[PATCH bpf-next v3 0/3] Global subprogs in RCU/{preempt,irq}-disabled sections

[PATCH bpf-next v3 0/3] Global subprogs in RCU/{preempt,irq}-disabled sections

[Kumar Kartikeya Dwivedi]

Small change to allow non-sleepable global subprogs in
RCU, preempt-disabled, and irq-disabled sections. For
now, we don't lift the limitation for locks as it requires
more analysis, and will do this one resilient spin locks
land.

This surfaced a bug where sleepable global subprogs were
allowed in RCU read sections, that has been fixed. Tests
have been added to cover various cases.

Changelog:
----------
v2 -> v3
v2: https://lore.kernel.org/bpf/20250301030205.1221223-1-memxor@gmail.com

  * Fix broken to_be_replaced argument in the selftest.
  * Adjust selftest program type.

v1 -> v2
v1: https://lore.kernel.org/bpf/20250228162858.1073529-1-memxor@gmail.com

  * Rename subprog_info[i].sleepable to might_sleep, which more
    accurately reflects the nature of the bit. 'sleepable' means whether
    a given context is allowed to, while might_sleep captures if it
    does.
  * Disallow extensions that might sleep to attach to targets that don't
    sleep, since they'd be permitted to be called in atomic contexts. (Eduard)
  * Add tests for mixing non-sleepable and sleepable global function
    calls, and extensions attaching to non-sleepable global functions. (Eduard)
  * Rename changes_pkt_data -> summarization

Kumar Kartikeya Dwivedi (3):
  bpf: Summarize sleepable global subprogs
  selftests/bpf: Test sleepable global subprogs in atomic contexts
  selftests/bpf: Add tests for extending sleepable global subprogs

 include/linux/bpf.h                           |   1 +
 include/linux/bpf_verifier.h                  |   1 +
 kernel/bpf/verifier.c                         |  62 ++++++--
 .../bpf/prog_tests/changes_pkt_data.c         | 107 -------------
 .../selftests/bpf/prog_tests/rcu_read_lock.c  |   3 +
 .../selftests/bpf/prog_tests/spin_lock.c      |   3 +
 .../selftests/bpf/prog_tests/summarization.c  | 144 ++++++++++++++++++
 .../selftests/bpf/progs/changes_pkt_data.c    |  39 -----
 tools/testing/selftests/bpf/progs/irq.c       |  71 ++++++++-
 .../selftests/bpf/progs/preempt_lock.c        |  68 ++++++++-
 .../selftests/bpf/progs/rcu_read_lock.c       |  58 +++++++
 .../selftests/bpf/progs/summarization.c       |  78 ++++++++++
 ...ta_freplace.c => summarization_freplace.c} |  17 ++-
 .../selftests/bpf/progs/test_spin_lock_fail.c |  69 +++++++++
 14 files changed, 558 insertions(+), 163 deletions(-)
 delete mode 100644 tools/testing/selftests/bpf/prog_tests/changes_pkt_data.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/summarization.c
 delete mode 100644 tools/testing/selftests/bpf/progs/changes_pkt_data.c
 create mode 100644 tools/testing/selftests/bpf/progs/summarization.c
 rename tools/testing/selftests/bpf/progs/{changes_pkt_data_freplace.c => summarization_freplace.c} (57%)


base-commit: 0b9363131daf4227d5ae11ee677acdcfff06e938
-- 
2.43.5

[PATCH bpf-next v3 1/3] bpf: Summarize sleepable global subprogs

[Kumar Kartikeya Dwivedi]

The verifier currently does not permit global subprog calls when a lock
is held, preemption is disabled, or when IRQs are disabled. This is
because we don't know whether the global subprog calls sleepable
functions or not.

In case of locks, there's an additional reason: functions called by the
global subprog may hold additional locks etc. The verifier won't know
while verifying the global subprog whether it was called in context
where a spin lock is already held by the program.

Perform summarization of the sleepable nature of a global subprog just
like changes_pkt_data and then allow calls to global subprogs for
non-sleepable ones from atomic context.

While making this change, I noticed that RCU read sections had no
protection against sleepable global subprog calls, include it in the
checks and fix this while we're at it.

Care needs to be taken to not allow global subprog calls when regular
bpf_spin_lock is held. When resilient spin locks is held, we want to
potentially have this check relaxed, but not for now.

Also make sure extensions freplacing global functions cannot do so
in case the target is non-sleepable, but the extension is. The other
combination is ok.

Tests are included in the next patch to handle all special conditions.

Fixes: 9bb00b2895cb ("bpf: Add kfunc bpf_rcu_read_lock/unlock()")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 include/linux/bpf.h          |  1 +
 include/linux/bpf_verifier.h |  1 +
 kernel/bpf/verifier.c        | 62 ++++++++++++++++++++++++++++--------
 3 files changed, 50 insertions(+), 14 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index aec102868b93..4c4028d865ee 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1531,6 +1531,7 @@ struct bpf_prog_aux {
 	bool jits_use_priv_stack;
 	bool priv_stack_requested;
 	bool changes_pkt_data;
+	bool might_sleep;
 	u64 prog_array_member_cnt; /* counts how many times as member of prog_array */
 	struct mutex ext_mutex; /* mutex for is_extended and prog_array_member_cnt */
 	struct bpf_arena *arena;
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index bbd013c38ff9..d338f2a96bba 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -667,6 +667,7 @@ struct bpf_subprog_info {
 	/* true if bpf_fastcall stack region is used by functions that can't be inlined */
 	bool keep_fastcall_stack: 1;
 	bool changes_pkt_data: 1;
+	bool might_sleep: 1;
 
 	enum priv_stack_mode priv_stack_mode;
 	u8 arg_cnt;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index dcd0da4e62fc..eb1624f6e743 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10317,23 +10317,18 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 	if (subprog_is_global(env, subprog)) {
 		const char *sub_name = subprog_name(env, subprog);
 
-		/* Only global subprogs cannot be called with a lock held. */
 		if (env->cur_state->active_locks) {
 			verbose(env, "global function calls are not allowed while holding a lock,\n"
 				     "use static function instead\n");
 			return -EINVAL;
 		}
 
-		/* Only global subprogs cannot be called with preemption disabled. */
-		if (env->cur_state->active_preempt_locks) {
-			verbose(env, "global function calls are not allowed with preemption disabled,\n"
-				     "use static function instead\n");
-			return -EINVAL;
-		}
-
-		if (env->cur_state->active_irq_id) {
-			verbose(env, "global function calls are not allowed with IRQs disabled,\n"
-				     "use static function instead\n");
+		if (env->subprog_info[subprog].might_sleep &&
+		    (env->cur_state->active_rcu_lock || env->cur_state->active_preempt_locks ||
+		     env->cur_state->active_irq_id || !in_sleepable(env))) {
+			verbose(env, "global functions that may sleep are not allowed in non-sleepable context,\n"
+				     "i.e., in a RCU/IRQ/preempt-disabled section, or in\n"
+				     "a non-sleepable BPF program context\n");
 			return -EINVAL;
 		}
 
@@ -16703,6 +16698,14 @@ static void mark_subprog_changes_pkt_data(struct bpf_verifier_env *env, int off)
 	subprog->changes_pkt_data = true;
 }
 
+static void mark_subprog_might_sleep(struct bpf_verifier_env *env, int off)
+{
+	struct bpf_subprog_info *subprog;
+
+	subprog = find_containing_subprog(env, off);
+	subprog->might_sleep = true;
+}
+
 /* 't' is an index of a call-site.
  * 'w' is a callee entry point.
  * Eventually this function would be called when env->cfg.insn_state[w] == EXPLORED.
@@ -16716,6 +16719,7 @@ static void merge_callee_effects(struct bpf_verifier_env *env, int t, int w)
 	caller = find_containing_subprog(env, t);
 	callee = find_containing_subprog(env, w);
 	caller->changes_pkt_data |= callee->changes_pkt_data;
+	caller->might_sleep |= callee->might_sleep;
 }
 
 /* non-recursive DFS pseudo code
@@ -17183,9 +17187,20 @@ static int visit_insn(int t, struct bpf_verifier_env *env)
 			mark_prune_point(env, t);
 			mark_jmp_point(env, t);
 		}
-		if (bpf_helper_call(insn) && bpf_helper_changes_pkt_data(insn->imm))
-			mark_subprog_changes_pkt_data(env, t);
-		if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
+		if (bpf_helper_call(insn)) {
+			const struct bpf_func_proto *fp;
+
+			ret = get_helper_proto(env, insn->imm, &fp);
+			/* If called in a non-sleepable context program will be
+			 * rejected anyway, so we should end up with precise
+			 * sleepable marks on subprogs, except for dead code
+			 * elimination.
+			 */
+			if (ret == 0 && fp->might_sleep)
+				mark_subprog_might_sleep(env, t);
+			if (bpf_helper_changes_pkt_data(insn->imm))
+				mark_subprog_changes_pkt_data(env, t);
+		} else if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) {
 			struct bpf_kfunc_call_arg_meta meta;
 
 			ret = fetch_kfunc_meta(env, insn, &meta, NULL);
@@ -17204,6 +17219,13 @@ static int visit_insn(int t, struct bpf_verifier_env *env)
 				 */
 				mark_force_checkpoint(env, t);
 			}
+			/* Same as helpers, if called in a non-sleepable context
+			 * program will be rejected anyway, so we should end up
+			 * with precise sleepable marks on subprogs, except for
+			 * dead code elimination.
+			 */
+			if (ret == 0 && is_kfunc_sleepable(&meta))
+				mark_subprog_might_sleep(env, t);
 		}
 		return visit_func_call_insn(t, insns, env, insn->src_reg == BPF_PSEUDO_CALL);
 
@@ -17320,6 +17342,7 @@ static int check_cfg(struct bpf_verifier_env *env)
 	}
 	ret = 0; /* cfg looks good */
 	env->prog->aux->changes_pkt_data = env->subprog_info[0].changes_pkt_data;
+	env->prog->aux->might_sleep = env->subprog_info[0].might_sleep;
 
 err_free:
 	kvfree(insn_state);
@@ -20845,6 +20868,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
 		func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable;
 		func[i]->aux->exception_cb = env->subprog_info[i].is_exception_cb;
 		func[i]->aux->changes_pkt_data = env->subprog_info[i].changes_pkt_data;
+		func[i]->aux->might_sleep = env->subprog_info[i].might_sleep;
 		if (!i)
 			func[i]->aux->exception_boundary = env->seen_exception;
 		func[i] = bpf_int_jit_compile(func[i]);
@@ -22723,6 +22747,7 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 	if (tgt_prog) {
 		struct bpf_prog_aux *aux = tgt_prog->aux;
 		bool tgt_changes_pkt_data;
+		bool tgt_might_sleep;
 
 		if (bpf_prog_is_dev_bound(prog->aux) &&
 		    !bpf_prog_dev_bound_match(prog, tgt_prog)) {
@@ -22765,6 +22790,15 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 					"Extension program changes packet data, while original does not\n");
 				return -EINVAL;
 			}
+
+			tgt_might_sleep = aux->func
+					  ? aux->func[subprog]->aux->might_sleep
+					  : aux->might_sleep;
+			if (prog->aux->might_sleep && !tgt_might_sleep) {
+				bpf_log(log,
+					"Extension program may sleep, while original does not\n");
+				return -EINVAL;
+			}
 		}
 		if (!tgt_prog->jited) {
 			bpf_log(log, "Can attach to only JITed progs\n");
-- 
2.43.5

[PATCH bpf-next v3 2/3] selftests/bpf: Test sleepable global subprogs in atomic contexts

[Kumar Kartikeya Dwivedi]

Add tests for rejecting sleepable and accepting non-sleepable global
function calls in atomic contexts. For spin locks, we still reject
all global function calls. Once resilient spin locks land, we will
carefully lift in cases where we deem it safe.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 .../selftests/bpf/prog_tests/rcu_read_lock.c  |  3 +
 .../selftests/bpf/prog_tests/spin_lock.c      |  3 +
 tools/testing/selftests/bpf/progs/irq.c       | 71 ++++++++++++++++++-
 .../selftests/bpf/progs/preempt_lock.c        | 68 +++++++++++++++++-
 .../selftests/bpf/progs/rcu_read_lock.c       | 58 +++++++++++++++
 .../selftests/bpf/progs/test_spin_lock_fail.c | 69 ++++++++++++++++++
 6 files changed, 270 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c b/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c
index ebe0c12b5536..c9f855e5da24 100644
--- a/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c
+++ b/tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c
@@ -81,6 +81,9 @@ static const char * const inproper_region_tests[] = {
 	"nested_rcu_region",
 	"rcu_read_lock_global_subprog_lock",
 	"rcu_read_lock_global_subprog_unlock",
+	"rcu_read_lock_sleepable_helper_global_subprog",
+	"rcu_read_lock_sleepable_kfunc_global_subprog",
+	"rcu_read_lock_sleepable_global_subprog_indirect",
 };
 
 static void test_inproper_region(void)
diff --git a/tools/testing/selftests/bpf/prog_tests/spin_lock.c b/tools/testing/selftests/bpf/prog_tests/spin_lock.c
index 2b0068742ef9..e3ea5dc2f697 100644
--- a/tools/testing/selftests/bpf/prog_tests/spin_lock.c
+++ b/tools/testing/selftests/bpf/prog_tests/spin_lock.c
@@ -50,6 +50,9 @@ static struct {
 	{ "lock_id_mismatch_innermapval_mapval", "bpf_spin_unlock of different lock" },
 	{ "lock_global_subprog_call1", "global function calls are not allowed while holding a lock" },
 	{ "lock_global_subprog_call2", "global function calls are not allowed while holding a lock" },
+	{ "lock_global_sleepable_helper_subprog", "global function calls are not allowed while holding a lock" },
+	{ "lock_global_sleepable_kfunc_subprog", "global function calls are not allowed while holding a lock" },
+	{ "lock_global_sleepable_subprog_indirect", "global function calls are not allowed while holding a lock" },
 };
 
 static int match_regex(const char *pattern, const char *string)
diff --git a/tools/testing/selftests/bpf/progs/irq.c b/tools/testing/selftests/bpf/progs/irq.c
index b0b53d980964..298d48d7886d 100644
--- a/tools/testing/selftests/bpf/progs/irq.c
+++ b/tools/testing/selftests/bpf/progs/irq.c
@@ -222,7 +222,7 @@ int __noinline global_local_irq_balance(void)
 }
 
 SEC("?tc")
-__failure __msg("global function calls are not allowed with IRQs disabled")
+__success
 int irq_global_subprog(struct __sk_buff *ctx)
 {
 	unsigned long flags;
@@ -441,4 +441,73 @@ int irq_ooo_refs_array(struct __sk_buff *ctx)
 	return 0;
 }
 
+int __noinline
+global_subprog(int i)
+{
+	if (i)
+		bpf_printk("%p", &i);
+	return i;
+}
+
+int __noinline
+global_sleepable_helper_subprog(int i)
+{
+	if (i)
+		bpf_copy_from_user(&i, sizeof(i), NULL);
+	return i;
+}
+
+int __noinline
+global_sleepable_kfunc_subprog(int i)
+{
+	if (i)
+		bpf_copy_from_user_str(&i, sizeof(i), NULL, 0);
+	global_subprog(i);
+	return i;
+}
+
+int __noinline
+global_subprog_calling_sleepable_global(int i)
+{
+	if (!i)
+		global_sleepable_kfunc_subprog(i);
+	return i;
+}
+
+SEC("?syscall")
+__success
+int irq_non_sleepable_global_subprog(void *ctx)
+{
+	unsigned long flags;
+
+	bpf_local_irq_save(&flags);
+	global_subprog(0);
+	bpf_local_irq_restore(&flags);
+	return 0;
+}
+
+SEC("?syscall")
+__failure __msg("global functions that may sleep are not allowed in non-sleepable context")
+int irq_sleepable_helper_global_subprog(void *ctx)
+{
+	unsigned long flags;
+
+	bpf_local_irq_save(&flags);
+	global_sleepable_helper_subprog(0);
+	bpf_local_irq_restore(&flags);
+	return 0;
+}
+
+SEC("?syscall")
+__failure __msg("global functions that may sleep are not allowed in non-sleepable context")
+int irq_sleepable_global_subprog_indirect(void *ctx)
+{
+	unsigned long flags;
+
+	bpf_local_irq_save(&flags);
+	global_subprog_calling_sleepable_global(0);
+	bpf_local_irq_restore(&flags);
+	return 0;
+}
+
 char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/preempt_lock.c b/tools/testing/selftests/bpf/progs/preempt_lock.c
index 6c5797bf0ead..7d04254e61f1 100644
--- a/tools/testing/selftests/bpf/progs/preempt_lock.c
+++ b/tools/testing/selftests/bpf/progs/preempt_lock.c
@@ -134,7 +134,7 @@ int __noinline preempt_global_subprog(void)
 }
 
 SEC("?tc")
-__failure __msg("global function calls are not allowed with preemption disabled")
+__success
 int preempt_global_subprog_test(struct __sk_buff *ctx)
 {
 	preempt_disable();
@@ -143,4 +143,70 @@ int preempt_global_subprog_test(struct __sk_buff *ctx)
 	return 0;
 }
 
+int __noinline
+global_subprog(int i)
+{
+	if (i)
+		bpf_printk("%p", &i);
+	return i;
+}
+
+int __noinline
+global_sleepable_helper_subprog(int i)
+{
+	if (i)
+		bpf_copy_from_user(&i, sizeof(i), NULL);
+	return i;
+}
+
+int __noinline
+global_sleepable_kfunc_subprog(int i)
+{
+	if (i)
+		bpf_copy_from_user_str(&i, sizeof(i), NULL, 0);
+	global_subprog(i);
+	return i;
+}
+
+int __noinline
+global_subprog_calling_sleepable_global(int i)
+{
+	if (!i)
+		global_sleepable_kfunc_subprog(i);
+	return i;
+}
+
+SEC("?syscall")
+__failure __msg("global functions that may sleep are not allowed in non-sleepable context")
+int preempt_global_sleepable_helper_subprog(struct __sk_buff *ctx)
+{
+	preempt_disable();
+	if (ctx->mark)
+		global_sleepable_helper_subprog(ctx->mark);
+	preempt_enable();
+	return 0;
+}
+
+SEC("?syscall")
+__failure __msg("global functions that may sleep are not allowed in non-sleepable context")
+int preempt_global_sleepable_kfunc_subprog(struct __sk_buff *ctx)
+{
+	preempt_disable();
+	if (ctx->mark)
+		global_sleepable_kfunc_subprog(ctx->mark);
+	preempt_enable();
+	return 0;
+}
+
+SEC("?syscall")
+__failure __msg("global functions that may sleep are not allowed in non-sleepable context")
+int preempt_global_sleepable_subprog_indirect(struct __sk_buff *ctx)
+{
+	preempt_disable();
+	if (ctx->mark)
+		global_subprog_calling_sleepable_global(ctx->mark);
+	preempt_enable();
+	return 0;
+}
+
 char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/rcu_read_lock.c b/tools/testing/selftests/bpf/progs/rcu_read_lock.c
index ab3a532b7dd6..5cf1ae637ec7 100644
--- a/tools/testing/selftests/bpf/progs/rcu_read_lock.c
+++ b/tools/testing/selftests/bpf/progs/rcu_read_lock.c
@@ -439,3 +439,61 @@ int rcu_read_lock_global_subprog_unlock(void *ctx)
 	ret += global_subprog_unlock(ret);
 	return 0;
 }
+
+int __noinline
+global_sleepable_helper_subprog(int i)
+{
+	if (i)
+		bpf_copy_from_user(&i, sizeof(i), NULL);
+	return i;
+}
+
+int __noinline
+global_sleepable_kfunc_subprog(int i)
+{
+	if (i)
+		bpf_copy_from_user_str(&i, sizeof(i), NULL, 0);
+	global_subprog(i);
+	return i;
+}
+
+int __noinline
+global_subprog_calling_sleepable_global(int i)
+{
+	if (!i)
+		global_sleepable_kfunc_subprog(i);
+	return i;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int rcu_read_lock_sleepable_helper_global_subprog(void *ctx)
+{
+	volatile int ret = 0;
+
+	bpf_rcu_read_lock();
+	ret += global_sleepable_helper_subprog(ret);
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int rcu_read_lock_sleepable_kfunc_global_subprog(void *ctx)
+{
+	volatile int ret = 0;
+
+	bpf_rcu_read_lock();
+	ret += global_sleepable_kfunc_subprog(ret);
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int rcu_read_lock_sleepable_global_subprog_indirect(void *ctx)
+{
+	volatile int ret = 0;
+
+	bpf_rcu_read_lock();
+	ret += global_subprog_calling_sleepable_global(ret);
+	bpf_rcu_read_unlock();
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/test_spin_lock_fail.c b/tools/testing/selftests/bpf/progs/test_spin_lock_fail.c
index 1c8b678e2e9a..f678ee6bd7ea 100644
--- a/tools/testing/selftests/bpf/progs/test_spin_lock_fail.c
+++ b/tools/testing/selftests/bpf/progs/test_spin_lock_fail.c
@@ -245,4 +245,73 @@ int lock_global_subprog_call2(struct __sk_buff *ctx)
 	return ret;
 }
 
+int __noinline
+global_subprog_int(int i)
+{
+	if (i)
+		bpf_printk("%p", &i);
+	return i;
+}
+
+int __noinline
+global_sleepable_helper_subprog(int i)
+{
+	if (i)
+		bpf_copy_from_user(&i, sizeof(i), NULL);
+	return i;
+}
+
+int __noinline
+global_sleepable_kfunc_subprog(int i)
+{
+	if (i)
+		bpf_copy_from_user_str(&i, sizeof(i), NULL, 0);
+	global_subprog_int(i);
+	return i;
+}
+
+int __noinline
+global_subprog_calling_sleepable_global(int i)
+{
+	if (!i)
+		global_sleepable_kfunc_subprog(i);
+	return i;
+}
+
+SEC("?syscall")
+int lock_global_sleepable_helper_subprog(struct __sk_buff *ctx)
+{
+	int ret = 0;
+
+	bpf_spin_lock(&lockA);
+	if (ctx->mark == 42)
+		ret = global_sleepable_helper_subprog(ctx->mark);
+	bpf_spin_unlock(&lockA);
+	return ret;
+}
+
+SEC("?syscall")
+int lock_global_sleepable_kfunc_subprog(struct __sk_buff *ctx)
+{
+	int ret = 0;
+
+	bpf_spin_lock(&lockA);
+	if (ctx->mark == 42)
+		ret = global_sleepable_kfunc_subprog(ctx->mark);
+	bpf_spin_unlock(&lockA);
+	return ret;
+}
+
+SEC("?syscall")
+int lock_global_sleepable_subprog_indirect(struct __sk_buff *ctx)
+{
+	int ret = 0;
+
+	bpf_spin_lock(&lockA);
+	if (ctx->mark == 42)
+		ret = global_subprog_calling_sleepable_global(ctx->mark);
+	bpf_spin_unlock(&lockA);
+	return ret;
+}
+
 char _license[] SEC("license") = "GPL";
-- 
2.43.5

[PATCH bpf-next v3 3/3] selftests/bpf: Add tests for extending sleepable global subprogs

[Kumar Kartikeya Dwivedi]

Add tests for freplace behavior with the combination of sleepable
and non-sleepable global subprogs. The changes_pkt_data selftest
did all the hardwork, so simply rename it and include new support
for more summarization tests for might_sleep bit.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 .../bpf/prog_tests/changes_pkt_data.c         | 107 -------------
 .../selftests/bpf/prog_tests/summarization.c  | 144 ++++++++++++++++++
 .../selftests/bpf/progs/changes_pkt_data.c    |  39 -----
 .../selftests/bpf/progs/summarization.c       |  78 ++++++++++
 ...ta_freplace.c => summarization_freplace.c} |  17 ++-
 5 files changed, 238 insertions(+), 147 deletions(-)
 delete mode 100644 tools/testing/selftests/bpf/prog_tests/changes_pkt_data.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/summarization.c
 delete mode 100644 tools/testing/selftests/bpf/progs/changes_pkt_data.c
 create mode 100644 tools/testing/selftests/bpf/progs/summarization.c
 rename tools/testing/selftests/bpf/progs/{changes_pkt_data_freplace.c => summarization_freplace.c} (57%)

diff --git a/tools/testing/selftests/bpf/prog_tests/changes_pkt_data.c b/tools/testing/selftests/bpf/prog_tests/changes_pkt_data.c
deleted file mode 100644
index 7526de379081..000000000000
--- a/tools/testing/selftests/bpf/prog_tests/changes_pkt_data.c
+++ /dev/null
@@ -1,107 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include "bpf/libbpf.h"
-#include "changes_pkt_data_freplace.skel.h"
-#include "changes_pkt_data.skel.h"
-#include <test_progs.h>
-
-static void print_verifier_log(const char *log)
-{
-	if (env.verbosity >= VERBOSE_VERY)
-		fprintf(stdout, "VERIFIER LOG:\n=============\n%s=============\n", log);
-}
-
-static void test_aux(const char *main_prog_name,
-		     const char *to_be_replaced,
-		     const char *replacement,
-		     bool expect_load)
-{
-	struct changes_pkt_data_freplace *freplace = NULL;
-	struct bpf_program *freplace_prog = NULL;
-	struct bpf_program *main_prog = NULL;
-	LIBBPF_OPTS(bpf_object_open_opts, opts);
-	struct changes_pkt_data *main = NULL;
-	char log[16*1024];
-	int err;
-
-	opts.kernel_log_buf = log;
-	opts.kernel_log_size = sizeof(log);
-	if (env.verbosity >= VERBOSE_SUPER)
-		opts.kernel_log_level = 1 | 2 | 4;
-	main = changes_pkt_data__open_opts(&opts);
-	if (!ASSERT_OK_PTR(main, "changes_pkt_data__open"))
-		goto out;
-	main_prog = bpf_object__find_program_by_name(main->obj, main_prog_name);
-	if (!ASSERT_OK_PTR(main_prog, "main_prog"))
-		goto out;
-	bpf_program__set_autoload(main_prog, true);
-	err = changes_pkt_data__load(main);
-	print_verifier_log(log);
-	if (!ASSERT_OK(err, "changes_pkt_data__load"))
-		goto out;
-	freplace = changes_pkt_data_freplace__open_opts(&opts);
-	if (!ASSERT_OK_PTR(freplace, "changes_pkt_data_freplace__open"))
-		goto out;
-	freplace_prog = bpf_object__find_program_by_name(freplace->obj, replacement);
-	if (!ASSERT_OK_PTR(freplace_prog, "freplace_prog"))
-		goto out;
-	bpf_program__set_autoload(freplace_prog, true);
-	bpf_program__set_autoattach(freplace_prog, true);
-	bpf_program__set_attach_target(freplace_prog,
-				       bpf_program__fd(main_prog),
-				       to_be_replaced);
-	err = changes_pkt_data_freplace__load(freplace);
-	print_verifier_log(log);
-	if (expect_load) {
-		ASSERT_OK(err, "changes_pkt_data_freplace__load");
-	} else {
-		ASSERT_ERR(err, "changes_pkt_data_freplace__load");
-		ASSERT_HAS_SUBSTR(log, "Extension program changes packet data", "error log");
-	}
-
-out:
-	changes_pkt_data_freplace__destroy(freplace);
-	changes_pkt_data__destroy(main);
-}
-
-/* There are two global subprograms in both changes_pkt_data.skel.h:
- * - one changes packet data;
- * - another does not.
- * It is ok to freplace subprograms that change packet data with those
- * that either do or do not. It is only ok to freplace subprograms
- * that do not change packet data with those that do not as well.
- * The below tests check outcomes for each combination of such freplace.
- * Also test a case when main subprogram itself is replaced and is a single
- * subprogram in a program.
- */
-void test_changes_pkt_data_freplace(void)
-{
-	struct {
-		const char *main;
-		const char *to_be_replaced;
-		bool changes;
-	} mains[] = {
-		{ "main_with_subprogs",   "changes_pkt_data",         true },
-		{ "main_with_subprogs",   "does_not_change_pkt_data", false },
-		{ "main_changes",         "main_changes",             true },
-		{ "main_does_not_change", "main_does_not_change",     false },
-	};
-	struct {
-		const char *func;
-		bool changes;
-	} replacements[] = {
-		{ "changes_pkt_data",         true },
-		{ "does_not_change_pkt_data", false }
-	};
-	char buf[64];
-
-	for (int i = 0; i < ARRAY_SIZE(mains); ++i) {
-		for (int j = 0; j < ARRAY_SIZE(replacements); ++j) {
-			snprintf(buf, sizeof(buf), "%s_with_%s",
-				 mains[i].to_be_replaced, replacements[j].func);
-			if (!test__start_subtest(buf))
-				continue;
-			test_aux(mains[i].main, mains[i].to_be_replaced, replacements[j].func,
-				 mains[i].changes || !replacements[j].changes);
-		}
-	}
-}
diff --git a/tools/testing/selftests/bpf/prog_tests/summarization.c b/tools/testing/selftests/bpf/prog_tests/summarization.c
new file mode 100644
index 000000000000..5dd6c120a838
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/summarization.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "bpf/libbpf.h"
+#include "summarization_freplace.skel.h"
+#include "summarization.skel.h"
+#include <test_progs.h>
+
+static void print_verifier_log(const char *log)
+{
+	if (env.verbosity >= VERBOSE_VERY)
+		fprintf(stdout, "VERIFIER LOG:\n=============\n%s=============\n", log);
+}
+
+static void test_aux(const char *main_prog_name,
+		     const char *to_be_replaced,
+		     const char *replacement,
+		     bool expect_load,
+		     const char *err_msg)
+{
+	struct summarization_freplace *freplace = NULL;
+	struct bpf_program *freplace_prog = NULL;
+	struct bpf_program *main_prog = NULL;
+	LIBBPF_OPTS(bpf_object_open_opts, opts);
+	struct summarization *main = NULL;
+	char log[16*1024];
+	int err;
+
+	opts.kernel_log_buf = log;
+	opts.kernel_log_size = sizeof(log);
+	if (env.verbosity >= VERBOSE_SUPER)
+		opts.kernel_log_level = 1 | 2 | 4;
+	main = summarization__open_opts(&opts);
+	if (!ASSERT_OK_PTR(main, "summarization__open"))
+		goto out;
+	main_prog = bpf_object__find_program_by_name(main->obj, main_prog_name);
+	if (!ASSERT_OK_PTR(main_prog, "main_prog"))
+		goto out;
+	bpf_program__set_autoload(main_prog, true);
+	err = summarization__load(main);
+	print_verifier_log(log);
+	if (!ASSERT_OK(err, "summarization__load"))
+		goto out;
+	freplace = summarization_freplace__open_opts(&opts);
+	if (!ASSERT_OK_PTR(freplace, "summarization_freplace__open"))
+		goto out;
+	freplace_prog = bpf_object__find_program_by_name(freplace->obj, replacement);
+	if (!ASSERT_OK_PTR(freplace_prog, "freplace_prog"))
+		goto out;
+	bpf_program__set_autoload(freplace_prog, true);
+	bpf_program__set_autoattach(freplace_prog, true);
+	bpf_program__set_attach_target(freplace_prog,
+				       bpf_program__fd(main_prog),
+				       to_be_replaced);
+	err = summarization_freplace__load(freplace);
+	print_verifier_log(log);
+
+	/* The might_sleep extension doesn't work yet as sleepable calls are not
+	 * allowed, but preserve the check in case it's supported later and then
+	 * this particular combination can be enabled.
+	 */
+	if (!strcmp("might_sleep", replacement) && err) {
+		ASSERT_HAS_SUBSTR(log, "helper call might sleep in a non-sleepable prog", "error log");
+		ASSERT_EQ(err, -EINVAL, "err");
+		test__skip();
+		goto out;
+	}
+
+	if (expect_load) {
+		ASSERT_OK(err, "summarization_freplace__load");
+	} else {
+		ASSERT_ERR(err, "summarization_freplace__load");
+		ASSERT_HAS_SUBSTR(log, err_msg, "error log");
+	}
+
+out:
+	summarization_freplace__destroy(freplace);
+	summarization__destroy(main);
+}
+
+/* There are two global subprograms in both summarization.skel.h:
+ * - one changes packet data;
+ * - another does not.
+ * It is ok to freplace subprograms that change packet data with those
+ * that either do or do not. It is only ok to freplace subprograms
+ * that do not change packet data with those that do not as well.
+ * The below tests check outcomes for each combination of such freplace.
+ * Also test a case when main subprogram itself is replaced and is a single
+ * subprogram in a program.
+ *
+ * This holds for might_sleep programs. It is ok to replace might_sleep with
+ * might_sleep and with does_not_sleep, but does_not_sleep cannot be replaced
+ * with might_sleep.
+ */
+void test_summarization_freplace(void)
+{
+	struct {
+		const char *main;
+		const char *to_be_replaced;
+		bool has_side_effect;
+	} mains[2][4] = {
+		{
+			{ "main_changes_with_subprogs",		"changes_pkt_data",	    true },
+			{ "main_changes_with_subprogs",		"does_not_change_pkt_data", false },
+			{ "main_changes",			"main_changes",             true },
+			{ "main_does_not_change",		"main_does_not_change",     false },
+		},
+		{
+			{ "main_might_sleep_with_subprogs",	"might_sleep",		    true },
+			{ "main_might_sleep_with_subprogs",	"does_not_sleep",	    false },
+			{ "main_might_sleep",			"main_might_sleep",	    true },
+			{ "main_does_not_sleep",		"main_does_not_sleep",	    false },
+		},
+	};
+	const char *pkt_err = "Extension program changes packet data";
+	const char *slp_err = "Extension program may sleep";
+	struct {
+		const char *func;
+		bool has_side_effect;
+		const char *err_msg;
+	} replacements[2][2] = {
+		{
+			{ "changes_pkt_data",	      true,	pkt_err },
+			{ "does_not_change_pkt_data", false,	pkt_err },
+		},
+		{
+			{ "might_sleep",	      true,	slp_err },
+			{ "does_not_sleep",	      false,	slp_err },
+		},
+	};
+	char buf[64];
+
+	for (int t = 0; t < 2; t++) {
+		for (int i = 0; i < ARRAY_SIZE(mains); ++i) {
+			for (int j = 0; j < ARRAY_SIZE(replacements); ++j) {
+				snprintf(buf, sizeof(buf), "%s_with_%s",
+					 mains[t][i].to_be_replaced, replacements[t][j].func);
+				if (!test__start_subtest(buf))
+					continue;
+				test_aux(mains[t][i].main, mains[t][i].to_be_replaced, replacements[t][j].func,
+					 mains[t][i].has_side_effect || !replacements[t][j].has_side_effect,
+					 replacements[t][j].err_msg);
+			}
+		}
+	}
+}
diff --git a/tools/testing/selftests/bpf/progs/changes_pkt_data.c b/tools/testing/selftests/bpf/progs/changes_pkt_data.c
deleted file mode 100644
index 43cada48b28a..000000000000
--- a/tools/testing/selftests/bpf/progs/changes_pkt_data.c
+++ /dev/null
@@ -1,39 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-#include <linux/bpf.h>
-#include <bpf/bpf_helpers.h>
-
-__noinline
-long changes_pkt_data(struct __sk_buff *sk)
-{
-	return bpf_skb_pull_data(sk, 0);
-}
-
-__noinline __weak
-long does_not_change_pkt_data(struct __sk_buff *sk)
-{
-	return 0;
-}
-
-SEC("?tc")
-int main_with_subprogs(struct __sk_buff *sk)
-{
-	changes_pkt_data(sk);
-	does_not_change_pkt_data(sk);
-	return 0;
-}
-
-SEC("?tc")
-int main_changes(struct __sk_buff *sk)
-{
-	bpf_skb_pull_data(sk, 0);
-	return 0;
-}
-
-SEC("?tc")
-int main_does_not_change(struct __sk_buff *sk)
-{
-	return 0;
-}
-
-char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/summarization.c b/tools/testing/selftests/bpf/progs/summarization.c
new file mode 100644
index 000000000000..f89effe82c9e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/summarization.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+__noinline
+long changes_pkt_data(struct __sk_buff *sk)
+{
+	return bpf_skb_pull_data(sk, 0);
+}
+
+__noinline __weak
+long does_not_change_pkt_data(struct __sk_buff *sk)
+{
+	return 0;
+}
+
+SEC("?tc")
+int main_changes_with_subprogs(struct __sk_buff *sk)
+{
+	changes_pkt_data(sk);
+	does_not_change_pkt_data(sk);
+	return 0;
+}
+
+SEC("?tc")
+int main_changes(struct __sk_buff *sk)
+{
+	bpf_skb_pull_data(sk, 0);
+	return 0;
+}
+
+SEC("?tc")
+int main_does_not_change(struct __sk_buff *sk)
+{
+	return 0;
+}
+
+__noinline
+long might_sleep(struct pt_regs *ctx __arg_ctx)
+{
+	int i;
+
+	bpf_copy_from_user(&i, sizeof(i), NULL);
+	return i;
+}
+
+__noinline __weak
+long does_not_sleep(struct pt_regs *ctx __arg_ctx)
+{
+	return 0;
+}
+
+SEC("?uprobe.s")
+int main_might_sleep_with_subprogs(struct pt_regs *ctx)
+{
+	might_sleep(ctx);
+	does_not_sleep(ctx);
+	return 0;
+}
+
+SEC("?uprobe.s")
+int main_might_sleep(struct pt_regs *ctx)
+{
+	int i;
+
+	bpf_copy_from_user(&i, sizeof(i), NULL);
+	return i;
+}
+
+SEC("?uprobe.s")
+int main_does_not_sleep(struct pt_regs *ctx)
+{
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/changes_pkt_data_freplace.c b/tools/testing/selftests/bpf/progs/summarization_freplace.c
similarity index 57%
rename from tools/testing/selftests/bpf/progs/changes_pkt_data_freplace.c
rename to tools/testing/selftests/bpf/progs/summarization_freplace.c
index f9a622705f1b..935f00e0e9ea 100644
--- a/tools/testing/selftests/bpf/progs/changes_pkt_data_freplace.c
+++ b/tools/testing/selftests/bpf/progs/summarization_freplace.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
-#include <linux/bpf.h>
+#include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
 
 SEC("?freplace")
@@ -15,4 +15,19 @@ long does_not_change_pkt_data(struct __sk_buff *sk)
 	return 0;
 }
 
+SEC("?freplace")
+long might_sleep(struct pt_regs *ctx)
+{
+	int i;
+
+	bpf_copy_from_user(&i, sizeof(i), NULL);
+	return i;
+}
+
+SEC("?freplace")
+long does_not_sleep(struct pt_regs *ctx)
+{
+	return 0;
+}
+
 char _license[] SEC("license") = "GPL";
-- 
2.43.5

Re: [PATCH bpf-next v3 0/3] Global subprogs in RCU/{preempt,irq}-disabled sections

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Sat,  1 Mar 2025 07:18:43 -0800 you wrote:
> Small change to allow non-sleepable global subprogs in
> RCU, preempt-disabled, and irq-disabled sections. For
> now, we don't lift the limitation for locks as it requires
> more analysis, and will do this one resilient spin locks
> land.
> 
> This surfaced a bug where sleepable global subprogs were
> allowed in RCU read sections, that has been fixed. Tests
> have been added to cover various cases.
> 
> [...]

Here is the summary with links:
  - [bpf-next,v3,1/3] bpf: Summarize sleepable global subprogs
    https://git.kernel.org/bpf/bpf-next/c/90d8c8980b5c
  - [bpf-next,v3,2/3] selftests/bpf: Test sleepable global subprogs in atomic contexts
    https://git.kernel.org/bpf/bpf-next/c/6e2cc6067e73
  - [bpf-next,v3,3/3] selftests/bpf: Add tests for extending sleepable global subprogs
    https://git.kernel.org/bpf/bpf-next/c/ce9add7b9028

You are awesome, thank you!
-- 
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