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([2620:10d:c090:400::5:9746]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3434958c3adsm38882252eec.22.2026.09.28.14.53.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Sep 2026 14:53:02 -0700 (PDT) From: Vineet Gupta X-Google-Original-From: Vineet Gupta Message-ID: <6cadba40-10bb-4acf-9a32-d22a270ada8d@linux.dev> Date: Mon, 28 Sep 2026 14:52:59 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 bpf-next 2/2] selftests/bpf: Add linked_externs test for externs in allocated sections To: Andrii Nakryiko , bpf@vger.kernel.org Cc: kernel-team@meta.com, Ihor Solodrai Newsgroups: gmane.linux.kernel.bpf References: <20260926000243.2830819-1-andrii@kernel.org> <20260926000243.2830819-2-andrii@kernel.org> Content-Language: en-US In-Reply-To: <20260926000243.2830819-2-andrii@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=fuNJ914f c=1 sm=1 tr=0 ts=6abae1c1 cx=c_pps a=kVLUcbK0zfr7ocalXnG1qA==:117 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=7x6HtfJdh03M6CCDgxCd:22 a=_1IyUuN4QrATX339ibzo:22 a=NEAV23lmAAAA:8 a=VwQbUJbxAAAA:8 a=i-6TwEPlgW01CNtUTPMA:9 a=QEXdDO2ut3YA:10 a=vr4QvYf-bLy2KjpDp97w:22 X-Proofpoint-ORIG-GUID: TGfgGZ8TuKL0eg2ryZsHUOy3lcCyFP52 X-Proofpoint-GUID: TGfgGZ8TuKL0eg2ryZsHUOy3lcCyFP52 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI4MDA4NiBTYWx0ZWRfX1KUA4y7FwfnK j8W8eQWxXXw4GyXZHP1TyY7mJ+3W5FRdV8Fps0cjuLSHVkj2fUx3mIQeSzlwTChn3KZ39H3yjul 6zguu4Dkt+EZv9R46+9nENYYINO4RDQ= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI4MDA4NiBTYWx0ZWRfX/KBlKJBNJtDA LvVOn/R8P5fGmgx8GS6BnuOEV5B5TWYSb1ryNT2leopQD/CGb1271Vjw670epcw6wwp62H3PDTk ZHvufdrWtVQcfVlIjr21JRLr0ynxbnQ5dEQsbUSMAa7dqFRNMj2/bKYRz0NbjJiHWrMLKOOYcZN UkjKm/U86E1yJ0xeBMaxE91kXzfrqpaREclYTrE0x5Uj+lS892Bm2HUrCOuvCUzeenVyOMEQPP4 4XvFCXWZxMRGKzQaCRJzwMwmp+xWmdYWr933L35V+uVjj3VWMcmjImgoFFP+t+arjbNRY/FzOUQ kdfeMVeDbpAHa72m3rDNYwLumigmCFlR9E2t+QomuyYnVDMQ1M+QkDJZc7EnExZtVpGkmMGAQQB XkF6vve5Lubrti6KZYz5+dAjKJQSOrSxkO1bH1T7eCgOZ3oIwuWmt5LFASH97+rx3xL9uyiYw4K C2645I9aIs810bnAHrg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-28_06,2026-09-21_02,2025-10-01_01 Hi Andrii, On 9/25/26 5:02 PM, Andrii Nakryiko wrote: > Add two objects that define an arena global each and declare the > other one's as extern, linked into a single skeleton with the > extern-declaring object first. > > The skeleton build relinks the linked object twice more, which fixes > up DATASEC offsets from the ELF symbol table, so the test also drives > the libbpf linker directly: it links linked_arena1.bpf.o on its own, > links the result with linked_arena2.bpf.o, checks that no variable in > the .addr_space.1 DATASEC is left extern, and loads the object. The > same is done with linked_maps1/2.bpf.o, which have an extern map in > .maps. > > Signed-off-by: Andrii Nakryiko > --- > tools/testing/selftests/bpf/Makefile.skel | 3 +- > .../selftests/bpf/prog_tests/linked_externs.c | 109 ++++++++++++++++++ > .../selftests/bpf/progs/linked_arena1.c | 22 ++++ > .../selftests/bpf/progs/linked_arena2.c | 18 +++ > 4 files changed, 151 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/bpf/prog_tests/linked_externs.c > create mode 100644 tools/testing/selftests/bpf/progs/linked_arena1.c > create mode 100644 tools/testing/selftests/bpf/progs/linked_arena2.c This is tripping up CI, fails with BPF_GCC [1] and some more (sched-ext) Fix for gcc build failure is posted here [2] [1] https://github.com/kernel-patches/bpf/actions/runs/36243003457 [2] https://lore.kernel.org/bpf/20260928215110.3966357-1-vineet.gupta@linux.dev/T/#u Thx, -Vineet > > diff --git a/tools/testing/selftests/bpf/Makefile.skel b/tools/testing/selftests/bpf/Makefile.skel > index 3d92cdca62ed..2e22bb901bf3 100644 > --- a/tools/testing/selftests/bpf/Makefile.skel > +++ b/tools/testing/selftests/bpf/Makefile.skel > @@ -23,7 +23,7 @@ BPF_OBJS := $(patsubst %.c,$(RDIR)/%.bpf.o,$(BPF_SRCS)) > SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c > > LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \ > - linked_vars.skel.h linked_maps.skel.h \ > + linked_vars.skel.h linked_maps.skel.h linked_arena.skel.h \ > test_subskeleton.skel.h test_subskeleton_lib.skel.h \ > test_usdt.skel.h tracing_multi.skel.h \ > tracing_multi_module.skel.h \ > @@ -46,6 +46,7 @@ test_static_linked.skel.h-deps := test_static_linked1.bpf.o test_static_linked2. > linked_funcs.skel.h-deps := linked_funcs1.bpf.o linked_funcs2.bpf.o > linked_vars.skel.h-deps := linked_vars1.bpf.o linked_vars2.bpf.o > linked_maps.skel.h-deps := linked_maps1.bpf.o linked_maps2.bpf.o > +linked_arena.skel.h-deps := linked_arena1.bpf.o linked_arena2.bpf.o > # In the subskeleton case, we want the test_subskeleton_lib.subskel.h file > # but that's created as a side-effect of the skel.h generation. > test_subskeleton.skel.h-deps := test_subskeleton_lib2.bpf.o test_subskeleton_lib.bpf.o test_subskeleton.bpf.o > diff --git a/tools/testing/selftests/bpf/prog_tests/linked_externs.c b/tools/testing/selftests/bpf/prog_tests/linked_externs.c > new file mode 100644 > index 000000000000..29358c82dc35 > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/linked_externs.c > @@ -0,0 +1,109 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ > +#include > +#include > +#include "linked_arena.skel.h" > + > +static void test_skel(void) > +{ > + LIBBPF_OPTS(bpf_test_run_opts, opts); > + struct linked_arena *skel; > + int err; > + > + skel = linked_arena__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "skel_open_and_load")) > + return; > + > + ASSERT_EQ(skel->arena->a_val, 1, "a_val_init"); > + ASSERT_EQ(skel->arena->b_val, 2, "b_val_init"); > + > + err = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.sum1), &opts); > + ASSERT_OK(err, "sum1_run"); > + ASSERT_EQ(opts.retval, 1 + 2, "sum1_retval"); > + > + err = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.bump2), &opts); > + ASSERT_OK(err, "bump2_run"); > + ASSERT_EQ(opts.retval, 11 + 22, "bump2_retval"); > + > + ASSERT_EQ(skel->arena->a_val, 11, "a_val"); > + ASSERT_EQ(skel->arena->b_val, 22, "b_val"); > + > + linked_arena__destroy(skel); > +} > + > +static int link_objs(const char *out, const char *in1, const char *in2) > +{ > + struct bpf_linker *linker; > + int err; > + > + linker = bpf_linker__new(out, NULL); > + if (!ASSERT_OK_PTR(linker, "linker_new")) > + return -EINVAL; > + > + err = bpf_linker__add_file(linker, in1, NULL); > + if (!ASSERT_OK(err, in1)) > + goto cleanup; > + if (in2) { > + err = bpf_linker__add_file(linker, in2, NULL); > + if (!ASSERT_OK(err, in2)) > + goto cleanup; > + } > + err = bpf_linker__finalize(linker); > + ASSERT_OK(err, "finalize"); > + > +cleanup: > + bpf_linker__free(linker); > + return err; > +} > + > +/* link in1 on its own first, then link the result with in2 */ > +static void test_relink(const char *in1, const char *in2, const char *sec_name) > +{ > + char out1[] = "/tmp/linked_externs.XXXXXX", out2[] = "/tmp/linked_externs.XXXXXX"; > + const struct btf_var_secinfo *vi; > + struct bpf_object *obj = NULL; > + const struct btf_type *t; > + struct btf *btf; > + int i, id, n; > + > + close(mkstemp(out1)); > + close(mkstemp(out2)); > + > + if (!ASSERT_OK(link_objs(out1, in1, NULL), "link_stage1") || > + !ASSERT_OK(link_objs(out2, out1, in2), "link_stage2")) > + goto cleanup; > + > + obj = bpf_object__open_file(out2, NULL); > + if (!ASSERT_OK_PTR(obj, "obj_open")) > + goto cleanup; > + > + btf = bpf_object__btf(obj); > + id = btf__find_by_name_kind(btf, sec_name, BTF_KIND_DATASEC); > + if (!ASSERT_GT(id, 0, "find_datasec")) > + goto cleanup; > + > + t = btf__type_by_id(btf, id); > + vi = btf_var_secinfos(t); > + n = btf_vlen(t); > + for (i = 0; i < n; i++) { > + t = btf__type_by_id(btf, vi[i].type); > + ASSERT_NEQ(btf_var(t)->linkage, BTF_VAR_GLOBAL_EXTERN, "var_resolved"); > + } > + > + ASSERT_OK(bpf_object__load(obj), "obj_load"); > + > +cleanup: > + bpf_object__close(obj); > + unlink(out1); > + unlink(out2); > +} > + > +void test_linked_externs(void) > +{ > + if (test__start_subtest("skel_arena")) > + test_skel(); > + if (test__start_subtest("relink_arena")) > + test_relink("linked_arena1.bpf.o", "linked_arena2.bpf.o", ".addr_space.1"); > + if (test__start_subtest("relink_maps")) > + test_relink("linked_maps1.bpf.o", "linked_maps2.bpf.o", ".maps"); > +} > diff --git a/tools/testing/selftests/bpf/progs/linked_arena1.c b/tools/testing/selftests/bpf/progs/linked_arena1.c > new file mode 100644 > index 000000000000..3e8788dec1d9 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/linked_arena1.c > @@ -0,0 +1,22 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ > +#include > +#include > +#include "bpf_arena_common.h" > + > +struct { > + __uint(type, BPF_MAP_TYPE_ARENA); > + __uint(map_flags, BPF_F_MMAPABLE); > + __uint(max_entries, 1); /* number of pages */ > +} arena SEC(".maps"); > + > +long __arena a_val = 1; > +extern long __arena b_val; /* defined in linked_arena2.c */ > + > +SEC("syscall") > +int sum1(void *ctx) > +{ > + return a_val + b_val; > +} > + > +char _license[] SEC("license") = "GPL"; > diff --git a/tools/testing/selftests/bpf/progs/linked_arena2.c b/tools/testing/selftests/bpf/progs/linked_arena2.c > new file mode 100644 > index 000000000000..d0bcdf18a4b6 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/linked_arena2.c > @@ -0,0 +1,18 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ > +#include > +#include > +#include "bpf_arena_common.h" > + > +long __arena b_val = 2; > +extern long __arena a_val; /* defined in linked_arena1.c */ > + > +SEC("syscall") > +int bump2(void *ctx) > +{ > + a_val += 10; > + b_val += 20; > + return a_val + b_val; > +} > + > +char _license[] SEC("license") = "GPL"; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit User-Agent: Mozilla Thunderbird Cc: kernel-team@meta.com, Ihor Solodrai Content-Language: en-US In-Reply-To: <20260926000243.2830819-2-andrii@kernel.org> Message-ID: <20260928215259.79HZdS5cr3XmU_Wrc6t2XMLDh4PKme5_iz3tc8_xFpo@z> Hi Andrii, On 9/25/26 5:02 PM, Andrii Nakryiko wrote: > Add two objects that define an arena global each and declare the > other one's as extern, linked into a single skeleton with the > extern-declaring object first. > > The skeleton build relinks the linked object twice more, which fixes > up DATASEC offsets from the ELF symbol table, so the test also drives > the libbpf linker directly: it links linked_arena1.bpf.o on its own, > links the result with linked_arena2.bpf.o, checks that no variable in > the .addr_space.1 DATASEC is left extern, and loads the object. The > same is done with linked_maps1/2.bpf.o, which have an extern map in > .maps. > > Signed-off-by: Andrii Nakryiko > --- > tools/testing/selftests/bpf/Makefile.skel | 3 +- > .../selftests/bpf/prog_tests/linked_externs.c | 109 ++++++++++++++++++ > .../selftests/bpf/progs/linked_arena1.c | 22 ++++ > .../selftests/bpf/progs/linked_arena2.c | 18 +++ > 4 files changed, 151 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/bpf/prog_tests/linked_externs.c > create mode 100644 tools/testing/selftests/bpf/progs/linked_arena1.c > create mode 100644 tools/testing/selftests/bpf/progs/linked_arena2.c This is tripping up CI, fails with BPF_GCC [1] and some more (sched-ext) Fix for gcc build failure is posted here [2] [1] https://github.com/kernel-patches/bpf/actions/runs/36243003457 [2] https://lore.kernel.org/bpf/20260928215110.3966357-1-vineet.gupta@linux.dev/T/#u Thx, -Vineet > > diff --git a/tools/testing/selftests/bpf/Makefile.skel b/tools/testing/selftests/bpf/Makefile.skel > index 3d92cdca62ed..2e22bb901bf3 100644 > --- a/tools/testing/selftests/bpf/Makefile.skel > +++ b/tools/testing/selftests/bpf/Makefile.skel > @@ -23,7 +23,7 @@ BPF_OBJS := $(patsubst %.c,$(RDIR)/%.bpf.o,$(BPF_SRCS)) > SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c > > LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \ > - linked_vars.skel.h linked_maps.skel.h \ > + linked_vars.skel.h linked_maps.skel.h linked_arena.skel.h \ > test_subskeleton.skel.h test_subskeleton_lib.skel.h \ > test_usdt.skel.h tracing_multi.skel.h \ > tracing_multi_module.skel.h \ > @@ -46,6 +46,7 @@ test_static_linked.skel.h-deps := test_static_linked1.bpf.o test_static_linked2. > linked_funcs.skel.h-deps := linked_funcs1.bpf.o linked_funcs2.bpf.o > linked_vars.skel.h-deps := linked_vars1.bpf.o linked_vars2.bpf.o > linked_maps.skel.h-deps := linked_maps1.bpf.o linked_maps2.bpf.o > +linked_arena.skel.h-deps := linked_arena1.bpf.o linked_arena2.bpf.o > # In the subskeleton case, we want the test_subskeleton_lib.subskel.h file > # but that's created as a side-effect of the skel.h generation. > test_subskeleton.skel.h-deps := test_subskeleton_lib2.bpf.o test_subskeleton_lib.bpf.o test_subskeleton.bpf.o > diff --git a/tools/testing/selftests/bpf/prog_tests/linked_externs.c b/tools/testing/selftests/bpf/prog_tests/linked_externs.c > new file mode 100644 > index 000000000000..29358c82dc35 > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/linked_externs.c > @@ -0,0 +1,109 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ > +#include > +#include > +#include "linked_arena.skel.h" > + > +static void test_skel(void) > +{ > + LIBBPF_OPTS(bpf_test_run_opts, opts); > + struct linked_arena *skel; > + int err; > + > + skel = linked_arena__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "skel_open_and_load")) > + return; > + > + ASSERT_EQ(skel->arena->a_val, 1, "a_val_init"); > + ASSERT_EQ(skel->arena->b_val, 2, "b_val_init"); > + > + err = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.sum1), &opts); > + ASSERT_OK(err, "sum1_run"); > + ASSERT_EQ(opts.retval, 1 + 2, "sum1_retval"); > + > + err = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.bump2), &opts); > + ASSERT_OK(err, "bump2_run"); > + ASSERT_EQ(opts.retval, 11 + 22, "bump2_retval"); > + > + ASSERT_EQ(skel->arena->a_val, 11, "a_val"); > + ASSERT_EQ(skel->arena->b_val, 22, "b_val"); > + > + linked_arena__destroy(skel); > +} > + > +static int link_objs(const char *out, const char *in1, const char *in2) > +{ > + struct bpf_linker *linker; > + int err; > + > + linker = bpf_linker__new(out, NULL); > + if (!ASSERT_OK_PTR(linker, "linker_new")) > + return -EINVAL; > + > + err = bpf_linker__add_file(linker, in1, NULL); > + if (!ASSERT_OK(err, in1)) > + goto cleanup; > + if (in2) { > + err = bpf_linker__add_file(linker, in2, NULL); > + if (!ASSERT_OK(err, in2)) > + goto cleanup; > + } > + err = bpf_linker__finalize(linker); > + ASSERT_OK(err, "finalize"); > + > +cleanup: > + bpf_linker__free(linker); > + return err; > +} > + > +/* link in1 on its own first, then link the result with in2 */ > +static void test_relink(const char *in1, const char *in2, const char *sec_name) > +{ > + char out1[] = "/tmp/linked_externs.XXXXXX", out2[] = "/tmp/linked_externs.XXXXXX"; > + const struct btf_var_secinfo *vi; > + struct bpf_object *obj = NULL; > + const struct btf_type *t; > + struct btf *btf; > + int i, id, n; > + > + close(mkstemp(out1)); > + close(mkstemp(out2)); > + > + if (!ASSERT_OK(link_objs(out1, in1, NULL), "link_stage1") || > + !ASSERT_OK(link_objs(out2, out1, in2), "link_stage2")) > + goto cleanup; > + > + obj = bpf_object__open_file(out2, NULL); > + if (!ASSERT_OK_PTR(obj, "obj_open")) > + goto cleanup; > + > + btf = bpf_object__btf(obj); > + id = btf__find_by_name_kind(btf, sec_name, BTF_KIND_DATASEC); > + if (!ASSERT_GT(id, 0, "find_datasec")) > + goto cleanup; > + > + t = btf__type_by_id(btf, id); > + vi = btf_var_secinfos(t); > + n = btf_vlen(t); > + for (i = 0; i < n; i++) { > + t = btf__type_by_id(btf, vi[i].type); > + ASSERT_NEQ(btf_var(t)->linkage, BTF_VAR_GLOBAL_EXTERN, "var_resolved"); > + } > + > + ASSERT_OK(bpf_object__load(obj), "obj_load"); > + > +cleanup: > + bpf_object__close(obj); > + unlink(out1); > + unlink(out2); > +} > + > +void test_linked_externs(void) > +{ > + if (test__start_subtest("skel_arena")) > + test_skel(); > + if (test__start_subtest("relink_arena")) > + test_relink("linked_arena1.bpf.o", "linked_arena2.bpf.o", ".addr_space.1"); > + if (test__start_subtest("relink_maps")) > + test_relink("linked_maps1.bpf.o", "linked_maps2.bpf.o", ".maps"); > +} > diff --git a/tools/testing/selftests/bpf/progs/linked_arena1.c b/tools/testing/selftests/bpf/progs/linked_arena1.c > new file mode 100644 > index 000000000000..3e8788dec1d9 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/linked_arena1.c > @@ -0,0 +1,22 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ > +#include > +#include > +#include "bpf_arena_common.h" > + > +struct { > + __uint(type, BPF_MAP_TYPE_ARENA); > + __uint(map_flags, BPF_F_MMAPABLE); > + __uint(max_entries, 1); /* number of pages */ > +} arena SEC(".maps"); > + > +long __arena a_val = 1; > +extern long __arena b_val; /* defined in linked_arena2.c */ > + > +SEC("syscall") > +int sum1(void *ctx) > +{ > + return a_val + b_val; > +} > + > +char _license[] SEC("license") = "GPL"; > diff --git a/tools/testing/selftests/bpf/progs/linked_arena2.c b/tools/testing/selftests/bpf/progs/linked_arena2.c > new file mode 100644 > index 000000000000..d0bcdf18a4b6 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/linked_arena2.c > @@ -0,0 +1,18 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ > +#include > +#include > +#include "bpf_arena_common.h" > + > +long __arena b_val = 2; > +extern long __arena a_val; /* defined in linked_arena1.c */ > + > +SEC("syscall") > +int bump2(void *ctx) > +{ > + a_val += 10; > + b_val += 20; > + return a_val + b_val; > +} > + > +char _license[] SEC("license") = "GPL";