[RFC PATCH bpf-next 13/13] selftests/bpf: Add a cpuv4 test runner for cpu=v4 testing

[Yonghong Song <yhs@fb.com>]

Similar to no-alu32 runner, a cpuv4 runner is created to test
bpf programs compiled with -mcpu=v4.

The following are some num-of-insn statistics for each newer
instructions, excluding naked asm (verifier_*) tests:
   insn pattern                # of instructions
   reg = (s8)reg               4
   reg = (s16)reg              2
   reg = (s32)reg              26
   reg = *(s8 *)(reg + off)    11
   reg = *(s16 *)(reg + off)   14
   reg = *(s32 *)(reg + off)   15214
   reg = bswap16 reg           133
   reg = bswap32 reg           38
   reg = bswap64 reg           14
   reg s/= reg                 0
   reg s%= reg                 0
   gotol <offset>              58

Note that in llvm -mcpu=v4 implementation, the compiler is a little
bit conservative about generating 'gotol' insn (32-bit branch offset)
as it didn't precise count the number of insns (e.g., some insns are
debug insns, etc.). Compared to old 'goto' insn, newer 'gotol' insn
should have comparable verification states to 'goto' insn.

I did not collect verifier stats now since I have not really
started to do proper range bound estimation with these
instructions.

With current patch set, all selftests passed with -mcpu=v4
when running test_progs-cpuv4 binary.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 tools/testing/selftests/bpf/Makefile | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 538df8fb8c42..5f901cb0df59 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -40,7 +40,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_sock test_sockmap get_cgroup_id_user \
 	test_cgroup_storage \
 	test_tcpnotify_user test_sysctl \
-	test_progs-no_alu32
+	test_progs-no_alu32 test_progs-cpuv4
 
 # Also test bpf-gcc, if present
 ifneq ($(BPF_GCC),)
@@ -379,6 +379,11 @@ define CLANG_NOALU32_BPF_BUILD_RULE
 	$(call msg,CLNG-BPF,$(TRUNNER_BINARY),$2)
 	$(Q)$(CLANG) $3 -O2 -target bpf -c $1 -mcpu=v2 -o $2
 endef
+# Similar to CLANG_BPF_BUILD_RULE, but with cpu-v4
+define CLANG_CPUV4_BPF_BUILD_RULE
+	$(call msg,CLNG-BPF,$(TRUNNER_BINARY),$2)
+	$(Q)$(CLANG) $3 -O2 -target bpf -c $1 -mcpu=v4 -o $2
+endef
 # Build BPF object using GCC
 define GCC_BPF_BUILD_RULE
 	$(call msg,GCC-BPF,$(TRUNNER_BINARY),$2)
@@ -421,7 +426,7 @@ LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.c,$(foreach skel,$(LINKED_SKELS),$($(ske
 # $eval()) and pass control to DEFINE_TEST_RUNNER_RULES.
 # Parameters:
 # $1 - test runner base binary name (e.g., test_progs)
-# $2 - test runner extra "flavor" (e.g., no_alu32, gcc-bpf, etc)
+# $2 - test runner extra "flavor" (e.g., no_alu32, cpuv4, gcc-bpf, etc)
 define DEFINE_TEST_RUNNER
 
 TRUNNER_OUTPUT := $(OUTPUT)$(if $2,/)$2
@@ -449,7 +454,7 @@ endef
 # Using TRUNNER_XXX variables, provided by callers of DEFINE_TEST_RUNNER and
 # set up by DEFINE_TEST_RUNNER itself, create test runner build rules with:
 # $1 - test runner base binary name (e.g., test_progs)
-# $2 - test runner extra "flavor" (e.g., no_alu32, gcc-bpf, etc)
+# $2 - test runner extra "flavor" (e.g., no_alu32, cpuv4, gcc-bpf, etc)
 define DEFINE_TEST_RUNNER_RULES
 
 ifeq ($($(TRUNNER_OUTPUT)-dir),)
@@ -580,6 +585,11 @@ TRUNNER_BPF_BUILD_RULE := CLANG_NOALU32_BPF_BUILD_RULE
 TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)
 $(eval $(call DEFINE_TEST_RUNNER,test_progs,no_alu32))
 
+# Define test_progs-cpuv4 test runner.
+TRUNNER_BPF_BUILD_RULE := CLANG_CPUV4_BPF_BUILD_RULE
+TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)
+$(eval $(call DEFINE_TEST_RUNNER,test_progs,cpuv4))
+
 # Define test_progs BPF-GCC-flavored test runner.
 ifneq ($(BPF_GCC),)
 TRUNNER_BPF_BUILD_RULE := GCC_BPF_BUILD_RULE
@@ -674,7 +684,7 @@ EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)	\
 	prog_tests/tests.h map_tests/tests.h verifier/tests.h		\
 	feature bpftool							\
 	$(addprefix $(OUTPUT)/,*.o *.skel.h *.lskel.h *.subskel.h	\
-			       no_alu32 bpf_gcc bpf_testmod.ko		\
+			       no_alu32 cpuv4 bpf_gcc bpf_testmod.ko	\
 			       liburandom_read.so)
 
 .PHONY: docs docs-clean
-- 
2.34.1