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([140.174.219.137]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8b2af043037sm1117130185a.48.2025.11.17.19.01.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Nov 2025 19:01:16 -0800 (PST) From: Emil Tsalapatis To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, memxor@gmail.com, andrii@kernel.org, eddyz87@gmail.com, yonghong.song@linux.dev, Emil Tsalapatis Subject: [PATCH v2 4/4] selftests/bpf: add tests for the arena offset of globals Date: Mon, 17 Nov 2025 22:00:58 -0500 Message-ID: <20251118030058.162967-5-emil@etsalapatis.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20251118030058.162967-1-emil@etsalapatis.com> References: <20251118030058.162967-1-emil@etsalapatis.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add tests for the new libbpf globals arena offset logic. The tests cover all three cases: The globals being small enough to be placed at the maximum possible offset, being as large as the arena itself and being placed at the very beginning, and requiring an intermediate offset into the arena. Signed-off-by: Emil Tsalapatis --- .../selftests/bpf/prog_tests/verifier.c | 6 ++ .../bpf/progs/verifier_arena_globals1.c | 60 ++++++++++++++++++ .../bpf/progs/verifier_arena_globals2.c | 49 +++++++++++++++ .../bpf/progs/verifier_arena_globals3.c | 61 +++++++++++++++++++ 4 files changed, 176 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/verifier_arena_globals1.c create mode 100644 tools/testing/selftests/bpf/progs/verifier_arena_globals2.c create mode 100644 tools/testing/selftests/bpf/progs/verifier_arena_globals3.c diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c index 4b4b081b46cc..0c64fbc9a194 100644 --- a/tools/testing/selftests/bpf/prog_tests/verifier.c +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c @@ -6,6 +6,9 @@ #include "verifier_and.skel.h" #include "verifier_arena.skel.h" #include "verifier_arena_large.skel.h" +#include "verifier_arena_globals1.skel.h" +#include "verifier_arena_globals2.skel.h" +#include "verifier_arena_globals3.skel.h" #include "verifier_array_access.skel.h" #include "verifier_async_cb_context.skel.h" #include "verifier_basic_stack.skel.h" @@ -147,6 +150,9 @@ static void run_tests_aux(const char *skel_name, void test_verifier_and(void) { RUN(verifier_and); } void test_verifier_arena(void) { RUN(verifier_arena); } void test_verifier_arena_large(void) { RUN(verifier_arena_large); } +void test_verifier_arena_globals1(void) { RUN(verifier_arena_globals1); } +void test_verifier_arena_globals2(void) { RUN(verifier_arena_globals2); } +void test_verifier_arena_globals3(void) { RUN(verifier_arena_globals3); } void test_verifier_basic_stack(void) { RUN(verifier_basic_stack); } void test_verifier_bitfield_write(void) { RUN(verifier_bitfield_write); } void test_verifier_bounds(void) { RUN(verifier_bounds); } diff --git a/tools/testing/selftests/bpf/progs/verifier_arena_globals1.c b/tools/testing/selftests/bpf/progs/verifier_arena_globals1.c new file mode 100644 index 000000000000..761844577981 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/verifier_arena_globals1.c @@ -0,0 +1,60 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */ + +#define BPF_NO_KFUNC_PROTOTYPES +#include +#include +#include +#include "bpf_experimental.h" +#include "bpf_arena_common.h" +#include "bpf_misc.h" + +#define ARENA_PAGES (64) + +/* Set in libbpf. */ +#define GLOBALS_PGOFF (16) + +struct { + __uint(type, BPF_MAP_TYPE_ARENA); + __uint(map_flags, BPF_F_MMAPABLE); + __uint(max_entries, ARENA_PAGES); /* Arena of 64 pages (standard offset is 16 pages) */ +#ifdef __TARGET_ARCH_arm64 + __ulong(map_extra, (1ull << 32) | (~0u - __PAGE_SIZE * ARENA_PAGES + 1)); +#else + __ulong(map_extra, (1ull << 44) | (~0u - __PAGE_SIZE * ARENA_PAGES + 1)); +#endif +} arena SEC(".maps"); + +/* + * Global data small enough that we can apply the maximum + * offset into the arena. Userspace will also use this to + * ensure the offset doesn't unexpectedly change from + * under us. + */ +char __arena global_data[PAGE_SIZE][ARENA_PAGES - GLOBALS_PGOFF]; + +SEC("syscall") +__success __retval(0) +int check_reserve1(void *ctx) +{ +#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) + __u8 __arena *guard, *globals; + int ret; + + guard = (void __arena *)arena_base(&arena); + globals = (void __arena *)(arena_base(&arena) + GLOBALS_PGOFF * PAGE_SIZE); + + /* Reserve the region we've offset the globals by. */ + ret = bpf_arena_reserve_pages(&arena, guard, GLOBALS_PGOFF); + if (ret) + return 1; + + /* Make sure the globals are placed GLOBALS_PGOFF pages in. */ + ret = bpf_arena_reserve_pages(&arena, globals, 1); + if (!ret) + return 2; +#endif + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/verifier_arena_globals2.c b/tools/testing/selftests/bpf/progs/verifier_arena_globals2.c new file mode 100644 index 000000000000..9b6a08135de5 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/verifier_arena_globals2.c @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */ + +#define BPF_NO_KFUNC_PROTOTYPES +#include +#include +#include +#include "bpf_misc.h" +#include "bpf_experimental.h" +#include "bpf_arena_common.h" + +#define ARENA_PAGES (32) + +struct { + __uint(type, BPF_MAP_TYPE_ARENA); + __uint(map_flags, BPF_F_MMAPABLE); + __uint(max_entries, ARENA_PAGES); /* Arena of 32 pages (standard offset is 16 pages) */ +#ifdef __TARGET_ARCH_arm64 + __ulong(map_extra, (1ull << 32) | (~0u - __PAGE_SIZE * ARENA_PAGES + 1)); +#else + __ulong(map_extra, (1ull << 44) | (~0u - __PAGE_SIZE * ARENA_PAGES + 1)); +#endif +} arena SEC(".maps"); + +/* + * Fill the entire arena with global data. + * The offset into the arena should be 0. + */ +char __arena global_data[PAGE_SIZE][ARENA_PAGES]; + +SEC("syscall") +__success __retval(0) +int check_reserve2(void *ctx) +{ +#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) + void __arena *guard; + int ret; + + guard = (void __arena *)arena_base(&arena); + + /* Make sure the data at offset 0 case is properly handled. */ + ret = bpf_arena_reserve_pages(&arena, guard, 1); + if (!ret) + return 1; +#endif + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/verifier_arena_globals3.c b/tools/testing/selftests/bpf/progs/verifier_arena_globals3.c new file mode 100644 index 000000000000..62d1a46955fd --- /dev/null +++ b/tools/testing/selftests/bpf/progs/verifier_arena_globals3.c @@ -0,0 +1,61 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */ + +#define BPF_NO_KFUNC_PROTOTYPES +#include +#include +#include +#include "bpf_misc.h" +#include "bpf_experimental.h" +#include "bpf_arena_common.h" + +#define ARENA_PAGES (32) + +#define ARENA_AVAIL_PAGES (6) + +struct { + __uint(type, BPF_MAP_TYPE_ARENA); + __uint(map_flags, BPF_F_MMAPABLE); + __uint(max_entries, ARENA_PAGES); /* Arena of 32 pages (standard offset is 16 pages) */ +#ifdef __TARGET_ARCH_arm64 + __ulong(map_extra, (1ull << 32) | (~0u - __PAGE_SIZE * ARENA_PAGES + 1)); +#else + __ulong(map_extra, (1ull << 44) | (~0u - __PAGE_SIZE * ARENA_PAGES + 1)); +#endif +} arena SEC(".maps"); + +/* + * Enough global data to fill most of the arena. Force libbpf to + * adjust the offset into the arena enough for the data to fit. + */ + +char __arena global_data[PAGE_SIZE][ARENA_PAGES - ARENA_AVAIL_PAGES]; + +SEC("syscall") +__success __retval(0) +int check_reserve3(void *ctx) +{ +#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) + void __arena *guard, *globals; + int ret; + + guard = (void __arena *)arena_base(&arena); + globals = (void __arena *)(arena_base(&arena) + 4 * PAGE_SIZE); + + /* + * The data should be offset 4 pages in (the largest + * possible power of 2 that still leaves enough room + * to the global data). + */ + ret = bpf_arena_reserve_pages(&arena, guard, 4); + if (ret) + return 1; + + ret = bpf_arena_reserve_pages(&arena, globals, 1); + if (!ret) + return 2; +#endif + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.49.0