objtool: Add 'alt_group' struct

Create a new struct associated with each group of alternatives
instructions.  This will help with the removal of fake jumps, and more
importantly with adding support for stack layout changes in
alternatives.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

1 files changed, 23 insertions, 6 deletions

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8976047cb648..9aa324b14d5d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -992,20 +992,28 @@ static int handle_group_alt(struct objtool_file *file,
 			    struct instruction *orig_insn,
 			    struct instruction **new_insn)
 {
-	static unsigned int alt_group_next_index = 1;
 	struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL;
-	unsigned int alt_group = alt_group_next_index++;
+	struct alt_group *orig_alt_group, *new_alt_group;
 	unsigned long dest_off;
 
+
+	orig_alt_group = malloc(sizeof(*orig_alt_group));
+	if (!orig_alt_group) {
+		WARN("malloc failed");
+		return -1;
+	}
 	last_orig_insn = NULL;
 	insn = orig_insn;
 	sec_for_each_insn_from(file, insn) {
 		if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
 			break;
 
-		insn->alt_group = alt_group;
+		insn->alt_group = orig_alt_group;
 		last_orig_insn = insn;
 	}
+	orig_alt_group->orig_group = NULL;
+	orig_alt_group->first_insn = orig_insn;
+	orig_alt_group->last_insn = last_orig_insn;
 
 	if (next_insn_same_sec(file, last_orig_insn)) {
 		fake_jump = malloc(sizeof(*fake_jump));
@@ -1036,8 +1044,13 @@ static int handle_group_alt(struct objtool_file *file,
 		return 0;
 	}
 
+	new_alt_group = malloc(sizeof(*new_alt_group));
+	if (!new_alt_group) {
+		WARN("malloc failed");
+		return -1;
+	}
+
 	last_new_insn = NULL;
-	alt_group = alt_group_next_index++;
 	insn = *new_insn;
 	sec_for_each_insn_from(file, insn) {
 		struct reloc *alt_reloc;
@@ -1049,7 +1062,7 @@ static int handle_group_alt(struct objtool_file *file,
 
 		insn->ignore = orig_insn->ignore_alts;
 		insn->func = orig_insn->func;
-		insn->alt_group = alt_group;
+		insn->alt_group = new_alt_group;
 
 		/*
 		 * Since alternative replacement code is copy/pasted by the
@@ -1098,6 +1111,10 @@ static int handle_group_alt(struct objtool_file *file,
 		return -1;
 	}
 
+	new_alt_group->orig_group = orig_alt_group;
+	new_alt_group->first_insn = *new_insn;
+	new_alt_group->last_insn = last_new_insn;
+
 	if (fake_jump)
 		list_add(&fake_jump->list, &last_new_insn->list);
 
@@ -2451,7 +2468,7 @@ static int validate_return(struct symbol *func, struct instruction *insn, struct
 static void fill_alternative_cfi(struct objtool_file *file, struct instruction *insn)
 {
 	struct instruction *first_insn = insn;
-	int alt_group = insn->alt_group;
+	struct alt_group *alt_group = insn->alt_group;
 
 	sec_for_each_insn_continue(file, insn) {
 		if (insn->alt_group != alt_group)