1 files changed, 56 insertions, 4 deletions

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index e8a1f699058a..5fc52ee3264c 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -51,7 +51,7 @@ struct instruction {
         unsigned int len, state;
         unsigned char type;
         unsigned long immediate;
-        bool alt_group, visited;
+        bool alt_group, visited, dead_end;
         struct symbol *call_dest;
         struct instruction *jump_dest;
         struct list_head alts;
@@ -330,6 +330,54 @@ static int decode_instructions(struct objtool_file *file)
 }
 
 /*
+ * Find all uses of the unreachable() macro, which are code path dead ends.
+ */
+static int add_dead_ends(struct objtool_file *file)
+{
+        struct section *sec;
+        struct rela *rela;
+        struct instruction *insn;
+        bool found;
+
+        sec = find_section_by_name(file->elf, ".rela__unreachable");
+        if (!sec)
+                return 0;
+
+        list_for_each_entry(rela, &sec->rela_list, list) {
+                if (rela->sym->type != STT_SECTION) {
+                        WARN("unexpected relocation symbol type in .rela__unreachable");
+                        return -1;
+                }
+                insn = find_insn(file, rela->sym->sec, rela->addend);
+                if (insn)
+                        insn = list_prev_entry(insn, list);
+                else if (rela->addend == rela->sym->sec->len) {
+                        found = false;
+                        list_for_each_entry_reverse(insn, &file->insn_list, list) {
+                                if (insn->sec == rela->sym->sec) {
+                                        found = true;
+                                        break;
+                                }
+                        }
+
+                        if (!found) {
+                                WARN("can't find unreachable insn at %s+0x%x",
+                                     rela->sym->sec->name, rela->addend);
+                                return -1;
+                        }
+                } else {
+                        WARN("can't find unreachable insn at %s+0x%x",
+                             rela->sym->sec->name, rela->addend);
+                        return -1;
+                }
+
+                insn->dead_end = true;
+        }
+
+        return 0;
+}
+
+/*
  * Warnings shouldn't be reported for ignored functions.
  */
 static void add_ignores(struct objtool_file *file)
@@ -843,6 +891,10 @@ static int decode_sections(struct objtool_file *file)
         if (ret)
                 return ret;
 
+        ret = add_dead_ends(file);
+        if (ret)
+                return ret;
+
         add_ignores(file);
 
         ret = add_jump_destinations(file);
@@ -1037,13 +1089,13 @@ static int validate_branch(struct objtool_file *file,
 
                         return 0;
 
-                case INSN_BUG:
-                        return 0;
-
                 default:
                         break;
                 }
 
+                if (insn->dead_end)
+                        return 0;
+
                 insn = next_insn_same_sec(file, insn);
                 if (!insn) {
                         WARN("%s: unexpected end of section", sec->name);