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
22 static constexpr uint32_t JitDescriptorVersion = 1;
23
24 extern "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.
29 LLVM_ATTRIBUTE_VISIBILITY_DEFAULT
30 struct jit_descriptor __jit_debug_descriptor = {JitDescriptorVersion, 0,
31 nullptr, nullptr};
32
33 // Debuggers that implement the GDB JIT interface put a special breakpoint in
34 // this function.
35 LLVM_ATTRIBUTE_VISIBILITY_DEFAULT
__jit_debug_register_code()36 LLVM_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
45 using namespace llvm;
46 using namespace llvm::orc;
47
48 // Register debug object, return error message or null for success.
appendJITDebugDescriptor(const char * ObjAddr,size_t Size)49 static 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
79 extern "C" orc::shared::CWrapperFunctionResult
llvm_orc_registerJITLoaderGDBAllocAction(const char * Data,size_t Size)80 llvm_orc_registerJITLoaderGDBAllocAction(const char *Data, size_t Size) {
81 using namespace orc::shared;
82 return WrapperFunction<SPSError(SPSExecutorAddrRange, bool)>::handle(
83 Data, Size,
84 [](ExecutorAddrRange R, bool AutoRegisterCode) {
85 appendJITDebugDescriptor(R.Start.toPtr<const char *>(),
86 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
95 extern "C" orc::shared::CWrapperFunctionResult
llvm_orc_registerJITLoaderGDBWrapper(const char * Data,uint64_t Size)96 llvm_orc_registerJITLoaderGDBWrapper(const char *Data, uint64_t Size) {
97 using namespace orc::shared;
98 return WrapperFunction<SPSError(SPSExecutorAddrRange, bool)>::handle(
99 Data, Size,
100 [](ExecutorAddrRange R, bool AutoRegisterCode) {
101 appendJITDebugDescriptor(R.Start.toPtr<const char *>(),
102 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