[PATCH bpf-next v11 03/12] bpf: change prototype of bpf_session_{cookie,is_return}

From: Menglong Dong <hidden>
Date: 2026-01-23 07:36:09
Also in: bpf, lkml
Subsystem: bpf [core], bpf [general] (safe dynamic programs and tools), bpf [security & lsm] (security audit and enforcement using bpf), bpf [selftests] (test runners & infrastructure), bpf [tracing], kernel selftest framework, the rest, tracing · Maintainers: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, KP Singh, Matt Bobrowski, Song Liu, Shuah Khan, Linus Torvalds, Steven Rostedt, Masami Hiramatsu

Add the function argument of "void *ctx" to bpf_session_cookie() and
bpf_session_is_return(), which is a preparation of the next patch.

The two kfunc is seldom used now, so it will not introduce much effect
to change their function prototype.

Signed-off-by: Menglong Dong <redacted>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
v10:
- drop the declaration of bpf_session_is_return() and bpf_session_cookie()
---
 kernel/bpf/verifier.c                             |  6 +++++-
 kernel/trace/bpf_trace.c                          |  4 ++--
 tools/testing/selftests/bpf/bpf_kfuncs.h          |  3 ---
 .../bpf/progs/kprobe_multi_session_cookie.c       | 15 +++++++--------
 .../selftests/bpf/progs/uprobe_multi_session.c    |  7 +++----
 .../bpf/progs/uprobe_multi_session_cookie.c       | 15 +++++++--------
 .../bpf/progs/uprobe_multi_session_recursive.c    | 11 +++++------
 7 files changed, 29 insertions(+), 32 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b3f912ad18ba..19fd16697262 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c

@@ -12484,6 +12484,7 @@ enum special_kfunc_type {
 	KF_bpf_arena_alloc_pages,
 	KF_bpf_arena_free_pages,
 	KF_bpf_arena_reserve_pages,
+	KF_bpf_session_is_return,
 };
 
 BTF_ID_LIST(special_kfunc_list)

@@ -12561,6 +12562,7 @@ BTF_ID(func, bpf_task_work_schedule_resume)
 BTF_ID(func, bpf_arena_alloc_pages)
 BTF_ID(func, bpf_arena_free_pages)
 BTF_ID(func, bpf_arena_reserve_pages)
+BTF_ID(func, bpf_session_is_return)
 
 static bool is_task_work_add_kfunc(u32 func_id)
 {

@@ -12615,7 +12617,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
 	struct bpf_reg_state *reg = &regs[regno];
 	bool arg_mem_size = false;
 
-	if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx])
+	if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx] ||
+	    meta->func_id == special_kfunc_list[KF_bpf_session_is_return] ||
+	    meta->func_id == special_kfunc_list[KF_bpf_session_cookie])
 		return KF_ARG_PTR_TO_CTX;
 
 	if (argno + 1 < nargs &&

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d466a1503da3..13f0a2de33b7 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c

@@ -3323,7 +3323,7 @@ static u64 bpf_uprobe_multi_entry_ip(struct bpf_run_ctx *ctx)
 
 __bpf_kfunc_start_defs();
 
-__bpf_kfunc bool bpf_session_is_return(void)
+__bpf_kfunc bool bpf_session_is_return(void *ctx)
 {
 	struct bpf_session_run_ctx *session_ctx;

@@ -3331,7 +3331,7 @@ __bpf_kfunc bool bpf_session_is_return(void)
 	return session_ctx->is_return;
 }
 
-__bpf_kfunc __u64 *bpf_session_cookie(void)
+__bpf_kfunc __u64 *bpf_session_cookie(void *ctx)
 {
 	struct bpf_session_run_ctx *session_ctx;

diff --git a/tools/testing/selftests/bpf/bpf_kfuncs.h b/tools/testing/selftests/bpf/bpf_kfuncs.h
index e0189254bb6e..7dad01439391 100644
--- a/tools/testing/selftests/bpf/bpf_kfuncs.h
+++ b/tools/testing/selftests/bpf/bpf_kfuncs.h

@@ -79,9 +79,6 @@ extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,
 				      struct bpf_dynptr *sig_ptr,
 				      struct bpf_key *trusted_keyring) __ksym;
 
-extern bool bpf_session_is_return(void) __ksym __weak;
-extern __u64 *bpf_session_cookie(void) __ksym __weak;
-
 struct dentry;
 /* Description
  *  Returns xattr of a dentry

diff --git a/tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c b/tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c
index 0835b5edf685..ad627016e3e5 100644
--- a/tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c
+++ b/tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c

@@ -1,9 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/bpf.h>
+#include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 #include <stdbool.h>
-#include "bpf_kfuncs.h"
 
 char _license[] SEC("license") = "GPL";

@@ -23,16 +22,16 @@ int BPF_PROG(trigger)
 	return 0;
 }
 
-static int check_cookie(__u64 val, __u64 *result)
+static int check_cookie(struct pt_regs *ctx, __u64 val, __u64 *result)
 {
 	__u64 *cookie;
 
 	if (bpf_get_current_pid_tgid() >> 32 != pid)
 		return 1;
 
-	cookie = bpf_session_cookie();
+	cookie = bpf_session_cookie(ctx);
 
-	if (bpf_session_is_return())
+	if (bpf_session_is_return(ctx))
 		*result = *cookie == val ? val : 0;
 	else
 		*cookie = val;

@@ -42,17 +41,17 @@ static int check_cookie(__u64 val, __u64 *result)
 SEC("kprobe.session/bpf_fentry_test1")
 int test_kprobe_1(struct pt_regs *ctx)
 {
-	return check_cookie(1, &test_kprobe_1_result);
+	return check_cookie(ctx, 1, &test_kprobe_1_result);
 }
 
 SEC("kprobe.session/bpf_fentry_test1")
 int test_kprobe_2(struct pt_regs *ctx)
 {
-	return check_cookie(2, &test_kprobe_2_result);
+	return check_cookie(ctx, 2, &test_kprobe_2_result);
 }
 
 SEC("kprobe.session/bpf_fentry_test1")
 int test_kprobe_3(struct pt_regs *ctx)
 {
-	return check_cookie(3, &test_kprobe_3_result);
+	return check_cookie(ctx, 3, &test_kprobe_3_result);
 }

diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi_session.c b/tools/testing/selftests/bpf/progs/uprobe_multi_session.c
index 30bff90b68dc..6e46bb00ff58 100644
--- a/tools/testing/selftests/bpf/progs/uprobe_multi_session.c
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi_session.c

@@ -1,9 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/bpf.h>
+#include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 #include <stdbool.h>
-#include "bpf_kfuncs.h"
 #include "bpf_misc.h"
 
 char _license[] SEC("license") = "GPL";

@@ -51,7 +50,7 @@ static int uprobe_multi_check(void *ctx, bool is_return)
 SEC("uprobe.session//proc/self/exe:uprobe_multi_func_*")
 int uprobe(struct pt_regs *ctx)
 {
-	return uprobe_multi_check(ctx, bpf_session_is_return());
+	return uprobe_multi_check(ctx, bpf_session_is_return(ctx));
 }
 
 static __always_inline bool verify_sleepable_user_copy(void)

@@ -67,5 +66,5 @@ int uprobe_sleepable(struct pt_regs *ctx)
 {
 	if (verify_sleepable_user_copy())
 		uprobe_multi_sleep_result++;
-	return uprobe_multi_check(ctx, bpf_session_is_return());
+	return uprobe_multi_check(ctx, bpf_session_is_return(ctx));
 }

diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi_session_cookie.c b/tools/testing/selftests/bpf/progs/uprobe_multi_session_cookie.c
index 5befdf944dc6..b5db196614a9 100644
--- a/tools/testing/selftests/bpf/progs/uprobe_multi_session_cookie.c
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi_session_cookie.c

@@ -1,9 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/bpf.h>
+#include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 #include <stdbool.h>
-#include "bpf_kfuncs.h"
 
 char _license[] SEC("license") = "GPL";

@@ -13,16 +12,16 @@ __u64 test_uprobe_1_result = 0;
 __u64 test_uprobe_2_result = 0;
 __u64 test_uprobe_3_result = 0;
 
-static int check_cookie(__u64 val, __u64 *result)
+static int check_cookie(struct pt_regs *ctx, __u64 val, __u64 *result)
 {
 	__u64 *cookie;
 
 	if (bpf_get_current_pid_tgid() >> 32 != pid)
 		return 1;
 
-	cookie = bpf_session_cookie();
+	cookie = bpf_session_cookie(ctx);
 
-	if (bpf_session_is_return())
+	if (bpf_session_is_return(ctx))
 		*result = *cookie == val ? val : 0;
 	else
 		*cookie = val;

@@ -32,17 +31,17 @@ static int check_cookie(__u64 val, __u64 *result)
 SEC("uprobe.session//proc/self/exe:uprobe_multi_func_1")
 int uprobe_1(struct pt_regs *ctx)
 {
-	return check_cookie(1, &test_uprobe_1_result);
+	return check_cookie(ctx, 1, &test_uprobe_1_result);
 }
 
 SEC("uprobe.session//proc/self/exe:uprobe_multi_func_2")
 int uprobe_2(struct pt_regs *ctx)
 {
-	return check_cookie(2, &test_uprobe_2_result);
+	return check_cookie(ctx, 2, &test_uprobe_2_result);
 }
 
 SEC("uprobe.session//proc/self/exe:uprobe_multi_func_3")
 int uprobe_3(struct pt_regs *ctx)
 {
-	return check_cookie(3, &test_uprobe_3_result);
+	return check_cookie(ctx, 3, &test_uprobe_3_result);
 }

diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c b/tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c
index 8fbcd69fae22..3ce309248a04 100644
--- a/tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c

@@ -1,9 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/bpf.h>
+#include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 #include <stdbool.h>
-#include "bpf_kfuncs.h"
 #include "bpf_misc.h"
 
 char _license[] SEC("license") = "GPL";

@@ -16,11 +15,11 @@ int idx_return = 0;
 __u64 test_uprobe_cookie_entry[6];
 __u64 test_uprobe_cookie_return[3];
 
-static int check_cookie(void)
+static int check_cookie(struct pt_regs *ctx)
 {
-	__u64 *cookie = bpf_session_cookie();
+	__u64 *cookie = bpf_session_cookie(ctx);
 
-	if (bpf_session_is_return()) {
+	if (bpf_session_is_return(ctx)) {
 		if (idx_return >= ARRAY_SIZE(test_uprobe_cookie_return))
 			return 1;
 		test_uprobe_cookie_return[idx_return++] = *cookie;

@@ -40,5 +39,5 @@ int uprobe_recursive(struct pt_regs *ctx)
 	if (bpf_get_current_pid_tgid() >> 32 != pid)
 		return 1;
 
-	return check_cookie();
+	return check_cookie(ctx);
 }

-- 
2.52.0

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