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 $NR of them
  11  *  @__VA_ARGS__: arguments for @f
  12  *
  13  * Avoid retpoline overhead for known builtin, checking @f vs each of them and
  14  * eventually invoking directly the builtin function. The functions are check
  15  * in the given order. Fallback to the indirect call.
  16  */
  17 #define INDIRECT_CALL_1(f, f1, ...)                                     \
  18         ({                                                              \
  19                 likely(f == f1) ? f1(__VA_ARGS__) : f(__VA_ARGS__);     \
  20         })
  21 #define INDIRECT_CALL_2(f, f2, f1, ...)                                 \
  22         ({                                                              \
  23                 likely(f == f2) ? f2(__VA_ARGS__) :                     \
  24                                   INDIRECT_CALL_1(f, f1, __VA_ARGS__);  \
  25         })
  26
  27 #define INDIRECT_CALLABLE_DECLARE(f)    f
  28 #define INDIRECT_CALLABLE_SCOPE
  29
  30 #else
  31 #define INDIRECT_CALL_1(f, f1, ...) f(__VA_ARGS__)
  32 #define INDIRECT_CALL_2(f, f2, f1, ...) f(__VA_ARGS__)
  33 #define INDIRECT_CALLABLE_DECLARE(f)
  34 #define INDIRECT_CALLABLE_SCOPE         static
  35 #endif
  36
  37 /*
  38  * We can use INDIRECT_CALL_$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