bpf: selftest: Add verifier tests for <8-byte scalar spill and refill

This patch adds a few verifier tests for <8-byte spill and refill.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210922004953.627183-1-kafai@fb.com

tools/testing/selftests/bpf/verifier/spill_fill.c

@@ -104,3 +104,164 @@
 	.result = ACCEPT,
 	.retval = POINTER_VALUE,
 },
+{
+	"Spill and refill a u32 const scalar.  Offset to skb->data",
+	.insns = {
+	BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+		    offsetof(struct __sk_buff, data)),
+	BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+		    offsetof(struct __sk_buff, data_end)),
+	/* r4 = 20 */
+	BPF_MOV32_IMM(BPF_REG_4, 20),
+	/* *(u32 *)(r10 -8) = r4 */
+	BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
+	/* r4 = *(u32 *)(r10 -8) */
+	BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_10, -8),
+	/* r0 = r2 */
+	BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+	/* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=inv20 */
+	BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_4),
+	/* if (r0 > r3) R0=pkt,off=20 R2=pkt R3=pkt_end R4=inv20 */
+	BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+	/* r0 = *(u32 *)r2 R0=pkt,off=20,r=20 R2=pkt,r=20 R3=pkt_end R4=inv20 */
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+},
+{
+	"Spill a u32 const, refill from another half of the uninit u32 from the stack",
+	.insns = {
+	/* r4 = 20 */
+	BPF_MOV32_IMM(BPF_REG_4, 20),
+	/* *(u32 *)(r10 -8) = r4 */
+	BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
+	/* r4 = *(u32 *)(r10 -4) fp-8=????rrrr*/
+	BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_10, -4),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.result = REJECT,
+	.errstr = "invalid read from stack off -4+0 size 4",
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+},
+{
+	"Spill a u32 const scalar.  Refill as u16.  Offset to skb->data",
+	.insns = {
+	BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+		    offsetof(struct __sk_buff, data)),
+	BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+		    offsetof(struct __sk_buff, data_end)),
+	/* r4 = 20 */
+	BPF_MOV32_IMM(BPF_REG_4, 20),
+	/* *(u32 *)(r10 -8) = r4 */
+	BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
+	/* r4 = *(u16 *)(r10 -8) */
+	BPF_LDX_MEM(BPF_H, BPF_REG_4, BPF_REG_10, -8),
+	/* r0 = r2 */
+	BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+	/* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=inv,umax=65535 */
+	BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_4),
+	/* if (r0 > r3) R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=inv,umax=65535 */
+	BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+	/* r0 = *(u32 *)r2 R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=inv20 */
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.result = REJECT,
+	.errstr = "invalid access to packet",
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+},
+{
+	"Spill a u32 const scalar.  Refill as u16 from fp-6.  Offset to skb->data",
+	.insns = {
+	BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+		    offsetof(struct __sk_buff, data)),
+	BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+		    offsetof(struct __sk_buff, data_end)),
+	/* r4 = 20 */
+	BPF_MOV32_IMM(BPF_REG_4, 20),
+	/* *(u32 *)(r10 -8) = r4 */
+	BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
+	/* r4 = *(u16 *)(r10 -6) */
+	BPF_LDX_MEM(BPF_H, BPF_REG_4, BPF_REG_10, -6),
+	/* r0 = r2 */
+	BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+	/* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=inv,umax=65535 */
+	BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_4),
+	/* if (r0 > r3) R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=inv,umax=65535 */
+	BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+	/* r0 = *(u32 *)r2 R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=inv20 */
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.result = REJECT,
+	.errstr = "invalid access to packet",
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+},
+{
+	"Spill and refill a u32 const scalar at non 8byte aligned stack addr.  Offset to skb->data",
+	.insns = {
+	BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+		    offsetof(struct __sk_buff, data)),
+	BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+		    offsetof(struct __sk_buff, data_end)),
+	/* r4 = 20 */
+	BPF_MOV32_IMM(BPF_REG_4, 20),
+	/* *(u32 *)(r10 -8) = r4 */
+	BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
+	/* *(u32 *)(r10 -4) = r4 */
+	BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -4),
+	/* r4 = *(u32 *)(r10 -4),  */
+	BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_10, -4),
+	/* r0 = r2 */
+	BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+	/* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=inv,umax=U32_MAX */
+	BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_4),
+	/* if (r0 > r3) R0=pkt,umax=U32_MAX R2=pkt R3=pkt_end R4=inv */
+	BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+	/* r0 = *(u32 *)r2 R0=pkt,umax=U32_MAX R2=pkt R3=pkt_end R4=inv */
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.result = REJECT,
+	.errstr = "invalid access to packet",
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+},
+{
+	"Spill and refill a umax=40 bounded scalar.  Offset to skb->data",
+	.insns = {
+	BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+		    offsetof(struct __sk_buff, data)),
+	BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+		    offsetof(struct __sk_buff, data_end)),
+	BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_1,
+		    offsetof(struct __sk_buff, tstamp)),
+	BPF_JMP_IMM(BPF_JLE, BPF_REG_4, 40, 2),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	/* *(u32 *)(r10 -8) = r4 R4=inv,umax=40 */
+	BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
+	/* r4 = (*u32 *)(r10 - 8) */
+	BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_10, -8),
+	/* r2 += r4 R2=pkt R4=inv,umax=40 */
+	BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_4),
+	/* r0 = r2 R2=pkt,umax=40 R4=inv,umax=40 */
+	BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+	/* r2 += 20 R0=pkt,umax=40 R2=pkt,umax=40 */
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, 20),
+	/* if (r2 > r3) R0=pkt,umax=40 R2=pkt,off=20,umax=40 */
+	BPF_JMP_REG(BPF_JGT, BPF_REG_2, BPF_REG_3, 1),
+	/* r0 = *(u32 *)r0 R0=pkt,r=20,umax=40 R2=pkt,off=20,r=20,umax=40 */
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+},