1 {
2 	"BPF_ATOMIC bounds propagation, mem->reg",
3 	.insns = {
4 		/* a = 0; */
5 		/*
6 		 * Note this is implemented with two separate instructions,
7 		 * where you might think one would suffice:
8 		 *
9 		 * BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
10 		 *
11 		 * This is because BPF_ST_MEM doesn't seem to set the stack slot
12 		 * type to 0 when storing an immediate.
13 		 */
14 		BPF_MOV64_IMM(BPF_REG_0, 0),
15 		BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
16 		/* b = atomic_fetch_add(&a, 1); */
17 		BPF_MOV64_IMM(BPF_REG_1, 1),
18 		BPF_ATOMIC_OP(BPF_DW, BPF_ADD | BPF_FETCH, BPF_REG_10, BPF_REG_1, -8),
19 		/* Verifier should be able to tell that this infinite loop isn't reachable. */
20 		/* if (b) while (true) continue; */
21 		BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, -1),
22 		BPF_EXIT_INSN(),
23 	},
24 	.result = ACCEPT,
25 	.result_unpriv = REJECT,
26 	.errstr_unpriv = "back-edge",
27 },
28