llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.cpp

   1 //===- JITLoaderGDB.h - Register objects via GDB JIT interface -*- 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 #include "llvm/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.h"
  10
  11 #include "llvm/Support/Compiler.h"
  12 #include "llvm/Support/FormatVariadic.h"
  13
  14 #include <cstdint>
  15 #include <mutex>
  16
  17 #define DEBUG_TYPE "orc"
  18
  19 // First version as landed in August 2009
  20 static constexpr uint32_t JitDescriptorVersion = 1;
  21
  22 extern "C" {
  23
  24 // We put information about the JITed function in this global, which the
  25 // debugger reads.  Make sure to specify the version statically, because the
  26 // debugger checks the version before we can set it during runtime.
  27 LLVM_ALWAYS_EXPORT
  28 struct jit_descriptor __jit_debug_descriptor = {JitDescriptorVersion, 0,
  29                                                 nullptr, nullptr};
  30
  31 // Debuggers that implement the GDB JIT interface put a special breakpoint in
  32 // this function.
  33 LLVM_ALWAYS_EXPORT
  34 LLVM_ATTRIBUTE_NOINLINE void __jit_debug_register_code() {
  35   // The noinline and the asm prevent calls to this function from being
  36   // optimized out.
  37 #if !defined(_MSC_VER)
  38   asm volatile("" ::: "memory");
  39 #endif
  40 }
  41 }
  42
  43 using namespace llvm;
  44 using namespace llvm::orc;
  45
  46 // Register debug object, return error message or null for success.
  47 static void appendJITDebugDescriptor(const char *ObjAddr, size_t Size) {
  48   LLVM_DEBUG({
  49     dbgs() << "Adding debug object to GDB JIT interface "
  50            << formatv("([{0:x16} -- {1:x16}])",
  51                       reinterpret_cast<uintptr_t>(ObjAddr),
  52                       reinterpret_cast<uintptr_t>(ObjAddr + Size))
  53            << "\n";
  54   });
  55
  56   jit_code_entry *E = new jit_code_entry;
  57   E->symfile_addr = ObjAddr;
  58   E->symfile_size = Size;
  59   E->prev_entry = nullptr;
  60
  61   // Serialize rendezvous with the debugger as well as access to shared data.
  62   static std::mutex JITDebugLock;
  63   std::lock_guard<std::mutex> Lock(JITDebugLock);
  64
  65   // Insert this entry at the head of the list.
  66   jit_code_entry *NextEntry = __jit_debug_descriptor.first_entry;
  67   E->next_entry = NextEntry;
  68   if (NextEntry) {
  69     NextEntry->prev_entry = E;
  70   }
  71
  72   __jit_debug_descriptor.first_entry = E;
  73   __jit_debug_descriptor.relevant_entry = E;
  74   __jit_debug_descriptor.action_flag = JIT_REGISTER_FN;
  75 }
  76
  77 extern "C" orc::shared::CWrapperFunctionResult
  78 llvm_orc_registerJITLoaderGDBAllocAction(const char *Data, size_t Size) {
  79   using namespace orc::shared;
  80   return WrapperFunction<SPSError(SPSExecutorAddrRange, bool)>::handle(
  81              Data, Size,
  82              [](ExecutorAddrRange R, bool AutoRegisterCode) {
  83                appendJITDebugDescriptor(R.Start.toPtr<const char *>(),
  84                                         R.size());
  85                // Run into the rendezvous breakpoint.
  86                if (AutoRegisterCode)
  87                  __jit_debug_register_code();
  88                return Error::success();
  89              })
  90       .release();
  91 }
  92
  93 extern "C" orc::shared::CWrapperFunctionResult
  94 llvm_orc_registerJITLoaderGDBWrapper(const char *Data, uint64_t Size) {
  95   using namespace orc::shared;
  96   return WrapperFunction<SPSError(SPSExecutorAddrRange, bool)>::handle(
  97              Data, Size,
  98              [](ExecutorAddrRange R, bool AutoRegisterCode) {
  99                appendJITDebugDescriptor(R.Start.toPtr<const char *>(),
 100                                         R.size());
 101                // Run into the rendezvous breakpoint.
 102                if (AutoRegisterCode)
 103                  __jit_debug_register_code();
 104                return Error::success();
 105              })
 106       .release();
 107 }