[PATCH bpf-next v6 2/2] selftests/bpf: Add trampolines single and multi-level pointer params test coverage

[Slava Imameev <slava.imameev@crowdstrike.com>]

Add single and multi-level pointer parameters and return value test
coverage for BPF trampolines. Includes verifier tests for single and
multi-level pointers. The tests check verifier logs for pointers
inferred as scalar() type.

Signed-off-by: Slava Imameev <slava.imameev@crowdstrike.com>
---
 net/bpf/test_run.c                            | 17 +++++
 .../selftests/bpf/prog_tests/verifier.c       |  2 +
 .../bpf/progs/verifier_ctx_ptr_param.c        | 68 +++++++++++++++++++
 3 files changed, 87 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/verifier_ctx_ptr_param.c

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 56bc8dc1e281..14c4814a7dab 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -567,6 +567,23 @@ noinline void bpf_fentry_test_sinfo(struct skb_shared_info *sinfo)
 {
 }
 
+noinline void bpf_fentry_test_ppvoid(void **pp)
+{
+}
+
+noinline void bpf_fentry_test_pppvoid(void ***ppp)
+{
+}
+
+noinline void bpf_fentry_test_ppfile(struct file **ppf)
+{
+}
+
+noinline struct file **bpf_fexit_test_ret_ppfile(void)
+{
+	return (struct file **)NULL;
+}
+
 __bpf_kfunc int bpf_modify_return_test(int a, int *b)
 {
 	*b += 1;
diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
index 8cdfd74c95d7..bcf01cb4cfe4 100644
--- a/tools/testing/selftests/bpf/prog_tests/verifier.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
@@ -115,6 +115,7 @@
 #include "verifier_lsm.skel.h"
 #include "verifier_jit_inline.skel.h"
 #include "irq.skel.h"
+#include "verifier_ctx_ptr_param.skel.h"
 
 #define MAX_ENTRIES 11
 
@@ -259,6 +260,7 @@ void test_verifier_lsm(void)                  { RUN(verifier_lsm); }
 void test_irq(void)			      { RUN(irq); }
 void test_verifier_mtu(void)		      { RUN(verifier_mtu); }
 void test_verifier_jit_inline(void)               { RUN(verifier_jit_inline); }
+void test_verifier_ctx_ptr_param(void)       { RUN(verifier_ctx_ptr_param); }
 
 static int init_test_val_map(struct bpf_object *obj, char *map_name)
 {
diff --git a/tools/testing/selftests/bpf/progs/verifier_ctx_ptr_param.c b/tools/testing/selftests/bpf/progs/verifier_ctx_ptr_param.c
new file mode 100644
index 000000000000..d5cc8fc01fe6
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/verifier_ctx_ptr_param.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Verifier tests for single- and multi-level pointer parameter handling
+ * Copyright (c) 2026 CrowdStrike, Inc.
+ */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+
+SEC("fentry/bpf_fentry_test_ppvoid")
+__description("fentry/void**: void ** inferred as scalar")
+__success __retval(0)
+__log_level(2)
+__msg("R1=ctx() R2=scalar()")
+__naked void fentry_ppvoid_as_scalar(void)
+{
+    asm volatile ("					\
+	r2 = *(u64 *)(r1 + 0);	\
+	r0 = 0;	\
+	exit;	\
+	" ::: __clobber_all);
+}
+
+SEC("fentry/bpf_fentry_test_pppvoid")
+__description("fentry/void***: void *** inferred as scalar")
+__success __retval(0)
+__log_level(2)
+__msg("R1=ctx() R2=scalar()")
+__naked void fentry_pppvoid_as_scalar(void)
+{
+    asm volatile ("					\
+	r2 = *(u64 *)(r1 + 0);	\
+	r0 = 0;	\
+	exit;	\
+	" ::: __clobber_all);
+}
+
+SEC("fentry/bpf_fentry_test_ppfile")
+__description("fentry/struct file**: struct file ** inferred as scalar")
+__success __retval(0)
+__log_level(2)
+__msg("R1=ctx() R2=scalar()")
+__naked void fentry_ppfile_as_scalar(void)
+{
+    asm volatile ("					\
+	r2 = *(u64 *)(r1 + 0);	\
+	r0 = 0;	\
+	exit;	\
+	" ::: __clobber_all);
+}
+
+SEC("fexit/bpf_fexit_test_ret_ppfile")
+__description("fexit/return struct file**: returned struct file ** inferred as scalar")
+__success __retval(0)
+__log_level(2)
+__msg("R1=ctx() R2=scalar()")
+__naked void fexit_ppfile_as_scalar(void)
+{
+    asm volatile ("					\
+	r2 = *(u64 *)(r1 + 0);	\
+	r0 = 0;	\
+	exit;	\
+	" ::: __clobber_all);
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.34.1