295 lines
9.9 KiB
C
295 lines
9.9 KiB
C
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/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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#ifndef __BPF_HELPERS__
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#define __BPF_HELPERS__
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/*
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* Note that bpf programs need to include either
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* vmlinux.h (auto-generated from BTF) or linux/types.h
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* in advance since bpf_helper_defs.h uses such types
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* as __u64.
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*/
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#include "bpf_helper_defs.h"
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#define __uint(name, val) int (*name)[val]
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#define __type(name, val) typeof(val) *name
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#define __array(name, val) typeof(val) *name[]
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/*
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* Helper macro to place programs, maps, license in
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* different sections in elf_bpf file. Section names
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* are interpreted by libbpf depending on the context (BPF programs, BPF maps,
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* extern variables, etc).
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* To allow use of SEC() with externs (e.g., for extern .maps declarations),
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* make sure __attribute__((unused)) doesn't trigger compilation warning.
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*/
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#if __GNUC__ && !__clang__
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/*
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* Pragma macros are broken on GCC
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* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578
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* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400
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*/
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#define SEC(name) __attribute__((section(name), used))
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#else
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#define SEC(name) \
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_Pragma("GCC diagnostic push") \
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_Pragma("GCC diagnostic ignored \"-Wignored-attributes\"") \
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__attribute__((section(name), used)) \
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_Pragma("GCC diagnostic pop") \
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#endif
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/* Avoid 'linux/stddef.h' definition of '__always_inline'. */
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#undef __always_inline
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#define __always_inline inline __attribute__((always_inline))
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#ifndef __noinline
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#define __noinline __attribute__((noinline))
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#endif
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#ifndef __weak
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#define __weak __attribute__((weak))
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#endif
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/*
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* Use __hidden attribute to mark a non-static BPF subprogram effectively
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* static for BPF verifier's verification algorithm purposes, allowing more
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* extensive and permissive BPF verification process, taking into account
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* subprogram's caller context.
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*/
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#define __hidden __attribute__((visibility("hidden")))
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/* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include
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* any system-level headers (such as stddef.h, linux/version.h, etc), and
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* commonly-used macros like NULL and KERNEL_VERSION aren't available through
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* vmlinux.h. This just adds unnecessary hurdles and forces users to re-define
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* them on their own. So as a convenience, provide such definitions here.
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*/
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#ifndef NULL
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#define NULL ((void *)0)
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#endif
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#ifndef KERNEL_VERSION
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#define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)))
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#endif
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/*
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* Helper macros to manipulate data structures
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*/
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/* offsetof() definition that uses __builtin_offset() might not preserve field
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* offset CO-RE relocation properly, so force-redefine offsetof() using
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* old-school approach which works with CO-RE correctly
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*/
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#undef offsetof
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#define offsetof(type, member) ((unsigned long)&((type *)0)->member)
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/* redefined container_of() to ensure we use the above offsetof() macro */
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#undef container_of
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#define container_of(ptr, type, member) \
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({ \
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void *__mptr = (void *)(ptr); \
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((type *)(__mptr - offsetof(type, member))); \
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})
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/*
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* Compiler (optimization) barrier.
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*/
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#ifndef barrier
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#define barrier() asm volatile("" ::: "memory")
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#endif
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/* Variable-specific compiler (optimization) barrier. It's a no-op which makes
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* compiler believe that there is some black box modification of a given
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* variable and thus prevents compiler from making extra assumption about its
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* value and potential simplifications and optimizations on this variable.
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*
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* E.g., compiler might often delay or even omit 32-bit to 64-bit casting of
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* a variable, making some code patterns unverifiable. Putting barrier_var()
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* in place will ensure that cast is performed before the barrier_var()
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* invocation, because compiler has to pessimistically assume that embedded
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* asm section might perform some extra operations on that variable.
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*
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* This is a variable-specific variant of more global barrier().
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*/
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#ifndef barrier_var
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#define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var))
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#endif
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/*
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* Helper macro to throw a compilation error if __bpf_unreachable() gets
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* built into the resulting code. This works given BPF back end does not
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* implement __builtin_trap(). This is useful to assert that certain paths
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* of the program code are never used and hence eliminated by the compiler.
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*
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* For example, consider a switch statement that covers known cases used by
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* the program. __bpf_unreachable() can then reside in the default case. If
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* the program gets extended such that a case is not covered in the switch
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* statement, then it will throw a build error due to the default case not
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* being compiled out.
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*/
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#ifndef __bpf_unreachable
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# define __bpf_unreachable() __builtin_trap()
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#endif
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/*
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* Helper function to perform a tail call with a constant/immediate map slot.
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*/
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#if __clang_major__ >= 8 && defined(__bpf__)
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static __always_inline void
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bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
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{
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if (!__builtin_constant_p(slot))
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__bpf_unreachable();
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/*
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* Provide a hard guarantee that LLVM won't optimize setting r2 (map
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* pointer) and r3 (constant map index) from _different paths_ ending
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* up at the _same_ call insn as otherwise we won't be able to use the
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* jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel
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* given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key
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* tracking for prog array pokes") for details on verifier tracking.
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*
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* Note on clobber list: we need to stay in-line with BPF calling
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* convention, so even if we don't end up using r0, r4, r5, we need
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* to mark them as clobber so that LLVM doesn't end up using them
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* before / after the call.
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*/
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asm volatile("r1 = %[ctx]\n\t"
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"r2 = %[map]\n\t"
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"r3 = %[slot]\n\t"
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"call 12"
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:: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot)
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: "r0", "r1", "r2", "r3", "r4", "r5");
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}
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#endif
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enum libbpf_pin_type {
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LIBBPF_PIN_NONE,
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/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
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LIBBPF_PIN_BY_NAME,
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};
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enum libbpf_tristate {
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TRI_NO = 0,
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TRI_YES = 1,
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TRI_MODULE = 2,
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};
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#define __kconfig __attribute__((section(".kconfig")))
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#define __ksym __attribute__((section(".ksyms")))
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#define __kptr __attribute__((btf_type_tag("kptr")))
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#define __kptr_ref __attribute__((btf_type_tag("kptr_ref")))
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#ifndef ___bpf_concat
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#define ___bpf_concat(a, b) a ## b
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#endif
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#ifndef ___bpf_apply
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#define ___bpf_apply(fn, n) ___bpf_concat(fn, n)
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#endif
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#ifndef ___bpf_nth
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#define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N
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#endif
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#ifndef ___bpf_narg
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#define ___bpf_narg(...) \
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___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
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#endif
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#define ___bpf_fill0(arr, p, x) do {} while (0)
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#define ___bpf_fill1(arr, p, x) arr[p] = x
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#define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args)
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#define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args)
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#define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args)
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#define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args)
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#define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args)
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#define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args)
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#define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args)
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#define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args)
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#define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args)
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#define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args)
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#define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args)
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#define ___bpf_fill(arr, args...) \
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___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args)
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/*
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* BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values
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* in a structure.
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*/
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#define BPF_SEQ_PRINTF(seq, fmt, args...) \
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({ \
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static const char ___fmt[] = fmt; \
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unsigned long long ___param[___bpf_narg(args)]; \
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\
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_Pragma("GCC diagnostic push") \
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_Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
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___bpf_fill(___param, args); \
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_Pragma("GCC diagnostic pop") \
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\
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bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \
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___param, sizeof(___param)); \
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})
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/*
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* BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of
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* an array of u64.
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*/
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#define BPF_SNPRINTF(out, out_size, fmt, args...) \
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({ \
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static const char ___fmt[] = fmt; \
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unsigned long long ___param[___bpf_narg(args)]; \
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\
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_Pragma("GCC diagnostic push") \
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_Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
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___bpf_fill(___param, args); \
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_Pragma("GCC diagnostic pop") \
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\
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bpf_snprintf(out, out_size, ___fmt, \
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___param, sizeof(___param)); \
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})
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#ifdef BPF_NO_GLOBAL_DATA
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#define BPF_PRINTK_FMT_MOD
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#else
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#define BPF_PRINTK_FMT_MOD static const
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#endif
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#define __bpf_printk(fmt, ...) \
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({ \
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BPF_PRINTK_FMT_MOD char ____fmt[] = fmt; \
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bpf_trace_printk(____fmt, sizeof(____fmt), \
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##__VA_ARGS__); \
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})
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/*
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* __bpf_vprintk wraps the bpf_trace_vprintk helper with variadic arguments
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* instead of an array of u64.
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*/
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#define __bpf_vprintk(fmt, args...) \
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({ \
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static const char ___fmt[] = fmt; \
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unsigned long long ___param[___bpf_narg(args)]; \
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\
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_Pragma("GCC diagnostic push") \
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_Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
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___bpf_fill(___param, args); \
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_Pragma("GCC diagnostic pop") \
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\
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bpf_trace_vprintk(___fmt, sizeof(___fmt), \
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___param, sizeof(___param)); \
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})
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/* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args
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* Otherwise use __bpf_vprintk
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*/
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#define ___bpf_pick_printk(...) \
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___bpf_nth(_, ##__VA_ARGS__, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \
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__bpf_vprintk, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \
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__bpf_vprintk, __bpf_vprintk, __bpf_printk /*3*/, __bpf_printk /*2*/,\
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__bpf_printk /*1*/, __bpf_printk /*0*/)
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/* Helper macro to print out debug messages */
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#define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args)
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#endif
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