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 $NR of them
  11 *  @__VA_ARGS__: arguments for @f
  12 *
  13 * Avoid retpoline overhead for known builtin, checking @f vs each of them and
  14 * eventually invoking directly the builtin function. The functions are check
  15 * in the given order. Fallback to the indirect call.
  16 */
  17#define INDIRECT_CALL_1(f, f1, ...)                                     \
  18        ({                                                              \
  19                likely(f == f1) ? f1(__VA_ARGS__) : f(__VA_ARGS__);     \
  20        })
  21#define INDIRECT_CALL_2(f, f2, f1, ...)                                 \
  22        ({                                                              \
  23                likely(f == f2) ? f2(__VA_ARGS__) :                     \
  24                                  INDIRECT_CALL_1(f, f1, __VA_ARGS__);  \
  25        })
  26
  27#define INDIRECT_CALLABLE_DECLARE(f)    f
  28#define INDIRECT_CALLABLE_SCOPE
  29
  30#else
  31#define INDIRECT_CALL_1(f, f1, ...) f(__VA_ARGS__)
  32#define INDIRECT_CALL_2(f, f2, f1, ...) f(__VA_ARGS__)
  33#define INDIRECT_CALLABLE_DECLARE(f)
  34#define INDIRECT_CALLABLE_SCOPE         static
  35#endif
  36
  37/*
  38 * We can use INDIRECT_CALL_$NR for ipv6 related functions only if ipv6 is
  39 * builtin, this macro simplify dealing with indirect calls with only ipv4/ipv6
  40 * alternatives
  41 */
  42#if IS_BUILTIN(CONFIG_IPV6)
  43#define INDIRECT_CALL_INET(f, f2, f1, ...) \
  44        INDIRECT_CALL_2(f, f2, f1, __VA_ARGS__)
  45#elif IS_ENABLED(CONFIG_INET)
  46#define INDIRECT_CALL_INET(f, f2, f1, ...) INDIRECT_CALL_1(f, f1, __VA_ARGS__)
  47#else
  48#define INDIRECT_CALL_INET(f, f2, f1, ...) f(__VA_ARGS__)
  49#endif
  50
  51#endif
  52