[PATCH v6 13/30] objtool: Identify the different types of alternatives

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

Alternative code, including jump table and exception table, is represented
with the same struct alternative structure. But there is no obvious way to
identify whether the struct represents alternative instructions, a jump
table or an exception table.

So add a type to struct alternative to clearly identify the type of
alternative.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
 tools/objtool/check.c                 | 13 ++++++++-----
 tools/objtool/include/objtool/check.h | 12 ++++++++++++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index e12dba144731f..20630df83e85c 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -27,11 +27,6 @@
 #include <linux/static_call_types.h>
 #include <linux/string.h>
 
-struct alternative {
-	struct alternative *next;
-	struct instruction *insn;
-};
-
 static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
 
 static struct cfi_init_state initial_func_cfi;
@@ -1945,6 +1940,7 @@ static int add_special_section_alts(struct objtool_file *file)
 	struct list_head special_alts;
 	struct instruction *orig_insn, *new_insn;
 	struct special_alt *special_alt, *tmp;
+	enum alternative_type alt_type;
 	struct alternative *alt;
 
 	if (special_get_alts(file->elf, &special_alts))
@@ -1980,9 +1976,15 @@ static int add_special_section_alts(struct objtool_file *file)
 			if (handle_group_alt(file, special_alt, orig_insn, &new_insn))
 				return -1;
 
+			alt_type = ALT_TYPE_INSTRUCTIONS;
+
 		} else if (special_alt->jump_or_nop) {
 			if (handle_jump_alt(file, special_alt, orig_insn, &new_insn))
 				return -1;
+
+			alt_type = ALT_TYPE_JUMP_TABLE;
+		} else {
+			alt_type = ALT_TYPE_EX_TABLE;
 		}
 
 		alt = calloc(1, sizeof(*alt));
@@ -1993,6 +1995,7 @@ static int add_special_section_alts(struct objtool_file *file)
 
 		alt->insn = new_insn;
 		alt->next = orig_insn->alts;
+		alt->type = alt_type;
 		orig_insn->alts = alt;
 
 		list_del(&special_alt->list);
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index fde958683485f..cbf4af58e29b2 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -38,6 +38,18 @@ struct alt_group {
 	bool ignore;
 };
 
+enum alternative_type {
+	ALT_TYPE_INSTRUCTIONS,
+	ALT_TYPE_JUMP_TABLE,
+	ALT_TYPE_EX_TABLE,
+};
+
+struct alternative {
+	struct alternative *next;
+	struct instruction *insn;
+	enum alternative_type type;
+};
+
 #define INSN_CHUNK_BITS		8
 #define INSN_CHUNK_SIZE		(1 << INSN_CHUNK_BITS)
 #define INSN_CHUNK_MAX		(INSN_CHUNK_SIZE - 1)
-- 
2.43.5