Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Alexei Starovoitov says:

====================
pull-request: bpf-next 2021-04-23

The following pull-request contains BPF updates for your *net-next* tree.

We've added 69 non-merge commits during the last 22 day(s) which contain
a total of 69 files changed, 3141 insertions(+), 866 deletions(-).

The main changes are:

1) Add BPF static linker support for extern resolution of global, from Andrii.

2) Refine retval for bpf_get_task_stack helper, from Dave.

3) Add a bpf_snprintf helper, from Florent.

4) A bunch of miscellaneous improvements from many developers.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

35 files changed, 1016 insertions, 114 deletions

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 6448c626498f..283e5ad8385e 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -21,13 +21,18 @@ endif
 
 BPF_GCC		?= $(shell command -v bpf-gcc;)
 SAN_CFLAGS	?=
-CFLAGS += -g -Og -rdynamic -Wall $(GENFLAGS) $(SAN_CFLAGS)		\
+CFLAGS += -g -O0 -rdynamic -Wall $(GENFLAGS) $(SAN_CFLAGS)		\
 	  -I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR)		\
 	  -I$(TOOLSINCDIR) -I$(APIDIR) -I$(OUTPUT)			\
 	  -Dbpf_prog_load=bpf_prog_test_load				\
 	  -Dbpf_load_program=bpf_test_load_program
 LDLIBS += -lcap -lelf -lz -lrt -lpthread
 
+# Silence some warnings when compiled with clang
+ifneq ($(LLVM),)
+CFLAGS += -Wno-unused-command-line-argument
+endif
+
 # Order correspond to 'make run_tests' order
 TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
 	test_verifier_log test_dev_cgroup \
@@ -182,7 +187,6 @@ $(OUTPUT)/runqslower: $(BPFOBJ) | $(DEFAULT_BPFTOOL)
 		    cp $(SCRATCH_DIR)/runqslower $@
 
 $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED): $(OUTPUT)/test_stub.o $(BPFOBJ)
-$(TEST_GEN_FILES): docs
 
 $(OUTPUT)/test_dev_cgroup: cgroup_helpers.c
 $(OUTPUT)/test_skb_cgroup_id_user: cgroup_helpers.c
@@ -201,10 +205,12 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)    \
 		    $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/bpftool
 	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)			       \
 		    CC=$(HOSTCC) LD=$(HOSTLD)				       \
-		    EXTRA_CFLAGS='-g -Og'				       \
+		    EXTRA_CFLAGS='-g -O0'				       \
 		    OUTPUT=$(HOST_BUILD_DIR)/bpftool/			       \
 		    prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install
 
+all: docs
+
 docs:
 	$(Q)RST2MAN_OPTS="--exit-status=1" $(MAKE) $(submake_extras)	\
 	            -f Makefile.docs					\
@@ -219,7 +225,7 @@ $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)		       \
 	   ../../../include/uapi/linux/bpf.h                                   \
 	   | $(INCLUDE_DIR) $(BUILD_DIR)/libbpf
 	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/ \
-		    EXTRA_CFLAGS='-g -Og'					       \
+		    EXTRA_CFLAGS='-g -O0'				       \
 		    DESTDIR=$(SCRATCH_DIR) prefix= all install_headers
 
 ifneq ($(BPFOBJ),$(HOST_BPFOBJ))
@@ -227,7 +233,7 @@ $(HOST_BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)                \
 	   ../../../include/uapi/linux/bpf.h                                   \
 	   | $(INCLUDE_DIR) $(HOST_BUILD_DIR)/libbpf
 	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR)                             \
-		    EXTRA_CFLAGS='-g -Og'					       \
+		    EXTRA_CFLAGS='-g -O0'				       \
 		    OUTPUT=$(HOST_BUILD_DIR)/libbpf/ CC=$(HOSTCC) LD=$(HOSTLD) \
 		    DESTDIR=$(HOST_SCRATCH_DIR)/ prefix= all install_headers
 endif
@@ -303,9 +309,15 @@ endef
 
 SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c
 
-LINKED_SKELS := test_static_linked.skel.h
+LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h		\
+		linked_vars.skel.h linked_maps.skel.h
 
 test_static_linked.skel.h-deps := test_static_linked1.o test_static_linked2.o
+linked_funcs.skel.h-deps := linked_funcs1.o linked_funcs2.o
+linked_vars.skel.h-deps := linked_vars1.o linked_vars2.o
+linked_maps.skel.h-deps := linked_maps1.o linked_maps2.o
+
+LINKED_BPF_SRCS := $(patsubst %.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
 
 # Set up extra TRUNNER_XXX "temporary" variables in the environment (relies on
 # $eval()) and pass control to DEFINE_TEST_RUNNER_RULES.
@@ -325,7 +337,7 @@ TRUNNER_TESTS_HDR := $(TRUNNER_TESTS_DIR)/tests.h
 TRUNNER_BPF_SRCS := $$(notdir $$(wildcard $(TRUNNER_BPF_PROGS_DIR)/*.c))
 TRUNNER_BPF_OBJS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.o, $$(TRUNNER_BPF_SRCS))
 TRUNNER_BPF_SKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.skel.h,	\
-				 $$(filter-out $(SKEL_BLACKLIST),	\
+				 $$(filter-out $(SKEL_BLACKLIST) $(LINKED_BPF_SRCS),\
 					       $$(TRUNNER_BPF_SRCS)))
 TRUNNER_BPF_SKELS_LINKED := $$(addprefix $$(TRUNNER_OUTPUT)/,$(LINKED_SKELS))
 TEST_GEN_FILES += $$(TRUNNER_BPF_OBJS)
@@ -481,7 +493,7 @@ $(OUTPUT)/test_verifier: test_verifier.c verifier/tests.h $(BPFOBJ) | $(OUTPUT)
 # Make sure we are able to include and link libbpf against c++.
 $(OUTPUT)/test_cpp: test_cpp.cpp $(OUTPUT)/test_core_extern.skel.h $(BPFOBJ)
 	$(call msg,CXX,,$@)
-	$(Q)$(CXX) $(CFLAGS) $^ $(LDLIBS) -o $@
+	$(Q)$(CXX) $(CFLAGS) $(filter %.a %.o %.cpp,$^) $(LDLIBS) -o $@
 
 # Benchmark runner
 $(OUTPUT)/bench_%.o: benchs/bench_%.c bench.h
diff --git a/tools/testing/selftests/bpf/README.rst b/tools/testing/selftests/bpf/README.rst
index 65fe318d1e71..3353778c30f8 100644
--- a/tools/testing/selftests/bpf/README.rst
+++ b/tools/testing/selftests/bpf/README.rst
@@ -193,3 +193,12 @@ Without it, the error from compiling bpf selftests looks like:
   libbpf: failed to find BTF for extern 'tcp_slow_start' [25] section: -2
 
 __ https://reviews.llvm.org/D93563
+
+Clang dependencies for static linking tests
+===========================================
+
+linked_vars, linked_maps, and linked_funcs tests depend on `Clang fix`__ to
+generate valid BTF information for weak variables. Please make sure you use
+Clang that contains the fix.
+
+__ https://reviews.llvm.org/D100362
diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config
index 37e1f303fc11..5192305159ec 100644
--- a/tools/testing/selftests/bpf/config
+++ b/tools/testing/selftests/bpf/config
@@ -44,3 +44,5 @@ CONFIG_SECURITYFS=y
 CONFIG_IMA_WRITE_POLICY=y
 CONFIG_IMA_READ_POLICY=y
 CONFIG_BLK_DEV_LOOP=y
+CONFIG_FUNCTION_TRACER=y
+CONFIG_DYNAMIC_FTRACE=y
diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index 74c45d557a2b..2d3590cfb5e1 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -147,6 +147,7 @@ static void test_task_stack(void)
 		return;
 
 	do_dummy_read(skel->progs.dump_task_stack);
+	do_dummy_read(skel->progs.get_task_user_stacks);
 
 	bpf_iter_task_stack__destroy(skel);
 }
diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
index 5c0448910426..63990842d20f 100644
--- a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
+++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
@@ -58,42 +58,73 @@ static void test_fexit_bpf2bpf_common(const char *obj_file,
 				      test_cb cb)
 {
 	struct bpf_object *obj = NULL, *tgt_obj;
+	__u32 retval, tgt_prog_id, info_len;
+	struct bpf_prog_info prog_info = {};
 	struct bpf_program **prog = NULL;
 	struct bpf_link **link = NULL;
-	__u32 duration = 0, retval;
 	int err, tgt_fd, i;
+	struct btf *btf;
 
 	err = bpf_prog_load(target_obj_file, BPF_PROG_TYPE_UNSPEC,
 			    &tgt_obj, &tgt_fd);
-	if (CHECK(err, "tgt_prog_load", "file %s err %d errno %d\n",
-		  target_obj_file, err, errno))
+	if (!ASSERT_OK(err, "tgt_prog_load"))
 		return;
 	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
 			    .attach_prog_fd = tgt_fd,
 			   );
 
+	info_len = sizeof(prog_info);
+	err = bpf_obj_get_info_by_fd(tgt_fd, &prog_info, &info_len);
+	if (!ASSERT_OK(err, "tgt_fd_get_info"))
+		goto close_prog;
+
+	tgt_prog_id = prog_info.id;
+	btf = bpf_object__btf(tgt_obj);
+
 	link = calloc(sizeof(struct bpf_link *), prog_cnt);
+	if (!ASSERT_OK_PTR(link, "link_ptr"))
+		goto close_prog;
+
 	prog = calloc(sizeof(struct bpf_program *), prog_cnt);
-	if (CHECK(!link || !prog, "alloc_memory", "failed to alloc memory"))
+	if (!ASSERT_OK_PTR(prog, "prog_ptr"))
 		goto close_prog;
 
 	obj = bpf_object__open_file(obj_file, &opts);
-	if (CHECK(IS_ERR_OR_NULL(obj), "obj_open",
-		  "failed to open %s: %ld\n", obj_file,
-		  PTR_ERR(obj)))
+	if (!ASSERT_OK_PTR(obj, "obj_open"))
 		goto close_prog;
 
 	err = bpf_object__load(obj);
-	if (CHECK(err, "obj_load", "err %d\n", err))
+	if (!ASSERT_OK(err, "obj_load"))
 		goto close_prog;
 
 	for (i = 0; i < prog_cnt; i++) {
+		struct bpf_link_info link_info;
+		char *tgt_name;
+		__s32 btf_id;
+
+		tgt_name = strstr(prog_name[i], "/");
+		if (!ASSERT_OK_PTR(tgt_name, "tgt_name"))
+			goto close_prog;
+		btf_id = btf__find_by_name_kind(btf, tgt_name + 1, BTF_KIND_FUNC);
+
 		prog[i] = bpf_object__find_program_by_title(obj, prog_name[i]);
-		if (CHECK(!prog[i], "find_prog", "prog %s not found\n", prog_name[i]))
+		if (!ASSERT_OK_PTR(prog[i], prog_name[i]))
 			goto close_prog;
+
 		link[i] = bpf_program__attach_trace(prog[i]);
-		if (CHECK(IS_ERR(link[i]), "attach_trace", "failed to link\n"))
+		if (!ASSERT_OK_PTR(link[i], "attach_trace"))
 			goto close_prog;
+
+		info_len = sizeof(link_info);
+		memset(&link_info, 0, sizeof(link_info));
+		err = bpf_obj_get_info_by_fd(bpf_link__fd(link[i]),
+					     &link_info, &info_len);
+		ASSERT_OK(err, "link_fd_get_info");
+		ASSERT_EQ(link_info.tracing.attach_type,
+			  bpf_program__get_expected_attach_type(prog[i]),
+			  "link_attach_type");
+		ASSERT_EQ(link_info.tracing.target_obj_id, tgt_prog_id, "link_tgt_obj_id");
+		ASSERT_EQ(link_info.tracing.target_btf_id, btf_id, "link_tgt_btf_id");
 	}
 
 	if (cb) {
@@ -106,10 +137,9 @@ static void test_fexit_bpf2bpf_common(const char *obj_file,
 		goto close_prog;
 
 	err = bpf_prog_test_run(tgt_fd, 1, &pkt_v6, sizeof(pkt_v6),
-				NULL, NULL, &retval, &duration);
-	CHECK(err || retval, "ipv6",
-	      "err %d errno %d retval %d duration %d\n",
-	      err, errno, retval, duration);
+				NULL, NULL, &retval, NULL);
+	ASSERT_OK(err, "prog_run");
+	ASSERT_EQ(retval, 0, "prog_run_ret");
 
 	if (check_data_map(obj, prog_cnt, false))
 		goto close_prog;
diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_sleep.c b/tools/testing/selftests/bpf/prog_tests/fexit_sleep.c
index 6c4d42a2386f..ccc7e8a34ab6 100644
--- a/tools/testing/selftests/bpf/prog_tests/fexit_sleep.c
+++ b/tools/testing/selftests/bpf/prog_tests/fexit_sleep.c
@@ -39,7 +39,7 @@ void test_fexit_sleep(void)
 		goto cleanup;
 
 	cpid = clone(do_sleep, child_stack + STACK_SIZE, CLONE_FILES | SIGCHLD, fexit_skel);
-	if (CHECK(cpid == -1, "clone", strerror(errno)))
+	if (CHECK(cpid == -1, "clone", "%s\n", strerror(errno)))
 		goto cleanup;
 
 	/* wait until first sys_nanosleep ends and second sys_nanosleep starts */
@@ -65,7 +65,7 @@ void test_fexit_sleep(void)
 	/* kill the thread to unwind sys_nanosleep stack through the trampoline */
 	kill(cpid, 9);
 
-	if (CHECK(waitpid(cpid, &wstatus, 0) == -1, "waitpid", strerror(errno)))
+	if (CHECK(waitpid(cpid, &wstatus, 0) == -1, "waitpid", "%s\n", strerror(errno)))
 		goto cleanup;
 	if (CHECK(WEXITSTATUS(wstatus) != 0, "exitstatus", "failed"))
 		goto cleanup;
diff --git a/tools/testing/selftests/bpf/prog_tests/linked_funcs.c b/tools/testing/selftests/bpf/prog_tests/linked_funcs.c
new file mode 100644
index 000000000000..e9916f2817ec
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/linked_funcs.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include <test_progs.h>
+#include <sys/syscall.h>
+#include "linked_funcs.skel.h"
+
+void test_linked_funcs(void)
+{
+	int err;
+	struct linked_funcs *skel;
+
+	skel = linked_funcs__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	skel->rodata->my_tid = syscall(SYS_gettid);
+	skel->bss->syscall_id = SYS_getpgid;
+
+	err = linked_funcs__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	err = linked_funcs__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto cleanup;
+
+	/* trigger */
+	syscall(SYS_getpgid);
+
+	ASSERT_EQ(skel->bss->output_val1, 2000 + 2000, "output_val1");
+	ASSERT_EQ(skel->bss->output_ctx1, SYS_getpgid, "output_ctx1");
+	ASSERT_EQ(skel->bss->output_weak1, 42, "output_weak1");
+
+	ASSERT_EQ(skel->bss->output_val2, 2 * 1000 + 2 * (2 * 1000), "output_val2");
+	ASSERT_EQ(skel->bss->output_ctx2, SYS_getpgid, "output_ctx2");
+	/* output_weak2 should never be updated */
+	ASSERT_EQ(skel->bss->output_weak2, 0, "output_weak2");
+
+cleanup:
+	linked_funcs__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/prog_tests/linked_maps.c b/tools/testing/selftests/bpf/prog_tests/linked_maps.c
new file mode 100644
index 000000000000..85dcaaaf2775
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/linked_maps.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include <test_progs.h>
+#include <sys/syscall.h>
+#include "linked_maps.skel.h"
+
+void test_linked_maps(void)
+{
+	int err;
+	struct linked_maps *skel;
+
+	skel = linked_maps__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	err = linked_maps__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto cleanup;
+
+	/* trigger */
+	syscall(SYS_getpgid);
+
+	ASSERT_EQ(skel->bss->output_first1, 2000, "output_first1");
+	ASSERT_EQ(skel->bss->output_second1, 2, "output_second1");
+	ASSERT_EQ(skel->bss->output_weak1, 2, "output_weak1");
+
+cleanup:
+	linked_maps__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/prog_tests/linked_vars.c b/tools/testing/selftests/bpf/prog_tests/linked_vars.c
new file mode 100644
index 000000000000..267166abe4c1
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/linked_vars.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include <test_progs.h>
+#include <sys/syscall.h>
+#include "linked_vars.skel.h"
+
+void test_linked_vars(void)
+{
+	int err;
+	struct linked_vars *skel;
+
+	skel = linked_vars__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	skel->bss->input_bss1 = 1000;
+	skel->bss->input_bss2 = 2000;
+	skel->bss->input_bss_weak = 3000;
+
+	err = linked_vars__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	err = linked_vars__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto cleanup;
+
+	/* trigger */
+	syscall(SYS_getpgid);
+
+	ASSERT_EQ(skel->bss->output_bss1, 1000 + 2000 + 3000, "output_bss1");
+	ASSERT_EQ(skel->bss->output_bss2, 1000 + 2000 + 3000, "output_bss2");
+	/* 10 comes from "winner" input_data_weak in first obj file */
+	ASSERT_EQ(skel->bss->output_data1, 1 + 2 + 10, "output_bss1");
+	ASSERT_EQ(skel->bss->output_data2, 1 + 2 + 10, "output_bss2");
+	/* 100 comes from "winner" input_rodata_weak in first obj file */
+	ASSERT_EQ(skel->bss->output_rodata1, 11 + 22 + 100, "output_weak1");
+	ASSERT_EQ(skel->bss->output_rodata2, 11 + 22 + 100, "output_weak2");
+
+cleanup:
+	linked_vars__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/prog_tests/map_ptr.c b/tools/testing/selftests/bpf/prog_tests/map_ptr.c
index c230a573c373..4972f92205c7 100644
--- a/tools/testing/selftests/bpf/prog_tests/map_ptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/map_ptr.c
@@ -12,11 +12,22 @@ void test_map_ptr(void)
 	__u32 duration = 0, retval;
 	char buf[128];
 	int err;
+	int page_size = getpagesize();
 
-	skel = map_ptr_kern__open_and_load();
-	if (CHECK(!skel, "skel_open_load", "open_load failed\n"))
+	skel = map_ptr_kern__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
 		return;
 
+	err = bpf_map__set_max_entries(skel->maps.m_ringbuf, page_size);
+	if (!ASSERT_OK(err, "bpf_map__set_max_entries"))
+		goto cleanup;
+
+	err = map_ptr_kern__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	skel->bss->page_size = page_size;
+
 	err = bpf_prog_test_run(bpf_program__fd(skel->progs.cg_skb), 1, &pkt_v4,
 				sizeof(pkt_v4), buf, NULL, &retval, NULL);
 
diff --git a/tools/testing/selftests/bpf/prog_tests/mmap.c b/tools/testing/selftests/bpf/prog_tests/mmap.c
index 9c3c5c0f068f..37b002ca1167 100644
--- a/tools/testing/selftests/bpf/prog_tests/mmap.c
+++ b/tools/testing/selftests/bpf/prog_tests/mmap.c
@@ -29,22 +29,36 @@ void test_mmap(void)
 	struct test_mmap *skel;
 	__u64 val = 0;
 
-	skel = test_mmap__open_and_load();
-	if (CHECK(!skel, "skel_open_and_load", "skeleton open/load failed\n"))
+	skel = test_mmap__open();
+	if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
 		return;
 
+	err = bpf_map__set_max_entries(skel->maps.rdonly_map, page_size);
+	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
+		goto cleanup;
+
+	/* at least 4 pages of data */
+	err = bpf_map__set_max_entries(skel->maps.data_map,
+				       4 * (page_size / sizeof(u64)));
+	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
+		goto cleanup;
+
+	err = test_mmap__load(skel);
+	if (CHECK(err != 0, "skel_load", "skeleton load failed\n"))
+		goto cleanup;
+
 	bss_map = skel->maps.bss;
 	data_map = skel->maps.data_map;
 	data_map_fd = bpf_map__fd(data_map);
 
 	rdmap_fd = bpf_map__fd(skel->maps.rdonly_map);
-	tmp1 = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, rdmap_fd, 0);
+	tmp1 = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, rdmap_fd, 0);
 	if (CHECK(tmp1 != MAP_FAILED, "rdonly_write_mmap", "unexpected success\n")) {
-		munmap(tmp1, 4096);
+		munmap(tmp1, page_size);
 		goto cleanup;
 	}
 	/* now double-check if it's mmap()'able at all */
-	tmp1 = mmap(NULL, 4096, PROT_READ, MAP_SHARED, rdmap_fd, 0);
+	tmp1 = mmap(NULL, page_size, PROT_READ, MAP_SHARED, rdmap_fd, 0);
 	if (CHECK(tmp1 == MAP_FAILED, "rdonly_read_mmap", "failed: %d\n", errno))
 		goto cleanup;
 
diff --git a/tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c b/tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c
index 31a3114906e2..2535788e135f 100644
--- a/tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c
+++ b/tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c
@@ -68,10 +68,10 @@ static void test_ns_current_pid_tgid_new_ns(void)
 	cpid = clone(test_current_pid_tgid, child_stack + STACK_SIZE,
 		     CLONE_NEWPID | SIGCHLD, NULL);
 
-	if (CHECK(cpid == -1, "clone", strerror(errno)))
+	if (CHECK(cpid == -1, "clone", "%s\n", strerror(errno)))
 		return;
 
-	if (CHECK(waitpid(cpid, &wstatus, 0) == -1, "waitpid", strerror(errno)))
+	if (CHECK(waitpid(cpid, &wstatus, 0) == -1, "waitpid", "%s\n", strerror(errno)))
 		return;
 
 	if (CHECK(WEXITSTATUS(wstatus) != 0, "newns_pidtgid", "failed"))
diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
index fddbc5db5d6a..de78617f6550 100644
--- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
@@ -87,11 +87,20 @@ void test_ringbuf(void)
 	pthread_t thread;
 	long bg_ret = -1;
 	int err, cnt;
+	int page_size = getpagesize();
 
-	skel = test_ringbuf__open_and_load();
-	if (CHECK(!skel, "skel_open_load", "skeleton open&load failed\n"))
+	skel = test_ringbuf__open();
+	if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
 		return;
 
+	err = bpf_map__set_max_entries(skel->maps.ringbuf, page_size);
+	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
+		goto cleanup;
+
+	err = test_ringbuf__load(skel);
+	if (CHECK(err != 0, "skel_load", "skeleton load failed\n"))
+		goto cleanup;
+
 	/* only trigger BPF program for current process */
 	skel->bss->pid = getpid();
 
@@ -110,9 +119,9 @@ void test_ringbuf(void)
 	CHECK(skel->bss->avail_data != 3 * rec_sz,
 	      "err_avail_size", "exp %ld, got %ld\n",
 	      3L * rec_sz, skel->bss->avail_data);
-	CHECK(skel->bss->ring_size != 4096,
+	CHECK(skel->bss->ring_size != page_size,
 	      "err_ring_size", "exp %ld, got %ld\n",
-	      4096L, skel->bss->ring_size);
+	      (long)page_size, skel->bss->ring_size);
 	CHECK(skel->bss->cons_pos != 0,
 	      "err_cons_pos", "exp %ld, got %ld\n",
 	      0L, skel->bss->cons_pos);
diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
index d37161e59bb2..cef63e703924 100644
--- a/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
+++ b/tools/testing/selftests/bpf/prog_tests/ringbuf_multi.c
@@ -41,13 +41,42 @@ static int process_sample(void *ctx, void *data, size_t len)
 void test_ringbuf_multi(void)
 {
 	struct test_ringbuf_multi *skel;
-	struct ring_buffer *ringbuf;
+	struct ring_buffer *ringbuf = NULL;
 	int err;
+	int page_size = getpagesize();
+	int proto_fd = -1;
 
-	skel = test_ringbuf_multi__open_and_load();
-	if (CHECK(!skel, "skel_open_load", "skeleton open&load failed\n"))
+	skel = test_ringbuf_multi__open();
+	if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
 		return;
 
+	err = bpf_map__set_max_entries(skel->maps.ringbuf1, page_size);
+	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
+		goto cleanup;
+
+	err = bpf_map__set_max_entries(skel->maps.ringbuf2, page_size);
+	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
+		goto cleanup;
+
+	err = bpf_map__set_max_entries(bpf_map__inner_map(skel->maps.ringbuf_arr), page_size);
+	if (CHECK(err != 0, "bpf_map__set_max_entries", "bpf_map__set_max_entries failed\n"))
+		goto cleanup;
+
+	proto_fd = bpf_create_map(BPF_MAP_TYPE_RINGBUF, 0, 0, page_size, 0);
+	if (CHECK(proto_fd == -1, "bpf_create_map", "bpf_create_map failed\n"))
+		goto cleanup;
+
+	err = bpf_map__set_inner_map_fd(skel->maps.ringbuf_hash, proto_fd);
+	if (CHECK(err != 0, "bpf_map__set_inner_map_fd", "bpf_map__set_inner_map_fd failed\n"))
+		goto cleanup;
+
+	err = test_ringbuf_multi__load(skel);
+	if (CHECK(err != 0, "skel_load", "skeleton load failed\n"))
+		goto cleanup;
+
+	close(proto_fd);
+	proto_fd = -1;
+
 	/* only trigger BPF program for current process */
 	skel->bss->pid = getpid();
 
@@ -97,6 +126,8 @@ void test_ringbuf_multi(void)
 	      2L, skel->bss->total);
 
 cleanup:
+	if (proto_fd >= 0)
+		close(proto_fd);
 	ring_buffer__free(ringbuf);
 	test_ringbuf_multi__destroy(skel);
 }
diff --git a/tools/testing/selftests/bpf/prog_tests/snprintf.c b/tools/testing/selftests/bpf/prog_tests/snprintf.c
new file mode 100644
index 000000000000..a958c22aec75
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/snprintf.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Google LLC. */
+
+#include <test_progs.h>
+#include "test_snprintf.skel.h"
+#include "test_snprintf_single.skel.h"
+
+#define EXP_NUM_OUT  "-8 9 96 -424242 1337 DABBAD00"
+#define EXP_NUM_RET  sizeof(EXP_NUM_OUT)
+
+#define EXP_IP_OUT   "127.000.000.001 0000:0000:0000:0000:0000:0000:0000:0001"
+#define EXP_IP_RET   sizeof(EXP_IP_OUT)
+
+/* The third specifier, %pB, depends on compiler inlining so don't check it */
+#define EXP_SYM_OUT  "schedule schedule+0x0/"
+#define MIN_SYM_RET  sizeof(EXP_SYM_OUT)
+
+/* The third specifier, %p, is a hashed pointer which changes on every reboot */
+#define EXP_ADDR_OUT "0000000000000000 ffff00000add4e55 "
+#define EXP_ADDR_RET sizeof(EXP_ADDR_OUT "unknownhashedptr")
+
+#define EXP_STR_OUT  "str1 longstr"
+#define EXP_STR_RET  sizeof(EXP_STR_OUT)
+
+#define EXP_OVER_OUT "%over"
+#define EXP_OVER_RET 10
+
+#define EXP_PAD_OUT "    4 000"
+#define EXP_PAD_RET 900007
+
+#define EXP_NO_ARG_OUT "simple case"
+#define EXP_NO_ARG_RET 12
+
+#define EXP_NO_BUF_RET 29
+
+void test_snprintf_positive(void)
+{
+	char exp_addr_out[] = EXP_ADDR_OUT;
+	char exp_sym_out[]  = EXP_SYM_OUT;
+	struct test_snprintf *skel;
+
+	skel = test_snprintf__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	if (!ASSERT_OK(test_snprintf__attach(skel), "skel_attach"))
+		goto cleanup;
+
+	/* trigger tracepoint */
+	usleep(1);
+
+	ASSERT_STREQ(skel->bss->num_out, EXP_NUM_OUT, "num_out");
+	ASSERT_EQ(skel->bss->num_ret, EXP_NUM_RET, "num_ret");
+
+	ASSERT_STREQ(skel->bss->ip_out, EXP_IP_OUT, "ip_out");
+	ASSERT_EQ(skel->bss->ip_ret, EXP_IP_RET, "ip_ret");
+
+	ASSERT_OK(memcmp(skel->bss->sym_out, exp_sym_out,
+			 sizeof(exp_sym_out) - 1), "sym_out");
+	ASSERT_LT(MIN_SYM_RET, skel->bss->sym_ret, "sym_ret");
+
+	ASSERT_OK(memcmp(skel->bss->addr_out, exp_addr_out,
+			 sizeof(exp_addr_out) - 1), "addr_out");
+	ASSERT_EQ(skel->bss->addr_ret, EXP_ADDR_RET, "addr_ret");
+
+	ASSERT_STREQ(skel->bss->str_out, EXP_STR_OUT, "str_out");
+	ASSERT_EQ(skel->bss->str_ret, EXP_STR_RET, "str_ret");
+
+	ASSERT_STREQ(skel->bss->over_out, EXP_OVER_OUT, "over_out");
+	ASSERT_EQ(skel->bss->over_ret, EXP_OVER_RET, "over_ret");
+
+	ASSERT_STREQ(skel->bss->pad_out, EXP_PAD_OUT, "pad_out");
+	ASSERT_EQ(skel->bss->pad_ret, EXP_PAD_RET, "pad_ret");
+
+	ASSERT_STREQ(skel->bss->noarg_out, EXP_NO_ARG_OUT, "no_arg_out");
+	ASSERT_EQ(skel->bss->noarg_ret, EXP_NO_ARG_RET, "no_arg_ret");
+
+	ASSERT_EQ(skel->bss->nobuf_ret, EXP_NO_BUF_RET, "no_buf_ret");
+
+cleanup:
+	test_snprintf__destroy(skel);
+}
+
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+/* Loads an eBPF object calling bpf_snprintf with up to 10 characters of fmt */
+static int load_single_snprintf(char *fmt)
+{
+	struct test_snprintf_single *skel;
+	int ret;
+
+	skel = test_snprintf_single__open();
+	if (!skel)
+		return -EINVAL;
+
+	memcpy(skel->rodata->fmt, fmt, min(strlen(fmt) + 1, 10));
+
+	ret = test_snprintf_single__load(skel);
+	test_snprintf_single__destroy(skel);
+
+	return ret;
+}
+
+void test_snprintf_negative(void)
+{
+	ASSERT_OK(load_single_snprintf("valid %d"), "valid usage");
+
+	ASSERT_ERR(load_single_snprintf("0123456789"), "no terminating zero");
+	ASSERT_ERR(load_single_snprintf("%d %d"), "too many specifiers");
+	ASSERT_ERR(load_single_snprintf("%pi5"), "invalid specifier 1");
+	ASSERT_ERR(load_single_snprintf("%a"), "invalid specifier 2");
+	ASSERT_ERR(load_single_snprintf("%"), "invalid specifier 3");
+	ASSERT_ERR(load_single_snprintf("%12345678"), "invalid specifier 4");
+	ASSERT_ERR(load_single_snprintf("%--------"), "invalid specifier 5");
+	ASSERT_ERR(load_single_snprintf("\x80"), "non ascii character");
+	ASSERT_ERR(load_single_snprintf("\x1"), "non printable character");
+}
+
+void test_snprintf(void)
+{
+	if (test__start_subtest("snprintf_positive"))
+		test_snprintf_positive();
+	if (test__start_subtest("snprintf_negative"))
+		test_snprintf_negative();
+}
diff --git a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
index d5b44b135c00..4b937e5dbaca 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockopt_sk.c
@@ -3,6 +3,7 @@
 #include "cgroup_helpers.h"
 
 #include <linux/tcp.h>
+#include "sockopt_sk.skel.h"
 
 #ifndef SOL_TCP
 #define SOL_TCP IPPROTO_TCP
@@ -191,60 +192,30 @@ err:
 	return -1;
 }
 
-static int prog_attach(struct bpf_object *obj, int cgroup_fd, const char *title)
+static void run_test(int cgroup_fd)
 {
-	enum bpf_attach_type attach_type;
-	enum bpf_prog_type prog_type;
-	struct bpf_program *prog;
-	int err;
+	struct sockopt_sk *skel;
 
-	err = libbpf_prog_type_by_name(title, &prog_type, &attach_type);
-	if (err) {
-		log_err("Failed to deduct types for %s BPF program", title);
-		return -1;
-	}
+	skel = sockopt_sk__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_load"))
+		goto cleanup;
 
-	prog = bpf_object__find_program_by_title(obj, title);
-	if (!prog) {
-		log_err("Failed to find %s BPF program", title);
-		return -1;
-	}
-
-	err = bpf_prog_attach(bpf_program__fd(prog), cgroup_fd,
-			      attach_type, 0);
-	if (err) {
-		log_err("Failed to attach %s BPF program", title);
-		return -1;
-	}
-
-	return 0;
-}
-
-static void run_test(int cgroup_fd)
-{
-	struct bpf_prog_load_attr attr = {
-		.file = "./sockopt_sk.o",
-	};
-	struct bpf_object *obj;
-	int ignored;
-	int err;
-
-	err = bpf_prog_load_xattr(&attr, &obj, &ignored);
-	if (CHECK_FAIL(err))
-		return;
+	skel->bss->page_size = getpagesize();
 
-	err = prog_attach(obj, cgroup_fd, "cgroup/getsockopt");
-	if (CHECK_FAIL(err))
-		goto close_bpf_object;
+	skel->links._setsockopt =
+		bpf_program__attach_cgroup(skel->progs._setsockopt, cgroup_fd);
+	if (!ASSERT_OK_PTR(skel->links._setsockopt, "setsockopt_link"))
+		goto cleanup;
 
-	err = prog_attach(obj, cgroup_fd, "cgroup/setsockopt");
-	if (CHECK_FAIL(err))
-		goto close_bpf_object;
+	skel->links._getsockopt =
+		bpf_program__attach_cgroup(skel->progs._getsockopt, cgroup_fd);
+	if (!ASSERT_OK_PTR(skel->links._getsockopt, "getsockopt_link"))
+		goto cleanup;
 
-	CHECK_FAIL(getsetsockopt());
+	ASSERT_OK(getsetsockopt(), "getsetsockopt");
 
-close_bpf_object:
-	bpf_object__close(obj);
+cleanup:
+	sockopt_sk__destroy(skel);
 }
 
 void test_sockopt_sk(void)
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
index 50e59a2e142e..43c36f5f7649 100644
--- a/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
@@ -35,3 +35,30 @@ int dump_task_stack(struct bpf_iter__task *ctx)
 
 	return 0;
 }
+
+SEC("iter/task")
+int get_task_user_stacks(struct bpf_iter__task *ctx)
+{
+	struct seq_file *seq = ctx->meta->seq;
+	struct task_struct *task = ctx->task;
+	uint64_t buf_sz = 0;
+	int64_t res;
+
+	if (task == (void *)0)
+		return 0;
+
+	res = bpf_get_task_stack(task, entries,
+			MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, BPF_F_USER_STACK);
+	if (res <= 0)
+		return 0;
+
+	buf_sz += res;
+
+	/* If the verifier doesn't refine bpf_get_task_stack res, and instead
+	 * assumes res is entirely unknown, this program will fail to load as
+	 * the verifier will believe that max buf_sz value allows reading
+	 * past the end of entries in bpf_seq_write call
+	 */
+	bpf_seq_write(seq, &entries, buf_sz);
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/linked_funcs1.c b/tools/testing/selftests/bpf/progs/linked_funcs1.c
new file mode 100644
index 000000000000..b964ec1390c2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_funcs1.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+/* weak and shared between two files */
+const volatile int my_tid __weak;
+long syscall_id __weak;
+
+int output_val1;
+int output_ctx1;
+int output_weak1;
+
+/* same "subprog" name in all files, but it's ok because they all are static */
+static __noinline int subprog(int x)
+{
+	/* but different formula */
+	return x * 1;
+}
+
+/* Global functions can't be void */
+int set_output_val1(int x)
+{
+	output_val1 = x + subprog(x);
+	return x;
+}
+
+/* This function can't be verified as global, as it assumes raw_tp/sys_enter
+ * context and accesses syscall id (second argument). So we mark it as
+ * __hidden, so that libbpf will mark it as static in the final object file,
+ * right before verifying it in the kernel.
+ *
+ * But we don't mark it as __hidden here, rather at extern site. __hidden is
+ * "contaminating" visibility, so it will get propagated from either extern or
+ * actual definition (including from the losing __weak definition).
+ */
+void set_output_ctx1(__u64 *ctx)
+{
+	output_ctx1 = ctx[1]; /* long id, same as in BPF_PROG below */
+}
+
+/* this weak instance should win because it's the first one */
+__weak int set_output_weak(int x)
+{
+	output_weak1 = x;
+	return x;
+}
+
+extern int set_output_val2(int x);
+
+/* here we'll force set_output_ctx2() to be __hidden in the final obj file */
+__hidden extern void set_output_ctx2(__u64 *ctx);
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler1, struct pt_regs *regs, long id)
+{
+	if (my_tid != (u32)bpf_get_current_pid_tgid() || id != syscall_id)
+		return 0;
+
+	set_output_val2(1000);
+	set_output_ctx2(ctx); /* ctx definition is hidden in BPF_PROG macro */
+
+	/* keep input value the same across both files to avoid dependency on
+	 * handler call order; differentiate by output_weak1 vs output_weak2.
+	 */
+	set_output_weak(42);
+
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/linked_funcs2.c b/tools/testing/selftests/bpf/progs/linked_funcs2.c
new file mode 100644
index 000000000000..575e958e60b7
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_funcs2.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+/* weak and shared between both files */
+const volatile int my_tid __weak;
+long syscall_id __weak;
+
+int output_val2;
+int output_ctx2;
+int output_weak2; /* should stay zero */
+
+/* same "subprog" name in all files, but it's ok because they all are static */
+static __noinline int subprog(int x)
+{
+	/* but different formula */
+	return x * 2;
+}
+
+/* Global functions can't be void */
+int set_output_val2(int x)
+{
+	output_val2 = 2 * x + 2 * subprog(x);
+	return 2 * x;
+}
+
+/* This function can't be verified as global, as it assumes raw_tp/sys_enter
+ * context and accesses syscall id (second argument). So we mark it as
+ * __hidden, so that libbpf will mark it as static in the final object file,
+ * right before verifying it in the kernel.
+ *
+ * But we don't mark it as __hidden here, rather at extern site. __hidden is
+ * "contaminating" visibility, so it will get propagated from either extern or
+ * actual definition (including from the losing __weak definition).
+ */
+void set_output_ctx2(__u64 *ctx)
+{
+	output_ctx2 = ctx[1]; /* long id, same as in BPF_PROG below */
+}
+
+/* this weak instance should lose, because it will be processed second */
+__weak int set_output_weak(int x)
+{
+	output_weak2 = x;
+	return 2 * x;
+}
+
+extern int set_output_val1(int x);
+
+/* here we'll force set_output_ctx1() to be __hidden in the final obj file */
+__hidden extern void set_output_ctx1(__u64 *ctx);
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler2, struct pt_regs *regs, long id)
+{
+	if (my_tid != (u32)bpf_get_current_pid_tgid() || id != syscall_id)
+		return 0;
+
+	set_output_val1(2000);
+	set_output_ctx1(ctx); /* ctx definition is hidden in BPF_PROG macro */
+
+	/* keep input value the same across both files to avoid dependency on
+	 * handler call order; differentiate by output_weak1 vs output_weak2.
+	 */
+	set_output_weak(42);
+
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/linked_maps1.c b/tools/testing/selftests/bpf/progs/linked_maps1.c
new file mode 100644
index 000000000000..52291515cc72
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_maps1.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+struct my_key { long x; };
+struct my_value { long x; };
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__type(key, struct my_key);
+	__type(value, struct my_value);
+	__uint(max_entries, 16);
+} map1 SEC(".maps");
+
+ /* Matches map2 definition in linked_maps2.c. Order of the attributes doesn't
+  * matter.
+  */
+typedef struct {
+	__uint(max_entries, 8);
+	__type(key, int);
+	__type(value, int);
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+} map2_t;
+
+extern map2_t map2 SEC(".maps");
+
+/* This should be the winning map definition, but we have no way of verifying,
+ * so we just make sure that it links and works without errors
+ */
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__type(key, int);
+	__type(value, int);
+	__uint(max_entries, 16);
+} map_weak __weak SEC(".maps");
+
+int output_first1;
+int output_second1;
+int output_weak1;
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler_enter1)
+{
+	/* update values with key = 1 */
+	int key = 1, val = 1;
+	struct my_key key_struct = { .x = 1 };
+	struct my_value val_struct = { .x = 1000 };
+
+	bpf_map_update_elem(&map1, &key_struct, &val_struct, 0);
+	bpf_map_update_elem(&map2, &key, &val, 0);
+	bpf_map_update_elem(&map_weak, &key, &val, 0);
+
+	return 0;
+}
+
+SEC("raw_tp/sys_exit")
+int BPF_PROG(handler_exit1)
+{
+	/* lookup values with key = 2, set in another file */
+	int key = 2, *val;
+	struct my_key key_struct = { .x = 2 };
+	struct my_value *value_struct;
+
+	value_struct = bpf_map_lookup_elem(&map1, &key_struct);
+	if (value_struct)
+		output_first1 = value_struct->x;
+
+	val = bpf_map_lookup_elem(&map2, &key);
+	if (val)
+		output_second1 = *val;
+
+	val = bpf_map_lookup_elem(&map_weak, &key);
+	if (val)
+		output_weak1 = *val;
+	
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/linked_maps2.c b/tools/testing/selftests/bpf/progs/linked_maps2.c
new file mode 100644
index 000000000000..0693687474ed
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_maps2.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+/* modifiers and typedefs are ignored when comparing key/value types */
+typedef struct my_key { long x; } key_type;
+typedef struct my_value { long x; } value_type;
+
+extern struct {
+	__uint(max_entries, 16);
+	__type(key, key_type);
+	__type(value, value_type);
+	__uint(type, BPF_MAP_TYPE_HASH);
+} map1 SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__type(key, int);
+	__type(value, int);
+	__uint(max_entries, 8);
+} map2 SEC(".maps");
+
+/* this definition will lose, but it has to exactly match the winner */
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__type(key, int);
+	__type(value, int);
+	__uint(max_entries, 16);
+} map_weak __weak SEC(".maps");
+
+int output_first2;
+int output_second2;
+int output_weak2;
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler_enter2)
+{
+	/* update values with key = 2 */
+	int key = 2, val = 2;
+	key_type key_struct = { .x = 2 };
+	value_type val_struct = { .x = 2000 };
+
+	bpf_map_update_elem(&map1, &key_struct, &val_struct, 0);
+	bpf_map_update_elem(&map2, &key, &val, 0);
+	bpf_map_update_elem(&map_weak, &key, &val, 0);
+
+	return 0;
+}
+
+SEC("raw_tp/sys_exit")
+int BPF_PROG(handler_exit2)
+{
+	/* lookup values with key = 1, set in another file */
+	int key = 1, *val;
+	key_type key_struct = { .x = 1 };
+	value_type *value_struct;
+
+	value_struct = bpf_map_lookup_elem(&map1, &key_struct);
+	if (value_struct)
+		output_first2 = value_struct->x;
+
+	val = bpf_map_lookup_elem(&map2, &key);
+	if (val)
+		output_second2 = *val;
+
+	val = bpf_map_lookup_elem(&map_weak, &key);
+	if (val)
+		output_weak2 = *val;
+
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/linked_vars1.c b/tools/testing/selftests/bpf/progs/linked_vars1.c
new file mode 100644
index 000000000000..ef9e9d0bb0ca
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_vars1.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+extern int LINUX_KERNEL_VERSION __kconfig;
+/* this weak extern will be strict due to the other file's strong extern */
+extern bool CONFIG_BPF_SYSCALL __kconfig __weak;
+extern const void bpf_link_fops __ksym __weak;
+
+int input_bss1;
+int input_data1 = 1;
+const volatile int input_rodata1 = 11;
+
+int input_bss_weak __weak;
+/* these two definitions should win */
+int input_data_weak __weak = 10;
+const volatile int input_rodata_weak __weak = 100;
+
+extern int input_bss2;
+extern int input_data2;
+extern const int input_rodata2;
+
+int output_bss1;
+int output_data1;
+int output_rodata1;
+
+long output_sink1;
+
+static __noinline int get_bss_res(void)
+{
+	/* just make sure all the relocations work against .text as well */
+	return input_bss1 + input_bss2 + input_bss_weak;
+}
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler1)
+{
+	output_bss1 = get_bss_res();
+	output_data1 = input_data1 + input_data2 + input_data_weak;
+	output_rodata1 = input_rodata1 + input_rodata2 + input_rodata_weak;
+
+	/* make sure we actually use above special externs, otherwise compiler
+	 * will optimize them out
+	 */
+	output_sink1 = LINUX_KERNEL_VERSION
+		       + CONFIG_BPF_SYSCALL
+		       + (long)&bpf_link_fops;
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/linked_vars2.c b/tools/testing/selftests/bpf/progs/linked_vars2.c
new file mode 100644
index 000000000000..e4f5bd388a3c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/linked_vars2.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+extern int LINUX_KERNEL_VERSION __kconfig;
+/* when an extern is defined as both strong and weak, resulting symbol will be strong */
+extern bool CONFIG_BPF_SYSCALL __kconfig;
+extern const void __start_BTF __ksym;
+
+int input_bss2;
+int input_data2 = 2;
+const volatile int input_rodata2 = 22;
+
+int input_bss_weak __weak;
+/* these two weak variables should lose */
+int input_data_weak __weak = 20;
+const volatile int input_rodata_weak __weak = 200;
+
+extern int input_bss1;
+extern int input_data1;
+extern const int input_rodata1;
+
+int output_bss2;
+int output_data2;
+int output_rodata2;
+
+int output_sink2;
+
+static __noinline int get_data_res(void)
+{
+	/* just make sure all the relocations work against .text as well */
+	return input_data1 + input_data2 + input_data_weak;
+}
+
+SEC("raw_tp/sys_enter")
+int BPF_PROG(handler2)
+{
+	output_bss2 = input_bss1 + input_bss2 + input_bss_weak;
+	output_data2 = get_data_res();
+	output_rodata2 = input_rodata1 + input_rodata2 + input_rodata_weak;
+
+	/* make sure we actually use above special externs, otherwise compiler
+	 * will optimize them out
+	 */
+	output_sink2 = LINUX_KERNEL_VERSION
+		       + CONFIG_BPF_SYSCALL
+		       + (long)&__start_BTF;
+
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/map_ptr_kern.c b/tools/testing/selftests/bpf/progs/map_ptr_kern.c
index d8850bc6a9f1..d1d304c980f0 100644
--- a/tools/testing/selftests/bpf/progs/map_ptr_kern.c
+++ b/tools/testing/selftests/bpf/progs/map_ptr_kern.c
@@ -12,6 +12,7 @@ _Static_assert(MAX_ENTRIES < LOOP_BOUND, "MAX_ENTRIES must be < LOOP_BOUND");
 
 enum bpf_map_type g_map_type = BPF_MAP_TYPE_UNSPEC;
 __u32 g_line = 0;
+int page_size = 0; /* userspace should set it */
 
 #define VERIFY_TYPE(type, func) ({	\
 	g_map_type = type;		\
@@ -635,7 +636,6 @@ struct bpf_ringbuf_map {
 
 struct {
 	__uint(type, BPF_MAP_TYPE_RINGBUF);
-	__uint(max_entries, 1 << 12);
 } m_ringbuf SEC(".maps");
 
 static inline int check_ringbuf(void)
@@ -643,7 +643,7 @@ static inline int check_ringbuf(void)
 	struct bpf_ringbuf_map *ringbuf = (struct bpf_ringbuf_map *)&m_ringbuf;
 	struct bpf_map *map = (struct bpf_map *)&m_ringbuf;
 
-	VERIFY(check(&ringbuf->map, map, 0, 0, 1 << 12));
+	VERIFY(check(&ringbuf->map, map, 0, 0, page_size));
 
 	return 1;
 }
diff --git a/tools/testing/selftests/bpf/progs/sockmap_tcp_msg_prog.c b/tools/testing/selftests/bpf/progs/sockmap_tcp_msg_prog.c
index fdb4bf4408fa..eeaf6e75c9a2 100644
--- a/tools/testing/selftests/bpf/progs/sockmap_tcp_msg_prog.c
+++ b/tools/testing/selftests/bpf/progs/sockmap_tcp_msg_prog.c
@@ -8,18 +8,6 @@ int _version SEC("version") = 1;
 SEC("sk_msg1")
 int bpf_prog1(struct sk_msg_md *msg)
 {
-	void *data_end = (void *)(long) msg->data_end;
-	void *data = (void *)(long) msg->data;
-
-	char *d;
-
-	if (data + 8 > data_end)
-		return SK_DROP;
-
-	bpf_printk("data length %i\n", (__u64)msg->data_end - (__u64)msg->data);
-	d = (char *)data;
-	bpf_printk("hello sendmsg hook %i %i\n", d[0], d[1]);
-
 	return SK_PASS;
 }
 
diff --git a/tools/testing/selftests/bpf/progs/sockopt_sk.c b/tools/testing/selftests/bpf/progs/sockopt_sk.c
index d3597f81e6e9..8acdb99b5959 100644
--- a/tools/testing/selftests/bpf/progs/sockopt_sk.c
+++ b/tools/testing/selftests/bpf/progs/sockopt_sk.c
@@ -6,11 +6,8 @@
 #include <bpf/bpf_helpers.h>
 
 char _license[] SEC("license") = "GPL";
-__u32 _version SEC("version") = 1;
 
-#ifndef PAGE_SIZE
-#define PAGE_SIZE 4096
-#endif
+int page_size = 0; /* userspace should set it */
 
 #ifndef SOL_TCP
 #define SOL_TCP IPPROTO_TCP
@@ -90,7 +87,7 @@ int _getsockopt(struct bpf_sockopt *ctx)
 		 * program can only see the first PAGE_SIZE
 		 * bytes of data.
 		 */
-		if (optval_end - optval != PAGE_SIZE)
+		if (optval_end - optval != page_size)
 			return 0; /* EPERM, unexpected data size */
 
 		return 1;
@@ -161,7 +158,7 @@ int _setsockopt(struct bpf_sockopt *ctx)
 
 	if (ctx->level == SOL_IP && ctx->optname == IP_FREEBIND) {
 		/* Original optlen is larger than PAGE_SIZE. */
-		if (ctx->optlen != PAGE_SIZE * 2)
+		if (ctx->optlen != page_size * 2)
 			return 0; /* EPERM, unexpected data size */
 
 		if (optval + 1 > optval_end)
@@ -175,7 +172,7 @@ int _setsockopt(struct bpf_sockopt *ctx)
 		 * program can only see the first PAGE_SIZE
 		 * bytes of data.
 		 */
-		if (optval_end - optval != PAGE_SIZE)
+		if (optval_end - optval != page_size)
 			return 0; /* EPERM, unexpected data size */
 
 		return 1;
diff --git a/tools/testing/selftests/bpf/progs/test_mmap.c b/tools/testing/selftests/bpf/progs/test_mmap.c
index 4eb42cff5fe9..5a5cc19a15bf 100644
--- a/tools/testing/selftests/bpf/progs/test_mmap.c
+++ b/tools/testing/selftests/bpf/progs/test_mmap.c
@@ -9,7 +9,6 @@ char _license[] SEC("license") = "GPL";
 
 struct {
 	__uint(type, BPF_MAP_TYPE_ARRAY);
-	__uint(max_entries, 4096);
 	__uint(map_flags, BPF_F_MMAPABLE | BPF_F_RDONLY_PROG);
 	__type(key, __u32);
 	__type(value, char);
@@ -17,7 +16,6 @@ struct {
 
 struct {
 	__uint(type, BPF_MAP_TYPE_ARRAY);
-	__uint(max_entries, 512 * 4); /* at least 4 pages of data */
 	__uint(map_flags, BPF_F_MMAPABLE);
 	__type(key, __u32);
 	__type(value, __u64);
diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf.c b/tools/testing/selftests/bpf/progs/test_ringbuf.c
index 8ba9959b036b..6b3f288b7c63 100644
--- a/tools/testing/selftests/bpf/progs/test_ringbuf.c
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf.c
@@ -15,7 +15,6 @@ struct sample {
 
 struct {
 	__uint(type, BPF_MAP_TYPE_RINGBUF);
-	__uint(max_entries, 1 << 12);
 } ringbuf SEC(".maps");
 
 /* inputs */
diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c b/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
index edf3b6953533..197b86546dca 100644
--- a/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf_multi.c
@@ -15,7 +15,6 @@ struct sample {
 
 struct ringbuf_map {
 	__uint(type, BPF_MAP_TYPE_RINGBUF);
-	__uint(max_entries, 1 << 12);
 } ringbuf1 SEC(".maps"),
   ringbuf2 SEC(".maps");
 
@@ -31,6 +30,17 @@ struct {
 	},
 };
 
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
+	__uint(max_entries, 1);
+	__type(key, int);
+	__array(values, struct ringbuf_map);
+} ringbuf_hash SEC(".maps") = {
+	.values = {
+		[0] = &ringbuf1,
+	},
+};
+
 /* inputs */
 int pid = 0;
 int target_ring = 0;
diff --git a/tools/testing/selftests/bpf/progs/test_snprintf.c b/tools/testing/selftests/bpf/progs/test_snprintf.c
new file mode 100644
index 000000000000..951a0301c553
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_snprintf.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Google LLC. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char num_out[64] = {};
+long num_ret = 0;
+
+char ip_out[64] = {};
+long ip_ret = 0;
+
+char sym_out[64] = {};
+long sym_ret = 0;
+
+char addr_out[64] = {};
+long addr_ret = 0;
+
+char str_out[64] = {};
+long str_ret = 0;
+
+char over_out[6] = {};
+long over_ret = 0;
+
+char pad_out[10] = {};
+long pad_ret = 0;
+
+char noarg_out[64] = {};
+long noarg_ret = 0;
+
+long nobuf_ret = 0;
+
+extern const void schedule __ksym;
+
+SEC("raw_tp/sys_enter")
+int handler(const void *ctx)
+{
+	/* Convenient values to pretty-print */
+	const __u8 ex_ipv4[] = {127, 0, 0, 1};
+	const __u8 ex_ipv6[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
+	static const char str1[] = "str1";
+	static const char longstr[] = "longstr";
+
+	/* Integer types */
+	num_ret  = BPF_SNPRINTF(num_out, sizeof(num_out),
+				"%d %u %x %li %llu %lX",
+				-8, 9, 150, -424242, 1337, 0xDABBAD00);
+	/* IP addresses */
+	ip_ret   = BPF_SNPRINTF(ip_out, sizeof(ip_out), "%pi4 %pI6",
+				&ex_ipv4, &ex_ipv6);
+	/* Symbol lookup formatting */
+	sym_ret  = BPF_SNPRINTF(sym_out,  sizeof(sym_out), "%ps %pS %pB",
+				&schedule, &schedule, &schedule);
+	/* Kernel pointers */
+	addr_ret = BPF_SNPRINTF(addr_out, sizeof(addr_out), "%pK %px %p",
+				0, 0xFFFF00000ADD4E55, 0xFFFF00000ADD4E55);
+	/* Strings embedding */
+	str_ret  = BPF_SNPRINTF(str_out, sizeof(str_out), "%s %+05s",
+				str1, longstr);
+	/* Overflow */
+	over_ret = BPF_SNPRINTF(over_out, sizeof(over_out), "%%overflow");
+	/* Padding of fixed width numbers */
+	pad_ret = BPF_SNPRINTF(pad_out, sizeof(pad_out), "%5d %0900000X", 4, 4);
+	/* No args */
+	noarg_ret = BPF_SNPRINTF(noarg_out, sizeof(noarg_out), "simple case");
+	/* No buffer */
+	nobuf_ret = BPF_SNPRINTF(NULL, 0, "only interested in length %d", 60);
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/test_snprintf_single.c b/tools/testing/selftests/bpf/progs/test_snprintf_single.c
new file mode 100644
index 000000000000..402adaf344f9
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_snprintf_single.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Google LLC. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+/* The format string is filled from the userspace such that loading fails */
+static const char fmt[10];
+
+SEC("raw_tp/sys_enter")
+int handler(const void *ctx)
+{
+	unsigned long long arg = 42;
+
+	bpf_snprintf(NULL, 0, fmt, &arg, sizeof(arg));
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
index ba6eadfec565..e7b673117436 100644
--- a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
@@ -396,7 +396,7 @@ int _ip6vxlan_get_tunnel(struct __sk_buff *skb)
 SEC("geneve_set_tunnel")
 int _geneve_set_tunnel(struct __sk_buff *skb)
 {
-	int ret, ret2;
+	int ret;
 	struct bpf_tunnel_key key;
 	struct geneve_opt gopt;
 
diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
index e87c8546230e..ee7e3b45182a 100644
--- a/tools/testing/selftests/bpf/test_progs.h
+++ b/tools/testing/selftests/bpf/test_progs.h
@@ -210,7 +210,7 @@ extern int test__join_cgroup(const char *path);
 #define ASSERT_ERR_PTR(ptr, name) ({					\
 	static int duration = 0;					\
 	const void *___res = (ptr);					\
-	bool ___ok = IS_ERR(___res)					\
+	bool ___ok = IS_ERR(___res);					\
 	CHECK(!___ok, (name), "unexpected pointer: %p\n", ___res);	\
 	___ok;								\
 })
diff --git a/tools/testing/selftests/bpf/verifier/bpf_get_stack.c b/tools/testing/selftests/bpf/verifier/bpf_get_stack.c
index 69b048cf46d9..3e024c891178 100644
--- a/tools/testing/selftests/bpf/verifier/bpf_get_stack.c
+++ b/tools/testing/selftests/bpf/verifier/bpf_get_stack.c
@@ -42,3 +42,46 @@
 	.result = ACCEPT,
 	.prog_type = BPF_PROG_TYPE_TRACEPOINT,
 },
+{
+	"bpf_get_task_stack return R0 range is refined",
+	.insns = {
+	BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
+	BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_6, 0), // ctx->meta->seq
+	BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_1, 8), // ctx->task
+	BPF_LD_MAP_FD(BPF_REG_1, 0), // fixup_map_array_48b
+	BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0, 2),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_0),
+	BPF_MOV64_REG(BPF_REG_9, BPF_REG_0), // keep buf for seq_write
+	BPF_MOV64_IMM(BPF_REG_3, 48),
+	BPF_MOV64_IMM(BPF_REG_4, 0),
+	BPF_EMIT_CALL(BPF_FUNC_get_task_stack),
+	BPF_JMP_IMM(BPF_JSGT, BPF_REG_0, 0, 2),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_9),
+	BPF_MOV64_REG(BPF_REG_3, BPF_REG_0),
+	BPF_EMIT_CALL(BPF_FUNC_seq_write),
+
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+	.prog_type = BPF_PROG_TYPE_TRACING,
+	.expected_attach_type = BPF_TRACE_ITER,
+	.kfunc = "task",
+	.runs = -1, // Don't run, just load
+	.fixup_map_array_48b = { 3 },
+},
diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk
index a5ce26d548e4..9a41d8bb9ff1 100644
--- a/tools/testing/selftests/lib.mk
+++ b/tools/testing/selftests/lib.mk
@@ -1,6 +1,10 @@
 # This mimics the top-level Makefile. We do it explicitly here so that this
 # Makefile can operate with or without the kbuild infrastructure.
+ifneq ($(LLVM),)
+CC := clang
+else
 CC := $(CROSS_COMPILE)gcc
+endif
 
 ifeq (0,$(MAKELEVEL))
     ifeq ($(OUTPUT),)