diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 4f3204364caa54..5cadcea035e044 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;
 
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 68b38925a74f08..44f937015e1e25 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -264,11 +264,11 @@ static __init void early_pci_serial_init(char *s)
 	bar0 = read_pci_config(bus, slot, func, PCI_BASE_ADDRESS_0);
 
 	/*
-	 * Verify it is a UART type device
+	 * Verify it is a 16550-UART type device
 	 */
 	if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) &&
 	     (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) ||
-	   (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */ {
+	    (((classcode >> 8) & 0xff) != PCI_SERIAL_16550_COMPATIBLE)) {
 		if (!force)
 			return;
 	}
@@ -276,22 +276,22 @@ static __init void early_pci_serial_init(char *s)
 	/*
 	 * Determine if it is IO or memory mapped
 	 */
-	if (bar0 & 0x01) {
+	if ((bar0 & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO) {
 		/* it is IO mapped */
 		serial_in = io_serial_in;
 		serial_out = io_serial_out;
-		early_serial_base = bar0&0xfffffffc;
+		early_serial_base = bar0 & PCI_BASE_ADDRESS_IO_MASK;
 		write_pci_config(bus, slot, func, PCI_COMMAND,
-						cmdreg|PCI_COMMAND_IO);
+				 cmdreg|PCI_COMMAND_IO);
 	} else {
 		/* It is memory mapped - assume 32-bit alignment */
 		serial_in = mem32_serial_in;
 		serial_out = mem32_serial_out;
 		/* WARNING! assuming the address is always in the first 4G */
 		early_serial_base =
-			(unsigned long)early_ioremap(bar0 & 0xfffffff0, 0x10);
+			(unsigned long)early_ioremap(bar0 & PCI_BASE_ADDRESS_MEM_MASK, 0x10);
 		write_pci_config(bus, slot, func, PCI_COMMAND,
-						cmdreg|PCI_COMMAND_MEMORY);
+				 cmdreg|PCI_COMMAND_MEMORY);
 	}
 
 	/*
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index c1f6c1c51d998f..4922517ddb0d5f 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -419,7 +419,9 @@ static void emit_indirect_jump(u8 **pprog, int reg, u8 *ip)
 		OPTIMIZER_HIDE_VAR(reg);
 		emit_jump(&prog, &__x86_indirect_thunk_array[reg], ip);
 	} else {
-		EMIT2(0xFF, 0xE0 + reg);
+		EMIT2(0xFF, 0xE0 + reg);	/* jmp *%\reg */
+		if (IS_ENABLED(CONFIG_RETPOLINE) || IS_ENABLED(CONFIG_SLS))
+			EMIT1(0xCC);		/* int3 */
 	}
 
 	*pprog = prog;
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index 15b49e655ce364..b362d90eb9b0bf 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -75,6 +75,9 @@
 #define PCI_CLASS_COMMUNICATION_MODEM	0x0703
 #define PCI_CLASS_COMMUNICATION_OTHER	0x0780
 
+/* Interface for SERIAL/MODEM */
+#define PCI_SERIAL_16550_COMPATIBLE	0x02
+
 #define PCI_BASE_CLASS_SYSTEM		0x08
 #define PCI_CLASS_SYSTEM_PIC		0x0800
 #define PCI_CLASS_SYSTEM_PIC_IOAPIC	0x080010