selftests/bpf: Some more atomic tests

Some new verifier tests that hit some important gaps in the parameter
space for atomic ops.

There are already exhaustive tests for the JIT part in
lib/test_bpf.c, but these exercise the verifier too.
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211015093318.1273686-1-jackmanb@google.com

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

@@ -119,3 +119,41 @@
 	},
 	.result = ACCEPT,
 },
+{
+	"Dest pointer in r0 - fail",
+	.insns = {
+		/* val = 0; */
+		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+		/* r0 = &val */
+		BPF_MOV64_REG(BPF_REG_0, BPF_REG_10),
+		/* r0 = atomic_cmpxchg(&val, r0, 1); */
+		BPF_MOV64_IMM(BPF_REG_1, 1),
+		BPF_ATOMIC_OP(BPF_DW, BPF_CMPXCHG, BPF_REG_10, BPF_REG_1, -8),
+		/* if (r0 != 0) exit(1); */
+		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_EXIT_INSN(),
+		/* exit(0); */
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+},
+{
+	"Dest pointer in r0 - succeed",
+	.insns = {
+		/* r0 = &val */
+		BPF_MOV64_REG(BPF_REG_0, BPF_REG_10),
+		/* val = r0; */
+		BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
+		/* r0 = atomic_cmpxchg(&val, r0, 0); */
+		BPF_MOV64_IMM(BPF_REG_1, 0),
+		BPF_ATOMIC_OP(BPF_DW, BPF_CMPXCHG, BPF_REG_10, BPF_REG_1, -8),
+		/* r1 = *r0 */
+		BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, -8),
+		/* exit(0); */
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+},

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

+#define __ATOMIC_FETCH_OP_TEST(src_reg, dst_reg, operand1, op, operand2, expect) \
+	{								\
+		"atomic fetch " #op ", src=" #dst_reg " dst=" #dst_reg,	\
+		.insns = {						\
+			/* u64 val = operan1; */			\
+			BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, operand1),	\
+			/* u64 old = atomic_fetch_add(&val, operand2); */ \
+			BPF_MOV64_REG(dst_reg, BPF_REG_10),		\
+			BPF_MOV64_IMM(src_reg, operand2),		\
+			BPF_ATOMIC_OP(BPF_DW, op,			\
+				      dst_reg, src_reg, -8),		\
+			/* if (old != operand1) exit(1); */		\
+			BPF_JMP_IMM(BPF_JEQ, src_reg, operand1, 2),	\
+			BPF_MOV64_IMM(BPF_REG_0, 1),			\
+			BPF_EXIT_INSN(),				\
+			/* if (val != result) exit (2); */		\
+			BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_10, -8),	\
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, expect, 2),	\
+			BPF_MOV64_IMM(BPF_REG_0, 2),			\
+			BPF_EXIT_INSN(),				\
+			/* exit(0); */					\
+			BPF_MOV64_IMM(BPF_REG_0, 0),			\
+			BPF_EXIT_INSN(),				\
+		},							\
+		.result = ACCEPT,					\
+	}
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_2, 1, BPF_ADD | BPF_FETCH, 2, 3),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_0, BPF_REG_1, 1, BPF_ADD | BPF_FETCH, 2, 3),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_0, 1, BPF_ADD | BPF_FETCH, 2, 3),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_2, BPF_REG_3, 1, BPF_ADD | BPF_FETCH, 2, 3),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_4, BPF_REG_5, 1, BPF_ADD | BPF_FETCH, 2, 3),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_9, BPF_REG_8, 1, BPF_ADD | BPF_FETCH, 2, 3),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_2, 0x010, BPF_AND | BPF_FETCH, 0x011, 0x010),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_0, BPF_REG_1, 0x010, BPF_AND | BPF_FETCH, 0x011, 0x010),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_0, 0x010, BPF_AND | BPF_FETCH, 0x011, 0x010),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_2, BPF_REG_3, 0x010, BPF_AND | BPF_FETCH, 0x011, 0x010),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_4, BPF_REG_5, 0x010, BPF_AND | BPF_FETCH, 0x011, 0x010),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_9, BPF_REG_8, 0x010, BPF_AND | BPF_FETCH, 0x011, 0x010),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_2, 0x010, BPF_OR | BPF_FETCH, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_0, BPF_REG_1, 0x010, BPF_OR | BPF_FETCH, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_0, 0x010, BPF_OR | BPF_FETCH, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_2, BPF_REG_3, 0x010, BPF_OR | BPF_FETCH, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_4, BPF_REG_5, 0x010, BPF_OR | BPF_FETCH, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_9, BPF_REG_8, 0x010, BPF_OR | BPF_FETCH, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_2, 0x010, BPF_XOR | BPF_FETCH, 0x011, 0x001),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_0, BPF_REG_1, 0x010, BPF_XOR | BPF_FETCH, 0x011, 0x001),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_0, 0x010, BPF_XOR | BPF_FETCH, 0x011, 0x001),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_2, BPF_REG_3, 0x010, BPF_XOR | BPF_FETCH, 0x011, 0x001),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_4, BPF_REG_5, 0x010, BPF_XOR | BPF_FETCH, 0x011, 0x001),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_9, BPF_REG_8, 0x010, BPF_XOR | BPF_FETCH, 0x011, 0x001),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_2, 0x010, BPF_XCHG, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_0, BPF_REG_1, 0x010, BPF_XCHG, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_1, BPF_REG_0, 0x010, BPF_XCHG, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_2, BPF_REG_3, 0x010, BPF_XCHG, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_4, BPF_REG_5, 0x010, BPF_XCHG, 0x011, 0x011),
+__ATOMIC_FETCH_OP_TEST(BPF_REG_9, BPF_REG_8, 0x010, BPF_XCHG, 0x011, 0x011),
+#undef __ATOMIC_FETCH_OP_TEST

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

+#define __INVALID_ATOMIC_ACCESS_TEST(op)					\
+	{								\
+		"atomic " #op " access through non-pointer ",			\
+		.insns = {						\
+			BPF_MOV64_IMM(BPF_REG_0, 1),			\
+			BPF_MOV64_IMM(BPF_REG_1, 0),			\
+			BPF_ATOMIC_OP(BPF_DW, op, BPF_REG_1, BPF_REG_0, -8), \
+			BPF_MOV64_IMM(BPF_REG_0, 0),			\
+			BPF_EXIT_INSN(),				\
+		},							\
+		.result = REJECT,					\
+		.errstr = "R1 invalid mem access 'inv'"			\
+	}
+__INVALID_ATOMIC_ACCESS_TEST(BPF_ADD),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_ADD | BPF_FETCH),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_ADD),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_ADD | BPF_FETCH),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_AND),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_AND | BPF_FETCH),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_OR),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_OR | BPF_FETCH),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_XOR),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_XOR | BPF_FETCH),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_XCHG),
+__INVALID_ATOMIC_ACCESS_TEST(BPF_CMPXCHG),