From 675b4e24bc50f4600b6bf3527fdbaa1f73498334 Mon Sep 17 00:00:00 2001 From: "Jose E. Marchesi" <jose.marchesi@oracle.com> Date: Tue, 7 May 2024 11:50:11 +0200 Subject: [PATCH] bpf: Temporarily define BPF_NO_PRESEVE_ACCESS_INDEX for GCC The vmlinux.h file generated by bpftool makes use of compiler pragmas in order to install the CO-RE preserve_access_index in all the struct types derived from the BTF info: #ifndef __VMLINUX_H__ #define __VMLINUX_H__ #ifndef BPF_NO_PRESERVE_ACCESS_INDEX #pragma clang attribute push (__attribute__((preserve_access_index)), apply_t = record #endif [... type definitions generated from kernel BTF ... ] #ifndef BPF_NO_PRESERVE_ACCESS_INDEX #pragma clang attribute pop #endif The `clang attribute push/pop' pragmas are specific to clang/llvm and are not supported by GCC. At the moment the BTF dumping services in libbpf do not support dicriminating between types dumped because they are directly referred and types dumped because they are dependencies. A suitable API is being worked now. See [1] and [2]. In the interim, this patch changes the selftests/bpf Makefile so it passes -DBPF_NO_PRESERVE_ACCESS_INDEX to GCC when it builds the selftests. This workaround is temporary, and may have an impact on the results of the GCC-built tests. [1] https://lore.kernel.org/bpf/20240503111836.25275-1-jose.marchesi@oracle.com/T/#u [2] https://lore.kernel.org/bpf/20240504205510.24785-1-jose.marchesi@oracle.com/T/#u Tested in bpf-next master. No regressions. Signed-off-by: Jose E. Marchesi <jose.marchesi@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240507095011.15867-1-jose.marchesi@oracle.com --- tools/testing/selftests/bpf/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 5d9c906bc3cba..f0c429cf44245 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -431,7 +431,7 @@ endef # Build BPF object using GCC define GCC_BPF_BUILD_RULE $(call msg,GCC-BPF,$(TRUNNER_BINARY),$2) - $(Q)$(BPF_GCC) $3 -Wno-attributes -O2 -c $1 -o $2 + $(Q)$(BPF_GCC) $3 -DBPF_NO_PRESERVE_ACCESS_INDEX -Wno-attributes -O2 -c $1 -o $2 endef SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c -- GitLab