Merge branch 'bpf-global-funcs'

Alexei Starovoitov says:

====================
Introduce static vs global functions and function by function verification.
This is another step toward dynamic re-linking (or replacement) of global
functions. See patch 2 for details.

v2->v3:
- cleaned up a check spotted by Song.
- rebased and dropped patch 2 that was trying to improve BTF based on ELF.
- added one more unit test for scalar return value from global func.

v1->v2:
- addressed review comments from Song, Andrii, Yonghong
- fixed memory leak in error path
- added modified ctx check
- added more tests in patch 7
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

include/linux/bpf.h

@@ -566,6 +566,7 @@ static inline void bpf_dispatcher_change_prog(struct bpf_dispatcher *d,
 #endif
 
 struct bpf_func_info_aux {
+	u16 linkage;
 	bool unreliable;
 };
 
@@ -1081,7 +1082,11 @@ int btf_distill_func_proto(struct bpf_verifier_log *log,
 			   const char *func_name,
 			   struct btf_func_model *m);
 
-int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog);
+struct bpf_reg_state;
+int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
+			     struct bpf_reg_state *regs);
+int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
+			  struct bpf_reg_state *reg);
 
 struct bpf_prog *bpf_prog_by_id(u32 id);
 

include/linux/bpf_verifier.h

@@ -304,11 +304,13 @@ struct bpf_insn_aux_data {
 	u64 map_key_state; /* constant (32 bit) key tracking for maps */
 	int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
 	int sanitize_stack_off; /* stack slot to be cleared */
-	bool seen; /* this insn was processed by the verifier */
+	u32 seen; /* this insn was processed by the verifier at env->pass_cnt */
 	bool zext_dst; /* this insn zero extends dst reg */
 	u8 alu_state; /* used in combination with alu_limit */
-	bool prune_point;
+
+	/* below fields are initialized once */
 	unsigned int orig_idx; /* original instruction index */
+	bool prune_point;
 };
 
 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
@@ -379,6 +381,7 @@ struct bpf_verifier_env {
 		int *insn_stack;
 		int cur_stack;
 	} cfg;
+	u32 pass_cnt; /* number of times do_check() was called */
 	u32 subprog_cnt;
 	/* number of instructions analyzed by the verifier */
 	u32 prev_insn_processed, insn_processed;
@@ -428,4 +431,7 @@ bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
 void
 bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);
 
+int check_ctx_reg(struct bpf_verifier_env *env,
+		  const struct bpf_reg_state *reg, int regno);
+
 #endif /* _LINUX_BPF_VERIFIER_H */

include/uapi/linux/btf.h

@@ -146,6 +146,12 @@ enum {
 	BTF_VAR_GLOBAL_EXTERN = 2,
 };
 
+enum btf_func_linkage {
+	BTF_FUNC_STATIC = 0,
+	BTF_FUNC_GLOBAL = 1,
+	BTF_FUNC_EXTERN = 2,
+};
+
 /* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
  * additional information related to the variable such as its linkage.
  */

kernel/bpf/btf.c

@@ -2651,8 +2651,8 @@ static s32 btf_func_check_meta(struct btf_verifier_env *env,
 		return -EINVAL;
 	}
 
-	if (btf_type_vlen(t)) {
-		btf_verifier_log_type(env, t, "vlen != 0");
+	if (btf_type_vlen(t) > BTF_FUNC_GLOBAL) {
+		btf_verifier_log_type(env, t, "Invalid func linkage");
 		return -EINVAL;
 	}
 
@@ -3506,7 +3506,8 @@ static u8 bpf_ctx_convert_map[] = {
 
 static const struct btf_member *
 btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,
-		      const struct btf_type *t, enum bpf_prog_type prog_type)
+		      const struct btf_type *t, enum bpf_prog_type prog_type,
+		      int arg)
 {
 	const struct btf_type *conv_struct;
 	const struct btf_type *ctx_struct;
@@ -3527,12 +3528,13 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,
 		 * is not supported yet.
 		 * BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
 		 */
-		bpf_log(log, "BPF program ctx type is not a struct\n");
+		if (log->level & BPF_LOG_LEVEL)
+			bpf_log(log, "arg#%d type is not a struct\n", arg);
 		return NULL;
 	}
 	tname = btf_name_by_offset(btf, t->name_off);
 	if (!tname) {
-		bpf_log(log, "BPF program ctx struct doesn't have a name\n");
+		bpf_log(log, "arg#%d struct doesn't have a name\n", arg);
 		return NULL;
 	}
 	/* prog_type is valid bpf program type. No need for bounds check. */
@@ -3565,11 +3567,12 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,
 static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
 				     struct btf *btf,
 				     const struct btf_type *t,
-				     enum bpf_prog_type prog_type)
+				     enum bpf_prog_type prog_type,
+				     int arg)
 {
 	const struct btf_member *prog_ctx_type, *kern_ctx_type;
 
-	prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type);
+	prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type, arg);
 	if (!prog_ctx_type)
 		return -ENOENT;
 	kern_ctx_type = prog_ctx_type + 1;
@@ -3731,7 +3734,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
 	info->reg_type = PTR_TO_BTF_ID;
 
 	if (tgt_prog) {
-		ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type);
+		ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type, arg);
 		if (ret > 0) {
 			info->btf_id = ret;
 			return true;
@@ -4112,11 +4115,16 @@ int btf_distill_func_proto(struct bpf_verifier_log *log,
 	return 0;
 }
 
-int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog)
+/* Compare BTF of a function with given bpf_reg_state.
+ * Returns:
+ * EFAULT - there is a verifier bug. Abort verification.
+ * EINVAL - there is a type mismatch or BTF is not available.
+ * 0 - BTF matches with what bpf_reg_state expects.
+ * Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
+ */
+int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
+			     struct bpf_reg_state *reg)
 {
-	struct bpf_verifier_state *st = env->cur_state;
-	struct bpf_func_state *func = st->frame[st->curframe];
-	struct bpf_reg_state *reg = func->regs;
 	struct bpf_verifier_log *log = &env->log;
 	struct bpf_prog *prog = env->prog;
 	struct btf *btf = prog->aux->btf;
@@ -4126,27 +4134,30 @@ int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog)
 	const char *tname;
 
 	if (!prog->aux->func_info)
-		return 0;
+		return -EINVAL;
 
 	btf_id = prog->aux->func_info[subprog].type_id;
 	if (!btf_id)
-		return 0;
+		return -EFAULT;
 
 	if (prog->aux->func_info_aux[subprog].unreliable)
-		return 0;
+		return -EINVAL;
 
 	t = btf_type_by_id(btf, btf_id);
 	if (!t || !btf_type_is_func(t)) {
-		bpf_log(log, "BTF of subprog %d doesn't point to KIND_FUNC\n",
+		/* These checks were already done by the verifier while loading
+		 * struct bpf_func_info
+		 */
+		bpf_log(log, "BTF of func#%d doesn't point to KIND_FUNC\n",
 			subprog);
-		return -EINVAL;
+		return -EFAULT;
 	}
 	tname = btf_name_by_offset(btf, t->name_off);
 
 	t = btf_type_by_id(btf, t->type);
 	if (!t || !btf_type_is_func_proto(t)) {
-		bpf_log(log, "Invalid type of func %s\n", tname);
-		return -EINVAL;
+		bpf_log(log, "Invalid BTF of func %s\n", tname);
+		return -EFAULT;
 	}
 	args = (const struct btf_param *)(t + 1);
 	nargs = btf_type_vlen(t);
@@ -4172,25 +4183,127 @@ int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog)
 				bpf_log(log, "R%d is not a pointer\n", i + 1);
 				goto out;
 			}
-			/* If program is passing PTR_TO_CTX into subprogram
-			 * check that BTF type matches.
+			/* If function expects ctx type in BTF check that caller
+			 * is passing PTR_TO_CTX.
 			 */
-			if (reg[i + 1].type == PTR_TO_CTX &&
-			    !btf_get_prog_ctx_type(log, btf, t, prog->type))
+			if (btf_get_prog_ctx_type(log, btf, t, prog->type, i)) {
+				if (reg[i + 1].type != PTR_TO_CTX) {
+					bpf_log(log,
+						"arg#%d expected pointer to ctx, but got %s\n",
+						i, btf_kind_str[BTF_INFO_KIND(t->info)]);
+					goto out;
+				}
+				if (check_ctx_reg(env, &reg[i + 1], i + 1))
 					goto out;
-			/* All other pointers are ok */
 				continue;
 			}
-		bpf_log(log, "Unrecognized argument type %s\n",
-			btf_kind_str[BTF_INFO_KIND(t->info)]);
+		}
+		bpf_log(log, "Unrecognized arg#%d type %s\n",
+			i, btf_kind_str[BTF_INFO_KIND(t->info)]);
 		goto out;
 	}
 	return 0;
 out:
-	/* LLVM optimizations can remove arguments from static functions. */
-	bpf_log(log,
-		"Type info disagrees with actual arguments due to compiler optimizations\n");
+	/* Compiler optimizations can remove arguments from static functions
+	 * or mismatched type can be passed into a global function.
+	 * In such cases mark the function as unreliable from BTF point of view.
+	 */
 	prog->aux->func_info_aux[subprog].unreliable = true;
+	return -EINVAL;
+}
+
+/* Convert BTF of a function into bpf_reg_state if possible
+ * Returns:
+ * EFAULT - there is a verifier bug. Abort verification.
+ * EINVAL - cannot convert BTF.
+ * 0 - Successfully converted BTF into bpf_reg_state
+ * (either PTR_TO_CTX or SCALAR_VALUE).
+ */
+int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
+			  struct bpf_reg_state *reg)
+{
+	struct bpf_verifier_log *log = &env->log;
+	struct bpf_prog *prog = env->prog;
+	struct btf *btf = prog->aux->btf;
+	const struct btf_param *args;
+	const struct btf_type *t;
+	u32 i, nargs, btf_id;
+	const char *tname;
+
+	if (!prog->aux->func_info ||
+	    prog->aux->func_info_aux[subprog].linkage != BTF_FUNC_GLOBAL) {
+		bpf_log(log, "Verifier bug\n");
+		return -EFAULT;
+	}
+
+	btf_id = prog->aux->func_info[subprog].type_id;
+	if (!btf_id) {
+		bpf_log(log, "Global functions need valid BTF\n");
+		return -EFAULT;
+	}
+
+	t = btf_type_by_id(btf, btf_id);
+	if (!t || !btf_type_is_func(t)) {
+		/* These checks were already done by the verifier while loading
+		 * struct bpf_func_info
+		 */
+		bpf_log(log, "BTF of func#%d doesn't point to KIND_FUNC\n",
+			subprog);
+		return -EFAULT;
+	}
+	tname = btf_name_by_offset(btf, t->name_off);
+
+	if (log->level & BPF_LOG_LEVEL)
+		bpf_log(log, "Validating %s() func#%d...\n",
+			tname, subprog);
+
+	if (prog->aux->func_info_aux[subprog].unreliable) {
+		bpf_log(log, "Verifier bug in function %s()\n", tname);
+		return -EFAULT;
+	}
+
+	t = btf_type_by_id(btf, t->type);
+	if (!t || !btf_type_is_func_proto(t)) {
+		bpf_log(log, "Invalid type of function %s()\n", tname);
+		return -EFAULT;
+	}
+	args = (const struct btf_param *)(t + 1);
+	nargs = btf_type_vlen(t);
+	if (nargs > 5) {
+		bpf_log(log, "Global function %s() with %d > 5 args. Buggy compiler.\n",
+			tname, nargs);
+		return -EINVAL;
+	}
+	/* check that function returns int */
+	t = btf_type_by_id(btf, t->type);
+	while (btf_type_is_modifier(t))
+		t = btf_type_by_id(btf, t->type);
+	if (!btf_type_is_int(t) && !btf_type_is_enum(t)) {
+		bpf_log(log,
+			"Global function %s() doesn't return scalar. Only those are supported.\n",
+			tname);
+		return -EINVAL;
+	}
+	/* Convert BTF function arguments into verifier types.
+	 * Only PTR_TO_CTX and SCALAR are supported atm.
+	 */
+	for (i = 0; i < nargs; i++) {
+		t = btf_type_by_id(btf, args[i].type);
+		while (btf_type_is_modifier(t))
+			t = btf_type_by_id(btf, t->type);
+		if (btf_type_is_int(t) || btf_type_is_enum(t)) {
+			reg[i + 1].type = SCALAR_VALUE;
+			continue;
+		}
+		if (btf_type_is_ptr(t) &&
+		    btf_get_prog_ctx_type(log, btf, t, prog->type, i)) {
+			reg[i + 1].type = PTR_TO_CTX;
+			continue;
+		}
+		bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n",
+			i, btf_kind_str[BTF_INFO_KIND(t->info)], tname);
+		return -EINVAL;
+	}
 	return 0;
 }
 

tools/include/uapi/linux/btf.h

@@ -146,6 +146,12 @@ enum {
 	BTF_VAR_GLOBAL_EXTERN = 2,
 };
 
+enum btf_func_linkage {
+	BTF_FUNC_STATIC = 0,
+	BTF_FUNC_GLOBAL = 1,
+	BTF_FUNC_EXTERN = 2,
+};
+
 /* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
  * additional information related to the variable such as its linkage.
  */

tools/lib/bpf/libbpf.c

@@ -173,6 +173,8 @@ struct bpf_capabilities {
 	__u32 btf_datasec:1;
 	/* BPF_F_MMAPABLE is supported for arrays */
 	__u32 array_mmap:1;
+	/* BTF_FUNC_GLOBAL is supported */
+	__u32 btf_func_global:1;
 };
 
 enum reloc_type {
@@ -2209,13 +2211,14 @@ static bool section_have_execinstr(struct bpf_object *obj, int idx)
 
 static void bpf_object__sanitize_btf(struct bpf_object *obj)
 {
+	bool has_func_global = obj->caps.btf_func_global;
 	bool has_datasec = obj->caps.btf_datasec;
 	bool has_func = obj->caps.btf_func;
 	struct btf *btf = obj->btf;
 	struct btf_type *t;
 	int i, j, vlen;
 
-	if (!obj->btf || (has_func && has_datasec))
+	if (!obj->btf || (has_func && has_datasec && has_func_global))
 		return;
 
 	for (i = 1; i <= btf__get_nr_types(btf); i++) {
@@ -2263,6 +2266,9 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj)
 		} else if (!has_func && btf_is_func(t)) {
 			/* replace FUNC with TYPEDEF */
 			t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
+		} else if (!has_func_global && btf_is_func(t)) {
+			/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
+			t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
 		}
 	}
 }
@@ -3205,6 +3211,32 @@ static int bpf_object__probe_btf_func(struct bpf_object *obj)
 	return 0;
 }
 
+static int bpf_object__probe_btf_func_global(struct bpf_object *obj)
+{
+	static const char strs[] = "\0int\0x\0a";
+	/* static void x(int a) {} */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* FUNC_PROTO */                                /* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+		BTF_PARAM_ENC(7, 1),
+		/* FUNC x BTF_FUNC_GLOBAL */                    /* [3] */
+		BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2),
+	};
+	int btf_fd;
+
+	btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
+				      strs, sizeof(strs));
+	if (btf_fd >= 0) {
+		obj->caps.btf_func_global = 1;
+		close(btf_fd);
+		return 1;
+	}
+
+	return 0;
+}
+
 static int bpf_object__probe_btf_datasec(struct bpf_object *obj)
 {
 	static const char strs[] = "\0x\0.data";
@@ -3260,6 +3292,7 @@ bpf_object__probe_caps(struct bpf_object *obj)
 		bpf_object__probe_name,
 		bpf_object__probe_global_data,
 		bpf_object__probe_btf_func,
+		bpf_object__probe_btf_func_global,
 		bpf_object__probe_btf_datasec,
 		bpf_object__probe_array_mmap,
 	};

tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c

@@ -48,6 +48,8 @@ void test_bpf_verif_scale(void)
 		{ "test_verif_scale2.o", BPF_PROG_TYPE_SCHED_CLS },
 		{ "test_verif_scale3.o", BPF_PROG_TYPE_SCHED_CLS },
 
+		{ "pyperf_global.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
+
 		/* full unroll by llvm */
 		{ "pyperf50.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
 		{ "pyperf100.o", BPF_PROG_TYPE_RAW_TRACEPOINT },

tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c

@@ -98,6 +98,7 @@ static void test_target_yes_callees(void)
 		"fexit/test_pkt_access",
 		"fexit/test_pkt_access_subprog1",
 		"fexit/test_pkt_access_subprog2",
+		"fexit/test_pkt_access_subprog3",
 	};
 	test_fexit_bpf2bpf_common("./fexit_bpf2bpf.o",
 				  "./test_pkt_access.o",

tools/testing/selftests/bpf/prog_tests/test_global_funcs.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include <test_progs.h>
+
+const char *err_str;
+bool found;
+
+static int libbpf_debug_print(enum libbpf_print_level level,
+			      const char *format, va_list args)
+{
+	char *log_buf;
+
+	if (level != LIBBPF_WARN ||
+	    strcmp(format, "libbpf: \n%s\n")) {
+		vprintf(format, args);
+		return 0;
+	}
+
+	log_buf = va_arg(args, char *);
+	if (!log_buf)
+		goto out;
+	if (strstr(log_buf, err_str) == 0)
+		found = true;
+out:
+	printf(format, log_buf);
+	return 0;
+}
+
+extern int extra_prog_load_log_flags;
+
+static int check_load(const char *file)
+{
+	struct bpf_prog_load_attr attr;
+	struct bpf_object *obj = NULL;
+	int err, prog_fd;
+
+	memset(&attr, 0, sizeof(struct bpf_prog_load_attr));
+	attr.file = file;
+	attr.prog_type = BPF_PROG_TYPE_UNSPEC;
+	attr.log_level = extra_prog_load_log_flags;
+	attr.prog_flags = BPF_F_TEST_RND_HI32;
+	found = false;
+	err = bpf_prog_load_xattr(&attr, &obj, &prog_fd);
+	bpf_object__close(obj);
+	return err;
+}
+
+struct test_def {
+	const char *file;
+	const char *err_str;
+};
+
+void test_test_global_funcs(void)
+{
+	struct test_def tests[] = {
+		{ "test_global_func1.o", "combined stack size of 4 calls is 544" },
+		{ "test_global_func2.o" },
+		{ "test_global_func3.o" , "the call stack of 8 frames" },
+		{ "test_global_func4.o" },
+		{ "test_global_func5.o" , "expected pointer to ctx, but got PTR" },
+		{ "test_global_func6.o" , "modified ctx ptr R2" },
+		{ "test_global_func7.o" , "foo() doesn't return scalar" },
+	};
+	libbpf_print_fn_t old_print_fn = NULL;
+	int err, i, duration = 0;
+
+	old_print_fn = libbpf_set_print(libbpf_debug_print);
+
+	for (i = 0; i < ARRAY_SIZE(tests); i++) {
+		const struct test_def *test = &tests[i];
+
+		if (!test__start_subtest(test->file))
+			continue;
+
+		err_str = test->err_str;
+		err = check_load(test->file);
+		CHECK_FAIL(!!err ^ !!err_str);
+		if (err_str)
+			CHECK(found, "", "expected string '%s'", err_str);
+	}
+	libbpf_set_print(old_print_fn);
+}

tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c

@@ -79,4 +79,19 @@ int test_subprog2(struct args_subprog2 *ctx)
 	test_result_subprog2 = 1;
 	return 0;
 }
+
+__u64 test_result_subprog3 = 0;
+BPF_TRACE_3("fexit/test_pkt_access_subprog3", test_subprog3,
+	    int, val, struct sk_buff *, skb, int, ret)
+{
+	int len;
+
+	__builtin_preserve_access_index(({
+		len = skb->len;
+	}));
+	if (len != 74 || ret != 74 * val || val != 3)
+		return 0;
+	test_result_subprog3 = 1;
+	return 0;
+}
 char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/progs/pyperf.h

@@ -154,7 +154,12 @@ struct {
 	__uint(value_size, sizeof(long long) * 127);
 } stackmap SEC(".maps");
 
-static __always_inline int __on_event(struct pt_regs *ctx)
+#ifdef GLOBAL_FUNC
+__attribute__((noinline))
+#else
+static __always_inline
+#endif
+int __on_event(struct bpf_raw_tracepoint_args *ctx)
 {
 	uint64_t pid_tgid = bpf_get_current_pid_tgid();
 	pid_t pid = (pid_t)(pid_tgid >> 32);
@@ -254,7 +259,7 @@ static __always_inline int __on_event(struct pt_regs *ctx)
 }
 
 SEC("raw_tracepoint/kfree_skb")
-int on_event(struct pt_regs* ctx)
+int on_event(struct bpf_raw_tracepoint_args* ctx)
 {
 	int i, ret = 0;
 	ret |= __on_event(ctx);

tools/testing/selftests/bpf/progs/pyperf_global.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#define STACK_MAX_LEN 50
+#define GLOBAL_FUNC
+#include "pyperf.h"

tools/testing/selftests/bpf/progs/test_global_func1.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2020 Facebook */
+#include <stddef.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+#ifndef MAX_STACK
+#define MAX_STACK (512 - 3 * 32 + 8)
+#endif
+
+static __attribute__ ((noinline))
+int f0(int var, struct __sk_buff *skb)
+{
+	return skb->len;
+}
+
+__attribute__ ((noinline))
+int f1(struct __sk_buff *skb)
+{
+	volatile char buf[MAX_STACK] = {};
+
+	return f0(0, skb) + skb->len;
+}
+
+int f3(int, struct __sk_buff *skb, int);
+
+__attribute__ ((noinline))
+int f2(int val, struct __sk_buff *skb)
+{
+	return f1(skb) + f3(val, skb, 1);
+}
+
+__attribute__ ((noinline))
+int f3(int val, struct __sk_buff *skb, int var)
+{
+	volatile char buf[MAX_STACK] = {};
+
+	return skb->ifindex * val * var;
+}
+
+SEC("classifier/test")
+int test_cls(struct __sk_buff *skb)
+{
+	return f0(1, skb) + f1(skb) + f2(2, skb) + f3(3, skb, 4);
+}

tools/testing/selftests/bpf/progs/test_global_func2.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2020 Facebook */
+#define MAX_STACK (512 - 3 * 32)
+#include "test_global_func1.c"

tools/testing/selftests/bpf/progs/test_global_func3.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2020 Facebook */
+#include <stddef.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+__attribute__ ((noinline))
+int f1(struct __sk_buff *skb)
+{
+	return skb->len;
+}
+
+__attribute__ ((noinline))
+int f2(int val, struct __sk_buff *skb)
+{
+	return f1(skb) + val;
+}
+
+__attribute__ ((noinline))
+int f3(int val, struct __sk_buff *skb, int var)
+{
+	return f2(var, skb) + val;
+}
+
+__attribute__ ((noinline))
+int f4(struct __sk_buff *skb)
+{
+	return f3(1, skb, 2);
+}
+
+__attribute__ ((noinline))
+int f5(struct __sk_buff *skb)
+{
+	return f4(skb);
+}
+
+__attribute__ ((noinline))
+int f6(struct __sk_buff *skb)
+{
+	return f5(skb);
+}
+
+__attribute__ ((noinline))
+int f7(struct __sk_buff *skb)
+{
+	return f6(skb);
+}
+
+#ifndef NO_FN8
+__attribute__ ((noinline))
+int f8(struct __sk_buff *skb)
+{
+	return f7(skb);
+}
+#endif
+
+SEC("classifier/test")
+int test_cls(struct __sk_buff *skb)
+{
+#ifndef NO_FN8
+	return f8(skb);
+#else
+	return f7(skb);
+#endif
+}

tools/testing/selftests/bpf/progs/test_global_func4.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2020 Facebook */
+#define NO_FN8
+#include "test_global_func3.c"

tools/testing/selftests/bpf/progs/test_global_func5.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2020 Facebook */
+#include <stddef.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+__attribute__ ((noinline))
+int f1(struct __sk_buff *skb)
+{
+	return skb->len;
+}
+
+int f3(int, struct __sk_buff *skb);
+
+__attribute__ ((noinline))
+int f2(int val, struct __sk_buff *skb)
+{
+	return f1(skb) + f3(val, (void *)&val); /* type mismatch */
+}
+
+__attribute__ ((noinline))
+int f3(int val, struct __sk_buff *skb)
+{
+	return skb->ifindex * val;
+}
+
+SEC("classifier/test")
+int test_cls(struct __sk_buff *skb)
+{
+	return f1(skb) + f2(2, skb) + f3(3, skb);
+}

tools/testing/selftests/bpf/progs/test_global_func6.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2020 Facebook */
+#include <stddef.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+__attribute__ ((noinline))
+int f1(struct __sk_buff *skb)
+{
+	return skb->len;
+}
+
+int f3(int, struct __sk_buff *skb);
+
+__attribute__ ((noinline))
+int f2(int val, struct __sk_buff *skb)
+{
+	return f1(skb) + f3(val, skb + 1); /* type mismatch */
+}
+
+__attribute__ ((noinline))
+int f3(int val, struct __sk_buff *skb)
+{
+	return skb->ifindex * val;
+}
+
+SEC("classifier/test")
+int test_cls(struct __sk_buff *skb)
+{
+	return f1(skb) + f2(2, skb) + f3(3, skb);
+}

tools/testing/selftests/bpf/progs/test_global_func7.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2020 Facebook */
+#include <stddef.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+__attribute__ ((noinline))
+void foo(struct __sk_buff *skb)
+{
+	skb->tc_index = 0;
+}
+
+SEC("classifier/test")
+int test_cls(struct __sk_buff *skb)
+{
+	foo(skb);
+	return 0;
+}

tools/testing/selftests/bpf/progs/test_pkt_access.c

@@ -47,6 +47,32 @@ int test_pkt_access_subprog2(int val, volatile struct __sk_buff *skb)
 	return skb->len * val;
 }
 
+#define MAX_STACK (512 - 2 * 32)
+
+__attribute__ ((noinline))
+int get_skb_len(struct __sk_buff *skb)
+{
+	volatile char buf[MAX_STACK] = {};
+
+	return skb->len;
+}
+
+int get_skb_ifindex(int, struct __sk_buff *skb, int);
+
+__attribute__ ((noinline))
+int test_pkt_access_subprog3(int val, struct __sk_buff *skb)
+{
+	return get_skb_len(skb) * get_skb_ifindex(val, skb, 1);
+}
+
+__attribute__ ((noinline))
+int get_skb_ifindex(int val, struct __sk_buff *skb, int var)
+{
+	volatile char buf[MAX_STACK] = {};
+
+	return skb->ifindex * val * var;
+}
+
 SEC("classifier/test_pkt_access")
 int test_pkt_access(struct __sk_buff *skb)
 {
@@ -82,6 +108,8 @@ int test_pkt_access(struct __sk_buff *skb)
 		return TC_ACT_SHOT;
 	if (test_pkt_access_subprog2(2, skb) != skb->len * 2)
 		return TC_ACT_SHOT;
+	if (test_pkt_access_subprog3(3, skb) != skb->len * 3 * skb->ifindex)
+		return TC_ACT_SHOT;
 	if (tcp) {
 		if (((void *)(tcp) + 20) > data_end || proto != 6)
 			return TC_ACT_SHOT;

tools/testing/selftests/bpf/progs/test_xdp_noinline.c

@@ -86,7 +86,7 @@ u32 jhash(const void *key, u32 length, u32 initval)
 	return c;
 }
 
-static __attribute__ ((noinline))
+__attribute__ ((noinline))
 u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
 {
 	a += initval;
@@ -96,7 +96,7 @@ u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
 	return c;
 }
 
-static __attribute__ ((noinline))
+__attribute__ ((noinline))
 u32 jhash_2words(u32 a, u32 b, u32 initval)
 {
 	return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2));