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authorLinus Torvalds <torvalds@linux-foundation.org>2017-02-28 10:15:59 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-28 10:15:59 -0800
commite72e58faa709d554f95431dbafd3374db5ed3fbb (patch)
treef73ee22c1f93a5e56d1930a29f82aae4f39aa956 /tools
parent74e3f63ce60eb81fbd39aa6c0353059b7e2cb5f7 (diff)
parent4e4636cf981b5b629fbfb78aa9f232e015f7d521 (diff)
downloadlinux-e72e58faa709d554f95431dbafd3374db5ed3fbb.tar.gz
Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fixes from Ingo Molnar: "A handful of objtool fixes related to unreachable code, plus a build fix for out of tree modules" * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Enclose contents of unreachable() macro in a block objtool: Prevent GCC from merging annotate_unreachable() objtool: Improve detection of BUG() and other dead ends objtool: Fix CONFIG_STACK_VALIDATION=y warning for out-of-tree modules
Diffstat (limited to 'tools')
-rw-r--r--tools/objtool/arch.h5
-rw-r--r--tools/objtool/arch/x86/decode.c3
-rw-r--r--tools/objtool/builtin-check.c60
3 files changed, 58 insertions, 10 deletions
diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h
index f7350fc..a59e061 100644
--- a/tools/objtool/arch.h
+++ b/tools/objtool/arch.h
@@ -31,9 +31,8 @@
#define INSN_CALL_DYNAMIC 8
#define INSN_RETURN 9
#define INSN_CONTEXT_SWITCH 10
-#define INSN_BUG 11
-#define INSN_NOP 12
-#define INSN_OTHER 13
+#define INSN_NOP 11
+#define INSN_OTHER 12
#define INSN_LAST INSN_OTHER
int arch_decode_instruction(struct elf *elf, struct section *sec,
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 039636f..6ac99e3 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -118,9 +118,6 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
op2 == 0x35)
/* sysenter, sysret */
*type = INSN_CONTEXT_SWITCH;
- else if (op2 == 0x0b || op2 == 0xb9)
- /* ud2 */
- *type = INSN_BUG;
else if (op2 == 0x0d || op2 == 0x1f)
/* nopl/nopw */
*type = INSN_NOP;
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index e8a1f69..5fc52ee 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);