ARM: net: make BPF_LD | BPF_IND instruction trigger r_X initialisation to 0.

Without this patch, if the only instructions using r_X are of the
BPF_LD | BPF_IND type, r_X would not be reset to 0, using whatever
value was there when entering the jited code. With this patch, r_X
will be correctly marked as used so it will be reset to 0 in the
prologue code.

This fix also makes the test "LD_IND byte default X" pass in the
test_bpf module when the ARM JIT is enabled.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: nschichan

arch/arm/net/bpf_jit_32.c

@@ -614,6 +614,7 @@ static int build_body(struct jit_ctx *ctx)
 		case BPF_LD | BPF_B | BPF_IND:
 			load_order = 0;
 load_ind:
+			update_on_xread(ctx);
 			OP_IMM3(ARM_ADD, r_off, r_X, k, ctx);
 			goto load_common;
 		case BPF_LDX | BPF_IMM: