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/ExecutionEngine/JITSymbol.h"
12#include "llvm/Support/BinaryStreamReader.h"
13#include "llvm/Support/FormatVariadic.h"
14
15#include <cstdint>
16#include <mutex>
17#include <utility>
18
19#define DEBUG_TYPE "orc"
20
21// First version as landed in August 2009
22static constexpr uint32_t JitDescriptorVersion = 1;
23
24extern "C" {
25
26// We put information about the JITed function in this global, which the
27// debugger reads. Make sure to specify the version statically, because the
28// debugger checks the version before we can set it during runtime.
29LLVM_ATTRIBUTE_VISIBILITY_DEFAULT
30struct jit_descriptor __jit_debug_descriptor = {.version: JitDescriptorVersion, .action_flag: 0,
31 .relevant_entry: nullptr, .first_entry: nullptr};
32
33// Debuggers that implement the GDB JIT interface put a special breakpoint in
34// this function.
35LLVM_ATTRIBUTE_VISIBILITY_DEFAULT
36LLVM_ATTRIBUTE_NOINLINE void __jit_debug_register_code() {
37 // The noinline and the asm prevent calls to this function from being
38 // optimized out.
39#if !defined(_MSC_VER)
40 asm volatile("" ::: "memory");
41#endif
42}
43}
44
45using namespace llvm;
46using namespace llvm::orc;
47
48// Register debug object, return error message or null for success.
49static void appendJITDebugDescriptor(const char *ObjAddr, size_t Size) {
50 LLVM_DEBUG({
51 dbgs() << "Adding debug object to GDB JIT interface "
52 << formatv("([{0:x16} -- {1:x16}])",
53 reinterpret_cast<uintptr_t>(ObjAddr),
54 reinterpret_cast<uintptr_t>(ObjAddr + Size))
55 << "\n";
56 });
57
58 jit_code_entry *E = new jit_code_entry;
59 E->symfile_addr = ObjAddr;
60 E->symfile_size = Size;
61 E->prev_entry = nullptr;
62
63 // Serialize rendezvous with the debugger as well as access to shared data.
64 static std::mutex JITDebugLock;
65 std::lock_guard<std::mutex> Lock(JITDebugLock);
66
67 // Insert this entry at the head of the list.
68 jit_code_entry *NextEntry = __jit_debug_descriptor.first_entry;
69 E->next_entry = NextEntry;
70 if (NextEntry) {
71 NextEntry->prev_entry = E;
72 }
73
74 __jit_debug_descriptor.first_entry = E;
75 __jit_debug_descriptor.relevant_entry = E;
76 __jit_debug_descriptor.action_flag = JIT_REGISTER_FN;
77}
78
79extern "C" orc::shared::CWrapperFunctionResult
80llvm_orc_registerJITLoaderGDBAllocAction(const char *Data, size_t Size) {
81 using namespace orc::shared;
82 return WrapperFunction<SPSError(SPSExecutorAddrRange, bool)>::handle(
83 ArgData: Data, ArgSize: Size,
84 Handler: [](ExecutorAddrRange R, bool AutoRegisterCode) {
85 appendJITDebugDescriptor(ObjAddr: R.Start.toPtr<const char *>(),
86 Size: R.size());
87 // Run into the rendezvous breakpoint.
88 if (AutoRegisterCode)
89 __jit_debug_register_code();
90 return Error::success();
91 })
92 .release();
93}
94
95extern "C" orc::shared::CWrapperFunctionResult
96llvm_orc_registerJITLoaderGDBWrapper(const char *Data, uint64_t Size) {
97 using namespace orc::shared;
98 return WrapperFunction<SPSError(SPSExecutorAddrRange, bool)>::handle(
99 ArgData: Data, ArgSize: Size,
100 Handler: [](ExecutorAddrRange R, bool AutoRegisterCode) {
101 appendJITDebugDescriptor(ObjAddr: R.Start.toPtr<const char *>(),
102 Size: R.size());
103 // Run into the rendezvous breakpoint.
104 if (AutoRegisterCode)
105 __jit_debug_register_code();
106 return Error::success();
107 })
108 .release();
109}
110

source code of llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.cpp