Commit 9f2f5d78 authored by Yonghong Song's avatar Yonghong Song Committed by Andrii Nakryiko
Browse files

libbpf: Improve BPF_PROG2 macro code quality and description 



Commit 34586d29 ("libbpf: Add new BPF_PROG2 macro") added BPF_PROG2
macro for trampoline based programs with struct arguments. Andrii
made a few suggestions to improve code quality and description.
This patch implemented these suggestions including better internal
macro name, consistent usage pattern for __builtin_choose_expr(),
simpler macro definition for always-inline func arguments and
better macro description.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarStanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20220910025214.1536510-1-yhs@fb.com
parent c12a0376

tools/lib/bpf/bpf_tracing.h

+91 −63
Original line number Diff line number Diff line
@@ -438,84 +438,112 @@ typeof(name(0)) name(unsigned long long *ctx) \ 
static __always_inline typeof(name(0))					    \

____##name(unsigned long long *ctx, ##args)



#ifndef ____bpf_nth

#define ____bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, N, ...) N

#ifndef ___bpf_nth2

#define ___bpf_nth2(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13,	\

		    _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, N, ...) N

#endif

#ifndef ____bpf_narg

#define ____bpf_narg(...) ____bpf_nth(_, ##__VA_ARGS__, 12, 12, 11, 11, 10, 10, 9, 9, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0)

#ifndef ___bpf_narg2

#define ___bpf_narg2(...)	\

	___bpf_nth2(_, ##__VA_ARGS__, 12, 12, 11, 11, 10, 10, 9, 9, 8, 8, 7, 7,	\

		    6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0)

#endif



#define BPF_REG_CNT(t) \

	(__builtin_choose_expr(sizeof(t) == 1 || sizeof(t) == 2 || sizeof(t) == 4 || sizeof(t) == 8, 1,	\

#define ___bpf_treg_cnt(t) \

	__builtin_choose_expr(sizeof(t) == 1, 1,	\

	__builtin_choose_expr(sizeof(t) == 2, 1,	\

	__builtin_choose_expr(sizeof(t) == 4, 1,	\

	__builtin_choose_expr(sizeof(t) == 8, 1,	\

	__builtin_choose_expr(sizeof(t) == 16, 2,	\

			       (void)0)))



#define ____bpf_reg_cnt0()			(0)

#define ____bpf_reg_cnt1(t, x)			(____bpf_reg_cnt0() + BPF_REG_CNT(t))

#define ____bpf_reg_cnt2(t, x, args...)		(____bpf_reg_cnt1(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt3(t, x, args...)		(____bpf_reg_cnt2(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt4(t, x, args...)		(____bpf_reg_cnt3(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt5(t, x, args...)		(____bpf_reg_cnt4(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt6(t, x, args...)		(____bpf_reg_cnt5(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt7(t, x, args...)		(____bpf_reg_cnt6(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt8(t, x, args...)		(____bpf_reg_cnt7(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt9(t, x, args...)		(____bpf_reg_cnt8(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt10(t, x, args...)	(____bpf_reg_cnt9(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt11(t, x, args...)	(____bpf_reg_cnt10(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt12(t, x, args...)	(____bpf_reg_cnt11(args) + BPF_REG_CNT(t))

#define ____bpf_reg_cnt(args...)	 ___bpf_apply(____bpf_reg_cnt, ____bpf_narg(args))(args)



#define ____bpf_union_arg(t, x, n) \

	__builtin_choose_expr(sizeof(t) == 1, ({ union { struct { __u8 x; } ___z; t x; } ___tmp = { .___z = {ctx[n]}}; ___tmp.x; }), \

	__builtin_choose_expr(sizeof(t) == 2, ({ union { struct { __u16 x; } ___z; t x; } ___tmp = { .___z = {ctx[n]} }; ___tmp.x; }), \

	__builtin_choose_expr(sizeof(t) == 4, ({ union { struct { __u32 x; } ___z; t x; } ___tmp = { .___z = {ctx[n]} }; ___tmp.x; }), \

	__builtin_choose_expr(sizeof(t) == 8, ({ union { struct { __u64 x; } ___z; t x; } ___tmp = {.___z = {ctx[n]} }; ___tmp.x; }), \

	__builtin_choose_expr(sizeof(t) == 16, ({ union { struct { __u64 x, y; } ___z; t x; } ___tmp = {.___z = {ctx[n], ctx[n + 1]} }; ___tmp.x; }), \

			      (void)0)))))



#define ____bpf_ctx_arg0(n, args...)

#define ____bpf_ctx_arg1(n, t, x)		, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt1(t, x))

#define ____bpf_ctx_arg2(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt2(t, x, args)) ____bpf_ctx_arg1(n, args)

#define ____bpf_ctx_arg3(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt3(t, x, args)) ____bpf_ctx_arg2(n, args)

#define ____bpf_ctx_arg4(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt4(t, x, args)) ____bpf_ctx_arg3(n, args)

#define ____bpf_ctx_arg5(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt5(t, x, args)) ____bpf_ctx_arg4(n, args)

#define ____bpf_ctx_arg6(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt6(t, x, args)) ____bpf_ctx_arg5(n, args)

#define ____bpf_ctx_arg7(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt7(t, x, args)) ____bpf_ctx_arg6(n, args)

#define ____bpf_ctx_arg8(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt8(t, x, args)) ____bpf_ctx_arg7(n, args)

#define ____bpf_ctx_arg9(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt9(t, x, args)) ____bpf_ctx_arg8(n, args)

#define ____bpf_ctx_arg10(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt10(t, x, args)) ____bpf_ctx_arg9(n, args)

#define ____bpf_ctx_arg11(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt11(t, x, args)) ____bpf_ctx_arg10(n, args)

#define ____bpf_ctx_arg12(n, t, x, args...)	, ____bpf_union_arg(t, x, n - ____bpf_reg_cnt12(t, x, args)) ____bpf_ctx_arg11(n, args)

#define ____bpf_ctx_arg(n, args...)	___bpf_apply(____bpf_ctx_arg, ____bpf_narg(args))(n, args)



#define ____bpf_ctx_decl0()

#define ____bpf_ctx_decl1(t, x)			, t x

#define ____bpf_ctx_decl2(t, x, args...)	, t x ____bpf_ctx_decl1(args)

#define ____bpf_ctx_decl3(t, x, args...)	, t x ____bpf_ctx_decl2(args)

#define ____bpf_ctx_decl4(t, x, args...)	, t x ____bpf_ctx_decl3(args)

#define ____bpf_ctx_decl5(t, x, args...)	, t x ____bpf_ctx_decl4(args)

#define ____bpf_ctx_decl6(t, x, args...)	, t x ____bpf_ctx_decl5(args)

#define ____bpf_ctx_decl7(t, x, args...)	, t x ____bpf_ctx_decl6(args)

#define ____bpf_ctx_decl8(t, x, args...)	, t x ____bpf_ctx_decl7(args)

#define ____bpf_ctx_decl9(t, x, args...)	, t x ____bpf_ctx_decl8(args)

#define ____bpf_ctx_decl10(t, x, args...)	, t x ____bpf_ctx_decl9(args)

#define ____bpf_ctx_decl11(t, x, args...)	, t x ____bpf_ctx_decl10(args)

#define ____bpf_ctx_decl12(t, x, args...)	, t x ____bpf_ctx_decl11(args)

#define ____bpf_ctx_decl(args...)	___bpf_apply(____bpf_ctx_decl, ____bpf_narg(args))(args)

#define ___bpf_reg_cnt0()		(0)

#define ___bpf_reg_cnt1(t, x)		(___bpf_reg_cnt0() + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt2(t, x, args...)	(___bpf_reg_cnt1(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt3(t, x, args...)	(___bpf_reg_cnt2(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt4(t, x, args...)	(___bpf_reg_cnt3(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt5(t, x, args...)	(___bpf_reg_cnt4(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt6(t, x, args...)	(___bpf_reg_cnt5(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt7(t, x, args...)	(___bpf_reg_cnt6(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt8(t, x, args...)	(___bpf_reg_cnt7(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt9(t, x, args...)	(___bpf_reg_cnt8(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt10(t, x, args...)	(___bpf_reg_cnt9(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt11(t, x, args...)	(___bpf_reg_cnt10(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt12(t, x, args...)	(___bpf_reg_cnt11(args) + ___bpf_treg_cnt(t))

#define ___bpf_reg_cnt(args...)	 ___bpf_apply(___bpf_reg_cnt, ___bpf_narg2(args))(args)



#define ___bpf_union_arg(t, x, n) \

	__builtin_choose_expr(sizeof(t) == 1, ({ union { __u8 z[1]; t x; } ___t = { .z = {ctx[n]}}; ___t.x; }), \

	__builtin_choose_expr(sizeof(t) == 2, ({ union { __u16 z[1]; t x; } ___t = { .z = {ctx[n]} }; ___t.x; }), \

	__builtin_choose_expr(sizeof(t) == 4, ({ union { __u32 z[1]; t x; } ___t = { .z = {ctx[n]} }; ___t.x; }), \

	__builtin_choose_expr(sizeof(t) == 8, ({ union { __u64 z[1]; t x; } ___t = {.z = {ctx[n]} }; ___t.x; }), \

	__builtin_choose_expr(sizeof(t) == 16, ({ union { __u64 z[2]; t x; } ___t = {.z = {ctx[n], ctx[n + 1]} }; ___t.x; }), \

			      (void)0)))))



#define ___bpf_ctx_arg0(n, args...)

#define ___bpf_ctx_arg1(n, t, x)		, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt1(t, x))

#define ___bpf_ctx_arg2(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt2(t, x, args)) ___bpf_ctx_arg1(n, args)

#define ___bpf_ctx_arg3(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt3(t, x, args)) ___bpf_ctx_arg2(n, args)

#define ___bpf_ctx_arg4(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt4(t, x, args)) ___bpf_ctx_arg3(n, args)

#define ___bpf_ctx_arg5(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt5(t, x, args)) ___bpf_ctx_arg4(n, args)

#define ___bpf_ctx_arg6(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt6(t, x, args)) ___bpf_ctx_arg5(n, args)

#define ___bpf_ctx_arg7(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt7(t, x, args)) ___bpf_ctx_arg6(n, args)

#define ___bpf_ctx_arg8(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt8(t, x, args)) ___bpf_ctx_arg7(n, args)

#define ___bpf_ctx_arg9(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt9(t, x, args)) ___bpf_ctx_arg8(n, args)

#define ___bpf_ctx_arg10(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt10(t, x, args)) ___bpf_ctx_arg9(n, args)

#define ___bpf_ctx_arg11(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt11(t, x, args)) ___bpf_ctx_arg10(n, args)

#define ___bpf_ctx_arg12(n, t, x, args...)	, ___bpf_union_arg(t, x, n - ___bpf_reg_cnt12(t, x, args)) ___bpf_ctx_arg11(n, args)

#define ___bpf_ctx_arg(args...)	___bpf_apply(___bpf_ctx_arg, ___bpf_narg2(args))(___bpf_reg_cnt(args), args)



#define ___bpf_ctx_decl0()

#define ___bpf_ctx_decl1(t, x)			, t x

#define ___bpf_ctx_decl2(t, x, args...)		, t x ___bpf_ctx_decl1(args)

#define ___bpf_ctx_decl3(t, x, args...)		, t x ___bpf_ctx_decl2(args)

#define ___bpf_ctx_decl4(t, x, args...)		, t x ___bpf_ctx_decl3(args)

#define ___bpf_ctx_decl5(t, x, args...)		, t x ___bpf_ctx_decl4(args)

#define ___bpf_ctx_decl6(t, x, args...)		, t x ___bpf_ctx_decl5(args)

#define ___bpf_ctx_decl7(t, x, args...)		, t x ___bpf_ctx_decl6(args)

#define ___bpf_ctx_decl8(t, x, args...)		, t x ___bpf_ctx_decl7(args)

#define ___bpf_ctx_decl9(t, x, args...)		, t x ___bpf_ctx_decl8(args)

#define ___bpf_ctx_decl10(t, x, args...)	, t x ___bpf_ctx_decl9(args)

#define ___bpf_ctx_decl11(t, x, args...)	, t x ___bpf_ctx_decl10(args)

#define ___bpf_ctx_decl12(t, x, args...)	, t x ___bpf_ctx_decl11(args)

#define ___bpf_ctx_decl(args...)	___bpf_apply(___bpf_ctx_decl, ___bpf_narg2(args))(args)



/*

 * BPF_PROG2 can handle struct arguments.

 * BPF_PROG2 is an enhanced version of BPF_PROG in order to handle struct

 * arguments. Since each struct argument might take one or two u64 values

 * in the trampoline stack, argument type size is needed to place proper number

 * of u64 values for each argument. Therefore, BPF_PROG2 has different

 * syntax from BPF_PROG. For example, for the following BPF_PROG syntax:

 *

 *   int BPF_PROG(test2, int a, int b) { ... }

 *

 * the corresponding BPF_PROG2 syntax is:

 *

 *   int BPF_PROG2(test2, int, a, int, b) { ... }

 *

 * where type and the corresponding argument name are separated by comma.

 *

 * Use BPF_PROG2 macro if one of the arguments might be a struct/union larger

 * than 8 bytes:

 *

 *   int BPF_PROG2(test_struct_arg, struct bpf_testmod_struct_arg_1, a, int, b,

 *		   int, c, int, d, struct bpf_testmod_struct_arg_2, e, int, ret)

 *   {

 *        // access a, b, c, d, e, and ret directly

 *        ...

 *   }

 */

#define BPF_PROG2(name, args...)						\

name(unsigned long long *ctx);							\

static __always_inline typeof(name(0))						\

____##name(unsigned long long *ctx ____bpf_ctx_decl(args));			\

____##name(unsigned long long *ctx ___bpf_ctx_decl(args));			\

typeof(name(0)) name(unsigned long long *ctx)					\

{										\

	return ____##name(ctx ____bpf_ctx_arg(____bpf_reg_cnt(args), args));	\

	return ____##name(ctx ___bpf_ctx_arg(args));				\

}										\

static __always_inline typeof(name(0))						\

____##name(unsigned long long *ctx ____bpf_ctx_decl(args))

____##name(unsigned long long *ctx ___bpf_ctx_decl(args))



struct pt_regs;