
@@ -61,6 +64,15 @@ static inline void disas_print_info(FILE *stream, struct instruction *insn,
static inline void disas_print_insn(FILE *stream, struct disas_context *dctx,
struct instruction *insn, int depth,
const char *format, ...) {}
+static inline char *disas_alt_name(struct alternative *alt)
+{
+ return NULL;
+}
+
+static inline const char *disas_alt_type_name(struct instruction *insn)
+{
+ return NULL;
+}
#endif /* DISAS */