[PATCH bpf-next v1 12/14] selftests/bpf: Test Program Structure diagnostic context

Exercise each corrected Program Structure report. Place a missing-table gotox
after another instruction so its attribution differs from the subprogram
start, and assert that the recursive-call reason names both ends of the edge.

Add malformed subprogram layouts for a branch crossing a subprogram boundary
and a subprogram that falls through its end. Both cases carry BTF line records
and assert that their structured reports include the corresponding source
function and file.

Link: https://lore.kernel.org/bpf/cf2f420c2b21de440a7dc51b1565c0f06d4b539640ee5c03384e5d77bcfb5686@mail.kernel.org/
Signed-off-by: Kumar Kartikeya Dwivedi <[email protected]>
---
 .../selftests/bpf/progs/verifier_cfg.c        | 40 +++++++++++++++++++
 .../selftests/bpf/progs/verifier_gotox.c      |  2 +
 .../selftests/bpf/progs/verifier_loops1.c     |  1 +
 3 files changed, 43 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_cfg.c b/tools/testing/selftests/bpf/progs/verifier_cfg.c
index c1f55e1d80a4..4416d915cdf3 100644
--- a/tools/testing/selftests/bpf/progs/verifier_cfg.c
+++ b/tools/testing/selftests/bpf/progs/verifier_cfg.c
@@ -55,6 +55,46 @@ __naked void out_of_range_jump2(void)
 "	::: __clobber_all);
 }
 
+static __naked __noinline __used int cross_subprog_target(void)
+{
+	asm volatile ("					\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("socket")
+__description("jump across subprogram boundary")
+__failure __msg("jump out of range from insn 1")
+__msg("jump_across_subprog_boundary @ verifier_cfg.c")
+__naked void jump_across_subprog_boundary(void)
+{
+	asm volatile ("					\
+	call cross_subprog_target;			\
+	goto +1;					\
+	exit;						\
+"	::: __clobber_all);
+}
+
+static __naked __noinline __used int fallthrough_subprog(void)
+{
+	asm volatile ("					\
+	r0 = 0;						\
+"	::: __clobber_all);
+}
+
+SEC("socket")
+__description("subprogram fallthrough")
+__failure __msg("last insn is not an exit or jmp")
+__msg("fallthrough_subprog @ verifier_cfg.c")
+__naked void subprog_fallthrough(void)
+{
+	asm volatile ("					\
+	call fallthrough_subprog;			\
+	exit;						\
+"	::: __clobber_all);
+}
+
 SEC("socket")
 __description("loop (back-edge)")
 __failure __msg("unreachable insn 1")
diff --git a/tools/testing/selftests/bpf/progs/verifier_gotox.c b/tools/testing/selftests/bpf/progs/verifier_gotox.c
index 5b18c9a27717..a835a4871021 100644
--- a/tools/testing/selftests/bpf/progs/verifier_gotox.c
+++ b/tools/testing/selftests/bpf/progs/verifier_gotox.c
@@ -53,9 +53,11 @@ DEFINE_SIMPLE_JUMP_TABLE_PROG(reserved_field_non_zero_imm, BPF_REG_0, 0, 1, __fa
  */
 SEC("socket")
 __failure __msg("no jump tables found for subprog starting at 0")
+__msg(">>> 1 | (0d) gotox r0")
 __naked void jump_table_no_jump_table(void)
 {
 	asm volatile ("						\
+	r0 = 0;							\
 	.8byte %[gotox_r0];					\
 	r0 = 1;							\
 	exit;							\
diff --git a/tools/testing/selftests/bpf/progs/verifier_loops1.c b/tools/testing/selftests/bpf/progs/verifier_loops1.c
index d248ce877f14..d1ec19b7f66b 100644
--- a/tools/testing/selftests/bpf/progs/verifier_loops1.c
+++ b/tools/testing/selftests/bpf/progs/verifier_loops1.c
@@ -139,6 +139,7 @@ SEC("tracepoint")
 __description("bounded recursion")
 __failure
 __msg("recursive call from")
+__msg("The call from bounded_recursion__1() to bounded_recursion__1() would make")
 __naked void bounded_recursion(void)
 {
 	asm volatile ("					\
-- 
2.53.0