tools/testing/selftests/bpf/bpf_trace_helpers.h

   1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
   2 #ifndef __BPF_TRACE_HELPERS_H
   3 #define __BPF_TRACE_HELPERS_H
   4
   5 #include <bpf/bpf_helpers.h>
   6
   7 #define ___bpf_concat(a, b) a ## b
   8 #define ___bpf_apply(fn, n) ___bpf_concat(fn, n)
   9 #define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N
  10 #define ___bpf_narg(...) \
  11         ___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
  12 #define ___bpf_empty(...) \
  13         ___bpf_nth(_, ##__VA_ARGS__, N, N, N, N, N, N, N, N, N, N, 0)
  14
  15 #define ___bpf_ctx_cast0() ctx
  16 #define ___bpf_ctx_cast1(x) ___bpf_ctx_cast0(), (void *)ctx[0]
  17 #define ___bpf_ctx_cast2(x, args...) ___bpf_ctx_cast1(args), (void *)ctx[1]
  18 #define ___bpf_ctx_cast3(x, args...) ___bpf_ctx_cast2(args), (void *)ctx[2]
  19 #define ___bpf_ctx_cast4(x, args...) ___bpf_ctx_cast3(args), (void *)ctx[3]
  20 #define ___bpf_ctx_cast5(x, args...) ___bpf_ctx_cast4(args), (void *)ctx[4]
  21 #define ___bpf_ctx_cast6(x, args...) ___bpf_ctx_cast5(args), (void *)ctx[5]
  22 #define ___bpf_ctx_cast7(x, args...) ___bpf_ctx_cast6(args), (void *)ctx[6]
  23 #define ___bpf_ctx_cast8(x, args...) ___bpf_ctx_cast7(args), (void *)ctx[7]
  24 #define ___bpf_ctx_cast9(x, args...) ___bpf_ctx_cast8(args), (void *)ctx[8]
  25 #define ___bpf_ctx_cast10(x, args...) ___bpf_ctx_cast9(args), (void *)ctx[9]
  26 #define ___bpf_ctx_cast11(x, args...) ___bpf_ctx_cast10(args), (void *)ctx[10]
  27 #define ___bpf_ctx_cast12(x, args...) ___bpf_ctx_cast11(args), (void *)ctx[11]
  28 #define ___bpf_ctx_cast(args...) \
  29         ___bpf_apply(___bpf_ctx_cast, ___bpf_narg(args))(args)
  30
  31 /*
  32  * BPF_PROG is a convenience wrapper for generic tp_btf/fentry/fexit and
  33  * similar kinds of BPF programs, that accept input arguments as a single
  34  * pointer to untyped u64 array, where each u64 can actually be a typed
  35  * pointer or integer of different size. Instead of requring user to write
  36  * manual casts and work with array elements by index, BPF_PROG macro
  37  * allows user to declare a list of named and typed input arguments in the
  38  * same syntax as for normal C function. All the casting is hidden and
  39  * performed transparently, while user code can just assume working with
  40  * function arguments of specified type and name.
  41  *
  42  * Original raw context argument is preserved as well as 'ctx' argument.
  43  * This is useful when using BPF helpers that expect original context
  44  * as one of the parameters (e.g., for bpf_perf_event_output()).
  45  */
  46 #define BPF_PROG(name, args...)                                             \
  47 name(unsigned long long *ctx);                                              \
  48 static __always_inline typeof(name(0))                                      \
  49 ____##name(unsigned long long *ctx, ##args);                                \
  50 typeof(name(0)) name(unsigned long long *ctx)                               \
  51 {                                                                           \
  52         _Pragma("GCC diagnostic push")                                      \
  53         _Pragma("GCC diagnostic ignored \"-Wint-conversion\"")              \
  54         return ____##name(___bpf_ctx_cast(args));                           \
  55         _Pragma("GCC diagnostic pop")                                       \
  56 }                                                                           \
  57 static __always_inline typeof(name(0))                                      \
  58 ____##name(unsigned long long *ctx, ##args)
  59
  60 struct pt_regs;
  61
  62 #define ___bpf_kprobe_args0() ctx
  63 #define ___bpf_kprobe_args1(x) \
  64         ___bpf_kprobe_args0(), (void *)PT_REGS_PARM1(ctx)
  65 #define ___bpf_kprobe_args2(x, args...) \
  66         ___bpf_kprobe_args1(args), (void *)PT_REGS_PARM2(ctx)
  67 #define ___bpf_kprobe_args3(x, args...) \
  68         ___bpf_kprobe_args2(args), (void *)PT_REGS_PARM3(ctx)
  69 #define ___bpf_kprobe_args4(x, args...) \
  70         ___bpf_kprobe_args3(args), (void *)PT_REGS_PARM4(ctx)
  71 #define ___bpf_kprobe_args5(x, args...) \
  72         ___bpf_kprobe_args4(args), (void *)PT_REGS_PARM5(ctx)
  73 #define ___bpf_kprobe_args(args...) \
  74         ___bpf_apply(___bpf_kprobe_args, ___bpf_narg(args))(args)
  75
  76 /*
  77  * BPF_KPROBE serves the same purpose for kprobes as BPF_PROG for
  78  * tp_btf/fentry/fexit BPF programs. It hides the underlying platform-specific
  79  * low-level way of getting kprobe input arguments from struct pt_regs, and
  80  * provides a familiar typed and named function arguments syntax and
  81  * semantics of accessing kprobe input paremeters.
  82  *
  83  * Original struct pt_regs* context is preserved as 'ctx' argument. This might
  84  * be necessary when using BPF helpers like bpf_perf_event_output().
  85  */
  86 #define BPF_KPROBE(name, args...)                                           \
  87 name(struct pt_regs *ctx);                                                  \
  88 static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args);\
  89 typeof(name(0)) name(struct pt_regs *ctx)                                   \
  90 {                                                                           \
  91         _Pragma("GCC diagnostic push")                                      \
  92         _Pragma("GCC diagnostic ignored \"-Wint-conversion\"")              \
  93         return ____##name(___bpf_kprobe_args(args));                        \
  94         _Pragma("GCC diagnostic pop")                                       \
  95 }                                                                           \
  96 static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)
  97
  98 #define ___bpf_kretprobe_args0() ctx
  99 #define ___bpf_kretprobe_argsN(x, args...) \
 100         ___bpf_kprobe_args(args), (void *)PT_REGS_RET(ctx)
 101 #define ___bpf_kretprobe_args(args...) \
 102         ___bpf_apply(___bpf_kretprobe_args, ___bpf_empty(args))(args)
 103
 104 /*
 105  * BPF_KRETPROBE is similar to BPF_KPROBE, except, in addition to listing all
 106  * input kprobe arguments, one last extra argument has to be specified, which
 107  * captures kprobe return value.
 108  */
 109 #define BPF_KRETPROBE(name, args...)                                        \
 110 name(struct pt_regs *ctx);                                                  \
 111 static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args);\
 112 typeof(name(0)) name(struct pt_regs *ctx)                                   \
 113 {                                                                           \
 114         _Pragma("GCC diagnostic push")                                      \
 115         _Pragma("GCC diagnostic ignored \"-Wint-conversion\"")              \
 116         return ____##name(___bpf_kretprobe_args(args));                     \
 117         _Pragma("GCC diagnostic pop")                                       \
 118 }                                                                           \
 119 static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)
 120 #endif