selftests: bpf: makefile support sub-register code-gen test mode

This patch enables testing some eBPF programs under sub-register
compilation mode.

Only enable this when there is BPF_JMP32 support on both LLVM and kernel.
This is because only after BPF_JMP32 added, code-gen for complex program
under sub-register mode will be clean enough to pass verification.

This patch splits TEST_GEN_FILES into BPF_OBJ_FILES and
BPF_OBJ_FILES_DUAL_COMPILE. The latter are those objects we would like to
compile for both default and sub-register mode. They are also objects used
by "test_progs".
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/Makefile

@@ -10,15 +10,14 @@ ifneq ($(wildcard $(GENHDR)),)
   GENFLAGS := -DHAVE_GENHDR
 endif
 
+CLANG		?= clang
+LLC		?= llc
+LLVM_OBJCOPY	?= llvm-objcopy
+LLVM_READELF	?= llvm-readelf
+BTF_PAHOLE	?= pahole
 CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(BPFDIR) -I$(GENDIR) $(GENFLAGS) -I../../../include
 LDLIBS += -lcap -lelf -lrt -lpthread
 
-TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read
-all: $(TEST_CUSTOM_PROGS)
-
-$(TEST_CUSTOM_PROGS): $(OUTPUT)/%: %.c
-	$(CC) -o $(TEST_CUSTOM_PROGS) -static $< -Wl,--build-id
-
 # 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_align test_verifier_log test_dev_cgroup test_tcpbpf_user \
@@ -26,21 +25,42 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_socket_cookie test_cgroup_storage test_select_reuseport test_section_names \
 	test_netcnt test_tcpnotify_user
 
-TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \
-	test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o     \
-	sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \
-	test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \
-	test_tcpnotify_kern.o \
-	sample_map_ret0.o test_tcpbpf_kern.o test_stacktrace_build_id.o \
-	sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o test_adjust_tail.o \
-	test_btf_haskv.o test_btf_nokv.o test_sockmap_kern.o test_tunnel_kern.o \
-	test_get_stack_rawtp.o test_sockmap_kern.o test_sockhash_kern.o \
-	test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
+BPF_OBJ_FILES = \
+	test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \
+	sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o \
+	test_tcpnotify_kern.o sample_map_ret0.o test_tcpbpf_kern.o \
+	sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o \
+	test_btf_haskv.o test_btf_nokv.o test_sockmap_kern.o \
+	test_tunnel_kern.o test_sockhash_kern.o test_lwt_seg6local.o \
+	sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
 	get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \
-	test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o \
-	test_sk_lookup_kern.o test_xdp_vlan.o test_queue_map.o test_stack_map.o \
+	test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o test_xdp_vlan.o \
 	xdp_dummy.o test_map_in_map.o
 
+# Objects are built with default compilation flags and with sub-register
+# code-gen enabled.
+BPF_OBJ_FILES_DUAL_COMPILE = \
+	test_pkt_access.o test_pkt_access.o test_xdp.o test_adjust_tail.o \
+	test_l4lb.o test_l4lb_noinline.o test_xdp_noinline.o test_tcp_estats.o \
+	test_obj_id.o test_pkt_md_access.o test_tracepoint.o \
+	test_stacktrace_map.o test_stacktrace_map.o test_stacktrace_build_id.o \
+	test_stacktrace_build_id.o test_get_stack_rawtp.o \
+	test_get_stack_rawtp.o test_tracepoint.o test_sk_lookup_kern.o \
+	test_queue_map.o test_stack_map.o
+
+TEST_GEN_FILES = $(BPF_OBJ_FILES) $(BPF_OBJ_FILES_DUAL_COMPILE)
+
+# Also test sub-register code-gen if LLVM + kernel both has eBPF v3 processor
+# support which is the first version to contain both ALU32 and JMP32
+# instructions.
+SUBREG_CODEGEN := $(shell echo "int cal(int a) { return a > 0; }" | \
+			$(CLANG) -target bpf -O2 -emit-llvm -S -x c - -o - | \
+			$(LLC) -mattr=+alu32 -mcpu=probe 2>&1 | \
+			grep 'if w')
+ifneq ($(SUBREG_CODEGEN),)
+TEST_GEN_FILES += $(patsubst %.o,alu32/%.o, $(BPF_OBJ_FILES_DUAL_COMPILE))
+endif
+
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \
 	test_libbpf.sh \
@@ -65,6 +85,13 @@ TEST_GEN_PROGS_EXTENDED = test_libbpf_open test_sock_addr test_skb_cgroup_id_use
 
 include ../lib.mk
 
+# NOTE: $(OUTPUT) won't get default value if used before lib.mk
+TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read
+all: $(TEST_CUSTOM_PROGS)
+
+$(OUTPUT)/urandom_read: $(OUTPUT)/%: %.c
+	$(CC) -o $@ -static $< -Wl,--build-id
+
 BPFOBJ := $(OUTPUT)/libbpf.a
 
 $(TEST_GEN_PROGS): $(BPFOBJ)
@@ -92,12 +119,6 @@ force:
 $(BPFOBJ): force
 	$(MAKE) -C $(BPFDIR) OUTPUT=$(OUTPUT)/
 
-CLANG ?= clang
-LLC   ?= llc
-LLVM_OBJCOPY ?= llvm-objcopy
-LLVM_READELF ?= llvm-readelf
-BTF_PAHOLE ?= pahole
-
 PROBE := $(shell $(LLC) -march=bpf -mcpu=probe -filetype=null /dev/null 2>&1)
 
 # Let newer LLVM versions transparently probe the kernel for availability
@@ -149,6 +170,30 @@ endif
 endif
 endif
 
+ifneq ($(SUBREG_CODEGEN),)
+ALU32_BUILD_DIR = $(OUTPUT)/alu32
+TEST_CUSTOM_PROGS += $(ALU32_BUILD_DIR)/test_progs_32
+$(ALU32_BUILD_DIR):
+	mkdir -p $@
+
+$(ALU32_BUILD_DIR)/urandom_read: $(OUTPUT)/urandom_read
+	cp $< $@
+
+$(ALU32_BUILD_DIR)/test_progs_32: test_progs.c $(ALU32_BUILD_DIR) \
+						$(ALU32_BUILD_DIR)/urandom_read
+	$(CC) $(CFLAGS) -o $(ALU32_BUILD_DIR)/test_progs_32 $< \
+		trace_helpers.c $(OUTPUT)/libbpf.a $(LDLIBS)
+
+$(ALU32_BUILD_DIR)/%.o: %.c $(ALU32_BUILD_DIR) $(ALU32_BUILD_DIR)/test_progs_32
+	$(CLANG) $(CLANG_FLAGS) \
+		 -O2 -target bpf -emit-llvm -c $< -o - |      \
+	$(LLC) -march=bpf -mattr=+alu32 -mcpu=$(CPU) $(LLC_FLAGS) \
+		-filetype=obj -o $@
+ifeq ($(DWARF2BTF),y)
+	$(BTF_PAHOLE) -J $@
+endif
+endif
+
 # Have one program compiled without "-target bpf" to test whether libbpf loads
 # it successfully
 $(OUTPUT)/test_xdp.o: test_xdp.c
@@ -167,4 +212,4 @@ ifeq ($(DWARF2BTF),y)
 	$(BTF_PAHOLE) -J $@
 endif
 
-EXTRA_CLEAN := $(TEST_CUSTOM_PROGS)
+EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) $(ALU32_BUILD_DIR)