[PATCH bpf-next v3 1/8] selftests/bpf: Build callx tests with GCC that defines __BPF_FEATURE_CALLX

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

Commit 7cd1f73b37ea ("selftests/bpf: Fix build of callx tests with GCC")
gated the callx progs on __clang__. GCC had indirect call support which was
recently refurbished along with a __BPF_FEATURE_CALLX macro [1], so gate
on that as well so once this GCC is released, the tests start passing.

Put the arch and compiler conditions in a CAN_USE_CALLX macro in
bpf_misc.h, and use it in all the test programs.

While at it, mark the placeholder programs left for unsupported
toolchains and arches with __skip(), so they report SKIP rather than OK.

[1] https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=ffe3ead4a8ad704b557b0cfa4f823df647c65a0d

Measured on bpf-next with a stock bpf-gcc that defines
__BPF_FEATURE_CALLX, test_progs before and after: 79 subtests run that
previously did not exist in the report, 78 OK and one @unpriv SKIP,
with no failures.  The two dummy placeholders retire and
callx_rodata_lskel goes SKIP -> OK.

Signed-off-by: Vineet Gupta <vineet.gupta@linux.dev>
---
 .../testing/selftests/bpf/prog_tests/callx_rodata_lskel.c  | 2 +-
 tools/testing/selftests/bpf/progs/bpf_misc.h               | 7 +++++++
 tools/testing/selftests/bpf/progs/callx_rodata.c           | 4 ++--
 tools/testing/selftests/bpf/progs/verifier_callx.c         | 5 ++---
 tools/testing/selftests/bpf/progs/verifier_callx_rodata.c  | 5 ++---
 5 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/callx_rodata_lskel.c b/tools/testing/selftests/bpf/prog_tests/callx_rodata_lskel.c
index f6ef67c3141e..acd821fb568f 100644
--- a/tools/testing/selftests/bpf/prog_tests/callx_rodata_lskel.c
+++ b/tools/testing/selftests/bpf/prog_tests/callx_rodata_lskel.c
@@ -36,7 +36,7 @@ static void __test_callx_rodata_lskel(void)
 	if (!ASSERT_OK_PTR(skel, "open"))
 		return;
 
-	/* gcc doesn't support indirect calls */
+	/* toolchain or JIT can't do callx */
 	if (skel->rodata->skip) {
 		test__skip();
 		goto out;
diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h
index d7f706c3bc4a..1b264480e128 100644
--- a/tools/testing/selftests/bpf/progs/bpf_misc.h
+++ b/tools/testing/selftests/bpf/progs/bpf_misc.h
@@ -295,6 +295,13 @@
 #define CAN_USE_LOAD_ACQ_STORE_REL
 #endif
 
+/* clang always emits callx, gcc only when it defines __BPF_FEATURE_CALLX */
+#if (defined(__TARGET_ARCH_arm64) || defined(__TARGET_ARCH_x86) ||	\
+     (defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64)) &&		\
+	(defined(__clang__) || defined(__BPF_FEATURE_CALLX))
+#define CAN_USE_CALLX
+#endif
+
 #if defined(__TARGET_ARCH_arm64) || defined(__TARGET_ARCH_x86)
 #define SPEC_V1
 #endif
diff --git a/tools/testing/selftests/bpf/progs/callx_rodata.c b/tools/testing/selftests/bpf/progs/callx_rodata.c
index e3f8335f80f8..8c28f01b7113 100644
--- a/tools/testing/selftests/bpf/progs/callx_rodata.c
+++ b/tools/testing/selftests/bpf/progs/callx_rodata.c
@@ -4,13 +4,14 @@
 #include <stdbool.h>
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
 
 /* set by user space before the programs are loaded, it's in .rodata too */
 const volatile int bias = 1;
 
 int op_idx;
 
-#ifdef __clang__
+#ifdef CAN_USE_CALLX
 
 const volatile bool skip = false;
 
@@ -48,7 +49,6 @@ int both_ops(void *ctx)
 
 #else
 
-/* gcc doesn't support indirect calls */
 const volatile bool skip = true;
 
 SEC("socket")
diff --git a/tools/testing/selftests/bpf/progs/verifier_callx.c b/tools/testing/selftests/bpf/progs/verifier_callx.c
index 7e59188d9fca..ca1aef34ab72 100644
--- a/tools/testing/selftests/bpf/progs/verifier_callx.c
+++ b/tools/testing/selftests/bpf/progs/verifier_callx.c
@@ -6,9 +6,7 @@
 #include "bpf_misc.h"
 #include "../../../include/linux/filter.h"
 
-/* gcc doesn't support indirect calls */
-#if defined(__clang__) && (defined(__TARGET_ARCH_x86) || defined(__TARGET_ARCH_arm64) || \
-    (defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64))
+#ifdef CAN_USE_CALLX
 
 #define CALLX_INSN(DST, SRC, OFF, IMM) \
 	BPF_RAW_INSN(BPF_JMP | BPF_CALL | BPF_X, DST, SRC, OFF, IMM)
@@ -1075,6 +1073,7 @@ int callx_c_ops_on_stack(void *ctx)
 #else
 
 SEC("socket")
+__skip("callx needs arch JIT and compiler support")
 __success
 int dummy(void *ctx)
 {
diff --git a/tools/testing/selftests/bpf/progs/verifier_callx_rodata.c b/tools/testing/selftests/bpf/progs/verifier_callx_rodata.c
index b2ee0c8e042b..642071fa7498 100644
--- a/tools/testing/selftests/bpf/progs/verifier_callx_rodata.c
+++ b/tools/testing/selftests/bpf/progs/verifier_callx_rodata.c
@@ -6,9 +6,7 @@
 #include "bpf_misc.h"
 #include "../../../include/linux/filter.h"
 
-/* gcc doesn't support indirect calls */
-#if defined(__clang__) && (defined(__TARGET_ARCH_x86) || defined(__TARGET_ARCH_arm64) || \
-    (defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64))
+#ifdef CAN_USE_CALLX
 
 /*
  * Read-only data with pointers to functions, where the compiler puts tables
@@ -992,6 +990,7 @@ int callx_c_packed_struct(void *ctx)
 #else
 
 SEC("socket")
+__skip("callx needs arch JIT and compiler support")
 __success
 int dummy(void *ctx)
 {
-- 
2.53.0-Meta