[PATCH v1 bpf-next 9/9] selftests/bpf: Add tests for new ja* instructions

[Anton Protopopov <aspsk@isovalent.com>]

Add several self-tests to test the new instructions and the new
BPF_STATIC_BRANCH_UPDATE syscall.

Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
---
 .../bpf/prog_tests/bpf_static_branches.c      | 269 ++++++++++++++++++
 1 file changed, 269 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/bpf_static_branches.c

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_static_branches.c b/tools/testing/selftests/bpf/prog_tests/bpf_static_branches.c
new file mode 100644
index 000000000000..6f54002e6e15
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_static_branches.c
@@ -0,0 +1,269 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Isovalent */
+
+#include <test_progs.h>
+
+#include <sys/syscall.h>
+#include <bpf/bpf.h>
+
+static inline int _bpf_prog_load(struct bpf_insn *insns, __u32 insn_cnt)
+{
+	union bpf_attr attr = {
+		.prog_type = BPF_PROG_TYPE_XDP, /* we don't care */
+		.insns     = ptr_to_u64(insns),
+		.insn_cnt  = insn_cnt,
+		.license   = ptr_to_u64("GPL"),
+	};
+
+	return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
+}
+
+enum {
+	OFF,
+	ON
+};
+
+static inline int bpf_static_branch_update(int prog_fd, __u32 insn_off, __u32 on)
+{
+	union bpf_attr attr = {
+		.static_branch.prog_fd = (__u32)prog_fd,
+		.static_branch.insn_off = insn_off,
+		.static_branch.on = on,
+	};
+
+	return syscall(__NR_bpf, BPF_STATIC_BRANCH_UPDATE, &attr, sizeof(attr));
+}
+
+#define BPF_JMP32_OR_NOP(IMM, OFF)				\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP32 | BPF_JA | BPF_K,		\
+		.dst_reg = 0,					\
+		.src_reg = BPF_STATIC_BRANCH_JA,		\
+		.off   = OFF,					\
+		.imm   = IMM })
+
+#define BPF_JMP_OR_NOP(IMM, OFF)				\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP | BPF_JA | BPF_K,		\
+		.dst_reg = 0,					\
+		.src_reg = BPF_STATIC_BRANCH_JA,		\
+		.off   = OFF,					\
+		.imm   = IMM })
+
+#define BPF_NOP_OR_JMP32(IMM, OFF)				\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP32 | BPF_JA | BPF_K,		\
+		.dst_reg = 0,					\
+		.src_reg = BPF_STATIC_BRANCH_JA |		\
+			   BPF_STATIC_BRANCH_NOP,		\
+		.off   = OFF,					\
+		.imm   = IMM })
+
+#define BPF_NOP_OR_JMP(IMM, OFF)				\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP | BPF_JA | BPF_K,		\
+		.dst_reg = 0,					\
+		.src_reg = BPF_STATIC_BRANCH_JA |		\
+			   BPF_STATIC_BRANCH_NOP,		\
+		.off   = OFF,					\
+		.imm   = IMM })
+
+static const struct bpf_insn insns0[] = {
+	BPF_JMP_OR_NOP(0, 1),
+	BPF_NOP_OR_JMP(0, 1),
+	BPF_JMP32_OR_NOP(1, 0),
+	BPF_NOP_OR_JMP32(1, 0),
+};
+
+static void check_ops(void)
+{
+	struct bpf_insn insns[] = {
+		{}, /* we will substitute this by insn0[i], i=0,1,2,3 */
+		BPF_JMP_IMM(BPF_JA, 0, 0, 1),
+		BPF_JMP_IMM(BPF_JA, 0, 0, -2),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	union bpf_attr attr = {
+		.prog_type = BPF_PROG_TYPE_XDP,
+		.insns     = ptr_to_u64(insns),
+		.insn_cnt  = ARRAY_SIZE(insns),
+		.license   = ptr_to_u64("GPL"),
+	};
+	bool stop = false;
+	int prog_fd[4];
+	int i;
+
+	for (i = 0; i < 4; i++) {
+		insns[0] = insns0[i];
+		prog_fd[i] = _bpf_prog_load(insns, ARRAY_SIZE(insns));
+		if (!ASSERT_GE(prog_fd[i], 0, "correct program"))
+			stop = true;
+	}
+
+	for (i = 0; i < 4; i++)
+		close(prog_fd[i]);
+
+	if (stop)
+		return;
+
+	/* load should fail: incorrect SRC */
+	for (i = 0; i < 4; i++) {
+		insns[0] = insns0[i];
+		insns[0].src_reg |= 4;
+		prog_fd[i] = _bpf_prog_load(insns, ARRAY_SIZE(insns));
+		if (!ASSERT_EQ(prog_fd[i], -1, "incorrect src"))
+			return;
+	}
+
+	/* load should fail: incorrect DST */
+	for (i = 0; i < 4; i++) {
+		insns[0] = insns0[i];
+		insns[0].dst_reg = i + 1; /* non-zero */
+		prog_fd[i] = _bpf_prog_load(insns, ARRAY_SIZE(insns));
+		if (!ASSERT_EQ(prog_fd[i], -1, "incorrect dst"))
+			return;
+	}
+
+	/* load should fail: both off and imm are set */
+	for (i = 0; i < 4; i++) {
+		insns[0] = insns0[i];
+		insns[0].imm = insns[0].off = insns0[i].imm ?: insns0[i].off;
+		prog_fd[i] = _bpf_prog_load(insns, ARRAY_SIZE(insns));
+		if (!ASSERT_EQ(prog_fd[i], -1, "incorrect imm/off"))
+			return;
+	}
+
+	/* load should fail: offset is incorrect */
+	for (i = 0; i < 4; i++) {
+		insns[0] = insns0[i];
+
+		if (insns0[i].imm)
+			insns[0].imm = -2;
+		else
+			insns[0].off = -2;
+		prog_fd[i] = _bpf_prog_load(insns, ARRAY_SIZE(insns));
+		if (!ASSERT_EQ(prog_fd[i], -1, "incorrect imm/off"))
+			return;
+
+		if (insns0[i].imm)
+			insns[0].imm = 42;
+		else
+			insns[0].off = 42;
+		prog_fd[i] = _bpf_prog_load(insns, ARRAY_SIZE(insns));
+		if (!ASSERT_EQ(prog_fd[i], -1, "incorrect imm/off"))
+			return;
+
+		/* 0 is not allowed */
+		insns[0].imm = insns[0].off = 0;
+		prog_fd[i] = _bpf_prog_load(insns, ARRAY_SIZE(insns));
+		if (!ASSERT_EQ(prog_fd[i], -1, "incorrect imm/off"))
+			return;
+	}
+
+	/* incorrect field is used */
+	for (i = 0; i < 4; i++) {
+		int tmp;
+
+		insns[0] = insns0[i];
+
+		tmp = insns[0].imm;
+		insns[0].imm = insns[0].off;
+		insns[0].off = tmp;
+
+		prog_fd[i] = _bpf_prog_load(insns, ARRAY_SIZE(insns));
+		if (!ASSERT_EQ(prog_fd[i], -1, "incorrect field"))
+			return;
+	}
+}
+
+static void check_syscall(void)
+{
+	struct bpf_insn insns[] = {
+		{}, /* we will substitute this by insn0[i], i=0,1,2,3 */
+		BPF_JMP_IMM(BPF_JA, 0, 0, 1),
+		BPF_JMP_IMM(BPF_JA, 0, 0, -2),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	union bpf_attr attr = {
+		.prog_type = BPF_PROG_TYPE_XDP,
+		.insns     = ptr_to_u64(insns),
+		.insn_cnt  = ARRAY_SIZE(insns),
+		.license   = ptr_to_u64("GPL"),
+	};
+	bool stop = false;
+	int prog_fd[4];
+	__u32 insn_off;
+	int ret;
+	int i;
+
+	for (i = 0; i < 4; i++) {
+		insns[0] = insns0[i];
+		prog_fd[i] = _bpf_prog_load(insns, ARRAY_SIZE(insns));
+		if (!ASSERT_GE(prog_fd[i], 0, "correct program"))
+			stop = true;
+	}
+
+	if (stop)
+		goto end;
+
+	for (i = 0; i < 4; i++) {
+		/* we can set branch off */
+		ret = bpf_static_branch_update(prog_fd[i], 0, OFF);
+		if (!ASSERT_EQ(ret, 0, "correct update"))
+			goto end;
+
+		/* we can set branch on */
+		ret = bpf_static_branch_update(prog_fd[i], 0, ON);
+		if (!ASSERT_EQ(ret, 0, "correct update"))
+			goto end;
+
+		/* incorrect.static_branch.on: can only be 0|1 */
+		ret = bpf_static_branch_update(prog_fd[i], 0, 2);
+		if (!ASSERT_EQ(ret, -1, "incorrect static_branch.on value"))
+			goto end;
+
+		/* incorrect static_branch.insn_off: can only be 0 in this case */
+		for (insn_off = 1; insn_off < 5; insn_off++) {
+			ret = bpf_static_branch_update(prog_fd[i], insn_off, OFF);
+			if (!ASSERT_EQ(ret, -1, "incorrect insn_off: not a correct insns"))
+				goto end;
+			if (!ASSERT_EQ(errno, EINVAL, "incorrect insn_off: not a correct insns"))
+				goto end;
+		}
+		ret = bpf_static_branch_update(prog_fd[i], 666, OFF);
+		if (!ASSERT_EQ(ret, -1, "incorrect insn_off: out of range"))
+			goto end;
+		if (!ASSERT_EQ(errno, ERANGE, "incorrect insn_off: out puf range"))
+			goto end;
+
+		/* bad file descriptor: no open file */
+		ret = bpf_static_branch_update(-1, 0, OFF);
+		if (!ASSERT_EQ(ret, -1, "incorrect prog_fd: no file"))
+			goto end;
+		if (!ASSERT_EQ(errno, EBADF, "incorrect prog_fd: no file"))
+			goto end;
+
+		/* bad file descriptor: not a bpf prog */
+		ret = bpf_static_branch_update(0, 0, OFF);
+		if (!ASSERT_EQ(ret, -1, "incorrect prog_fd: not a bpf prog"))
+			goto end;
+		if (!ASSERT_EQ(errno, EINVAL, "incorrect prog_fd: not a bpf prog"))
+			goto end;
+	}
+
+end:
+	for (i = 0; i < 4; i++)
+		close(prog_fd[i]);
+
+}
+
+void test_bpf_static_branches(void)
+{
+	if (test__start_subtest("check_ops"))
+		check_ops();
+
+	if (test__start_subtest("check_syscall"))
+		check_syscall();
+}
-- 
2.34.1