[PATCH bpf-next 3/3] selftests/bpf: Enable some of the blocked cpuv4 instruction tests for bpf-gcc

[Vineet Gupta <vineet.gupta@linux.dev>]

A bunch of tests are gated behind clang only __clang_major__ and thus
fail to build under BPF_GCC. What's worse is, before the prev patch they
were also declared as passing/OK.

This need not be because (a) bpf-gcc does support the feature in codegen
and (b) also advertises correctly with feature support preprocessor macros:

  __BPF_FEATURE_BSWAP, __BPF_FEATURE_GOTOL, __BPF_FEATURE_LDSX,
  __BPF_FEATURE_MOVSX, __BPF_FEATURE_SDIV_SMOD, __BPF_FEATURE_ST

So loosen up the gates to also add specific feature check.
clang >=18 has to stay, despite it being true for so long: clang only
defines __BPF_FEATURE_MOVSX and friends at -mcpu=v4, but assembles the
inline asm at -mcpu=v3 too, and dropping it would remove these tests from
the default test_progs flavour where they run today.

Since bpf-gcc doesn't support addr_space_cast, wrap the corresponding
tests under __BPF_FEATURE_ADDR_SPACE_CAST to skip under it.
And also move the map under that guard so that a bpf-gcc object does not
declare an arena map that no program in it references.

Recovered under BPF_GCC (programs per object, was 1 dummy each):

  verifier_sdiv    80
  verifier_movsx   17
  verifier_ldsx    14   (20 under clang; 5 arena tests,
                       kfunc_root and the arena map stay clang-only)
  verifier_bswap   13

CAN_USE_GOTOL and CAN_USE_BPF_ST only gate parts of a file, so those were
not dummies to begin with:

  compute_live_registers        17 -> 19  (21 under clang)
  verifier_gotol                 1 -> 2
  verifier_iterating_callbacks  34 -> 35

The clang builds are unchanged: verifier_ldsx still emits 20 programs under
the cpuv4 flavour.

One thing left alone: verifier_load_acquire.c and verifier_store_release.c
stay clang-only, and their gates are correct as gas doesn't implement
those (experimental -mxbpf not implemented at all). FWIW LLVM groups
those under -mcpu=v4 and defines __BPF_FEATURE_LOAD_ACQ_STORE_REL there.

Signed-off-by: Vineet Gupta <vineet.gupta@linux.dev>
---
 tools/testing/selftests/bpf/progs/bpf_misc.h   |  4 ++--
 .../bpf/progs/compute_live_registers.c         |  7 +++++++
 .../selftests/bpf/progs/verifier_bswap.c       |  2 +-
 .../selftests/bpf/progs/verifier_ldsx.c        | 18 +++++++++++-------
 .../selftests/bpf/progs/verifier_movsx.c       |  2 +-
 .../selftests/bpf/progs/verifier_sdiv.c        |  2 +-
 6 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h
index 88b0bfba83bb..eb88d9ce6c34 100644
--- a/tools/testing/selftests/bpf/progs/bpf_misc.h
+++ b/tools/testing/selftests/bpf/progs/bpf_misc.h
@@ -261,11 +261,11 @@
      (defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64) ||		\
      defined(__TARGET_ARCH_arm) || defined(__TARGET_ARCH_s390) ||	\
      defined(__TARGET_ARCH_loongarch)) &&				\
-	__clang_major__ >= 18
+	(__clang_major__ >= 18 || defined(__BPF_FEATURE_GOTOL))
 #define CAN_USE_GOTOL
 #endif
 
-#if __clang_major__ >= 18
+#if __clang_major__ >= 18 || defined(__BPF_FEATURE_ST)
 #define CAN_USE_BPF_ST
 #endif
 
diff --git a/tools/testing/selftests/bpf/progs/compute_live_registers.c b/tools/testing/selftests/bpf/progs/compute_live_registers.c
index 338e67cd8856..c7d5a0abff2c 100644
--- a/tools/testing/selftests/bpf/progs/compute_live_registers.c
+++ b/tools/testing/selftests/bpf/progs/compute_live_registers.c
@@ -299,7 +299,14 @@ __naked void gotol(void)
 		"r3 = 24;"
 		"if r1 > 0x7 goto +2;"
 		"r0 = r2;"
+#ifdef __clang__
 		"gotol +1;"
+#else
+		/* gas mis-parses 'gotol +1' as 'goto l+1', same encoding
+		 * without the sign (binutils PR gas/34558).
+		 */
+		"gotol 1;"
+#endif
 		"r0 = r3;"
 		"exit;"
 		:
diff --git a/tools/testing/selftests/bpf/progs/verifier_bswap.c b/tools/testing/selftests/bpf/progs/verifier_bswap.c
index 074faef5480e..48ffb5b242d2 100644
--- a/tools/testing/selftests/bpf/progs/verifier_bswap.c
+++ b/tools/testing/selftests/bpf/progs/verifier_bswap.c
@@ -8,7 +8,7 @@
 	(defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64) || \
 	defined(__TARGET_ARCH_arm) || defined(__TARGET_ARCH_s390) || \
 	defined(__TARGET_ARCH_loongarch)) && \
-	__clang_major__ >= 18
+	(__clang_major__ >= 18 || defined(__BPF_FEATURE_BSWAP))
 
 SEC("socket")
 __description("BSWAP, 16")
diff --git a/tools/testing/selftests/bpf/progs/verifier_ldsx.c b/tools/testing/selftests/bpf/progs/verifier_ldsx.c
index e58ea69e3854..75762e11b443 100644
--- a/tools/testing/selftests/bpf/progs/verifier_ldsx.c
+++ b/tools/testing/selftests/bpf/progs/verifier_ldsx.c
@@ -9,13 +9,7 @@
 	(defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64) || \
 	defined(__TARGET_ARCH_arm) || defined(__TARGET_ARCH_s390) || \
 	defined(__TARGET_ARCH_loongarch)) && \
-	__clang_major__ >= 18
-
-struct {
-	__uint(type, BPF_MAP_TYPE_ARENA);
-	__uint(map_flags, BPF_F_MMAPABLE);
-	__uint(max_entries, 1);
-} arena SEC(".maps");
+	(__clang_major__ >= 18 || defined(__BPF_FEATURE_LDSX))
 
 SEC("socket")
 __description("LDSX, S8")
@@ -263,6 +257,14 @@ __naked void ldsx_ctx_8(void)
 	: __clobber_all);
 }
 
+#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARENA);
+	__uint(map_flags, BPF_F_MMAPABLE);
+	__uint(max_entries, 1);
+} arena SEC(".maps");
+
 SEC("syscall")
 __description("Arena LDSX Disasm")
 __success
@@ -432,6 +434,8 @@ void kfunc_root(void)
 	bpf_arena_alloc_pages(0, 0, 0, 0, 0);
 }
 
+#endif /* __BPF_FEATURE_ADDR_SPACE_CAST */
+
 #else
 
 SEC("socket")
diff --git a/tools/testing/selftests/bpf/progs/verifier_movsx.c b/tools/testing/selftests/bpf/progs/verifier_movsx.c
index 5559c0583dd1..195b27a51224 100644
--- a/tools/testing/selftests/bpf/progs/verifier_movsx.c
+++ b/tools/testing/selftests/bpf/progs/verifier_movsx.c
@@ -8,7 +8,7 @@
 	(defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64) || \
 	defined(__TARGET_ARCH_arm) || defined(__TARGET_ARCH_s390) || \
 	defined(__TARGET_ARCH_loongarch)) && \
-	__clang_major__ >= 18
+	(__clang_major__ >= 18 || defined(__BPF_FEATURE_MOVSX))
 
 SEC("socket")
 __description("MOV32SX, S8")
diff --git a/tools/testing/selftests/bpf/progs/verifier_sdiv.c b/tools/testing/selftests/bpf/progs/verifier_sdiv.c
index 515644ace516..d6cbe1e27fd6 100644
--- a/tools/testing/selftests/bpf/progs/verifier_sdiv.c
+++ b/tools/testing/selftests/bpf/progs/verifier_sdiv.c
@@ -9,7 +9,7 @@
 	(defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64) || \
 	defined(__TARGET_ARCH_arm) || defined(__TARGET_ARCH_s390) || \
 	defined(__TARGET_ARCH_loongarch)) && \
-	__clang_major__ >= 18
+	(__clang_major__ >= 18 || defined(__BPF_FEATURE_SDIV_SMOD))
 
 SEC("socket")
 __description("SDIV32, non-zero imm divisor, check 1")
-- 
2.53.0-Meta