From: Emil Tsalapatis Date: Sun, 26 Apr 2026 19:03:32 +0000 (-0400) Subject: selftests/bpf: Add basic libarena scaffolding X-Git-Tag: v7.2-rc1~142^2~106^2~6 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d5327480a12a031f283c85c3c9c9201685099036;p=thirdparty%2Fkernel%2Flinux.git selftests/bpf: Add basic libarena scaffolding Add initial code and a Makefile for an arena-based BPF library. Modules can be added just by including the source file in the library's src/ subdirectory. Future commits will introduce the library code itself. The code includes workarounds that are removed in subsequent patches that ensure bisectability. Signed-off-by: Emil Tsalapatis Link: https://lore.kernel.org/r/20260426190338.4615-3-emil@etsalapatis.com Signed-off-by: Alexei Starovoitov --- diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index ac676d2a4a298..9fe30a665c2e2 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -151,6 +151,7 @@ override define CLEAN $(Q)$(RM) -r $(TEST_KMODS) $(Q)$(RM) -r $(EXTRA_CLEAN) $(Q)$(MAKE) -C test_kmods clean + $(Q)$(MAKE) -C libarena clean $(Q)$(MAKE) docs-clean endef @@ -522,6 +523,7 @@ LINKED_BPF_OBJS := $(foreach skel,$(LINKED_SKELS),$($(skel)-deps)) LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.c,$(LINKED_BPF_OBJS)) HEADERS_FOR_BPF_OBJS := $(wildcard $(BPFDIR)/*.bpf.h) \ + $(wildcard $(CURDIR)/libarena/include/*.[ch]) \ $(addprefix $(BPFDIR)/, bpf_core_read.h \ bpf_endian.h \ bpf_helpers.h \ @@ -737,6 +739,29 @@ $(VERIFY_SIG_HDR): $(VERIFICATION_CERT) echo "};"; \ echo "unsigned int test_progs_verification_cert_len = $$(wc -c < $<);") > $@ +LIBARENA_MAKE_ARGS = \ + BPFTOOL="$(BPFTOOL)" \ + INCLUDE_DIR="$(INCLUDE_DIR)" \ + LIBBPF_INCLUDE="$(HOST_INCLUDE_DIR)" \ + BPFOBJ="$(BPFOBJ)" \ + LDLIBS="$(LDLIBS) -lzstd" \ + CLANG="$(CLANG)" \ + BPF_CFLAGS="$(BPF_CFLAGS) $(CLANG_CFLAGS)" \ + BPF_TARGET_ENDIAN="$(BPF_TARGET_ENDIAN)" \ + Q="$(Q)" + +LIBARENA_BPF_DEPS := $(wildcard libarena/Makefile \ + libarena/include/* \ + libarena/include/libarena/* \ + libarena/src/* \ + libarena/selftests/* \ + libarena/*.bpf.o) + +LIBARENA_SKEL := libarena/libarena.skel.h + +$(LIBARENA_SKEL): $(INCLUDE_DIR)/vmlinux.h $(BPFOBJ) $(LIBARENA_BPF_DEPS) + +$(MAKE) -C libarena libarena.skel.h $(LIBARENA_MAKE_ARGS) + # Define test_progs test runner. TRUNNER_TESTS_DIR := prog_tests TRUNNER_BPF_PROGS_DIR := progs @@ -930,3 +955,5 @@ override define INSTALL_RULE rsync -a $(OUTPUT)/$$DIR/*.bpf.o $(INSTALL_PATH)/$$DIR;\ done endef + +libarena: $(LIBARENA_SKEL) diff --git a/tools/testing/selftests/bpf/libarena/Makefile b/tools/testing/selftests/bpf/libarena/Makefile new file mode 100644 index 0000000000000..e85b3ad968904 --- /dev/null +++ b/tools/testing/selftests/bpf/libarena/Makefile @@ -0,0 +1,69 @@ +# SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause +# Copyright (c) 2026 Meta Platforms, Inc. and affiliates. + +.PHONY: clean + +# Defaults for standalone builds + +CLANG ?= clang +BPFTOOL ?= bpftool +LDLIBS ?= -lbpf -lelf -lz -lrt -lpthread -lzstd + +ifeq ($(V),1) +Q = +msg = +else +Q ?= @ +msg = @printf ' %-8s%s %s%s\n' "$(1)" "$(if $(2), [$(2)])" "$(notdir $(3))" "$(if $(4), $(4))"; +endif + +IS_LITTLE_ENDIAN = $(shell $(CC) -dM -E - $@ + +libarena.bpf.o: $(LIBARENA_OBJECTS) + $(call msg,GEN-OBJ,libarena,$@) + $(Q)$(BPFTOOL) gen object $@ $^ + +%.bpf.o: %.bpf.c + $(call msg,CLNG-BPF,libarena,$@) + $(Q)$(CLANG) $(BPF_CFLAGS) $(BPF_TARGET_ENDIAN) -c $< -o $@ + +clean: + $(Q)rm -f *.skel.h *.bpf.o diff --git a/tools/testing/selftests/bpf/libarena/include/libarena/common.h b/tools/testing/selftests/bpf/libarena/include/libarena/common.h new file mode 100644 index 0000000000000..92b67b20ed153 --- /dev/null +++ b/tools/testing/selftests/bpf/libarena/include/libarena/common.h @@ -0,0 +1,79 @@ +// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ +#pragma once + +#ifdef __BPF__ + +#include + +#include "../../bpf_arena_common.h" +#include "../../progs/bpf_arena_spin_lock.h" + +#include + +#ifndef __BPF_FEATURE_ADDR_SPACE_CAST +#error "Arena allocators require bpf_addr_space_cast feature" +#endif + +#define arena_stdout(fmt, ...) bpf_stream_printk(1, (fmt), ##__VA_ARGS__) +#define arena_stderr(fmt, ...) bpf_stream_printk(2, (fmt), ##__VA_ARGS__) + +#ifndef __maybe_unused +#define __maybe_unused __attribute__((__unused__)) +#endif + +#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8))) + +#define ARENA_PAGES (1UL << (32 - __builtin_ffs(__PAGE_SIZE) + 1)) + +struct { + __uint(type, BPF_MAP_TYPE_ARENA); + __uint(map_flags, BPF_F_MMAPABLE); + __uint(max_entries, ARENA_PAGES); /* number of pages */ +#if defined(__TARGET_ARCH_arm64) || defined(__aarch64__) + __ulong(map_extra, (1ull << 32)); /* start of mmap() region */ +#else + __ulong(map_extra, (1ull << 44)); /* start of mmap() region */ +#endif +} arena __weak SEC(".maps"); + +/* + * This is a variable used to aid verification. The may_goto directive + * permits open-coded for loops, but requires that the index variable is + * imprecise. To force the variable to be imprecise, initialize it with + * the opaque volatile variable 0 instead of the constant 0. + */ +extern const volatile u32 zero; + +int arena_fls(__u64 word); + +#else /* ! __BPF__ */ + +#include + +#define __arena + +typedef uint8_t u8; +typedef uint16_t u16; +typedef uint32_t u32; +typedef uint64_t u64; +typedef int8_t s8; +typedef int16_t s16; +typedef int32_t s32; +typedef int64_t s64; + +/* Dummy "definition" for userspace. */ +#define arena_spinlock_t int + +#endif /* __BPF__ */ + +struct arena_get_info_args { + void __arena *arena_base; +}; + +struct arena_alloc_reserve_args { + u64 nr_pages; +}; + +/* Reasonable default number of pages reserved by arena_alloc_reserve. */ +#define ARENA_RESERVE_PAGES_DFL (8) diff --git a/tools/testing/selftests/bpf/libarena/include/libarena/userspace.h b/tools/testing/selftests/bpf/libarena/include/libarena/userspace.h new file mode 100644 index 0000000000000..0438a751d5fd0 --- /dev/null +++ b/tools/testing/selftests/bpf/libarena/include/libarena/userspace.h @@ -0,0 +1,99 @@ +// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ +#pragma once + +#include +#include +#include +#include + +#include +#include + +static inline int libarena_run_prog(int prog_fd) +{ + LIBBPF_OPTS(bpf_test_run_opts, opts); + int ret; + + ret = bpf_prog_test_run_opts(prog_fd, &opts); + if (ret) + return ret; + + return opts.retval; +} + +static inline bool libarena_is_test_prog(const char *name) +{ + return strstr(name, "test_") == name; +} + +static inline int libarena_run_prog_args(int prog_fd, void *args, size_t argsize) +{ + LIBBPF_OPTS(bpf_test_run_opts, opts); + int ret; + + opts.ctx_in = args; + opts.ctx_size_in = argsize; + + ret = bpf_prog_test_run_opts(prog_fd, &opts); + + return ret ?: opts.retval; +} + +static inline int libarena_get_arena_base(int arena_get_info_fd, + void **arena_base) +{ + LIBBPF_OPTS(bpf_test_run_opts, opts); + struct arena_get_info_args args = { .arena_base = NULL }; + int ret; + + opts.ctx_in = &args; + opts.ctx_size_in = sizeof(args); + + ret = bpf_prog_test_run_opts(arena_get_info_fd, &opts); + if (ret) + return ret; + if (opts.retval) + return opts.retval; + + *arena_base = args.arena_base; + return 0; +} + +static inline int libarena_get_globals_pages(int arena_get_globals_fd, + size_t arena_all_pages, + u64 *globals_pages) +{ + size_t pgsize = sysconf(_SC_PAGESIZE); + void *arena_base; + ssize_t i; + u8 *vec; + int ret; + + ret = libarena_get_arena_base(arena_get_globals_fd, &arena_base); + if (ret) + return ret; + + if (!arena_base) + return -EINVAL; + + vec = calloc(arena_all_pages, sizeof(*vec)); + if (!vec) + return -ENOMEM; + + if (mincore(arena_base, arena_all_pages * pgsize, vec) < 0) { + ret = -errno; + free(vec); + return ret; + } + + *globals_pages = 0; + for (i = arena_all_pages - 1; i >= 0; i--) { + if (!(vec[i] & 0x1)) + break; + *globals_pages += 1; + } + + free(vec); + return 0; +} diff --git a/tools/testing/selftests/bpf/libarena/src/common.bpf.c b/tools/testing/selftests/bpf/libarena/src/common.bpf.c new file mode 100644 index 0000000000000..659ccead5624e --- /dev/null +++ b/tools/testing/selftests/bpf/libarena/src/common.bpf.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ +#include + +const volatile u32 zero = 0; + +int arena_fls(__u64 word) +{ + if (!word) + return 0; + + return 64 - __builtin_clzll(word); +} + +SEC("syscall") +__weak int arena_get_info(struct arena_get_info_args *args) +{ + args->arena_base = arena_base(&arena); + + return 0; +} + +SEC("syscall") +__weak int arena_alloc_reserve(struct arena_alloc_reserve_args *args) +{ + return bpf_arena_reserve_pages(&arena, NULL, args->nr_pages); +} + +char _license[] SEC("license") = "GPL";