Merge tag 'x86_core_for_v6.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 core fixes from Borislav Petkov:

 - Make sure an INT3 is slapped after every unconditional retpoline JMP
   as both vendors suggest

 - Clean up pciserial a bit

* tag 'x86_core_for_v6.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86,retpoline: Be sure to emit INT3 after JMP *%\reg
  x86/earlyprintk: Clean up pciserial

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 4f3204364caa..5cadcea035e0 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -453,6 +453,15 @@ static int patch_retpoline(void *addr, struct insn *insn, u8 *bytes)
 		return ret;
 	i += ret;
 
+	/*
+	 * The compiler is supposed to EMIT an INT3 after every unconditional
+	 * JMP instruction due to AMD BTC. However, if the compiler is too old
+	 * or SLS isn't enabled, we still need an INT3 after indirect JMPs
+	 * even on Intel.
+	 */
+	if (op == JMP32_INSN_OPCODE && i < insn->length)
+		bytes[i++] = INT3_INSN_OPCODE;
+
 	for (; i < insn->length;)
 		bytes[i++] = BYTES_NOP1;