xref: /freebsd/contrib/llvm-project/llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.cpp (revision 5b56413d04e608379c9a306373554a8e4d321bc0)
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 struct jit_descriptor __jit_debug_descriptor = {JitDescriptorVersion, 0,
30                                                 nullptr, nullptr};
31 
32 // Debuggers that implement the GDB JIT interface put a special breakpoint in
33 // this function.
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 }
108