selftests/bpf: Add tests for subprog topological ordering

Add few tests for topo sort:
- linear chain: main -> A -> B
- diamond: main -> A, main -> B, A -> C, B -> C
- mixed global/static: main -> global -> static leaf
- shared callee: main -> leaf, main -> global -> leaf
- duplicate calls: main calls same subprog twice
- no calls: single subprog

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260403024422.87231-4-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
index bcf01cb4cfe4c77f6b62336cbe8983aab6956635..1ac366fd4daef84be1cf851618624cdf00b47eb4 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/verifier.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
@@ -93,6 +93,7 @@
 #include "verifier_stack_ptr.skel.h"
 #include "verifier_store_release.skel.h"
 #include "verifier_subprog_precision.skel.h"
+#include "verifier_subprog_topo.skel.h"
 #include "verifier_subreg.skel.h"
 #include "verifier_tailcall.skel.h"
 #include "verifier_tailcall_jit.skel.h"
@@ -238,6 +239,7 @@ void test_verifier_spin_lock(void)            { RUN(verifier_spin_lock); }
 void test_verifier_stack_ptr(void)            { RUN(verifier_stack_ptr); }
 void test_verifier_store_release(void)        { RUN(verifier_store_release); }
 void test_verifier_subprog_precision(void)    { RUN(verifier_subprog_precision); }
+void test_verifier_subprog_topo(void)        { RUN(verifier_subprog_topo); }
 void test_verifier_subreg(void)               { RUN(verifier_subreg); }
 void test_verifier_tailcall(void)             { RUN(verifier_tailcall); }
 void test_verifier_tailcall_jit(void)         { RUN(verifier_tailcall_jit); }

diff --git a/tools/testing/selftests/bpf/progs/verifier_subprog_topo.c b/tools/testing/selftests/bpf/progs/verifier_subprog_topo.c
new file mode 100644 (file)
index 0000000..e2b9d14
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/verifier_subprog_topo.c
@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+/* linear chain main -> A -> B */
+__naked __noinline __used
+static unsigned long linear_b(void)
+{
+       asm volatile (
+               "r0 = 42;"
+               "exit;"
+       );
+}
+
+__naked __noinline __used
+static unsigned long linear_a(void)
+{
+       asm volatile (
+               "call linear_b;"
+               "exit;"
+       );
+}
+
+SEC("?raw_tp")
+__success __log_level(2)
+__msg("topo_order[0] = linear_b")
+__msg("topo_order[1] = linear_a")
+__msg("topo_order[2] = topo_linear")
+__naked int topo_linear(void)
+{
+       asm volatile (
+               "call linear_a;"
+               "exit;"
+       );
+}
+
+/* diamond main -> A, main -> B, A -> C, B -> C */
+__naked __noinline __used
+static unsigned long diamond_c(void)
+{
+       asm volatile (
+               "r0 = 1;"
+               "exit;"
+       );
+}
+
+__naked __noinline __used
+static unsigned long diamond_b(void)
+{
+       asm volatile (
+               "call diamond_c;"
+               "exit;"
+       );
+}
+
+__naked __noinline __used
+static unsigned long diamond_a(void)
+{
+       asm volatile (
+               "call diamond_c;"
+               "exit;"
+       );
+}
+
+SEC("?raw_tp")
+__success __log_level(2)
+__msg("topo_order[0] = diamond_c")
+__msg("topo_order[3] = topo_diamond")
+__naked int topo_diamond(void)
+{
+       asm volatile (
+               "call diamond_a;"
+               "call diamond_b;"
+               "exit;"
+       );
+}
+
+/* main -> global_a (global) -> static_leaf (static, leaf) */
+__naked __noinline __used
+static unsigned long static_leaf(void)
+{
+       asm volatile (
+               "r0 = 7;"
+               "exit;"
+       );
+}
+
+__noinline __used
+int global_a(int x)
+{
+       return static_leaf();
+}
+
+SEC("?raw_tp")
+__success __log_level(2)
+__msg("topo_order[0] = static_leaf")
+__msg("topo_order[1] = global_a")
+__msg("topo_order[2] = topo_mixed")
+__naked int topo_mixed(void)
+{
+       asm volatile (
+               "r1 = 0;"
+               "call global_a;"
+               "exit;"
+       );
+}
+
+/*
+ * shared static callee from global and main:
+ * main -> shared_leaf (static)
+ * main -> global_b (global) -> shared_leaf (static)
+ */
+__naked __noinline __used
+static unsigned long shared_leaf(void)
+{
+       asm volatile (
+               "r0 = 99;"
+               "exit;"
+       );
+}
+
+__noinline __used
+int global_b(int x)
+{
+       return shared_leaf();
+}
+
+SEC("?raw_tp")
+__success __log_level(2)
+__msg("topo_order[0] = shared_leaf")
+__msg("topo_order[1] = global_b")
+__msg("topo_order[2] = topo_shared")
+__naked int topo_shared(void)
+{
+       asm volatile (
+               "call shared_leaf;"
+               "r1 = 0;"
+               "call global_b;"
+               "exit;"
+       );
+}
+
+/* duplicate calls to the same subprog */
+__naked __noinline __used
+static unsigned long dup_leaf(void)
+{
+       asm volatile (
+               "r0 = 0;"
+               "exit;"
+       );
+}
+
+SEC("?raw_tp")
+__success __log_level(2)
+__msg("topo_order[0] = dup_leaf")
+__msg("topo_order[1] = topo_dup_calls")
+__naked int topo_dup_calls(void)
+{
+       asm volatile (
+               "call dup_leaf;"
+               "call dup_leaf;"
+               "exit;"
+       );
+}
+
+/* main calls bpf_loop() with loop_cb as the callback */
+static int loop_cb(int idx, void *ctx)
+{
+       return 0;
+}
+
+SEC("?raw_tp")
+__success __log_level(2)
+__msg("topo_order[0] = loop_cb")
+__msg("topo_order[1] = topo_loop_cb")
+int topo_loop_cb(void)
+{
+       bpf_loop(1, loop_cb, NULL, 0);
+       return 0;
+}
+
+/*
+ * bpf_loop callback calling another subprog
+ * main -> bpf_loop(callback=loop_cb2) -> loop_cb2 -> loop_cb2_leaf
+ */
+__naked __noinline __used
+static unsigned long loop_cb2_leaf(void)
+{
+       asm volatile (
+               "r0 = 0;"
+               "exit;"
+       );
+}
+
+static int loop_cb2(int idx, void *ctx)
+{
+       return loop_cb2_leaf();
+}
+
+SEC("?raw_tp")
+__success __log_level(2)
+__msg("topo_order[0] = loop_cb2_leaf")
+__msg("topo_order[1] = loop_cb2")
+__msg("topo_order[2] = topo_loop_cb_chain")
+int topo_loop_cb_chain(void)
+{
+       bpf_loop(1, loop_cb2, NULL, 0);
+       return 0;
+}
+
+/* no calls (single subprog) */
+SEC("?raw_tp")
+__success __log_level(2)
+__msg("topo_order[0] = topo_no_calls")
+__naked int topo_no_calls(void)
+{
+       asm volatile (
+               "r0 = 0;"
+               "exit;"
+       );
+}
+
+char _license[] SEC("license") = "GPL";