Annotate the indirect calls/jumps in the CALL_NOSPEC/JUMP_NOSPEC
alternatives.
Acked-by: Josh Poimboeuf <jpoim...@redhat.com>
Reviewed-by: David Woodhouse <d...@amazon.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
arch/x86/include/asm/nospec-branch.h | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -67,6 +67,18 @@
.endm
/*
+ * This should be used immediately before an indirect jump/call. It tells
+ * objtool the subsequent indirect jump/call is vouched safe for retpoline
+ * builds.
+ */
+.macro ANNOTATE_RETPOLINE_SAFE
+ .Lannotate_\@:
+ .pushsection .discard.retpoline_safe
+ _ASM_PTR .Lannotate_\@
+ .popsection
+.endm
+
+/*
* These are the bare retpoline primitives for indirect jmp and call.
* Do not use these directly; they only exist to make the ALTERNATIVE
* invocation below less ugly.
@@ -102,9 +114,9 @@
.macro JMP_NOSPEC reg:req
#ifdef CONFIG_RETPOLINE
ANNOTATE_NOSPEC_ALTERNATIVE
- ALTERNATIVE_2 __stringify(jmp *\reg), \
+ ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *\reg), \
__stringify(RETPOLINE_JMP \reg), X86_FEATURE_RETPOLINE, \
- __stringify(lfence; jmp *\reg), X86_FEATURE_RETPOLINE_AMD
+ __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *\reg),
X86_FEATURE_RETPOLINE_AMD
#else
jmp *\reg
#endif
@@ -113,9 +125,9 @@
.macro CALL_NOSPEC reg:req
#ifdef CONFIG_RETPOLINE
ANNOTATE_NOSPEC_ALTERNATIVE
- ALTERNATIVE_2 __stringify(call *\reg), \
+ ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; call *\reg), \
__stringify(RETPOLINE_CALL \reg), X86_FEATURE_RETPOLINE,\
- __stringify(lfence; call *\reg), X86_FEATURE_RETPOLINE_AMD
+ __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *\reg),
X86_FEATURE_RETPOLINE_AMD
#else
call *\reg
#endif
@@ -143,6 +155,12 @@
".long 999b - .\n\t" \
".popsection\n\t"
+#define ANNOTATE_RETPOLINE_SAFE \
+ "999:\n\t" \
+ ".pushsection .discard.retpoline_safe\n\t" \
+ _ASM_PTR " 999b\n\t" \
+ ".popsection\n\t"
+
#if defined(CONFIG_X86_64) && defined(RETPOLINE)
/*
@@ -152,6 +170,7 @@
# define CALL_NOSPEC \
ANNOTATE_NOSPEC_ALTERNATIVE \
ALTERNATIVE( \
+ ANNOTATE_RETPOLINE_SAFE \
"call *%[thunk_target]\n", \
"call __x86_indirect_thunk_%V[thunk_target]\n", \
X86_FEATURE_RETPOLINE)
