diff --git a/include/linux/filter.h b/include/linux/filter.h
index f7880c716308..ac2272778f2e 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -46,12 +46,7 @@ struct bpf_prog_aux;
 #define BPF_REG_X	BPF_REG_7
 #define BPF_REG_TMP	BPF_REG_8
 
-/* Kernel hidden auxiliary/helper register for hardening step.
- * Only used by eBPF JITs. It's nothing more than a temporary
- * register that JITs use internally, only that here it's part
- * of eBPF instructions that have been rewritten for blinding
- * constants. See JIT pre-step in bpf_jit_blind_constants().
- */
+/* Kernel hidden auxiliary/helper register. */
 #define BPF_REG_AX		MAX_BPF_REG
 #define MAX_BPF_EXT_REG		(MAX_BPF_REG + 1)
 #define MAX_BPF_JIT_REG		MAX_BPF_EXT_REG
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index e59a72c7d092..e46106c6ac39 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -553,6 +553,26 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from,
 	BUILD_BUG_ON(BPF_REG_AX  + 1 != MAX_BPF_JIT_REG);
 	BUILD_BUG_ON(MAX_BPF_REG + 1 != MAX_BPF_JIT_REG);
 
+	/* Constraints on AX register:
+	 *
+	 * AX register is inaccessible from user space. It is mapped in
+	 * all JITs, and used here for constant blinding rewrites. It is
+	 * typically "stateless" meaning its contents are only valid within
+	 * the executed instruction, but not across several instructions.
+	 * There are a few exceptions however which are further detailed
+	 * below.
+	 *
+	 * Constant blinding is only used by JITs, not in the interpreter.
+	 * The interpreter uses AX in some occasions as a local temporary
+	 * register e.g. in DIV or MOD instructions.
+	 *
+	 * In restricted circumstances, the verifier can also use the AX
+	 * register for rewrites as long as they do not interfere with
+	 * the above cases!
+	 */
+	if (from->dst_reg == BPF_REG_AX || from->src_reg == BPF_REG_AX)
+		goto out;
+
 	if (from->imm == 0 &&
 	    (from->code == (BPF_ALU   | BPF_MOV | BPF_K) ||
 	     from->code == (BPF_ALU64 | BPF_MOV | BPF_K))) {