Merge tag 'x86-urgent-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:
 "Three small x86 fixes which did not make it into 6.1:

   - Remove a superfluous noinline which prevents GCC-7.3 to optimize a
     stub function away

   - Allow uprobes on REP NOP and do not treat them like word-sized
     branch instructions

   - Make the VDSO symbol export of __vdso_sgx_enter_enclave() depend on
     CONFIG_X86_SGX to prevent build failures with newer LLVM versions
     which rightfully detect that there is no function behind the
     symbol"

* tag 'x86-urgent-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vdso: Conditionally export __vdso_sgx_enter_enclave()
  uprobes/x86: Allow to probe a NOP instruction with 0x66 prefix
  x86/alternative: Remove noinline from __ibt_endbr_seal[_end]() stubs

Author: torvalds

arch/x86/entry/vdso/vdso.lds.S

@@ -27,7 +27,9 @@ VERSION {
 		__vdso_time;
 		clock_getres;
 		__vdso_clock_getres;
+#ifdef CONFIG_X86_SGX
 		__vdso_sgx_enter_enclave;
+#endif
 	local: *;
 	};
 }

arch/x86/kernel/alternative.c

@@ -624,7 +624,7 @@ void __init_or_module noinline apply_ibt_endbr(s32 *start, s32 *end)
 
 #else
 
-void __init_or_module noinline apply_ibt_endbr(s32 *start, s32 *end) { }
+void __init_or_module apply_ibt_endbr(s32 *start, s32 *end) { }
 
 #endif /* CONFIG_X86_KERNEL_IBT */
 

arch/x86/kernel/uprobes.c

@@ -722,8 +722,9 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
 	switch (opc1) {
 	case 0xeb:	/* jmp 8 */
 	case 0xe9:	/* jmp 32 */
-	case 0x90:	/* prefix* + nop; same as jmp with .offs = 0 */
 		break;
+	case 0x90:	/* prefix* + nop; same as jmp with .offs = 0 */
+		goto setup;
 
 	case 0xe8:	/* call relative */
 		branch_clear_offset(auprobe, insn);
@@ -753,6 +754,7 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
 			return -ENOTSUPP;
 	}
 
+setup:
 	auprobe->branch.opc1 = opc1;
 	auprobe->branch.ilen = insn->length;
 	auprobe->branch.offs = insn->immediate.value;