[PATCH 03/11] objtool: Convert ANNOTATE_RETPOLINE_SAFE to ANNOTATE

Peter Zijlstra
2023-12-04T09:40:19Z

arch/x86/include/asm/nospec-branch.h | 13 +-------
include/linux/objtool_types.h | 1
tools/include/linux/objtool_types.h | 1
tools/objtool/check.c | 52 ++++++++++++-----------------------
4 files changed, 22 insertions(+), 45 deletions(-)

--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -193,12 +193,7 @@
* objtool the subsequent indirect jump/call is vouched safe for retpoline
* builds.
*/
-.macro ANNOTATE_RETPOLINE_SAFE
-.Lhere_\@:
- .pushsection .discard.retpoline_safe
- .long .Lhere_\@
- .popsection
-.endm
+#define ANNOTATE_RETPOLINE_SAFE ANNOTATE type=ANNOTYPE_RETPOLINE_SAFE

/*
* (ab)use RETPOLINE_SAFE on RET to annotate away 'bare' RET instructions
@@ -317,11 +312,7 @@

#else /* __ASSEMBLY__ */

-#define ANNOTATE_RETPOLINE_SAFE \
- "999:\n\t" \
- ".pushsection .discard.retpoline_safe\n\t" \
- ".long 999b\n\t" \
- ".popsection\n\t"
+#define ANNOTATE_RETPOLINE_SAFE ASM_ANNOTATE(ANNOTYPE_RETPOLINE_SAFE)

typedef u8 retpoline_thunk_t[RETPOLINE_THUNK_SIZE];
extern retpoline_thunk_t __x86_indirect_thunk_array[];
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -58,5 +58,6 @@ struct unwind_hint {
* Annotate types
*/
#define ANNOTYPE_NOENDBR 1
+#define ANNOTYPE_RETPOLINE_SAFE 2

#endif /* _LINUX_OBJTOOL_TYPES_H */
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -58,5 +58,6 @@ struct unwind_hint {
* Annotate types
*/
#define ANNOTYPE_NOENDBR 1
+#define ANNOTYPE_RETPOLINE_SAFE 2

#endif /* _LINUX_OBJTOOL_TYPES_H */
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2308,12 +2308,12 @@ static int read_unwind_hints(struct objt
return 0;
}

-static int read_annotate(struct objtool_file *file, void (*func)(int type, struct instruction *insn))
+static int read_annotate(struct objtool_file *file, int (*func)(int type, struct instruction *insn))
{
struct section *rsec, *sec;
struct instruction *insn;
struct reloc *reloc;
- int type;
+ int type, ret;

rsec = find_section_by_name(file->elf, ".rela.discard.annotate");
if (!rsec)
@@ -2333,53 +2333,37 @@ static int read_annotate(struct objtool_

type = *(u32 *)(sec->data->d_buf + (reloc_idx(reloc) * sec->sh.sh_entsize) + 4);

- func(type, insn);
+ ret = func(type, insn);
+ if (ret < 0)
+ return ret;
}

return 0;
}

-static void __annotate_noendbr(int type, struct instruction *insn)
+static int __annotate_noendbr(int type, struct instruction *insn)
{
if (type != ANNOTYPE_NOENDBR)
- return;
+ return 0;

insn->noendbr = 1;
+ return 0;
}

-static int read_retpoline_hints(struct objtool_file *file)
+static int __annotate_retpoline_safe(int type, struct instruction *insn)
{
- struct section *rsec;
- struct instruction *insn;
- struct reloc *reloc;
-
- rsec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
- if (!rsec)
+ if (type != ANNOTYPE_RETPOLINE_SAFE)
return 0;

- for_each_reloc(rsec, reloc) {
- if (reloc->sym->type != STT_SECTION) {
- WARN("unexpected relocation symbol type in %s", rsec->name);
- return -1;
- }
-
- insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
- if (!insn) {
- WARN("bad .discard.retpoline_safe entry");
- return -1;
- }
-
- if (insn->type != INSN_JUMP_DYNAMIC &&
- insn->type != INSN_CALL_DYNAMIC &&
- insn->type != INSN_RETURN &&
- insn->type != INSN_NOP) {
- WARN_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
- return -1;
- }
-
- insn->retpoline_safe = true;
+ if (insn->type != INSN_JUMP_DYNAMIC &&
+ insn->type != INSN_CALL_DYNAMIC &&
+ insn->type != INSN_RETURN &&
+ insn->type != INSN_NOP) {
+ WARN_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
+ return -1;
}

+ insn->retpoline_safe = true;
return 0;
}

@@ -2666,7 +2650,7 @@ static int decode_sections(struct objtoo
if (ret)
return ret;

- ret = read_retpoline_hints(file);
+ ret = read_annotate(file, __annotate_retpoline_safe);
if (ret)
return ret;