objtool: Read the NOENDBR annotation

Read the new NOENDBR annotation. While there, attempt to not bloat
struct instruction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154319.586815435@infradead.org

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 894c9a7..6399394 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1866,6 +1866,29 @@ static int read_unwind_hints(struct objtool_file *file)
        return 0;
 }
 
+static int read_noendbr_hints(struct objtool_file *file)
+{
+       struct section *sec;
+       struct instruction *insn;
+       struct reloc *reloc;
+
+       sec = find_section_by_name(file->elf, ".rela.discard.noendbr");
+       if (!sec)
+               return 0;
+
+       list_for_each_entry(reloc, &sec->reloc_list, list) {
+               insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend);
+               if (!insn) {
+                       WARN("bad .discard.noendbr entry");
+                       return -1;
+               }
+
+               insn->noendbr = 1;
+       }
+
+       return 0;
+}
+
 static int read_retpoline_hints(struct objtool_file *file)
 {
        struct section *sec;
@@ -2099,6 +2122,10 @@ static int decode_sections(struct objtool_file *file)
        if (ret)
                return ret;
 
+       ret = read_noendbr_hints(file);
+       if (ret)
+               return ret;
+
        /*
         * Must be before add_{jump_call}_destination.
         */

diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 6cfff07..f10d737 100644 (file)
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -45,11 +45,18 @@ struct instruction {
        unsigned int len;
        enum insn_type type;
        unsigned long immediate;
-       bool dead_end, ignore, ignore_alts;
-       bool hint;
-       bool retpoline_safe;
+
+       u8 dead_end     : 1,
+          ignore       : 1,
+          ignore_alts  : 1,
+          hint         : 1,
+          retpoline_safe : 1,
+          noendbr      : 1;
+               /* 2 bit hole */
        s8 instr;
        u8 visited;
+       /* u8 hole */
+
        struct alt_group *alt_group;
        struct symbol *call_dest;
        struct instruction *jump_dest;