diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index d9dabd0c31fc..eb5734112cb4 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -150,6 +150,19 @@ static bool is_ereg(u32 reg)
 			     BIT(BPF_REG_AX));
 }
 
+/*
+ * is_ereg_8l() == true if BPF register 'reg' is mapped to access x86-64
+ * lower 8-bit registers dil,sil,bpl,spl,r8b..r15b, which need extra byte
+ * of encoding. al,cl,dl,bl have simpler encoding.
+ */
+static bool is_ereg_8l(u32 reg)
+{
+	return is_ereg(reg) ||
+	    (1 << reg) & (BIT(BPF_REG_1) |
+			  BIT(BPF_REG_2) |
+			  BIT(BPF_REG_FP));
+}
+
 /* add modifiers if 'reg' maps to x64 registers r8..r15 */
 static u8 add_1mod(u8 byte, u32 reg)
 {
@@ -771,9 +784,8 @@ st:			if (is_imm8(insn->off))
 			/* STX: *(u8*)(dst_reg + off) = src_reg */
 		case BPF_STX | BPF_MEM | BPF_B:
 			/* emit 'mov byte ptr [rax + off], al' */
-			if (is_ereg(dst_reg) || is_ereg(src_reg) ||
-			    /* have to add extra byte for x86 SIL, DIL regs */
-			    src_reg == BPF_REG_1 || src_reg == BPF_REG_2)
+			if (is_ereg(dst_reg) || is_ereg_8l(src_reg))
+				/* Add extra byte for eregs or SIL,DIL,BPL in src_reg */
 				EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x88);
 			else
 				EMIT1(0x88);