include/linux/indirect_call_wrapper.h

   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