diff options
Diffstat (limited to 'tools/lib/bpf/bpf_helpers.h')
| -rw-r--r-- | tools/lib/bpf/bpf_helpers.h | 221 |
1 files changed, 204 insertions, 17 deletions
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h index 963b1060d944..d4e4e388e625 100644 --- a/tools/lib/bpf/bpf_helpers.h +++ b/tools/lib/bpf/bpf_helpers.h @@ -13,6 +13,15 @@ #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 + +#ifndef likely +#define likely(x) (__builtin_expect(!!(x), 1)) +#endif + +#ifndef unlikely +#define unlikely(x) (__builtin_expect(!!(x), 0)) +#endif /* * Helper macro to place programs, maps, license in @@ -22,12 +31,25 @@ * 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)) @@ -64,15 +86,44 @@ /* * Helper macros to manipulate data structures */ -#ifndef offsetof -#define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER) -#endif -#ifndef container_of + +/* 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 /* @@ -94,7 +145,8 @@ /* * Helper function to perform a tail call with a constant/immediate map slot. */ -#if __clang_major__ >= 8 && defined(__bpf__) +#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) { @@ -122,18 +174,7 @@ bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) : "r0", "r1", "r2", "r3", "r4", "r5"); } #endif - -/* - * Helper structure used by eBPF C program - * to describe BPF map attributes to libbpf loader - */ -struct bpf_map_def { - unsigned int type; - unsigned int key_size; - unsigned int value_size; - unsigned int max_entries; - unsigned int map_flags; -}; +#endif enum libbpf_pin_type { LIBBPF_PIN_NONE, @@ -149,6 +190,33 @@ enum libbpf_tristate { #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"))) +#define __uptr __attribute__((btf_type_tag("uptr"))) + +#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_untrusted __attribute((btf_decl_tag("arg:untrusted"))) +#define __arg_arena __attribute((btf_decl_tag("arg:arena"))) #ifndef ___bpf_concat #define ___bpf_concat(a, b) a ## b @@ -247,6 +315,22 @@ enum libbpf_tristate { ___param, sizeof(___param)); \ }) +extern int bpf_stream_vprintk_impl(int stream_id, const char *fmt__str, const void *args, + __u32 len__sz, void *aux__prog) __weak __ksym; + +#define bpf_stream_printk(stream_id, 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_stream_vprintk_impl(stream_id, ___fmt, ___param, sizeof(___param), NULL); \ +}) + /* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args * Otherwise use __bpf_vprintk */ @@ -259,4 +343,107 @@ enum libbpf_tristate { /* 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 |