bpf, tests: Add tests for ALU operations implemented with function calls

32-bit JITs may implement complex ALU64 instructions using function calls.
The new tests check aspects related to this, such as register clobbering
and register argument re-ordering.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210809091829.810076-9-johan.almbladh@anyfinetworks.com

1 files changed, 141 insertions, 0 deletions

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 072f9c51bd9b..e3c256963020 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -1917,6 +1917,147 @@ static struct bpf_test tests[] = {
 		{ { 0, -1 } }
 	},
 	{
+		/*
+		 * Register (non-)clobbering test, in the case where a 32-bit
+		 * JIT implements complex ALU64 operations via function calls.
+		 * If so, the function call must be invisible in the eBPF
+		 * registers. The JIT must then save and restore relevant
+		 * registers during the call. The following tests check that
+		 * the eBPF registers retain their values after such a call.
+		 */
+		"INT: Register clobbering, R1 updated",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_ALU32_IMM(BPF_MOV, R1, 123456789),
+			BPF_ALU32_IMM(BPF_MOV, R2, 2),
+			BPF_ALU32_IMM(BPF_MOV, R3, 3),
+			BPF_ALU32_IMM(BPF_MOV, R4, 4),
+			BPF_ALU32_IMM(BPF_MOV, R5, 5),
+			BPF_ALU32_IMM(BPF_MOV, R6, 6),
+			BPF_ALU32_IMM(BPF_MOV, R7, 7),
+			BPF_ALU32_IMM(BPF_MOV, R8, 8),
+			BPF_ALU32_IMM(BPF_MOV, R9, 9),
+			BPF_ALU64_IMM(BPF_DIV, R1, 123456789),
+			BPF_JMP_IMM(BPF_JNE, R0, 0, 10),
+			BPF_JMP_IMM(BPF_JNE, R1, 1, 9),
+			BPF_JMP_IMM(BPF_JNE, R2, 2, 8),
+			BPF_JMP_IMM(BPF_JNE, R3, 3, 7),
+			BPF_JMP_IMM(BPF_JNE, R4, 4, 6),
+			BPF_JMP_IMM(BPF_JNE, R5, 5, 5),
+			BPF_JMP_IMM(BPF_JNE, R6, 6, 4),
+			BPF_JMP_IMM(BPF_JNE, R7, 7, 3),
+			BPF_JMP_IMM(BPF_JNE, R8, 8, 2),
+			BPF_JMP_IMM(BPF_JNE, R9, 9, 1),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } }
+	},
+	{
+		"INT: Register clobbering, R2 updated",
+		.u.insns_int = {
+			BPF_ALU32_IMM(BPF_MOV, R0, 0),
+			BPF_ALU32_IMM(BPF_MOV, R1, 1),
+			BPF_ALU32_IMM(BPF_MOV, R2, 2 * 123456789),
+			BPF_ALU32_IMM(BPF_MOV, R3, 3),
+			BPF_ALU32_IMM(BPF_MOV, R4, 4),
+			BPF_ALU32_IMM(BPF_MOV, R5, 5),
+			BPF_ALU32_IMM(BPF_MOV, R6, 6),
+			BPF_ALU32_IMM(BPF_MOV, R7, 7),
+			BPF_ALU32_IMM(BPF_MOV, R8, 8),
+			BPF_ALU32_IMM(BPF_MOV, R9, 9),
+			BPF_ALU64_IMM(BPF_DIV, R2, 123456789),
+			BPF_JMP_IMM(BPF_JNE, R0, 0, 10),
+			BPF_JMP_IMM(BPF_JNE, R1, 1, 9),
+			BPF_JMP_IMM(BPF_JNE, R2, 2, 8),
+			BPF_JMP_IMM(BPF_JNE, R3, 3, 7),
+			BPF_JMP_IMM(BPF_JNE, R4, 4, 6),
+			BPF_JMP_IMM(BPF_JNE, R5, 5, 5),
+			BPF_JMP_IMM(BPF_JNE, R6, 6, 4),
+			BPF_JMP_IMM(BPF_JNE, R7, 7, 3),
+			BPF_JMP_IMM(BPF_JNE, R8, 8, 2),
+			BPF_JMP_IMM(BPF_JNE, R9, 9, 1),
+			BPF_ALU32_IMM(BPF_MOV, R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } }
+	},
+	{
+		/*
+		 * Test 32-bit JITs that implement complex ALU64 operations as
+		 * function calls R0 = f(R1, R2), and must re-arrange operands.
+		 */
+#define NUMER 0xfedcba9876543210ULL
+#define DENOM 0x0123456789abcdefULL
+		"ALU64_DIV X: Operand register permutations",
+		.u.insns_int = {
+			/* R0 / R2 */
+			BPF_LD_IMM64(R0, NUMER),
+			BPF_LD_IMM64(R2, DENOM),
+			BPF_ALU64_REG(BPF_DIV, R0, R2),
+			BPF_JMP_IMM(BPF_JEQ, R0, NUMER / DENOM, 1),
+			BPF_EXIT_INSN(),
+			/* R1 / R0 */
+			BPF_LD_IMM64(R1, NUMER),
+			BPF_LD_IMM64(R0, DENOM),
+			BPF_ALU64_REG(BPF_DIV, R1, R0),
+			BPF_JMP_IMM(BPF_JEQ, R1, NUMER / DENOM, 1),
+			BPF_EXIT_INSN(),
+			/* R0 / R1 */
+			BPF_LD_IMM64(R0, NUMER),
+			BPF_LD_IMM64(R1, DENOM),
+			BPF_ALU64_REG(BPF_DIV, R0, R1),
+			BPF_JMP_IMM(BPF_JEQ, R0, NUMER / DENOM, 1),
+			BPF_EXIT_INSN(),
+			/* R2 / R0 */
+			BPF_LD_IMM64(R2, NUMER),
+			BPF_LD_IMM64(R0, DENOM),
+			BPF_ALU64_REG(BPF_DIV, R2, R0),
+			BPF_JMP_IMM(BPF_JEQ, R2, NUMER / DENOM, 1),
+			BPF_EXIT_INSN(),
+			/* R2 / R1 */
+			BPF_LD_IMM64(R2, NUMER),
+			BPF_LD_IMM64(R1, DENOM),
+			BPF_ALU64_REG(BPF_DIV, R2, R1),
+			BPF_JMP_IMM(BPF_JEQ, R2, NUMER / DENOM, 1),
+			BPF_EXIT_INSN(),
+			/* R1 / R2 */
+			BPF_LD_IMM64(R1, NUMER),
+			BPF_LD_IMM64(R2, DENOM),
+			BPF_ALU64_REG(BPF_DIV, R1, R2),
+			BPF_JMP_IMM(BPF_JEQ, R1, NUMER / DENOM, 1),
+			BPF_EXIT_INSN(),
+			/* R1 / R1 */
+			BPF_LD_IMM64(R1, NUMER),
+			BPF_ALU64_REG(BPF_DIV, R1, R1),
+			BPF_JMP_IMM(BPF_JEQ, R1, 1, 1),
+			BPF_EXIT_INSN(),
+			/* R2 / R2 */
+			BPF_LD_IMM64(R2, DENOM),
+			BPF_ALU64_REG(BPF_DIV, R2, R2),
+			BPF_JMP_IMM(BPF_JEQ, R2, 1, 1),
+			BPF_EXIT_INSN(),
+			/* R3 / R4 */
+			BPF_LD_IMM64(R3, NUMER),
+			BPF_LD_IMM64(R4, DENOM),
+			BPF_ALU64_REG(BPF_DIV, R3, R4),
+			BPF_JMP_IMM(BPF_JEQ, R3, NUMER / DENOM, 1),
+			BPF_EXIT_INSN(),
+			/* Successful return */
+			BPF_LD_IMM64(R0, 1),
+			BPF_EXIT_INSN(),
+		},
+		INTERNAL,
+		{ },
+		{ { 0, 1 } },
+#undef NUMER
+#undef DENOM
+	},
+	{
 		"check: missing ret",
 		.u.insns = {
 			BPF_STMT(BPF_LD | BPF_IMM, 1),