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authorPeter Zijlstra2022-03-08 16:30:49 +0100
committerPeter Zijlstra2022-03-15 10:32:44 +0100
commit0e5b613b4d4be3345dda349fb90dd73d2103302f (patch)
tree8c6a02510634e7c0046ae8bf34a5763979dd3c61 /tools/objtool
parent105cd68596392cfe15056a891b0723609dcad247 (diff)
objtool: Rework ASM_REACHABLE
Currently ASM_REACHABLE only works for UD2 instructions; reorder things to also allow over-riding dead_end_function(). To that end: - Mark INSN_BUG instructions in decode_instructions(), this saves having to iterate all instructions yet again. - Have add_call_destinations() set insn->dead_end for dead_end_function() calls. - Move add_dead_ends() *after* add_call_destinations() such that ASM_REACHABLE can clear the ->dead_end mark. - have validate_branch() only check ->dead_end. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.410010807@infradead.org
Diffstat (limited to 'tools/objtool')
-rw-r--r--tools/objtool/check.c33
1 files changed, 20 insertions, 13 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0c857e74c852..894c9a722555 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -395,6 +395,14 @@ static int decode_instructions(struct objtool_file *file)
if (ret)
goto err;
+ /*
+ * By default, "ud2" is a dead end unless otherwise
+ * annotated, because GCC 7 inserts it for certain
+ * divide-by-zero cases.
+ */
+ if (insn->type == INSN_BUG)
+ insn->dead_end = true;
+
hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
list_add_tail(&insn->list, &file->insn_list);
nr_insns++;
@@ -524,14 +532,6 @@ static int add_dead_ends(struct objtool_file *file)
struct instruction *insn;
/*
- * By default, "ud2" is a dead end unless otherwise annotated, because
- * GCC 7 inserts it for certain divide-by-zero cases.
- */
- for_each_insn(file, insn)
- if (insn->type == INSN_BUG)
- insn->dead_end = true;
-
- /*
* Check for manually annotated dead ends.
*/
sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
@@ -1114,6 +1114,9 @@ static void annotate_call_site(struct objtool_file *file,
list_add_tail(&insn->call_node, &file->mcount_loc_list);
return;
}
+
+ if (!sibling && dead_end_function(file, sym))
+ insn->dead_end = true;
}
static void add_call_dest(struct objtool_file *file, struct instruction *insn,
@@ -2089,10 +2092,6 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;
- ret = add_dead_ends(file);
- if (ret)
- return ret;
-
add_ignores(file);
add_uaccess_safe(file);
@@ -2131,6 +2130,14 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;
+ /*
+ * Must be after add_call_destinations() such that it can override
+ * dead_end_function() marks.
+ */
+ ret = add_dead_ends(file);
+ if (ret)
+ return ret;
+
ret = add_jump_table_alts(file);
if (ret)
return ret;
@@ -3138,7 +3145,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
return 1;
}
- if (dead_end_function(file, insn->call_dest))
+ if (insn->dead_end)
return 0;
break;