LXR linux/include/linux/indirect_call

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _LINUX_INDIRECT_CALL_WRAPPER_H
   3#define _LINUX_INDIRECT_CALL_WRAPPER_H
   4
   5#ifdef CONFIG_RETPOLINE
   6
   7/*
   8 * INDIRECT_CALL_$NR - wrapper for indirect calls with $NR known builtin
   9 *  @f: function pointer
  10 *  @f$NR: builtin functions names, up to $NR of them
  11 *  @__VA_ARGS__: arguments for @f
  12 *
  13 * Avoid retpoline overhead for known builtin, checking @f vs each of them and
  14 * eventually invoking directly the builtin function. The functions are check
  15 * in the given order. Fallback to the indirect call.
  16 */
  17#define INDIRECT_CALL_1(f, f1, ...)                                     \
  18        ({                                                              \
  19                likely(f == f1) ? f1(__VA_ARGS__) : f(__VA_ARGS__);     \
  20        })
  21#define INDIRECT_CALL_2(f, f2, f1, ...)                                 \
  22        ({                                                              \
  23                likely(f == f2) ? f2(__VA_ARGS__) :                     \
  24                                  INDIRECT_CALL_1(f, f1, __VA_ARGS__);  \
  25        })
  26#define INDIRECT_CALL_3(f, f3, f2, f1, ...)                                     \
  27        ({                                                                      \
  28                likely(f == f3) ? f3(__VA_ARGS__) :                             \
  29                                  INDIRECT_CALL_2(f, f2, f1, __VA_ARGS__);      \
  30        })
  31#define INDIRECT_CALL_4(f, f4, f3, f2, f1, ...)                                 \
  32        ({                                                                      \
  33                likely(f == f4) ? f4(__VA_ARGS__) :                             \
  34                                  INDIRECT_CALL_3(f, f3, f2, f1, __VA_ARGS__);  \
  35        })
  36
  37#define INDIRECT_CALLABLE_DECLARE(f)    f
  38#define INDIRECT_CALLABLE_SCOPE
  39
  40#else
  41#define INDIRECT_CALL_1(f, f1, ...) f(__VA_ARGS__)
  42#define INDIRECT_CALL_2(f, f2, f1, ...) f(__VA_ARGS__)
  43#define INDIRECT_CALL_3(f, f3, f2, f1, ...) f(__VA_ARGS__)
  44#define INDIRECT_CALL_4(f, f4, f3, f2, f1, ...) f(__VA_ARGS__)
  45#define INDIRECT_CALLABLE_DECLARE(f)
  46#define INDIRECT_CALLABLE_SCOPE         static
  47#endif
  48
  49/*
  50 * We can use INDIRECT_CALL_$NR for ipv6 related functions only if ipv6 is
  51 * builtin, this macro simplify dealing with indirect calls with only ipv4/ipv6
  52 * alternatives
  53 */
  54#if IS_BUILTIN(CONFIG_IPV6)
  55#define INDIRECT_CALL_INET(f, f2, f1, ...) \
  56        INDIRECT_CALL_2(f, f2, f1, __VA_ARGS__)
  57#elif IS_ENABLED(CONFIG_INET)
  58#define INDIRECT_CALL_INET(f, f2, f1, ...) INDIRECT_CALL_1(f, f1, __VA_ARGS__)
  59#else
  60#define INDIRECT_CALL_INET(f, f2, f1, ...) f(__VA_ARGS__)
  61#endif
  62
  63#endif
  64