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Temporary patches for GCC BPF (#333)
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‎ci/diffs/2001-selftests-bpf-add-fno-strict-aliasing-to-BPF_CFLAGS.patch‎

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From f44275e7155dc310d36516fc25be503da099781c Mon Sep 17 00:00:00 2001
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From: Ihor Solodrai <ihor.solodrai@pm.me>
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Date: Mon, 6 Jan 2025 20:17:31 +0000
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Subject: [PATCH] selftests/bpf: add -fno-strict-aliasing to BPF_CFLAGS
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Following the discussion at [1], set -fno-strict-aliasing flag for all
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BPF object build rules. Remove now unnecessary <test>-CFLAGS variables.
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[1] https://lore.kernel.org/bpf/20250106185447.951609-1-ihor.solodrai@pm.me/
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CC: Jose E. Marchesi <jose.marchesi@oracle.com>
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Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
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Acked-by: Eduard Zingerman <eddyz87@gmail.com>
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Link: https://lore.kernel.org/r/20250106201728.1219791-1-ihor.solodrai@pm.me
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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---
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tools/testing/selftests/bpf/Makefile | 28 +---------------------------
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1 file changed, 1 insertion(+), 27 deletions(-)
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diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
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index eb4d21651aa7..d5be2f94deef 100644
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--- a/tools/testing/selftests/bpf/Makefile
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+++ b/tools/testing/selftests/bpf/Makefile
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@@ -54,21 +54,6 @@ PCAP_LIBS := $(shell $(PKG_CONFIG) --libs libpcap 2>/dev/null)
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LDLIBS += $(PCAP_LIBS)
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CFLAGS += $(PCAP_CFLAGS)
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-# The following tests perform type punning and they may break strict
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-# aliasing rules, which are exploited by both GCC and clang by default
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-# while optimizing. This can lead to broken programs.
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-progs/bind4_prog.c-CFLAGS := -fno-strict-aliasing
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-progs/bind6_prog.c-CFLAGS := -fno-strict-aliasing
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-progs/dynptr_fail.c-CFLAGS := -fno-strict-aliasing
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-progs/linked_list_fail.c-CFLAGS := -fno-strict-aliasing
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-progs/map_kptr_fail.c-CFLAGS := -fno-strict-aliasing
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-progs/syscall.c-CFLAGS := -fno-strict-aliasing
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-progs/test_pkt_md_access.c-CFLAGS := -fno-strict-aliasing
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-progs/test_sk_lookup.c-CFLAGS := -fno-strict-aliasing
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-progs/timer_crash.c-CFLAGS := -fno-strict-aliasing
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-progs/test_global_func9.c-CFLAGS := -fno-strict-aliasing
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-progs/verifier_nocsr.c-CFLAGS := -fno-strict-aliasing
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-
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# Some utility functions use LLVM libraries
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jit_disasm_helpers.c-CFLAGS = $(LLVM_CFLAGS)
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@@ -103,18 +88,6 @@ progs/btf_dump_test_case_packing.c-bpf_gcc-CFLAGS := -Wno-error
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progs/btf_dump_test_case_padding.c-bpf_gcc-CFLAGS := -Wno-error
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progs/btf_dump_test_case_syntax.c-bpf_gcc-CFLAGS := -Wno-error
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-# The following tests do type-punning, via the __imm_insn macro, from
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-# `struct bpf_insn' to long and then uses the value. This triggers an
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-# "is used uninitialized" warning in GCC due to strict-aliasing
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-# rules.
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-progs/verifier_ref_tracking.c-bpf_gcc-CFLAGS := -fno-strict-aliasing
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-progs/verifier_unpriv.c-bpf_gcc-CFLAGS := -fno-strict-aliasing
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-progs/verifier_cgroup_storage.c-bpf_gcc-CFLAGS := -fno-strict-aliasing
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-progs/verifier_ld_ind.c-bpf_gcc-CFLAGS := -fno-strict-aliasing
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-progs/verifier_map_ret_val.c-bpf_gcc-CFLAGS := -fno-strict-aliasing
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-progs/verifier_spill_fill.c-bpf_gcc-CFLAGS := -fno-strict-aliasing
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-progs/verifier_subprog_precision.c-bpf_gcc-CFLAGS := -fno-strict-aliasing
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-progs/verifier_uninit.c-bpf_gcc-CFLAGS := -fno-strict-aliasing
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endif
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ifneq ($(CLANG_CPUV4),)
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@@ -474,6 +447,7 @@ CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG),$(CLANG_TARGET_ARCH))
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BPF_CFLAGS = -g -Wall -Werror -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) \
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-I$(INCLUDE_DIR) -I$(CURDIR) -I$(APIDIR) \
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-I$(abspath $(OUTPUT)/../usr/include) \
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+ -fno-strict-aliasing \
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-Wno-compare-distinct-pointer-types
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# TODO: enable me -Wsign-compare
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--
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2.47.1
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‎ci/diffs/2002-selftests-bpf-add-std-gnu11-to-BPF_CFLAGS-and-CFLAGS.patch‎

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From bab18c7db44d3aa6c84450095451580922359c7a Mon Sep 17 00:00:00 2001
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From: Ihor Solodrai <ihor.solodrai@pm.me>
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Date: Tue, 7 Jan 2025 23:58:18 +0000
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Subject: [PATCH] selftests/bpf: add -std=gnu11 to BPF_CFLAGS and CFLAGS
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Latest versions of GCC BPF use C23 standard by default. This causes
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compilation errors in vmlinux.h due to bool types declarations.
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Add -std=gnu11 to BPF_CFLAGS and CFLAGS. This aligns with the version
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of the standard used when building the kernel currently [1].
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For more details see the discussions at [2] and [3].
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[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Makefile#n465
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[2] https://lore.kernel.org/bpf/EYcXjcKDCJY7Yb0GGtAAb7nLKPEvrgWdvWpuNzXm2qi6rYMZDixKv5KwfVVMBq17V55xyC-A1wIjrqG3aw-Imqudo9q9X7D7nLU2gWgbN0w=@pm.me/
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[3] https://lore.kernel.org/bpf/20250106202715.1232864-1-ihor.solodrai@pm.me/
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CC: Jose E. Marchesi <jose.marchesi@oracle.com>
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Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
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Link: https://lore.kernel.org/r/20250107235813.2964472-1-ihor.solodrai@pm.me
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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---
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tools/testing/selftests/bpf/Makefile | 8 ++++++--
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1 file changed, 6 insertions(+), 2 deletions(-)
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diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
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index d5be2f94deef..ea9cee5de0f8 100644
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--- a/tools/testing/selftests/bpf/Makefile
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+++ b/tools/testing/selftests/bpf/Makefile
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@@ -41,7 +41,7 @@ srctree := $(patsubst %/,%,$(dir $(srctree)))
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srctree := $(patsubst %/,%,$(dir $(srctree)))
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endif
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-CFLAGS += -g $(OPT_FLAGS) -rdynamic \
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+CFLAGS += -g $(OPT_FLAGS) -rdynamic -std=gnu11 \
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-Wall -Werror -fno-omit-frame-pointer \
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$(GENFLAGS) $(SAN_CFLAGS) $(LIBELF_CFLAGS) \
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-I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR) \
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@@ -447,6 +447,7 @@ CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG),$(CLANG_TARGET_ARCH))
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BPF_CFLAGS = -g -Wall -Werror -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) \
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-I$(INCLUDE_DIR) -I$(CURDIR) -I$(APIDIR) \
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-I$(abspath $(OUTPUT)/../usr/include) \
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+ -std=gnu11 \
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-fno-strict-aliasing \
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-Wno-compare-distinct-pointer-types
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# TODO: enable me -Wsign-compare
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@@ -787,9 +788,12 @@ $(OUTPUT)/xdp_features: xdp_features.c $(OUTPUT)/network_helpers.o $(OUTPUT)/xdp
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$(Q)$(CC) $(CFLAGS) $(filter %.a %.o %.c,$^) $(LDLIBS) -o $@
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# Make sure we are able to include and link libbpf against c++.
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+CXXFLAGS += $(CFLAGS)
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+CXXFLAGS := $(subst -D_GNU_SOURCE=,,$(CXXFLAGS))
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+CXXFLAGS := $(subst -std=gnu11,-std=gnu++11,$(CXXFLAGS))
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$(OUTPUT)/test_cpp: test_cpp.cpp $(OUTPUT)/test_core_extern.skel.h $(BPFOBJ)
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$(call msg,CXX,,$@)
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- $(Q)$(CXX) $(subst -D_GNU_SOURCE=,,$(CFLAGS)) $(filter %.a %.o %.cpp,$^) $(LDLIBS) -o $@
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+ $(Q)$(CXX) $(CXXFLAGS) $(filter %.a %.o %.cpp,$^) $(LDLIBS) -o $@
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# Benchmark runner
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$(OUTPUT)/bench_%.o: benchs/bench_%.c bench.h $(BPFOBJ)
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--
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2.47.1
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