[PATCH v3 06/39] x86/text-patching: Make text_gen_insn() play nice with ANNOTATE_NOENDBR

Peter Zijlstra
2022-03-03T11:32:58Z

arch/x86/include/asm/text-patching.h | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -101,13 +101,21 @@ void *text_gen_insn(u8 opcode, const voi
static union text_poke_insn insn; /* per instance */
int size = text_opcode_size(opcode);

+ /*
+ * Hide the addresses to avoid the compiler folding in constants when
+ * referencing code, these can mess up annotations like
+ * ANNOTATE_NOENDBR.
+ */
+ OPTIMIZER_HIDE_VAR(addr);
+ OPTIMIZER_HIDE_VAR(dest);
+
insn.opcode = opcode;

if (size > 1) {
insn.disp = (long)dest - (long)(addr + size);
if (size == 2) {
/*
- * Ensure that for JMP9 the displacement
+ * Ensure that for JMP8 the displacement
* actually fits the signed byte.
*/
BUG_ON((insn.disp >> 31) != (insn.disp >> 7));