offload/plugins-nextgen/host/dynamic_ffi/ffi.cpp

   1 //===--- generic-elf-64bit/dynamic_ffi/ffi.cpp -------------------- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Implement subset of the FFI api by calling into the FFI library via dlopen
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/Support/DynamicLibrary.h"
  14
  15 #include "Shared/Debug.h"
  16 #include <memory>
  17
  18 #include "DLWrap.h"
  19 #include "ffi.h"
  20
  21 DLWRAP_INITIALIZE()
  22
  23 DLWRAP(ffi_call, 4);
  24 DLWRAP(ffi_prep_cif, 5);
  25
  26 DLWRAP_FINALIZE()
  27
  28 ffi_type ffi_type_void;
  29 ffi_type ffi_type_pointer;
  30
  31 // Name of the FFI shared library.
  32 constexpr const char *FFI_PATH = "libffi.so";
  33
  34 #define DYNAMIC_FFI_SUCCESS 0
  35 #define DYNAMIC_FFI_FAIL 1
  36
  37 // Initializes the dynamic FFI wrapper.
  38 uint32_t ffi_init() {
  39   std::string ErrMsg;
  40   auto DynlibHandle = std::make_unique<llvm::sys::DynamicLibrary>(
  41       llvm::sys::DynamicLibrary::getPermanentLibrary(FFI_PATH, &ErrMsg));
  42
  43   if (!DynlibHandle->isValid()) {
  44     DP("Unable to load library '%s': %s!\n", FFI_PATH, ErrMsg.c_str());
  45     return DYNAMIC_FFI_FAIL;
  46   }
  47
  48   for (size_t I = 0; I < dlwrap::size(); I++) {
  49     const char *Sym = dlwrap::symbol(I);
  50
  51     void *P = DynlibHandle->getAddressOfSymbol(Sym);
  52     if (P == nullptr) {
  53       DP("Unable to find '%s' in '%s'!\n", Sym, FFI_PATH);
  54       return DYNAMIC_FFI_FAIL;
  55     }
  56     DP("Implementing %s with dlsym(%s) -> %p\n", Sym, Sym, P);
  57
  58     *dlwrap::pointer(I) = P;
  59   }
  60
  61 #define DYNAMIC_INIT(SYMBOL)                                                   \
  62   {                                                                            \
  63     void *SymbolPtr = DynlibHandle->getAddressOfSymbol(#SYMBOL);               \
  64     if (!SymbolPtr) {                                                          \
  65       DP("Unable to find '%s' in '%s'!\n", #SYMBOL, FFI_PATH);                 \
  66       return DYNAMIC_FFI_FAIL;                                                 \
  67     }                                                                          \
  68     SYMBOL = *reinterpret_cast<decltype(SYMBOL) *>(SymbolPtr);                 \
  69   }
  70   DYNAMIC_INIT(ffi_type_void);
  71   DYNAMIC_INIT(ffi_type_pointer);
  72 #undef DYNAMIC_INIT
  73
  74   return DYNAMIC_FFI_SUCCESS;
  75 }