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편집 파일: bpf_helpers.h

/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ #ifndef __BPF_HELPERS__ #define __BPF_HELPERS__ /* * Note that bpf programs need to include either * vmlinux.h (auto-generated from BTF) or linux/types.h * in advance since bpf_helper_defs.h uses such types * as __u64. */ #include "bpf_helper_defs.h" #define __uint(name, val) int (*name)[val] #define __type(name, val) typeof(val) *name #define __array(name, val) typeof(val) *name[] #define __ulong(name, val) enum { ___bpf_concat(__unique_value, __COUNTER__) = val } name /* * Helper macro to place programs, maps, license in * different sections in elf_bpf file. Section names * are interpreted by libbpf depending on the context (BPF programs, BPF maps, * extern variables, etc). * To allow use of SEC() with externs (e.g., for extern .maps declarations), * make sure __attribute__((unused)) doesn't trigger compilation warning. */ #if __GNUC__ && !__clang__ /* * Pragma macros are broken on GCC * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400 */ #define SEC(name) __attribute__((section(name), used)) #else #define SEC(name) \ _Pragma("GCC diagnostic push") \ _Pragma("GCC diagnostic ignored \"-Wignored-attributes\"") \ __attribute__((section(name), used)) \ _Pragma("GCC diagnostic pop") \ #endif /* Avoid 'linux/stddef.h' definition of '__always_inline'. */ #undef __always_inline #define __always_inline inline __attribute__((always_inline)) #ifndef __noinline #define __noinline __attribute__((noinline)) #endif #ifndef __weak #define __weak __attribute__((weak)) #endif /* * Use __hidden attribute to mark a non-static BPF subprogram effectively * static for BPF verifier's verification algorithm purposes, allowing more * extensive and permissive BPF verification process, taking into account * subprogram's caller context. */ #define __hidden __attribute__((visibility("hidden"))) /* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include * any system-level headers (such as stddef.h, linux/version.h, etc), and * commonly-used macros like NULL and KERNEL_VERSION aren't available through * vmlinux.h. This just adds unnecessary hurdles and forces users to re-define * them on their own. So as a convenience, provide such definitions here. */ #ifndef NULL #define NULL ((void *)0) #endif #ifndef KERNEL_VERSION #define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c))) #endif /* * Helper macros to manipulate data structures */ /* offsetof() definition that uses __builtin_offset() might not preserve field * offset CO-RE relocation properly, so force-redefine offsetof() using * old-school approach which works with CO-RE correctly */ #undef offsetof #define offsetof(type, member) ((unsigned long)&((type *)0)->member) /* redefined container_of() to ensure we use the above offsetof() macro */ #undef container_of #define container_of(ptr, type, member) \ ({ \ void *__mptr = (void *)(ptr); \ ((type *)(__mptr - offsetof(type, member))); \ }) /* * Compiler (optimization) barrier. */ #ifndef barrier #define barrier() asm volatile("" ::: "memory") #endif /* Variable-specific compiler (optimization) barrier. It's a no-op which makes * compiler believe that there is some black box modification of a given * variable and thus prevents compiler from making extra assumption about its * value and potential simplifications and optimizations on this variable. * * E.g., compiler might often delay or even omit 32-bit to 64-bit casting of * a variable, making some code patterns unverifiable. Putting barrier_var() * in place will ensure that cast is performed before the barrier_var() * invocation, because compiler has to pessimistically assume that embedded * asm section might perform some extra operations on that variable. * * This is a variable-specific variant of more global barrier(). */ #ifndef barrier_var #define barrier_var(var) asm volatile("" : "+r"(var)) #endif /* * Helper macro to throw a compilation error if __bpf_unreachable() gets * built into the resulting code. This works given BPF back end does not * implement __builtin_trap(). This is useful to assert that certain paths * of the program code are never used and hence eliminated by the compiler. * * For example, consider a switch statement that covers known cases used by * the program. __bpf_unreachable() can then reside in the default case. If * the program gets extended such that a case is not covered in the switch * statement, then it will throw a build error due to the default case not * being compiled out. */ #ifndef __bpf_unreachable # define __bpf_unreachable() __builtin_trap() #endif /* * Helper function to perform a tail call with a constant/immediate map slot. */ #if (defined(__clang__) && __clang_major__ >= 8) || (!defined(__clang__) && __GNUC__ > 12) #if defined(__bpf__) static __always_inline void bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) { if (!__builtin_constant_p(slot)) __bpf_unreachable(); /* * Provide a hard guarantee that LLVM won't optimize setting r2 (map * pointer) and r3 (constant map index) from _different paths_ ending * up at the _same_ call insn as otherwise we won't be able to use the * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key * tracking for prog array pokes") for details on verifier tracking. * * Note on clobber list: we need to stay in-line with BPF calling * convention, so even if we don't end up using r0, r4, r5, we need * to mark them as clobber so that LLVM doesn't end up using them * before / after the call. */ asm volatile("r1 = %[ctx]\n\t" "r2 = %[map]\n\t" "r3 = %[slot]\n\t" "call 12" :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot) : "r0", "r1", "r2", "r3", "r4", "r5"); } #endif #endif enum libbpf_pin_type { LIBBPF_PIN_NONE, /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */ LIBBPF_PIN_BY_NAME, }; enum libbpf_tristate { TRI_NO = 0, TRI_YES = 1, TRI_MODULE = 2, }; #define __kconfig __attribute__((section(".kconfig"))) #define __ksym __attribute__((section(".ksyms"))) #define __kptr_untrusted __attribute__((btf_type_tag("kptr_untrusted"))) #define __kptr __attribute__((btf_type_tag("kptr"))) #define __percpu_kptr __attribute__((btf_type_tag("percpu_kptr"))) #if defined (__clang__) #define bpf_ksym_exists(sym) ({ \ _Static_assert(!__builtin_constant_p(!!sym), \ #sym " should be marked as __weak"); \ !!sym; \ }) #elif __GNUC__ > 8 #define bpf_ksym_exists(sym) ({ \ _Static_assert(__builtin_has_attribute (*sym, __weak__), \ #sym " should be marked as __weak"); \ !!sym; \ }) #else #define bpf_ksym_exists(sym) !!sym #endif #define __arg_ctx __attribute__((btf_decl_tag("arg:ctx"))) #define __arg_nonnull __attribute((btf_decl_tag("arg:nonnull"))) #define __arg_nullable __attribute((btf_decl_tag("arg:nullable"))) #define __arg_trusted __attribute((btf_decl_tag("arg:trusted"))) #define __arg_arena __attribute((btf_decl_tag("arg:arena"))) #ifndef ___bpf_concat #define ___bpf_concat(a, b) a ## b #endif #ifndef ___bpf_apply #define ___bpf_apply(fn, n) ___bpf_concat(fn, n) #endif #ifndef ___bpf_nth #define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N #endif #ifndef ___bpf_narg #define ___bpf_narg(...) \ ___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) #endif #define ___bpf_fill0(arr, p, x) do {} while (0) #define ___bpf_fill1(arr, p, x) arr[p] = x #define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args) #define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args) #define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args) #define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args) #define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args) #define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args) #define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args) #define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args) #define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args) #define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args) #define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args) #define ___bpf_fill(arr, args...) \ ___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args) /* * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values * in a structure. */ #define BPF_SEQ_PRINTF(seq, fmt, args...) \ ({ \ static const char ___fmt[] = fmt; \ unsigned long long ___param[___bpf_narg(args)]; \ \ _Pragma("GCC diagnostic push") \ _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ ___bpf_fill(___param, args); \ _Pragma("GCC diagnostic pop") \ \ bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \ ___param, sizeof(___param)); \ }) /* * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of * an array of u64. */ #define BPF_SNPRINTF(out, out_size, fmt, args...) \ ({ \ static const char ___fmt[] = fmt; \ unsigned long long ___param[___bpf_narg(args)]; \ \ _Pragma("GCC diagnostic push") \ _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ ___bpf_fill(___param, args); \ _Pragma("GCC diagnostic pop") \ \ bpf_snprintf(out, out_size, ___fmt, \ ___param, sizeof(___param)); \ }) #ifdef BPF_NO_GLOBAL_DATA #define BPF_PRINTK_FMT_MOD #else #define BPF_PRINTK_FMT_MOD static const #endif #define __bpf_printk(fmt, ...) \ ({ \ BPF_PRINTK_FMT_MOD char ____fmt[] = fmt; \ bpf_trace_printk(____fmt, sizeof(____fmt), \ ##__VA_ARGS__); \ }) /* * __bpf_vprintk wraps the bpf_trace_vprintk helper with variadic arguments * instead of an array of u64. */ #define __bpf_vprintk(fmt, args...) \ ({ \ static const char ___fmt[] = fmt; \ unsigned long long ___param[___bpf_narg(args)]; \ \ _Pragma("GCC diagnostic push") \ _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ ___bpf_fill(___param, args); \ _Pragma("GCC diagnostic pop") \ \ bpf_trace_vprintk(___fmt, sizeof(___fmt), \ ___param, sizeof(___param)); \ }) /* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args * Otherwise use __bpf_vprintk */ #define ___bpf_pick_printk(...) \ ___bpf_nth(_, ##__VA_ARGS__, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \ __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \ __bpf_vprintk, __bpf_vprintk, __bpf_printk /*3*/, __bpf_printk /*2*/,\ __bpf_printk /*1*/, __bpf_printk /*0*/) /* Helper macro to print out debug messages */ #define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args) struct bpf_iter_num; extern int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end) __weak __ksym; extern int *bpf_iter_num_next(struct bpf_iter_num *it) __weak __ksym; extern void bpf_iter_num_destroy(struct bpf_iter_num *it) __weak __ksym; #ifndef bpf_for_each /* bpf_for_each(iter_type, cur_elem, args...) provides generic construct for * using BPF open-coded iterators without having to write mundane explicit * low-level loop logic. Instead, it provides for()-like generic construct * that can be used pretty naturally. E.g., for some hypothetical cgroup * iterator, you'd write: * * struct cgroup *cg, *parent_cg = <...>; * * bpf_for_each(cgroup, cg, parent_cg, CG_ITER_CHILDREN) { * bpf_printk("Child cgroup id = %d", cg->cgroup_id); * if (cg->cgroup_id == 123) * break; * } * * I.e., it looks almost like high-level for each loop in other languages, * supports continue/break, and is verifiable by BPF verifier. * * For iterating integers, the difference between bpf_for_each(num, i, N, M) * and bpf_for(i, N, M) is in that bpf_for() provides additional proof to * verifier that i is in [N, M) range, and in bpf_for_each() case i is `int * *`, not just `int`. So for integers bpf_for() is more convenient. * * Note: this macro relies on C99 feature of allowing to declare variables * inside for() loop, bound to for() loop lifetime. It also utilizes GCC * extension: __attribute__((cleanup(<func>))), supported by both GCC and * Clang. */ #define bpf_for_each(type, cur, args...) for ( \ /* initialize and define destructor */ \ struct bpf_iter_##type ___it __attribute__((aligned(8), /* enforce, just in case */, \ cleanup(bpf_iter_##type##_destroy))), \ /* ___p pointer is just to call bpf_iter_##type##_new() *once* to init ___it */ \ *___p __attribute__((unused)) = ( \ bpf_iter_##type##_new(&___it, ##args), \ /* this is a workaround for Clang bug: it currently doesn't emit BTF */ \ /* for bpf_iter_##type##_destroy() when used from cleanup() attribute */ \ (void)bpf_iter_##type##_destroy, (void *)0); \ /* iteration and termination check */ \ (((cur) = bpf_iter_##type##_next(&___it))); \ ) #endif /* bpf_for_each */ #ifndef bpf_for /* bpf_for(i, start, end) implements a for()-like looping construct that sets * provided integer variable *i* to values starting from *start* through, * but not including, *end*. It also proves to BPF verifier that *i* belongs * to range [start, end), so this can be used for accessing arrays without * extra checks. * * Note: *start* and *end* are assumed to be expressions with no side effects * and whose values do not change throughout bpf_for() loop execution. They do * not have to be statically known or constant, though. * * Note: similarly to bpf_for_each(), it relies on C99 feature of declaring for() * loop bound variables and cleanup attribute, supported by GCC and Clang. */ #define bpf_for(i, start, end) for ( \ /* initialize and define destructor */ \ struct bpf_iter_num ___it __attribute__((aligned(8), /* enforce, just in case */ \ cleanup(bpf_iter_num_destroy))), \ /* ___p pointer is necessary to call bpf_iter_num_new() *once* to init ___it */ \ *___p __attribute__((unused)) = ( \ bpf_iter_num_new(&___it, (start), (end)), \ /* this is a workaround for Clang bug: it currently doesn't emit BTF */ \ /* for bpf_iter_num_destroy() when used from cleanup() attribute */ \ (void)bpf_iter_num_destroy, (void *)0); \ ({ \ /* iteration step */ \ int *___t = bpf_iter_num_next(&___it); \ /* termination and bounds check */ \ (___t && ((i) = *___t, (i) >= (start) && (i) < (end))); \ }); \ ) #endif /* bpf_for */ #ifndef bpf_repeat /* bpf_repeat(N) performs N iterations without exposing iteration number * * Note: similarly to bpf_for_each(), it relies on C99 feature of declaring for() * loop bound variables and cleanup attribute, supported by GCC and Clang. */ #define bpf_repeat(N) for ( \ /* initialize and define destructor */ \ struct bpf_iter_num ___it __attribute__((aligned(8), /* enforce, just in case */ \ cleanup(bpf_iter_num_destroy))), \ /* ___p pointer is necessary to call bpf_iter_num_new() *once* to init ___it */ \ *___p __attribute__((unused)) = ( \ bpf_iter_num_new(&___it, 0, (N)), \ /* this is a workaround for Clang bug: it currently doesn't emit BTF */ \ /* for bpf_iter_num_destroy() when used from cleanup() attribute */ \ (void)bpf_iter_num_destroy, (void *)0); \ bpf_iter_num_next(&___it); \ /* nothing here */ \ ) #endif /* bpf_repeat */ #endif