jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/Assertions.h>
8#include <AK/HashMap.h>
9#include <AK/NonnullOwnPtr.h>
10#include <AK/StringBuilder.h>
11#include <Kernel/API/SyscallString.h>
12#include <LibCore/ArgsParser.h>
13#include <LibCore/System.h>
14#include <LibDebug/DebugSession.h>
15#include <LibELF/Image.h>
16#include <LibMain/Main.h>
17#include <LibX86/Disassembler.h>
18#include <LibX86/Instruction.h>
19#include <signal.h>
20#include <stdlib.h>
21#include <string.h>
22#include <sys/arch/regs.h>
23#include <syscall.h>
24#include <unistd.h>
25
26static OwnPtr<Debug::DebugSession> g_debug_session;
27static bool g_should_output_color = false;
28
29static void handle_sigint(int)
30{
31 outln("Debugger: SIGINT");
32
33 // The destructor of DebugSession takes care of detaching
34 g_debug_session = nullptr;
35}
36
37static void print_function_call(DeprecatedString function_name, size_t depth)
38{
39 for (size_t i = 0; i < depth; ++i) {
40 out(" ");
41 }
42 outln("=> {}", function_name);
43}
44
45static void print_syscall(PtraceRegisters& regs, size_t depth)
46{
47 for (size_t i = 0; i < depth; ++i) {
48 out(" ");
49 }
50 StringView begin_color = g_should_output_color ? "\033[34;1m"sv : ""sv;
51 StringView end_color = g_should_output_color ? "\033[0m"sv : ""sv;
52#if ARCH(X86_64)
53 outln("=> {}SC_{}({:#x}, {:#x}, {:#x}){}",
54 begin_color,
55 Syscall::to_string((Syscall::Function)regs.rax),
56 regs.rdx,
57 regs.rcx,
58 regs.rbx,
59 end_color);
60#elif ARCH(AARCH64)
61 (void)regs;
62 (void)begin_color;
63 (void)end_color;
64 TODO_AARCH64();
65#else
66# error Unknown architecture
67#endif
68}
69
70static NonnullOwnPtr<HashMap<FlatPtr, X86::Instruction>> instrument_code()
71{
72 auto instrumented = make<HashMap<FlatPtr, X86::Instruction>>();
73 g_debug_session->for_each_loaded_library([&](Debug::LoadedLibrary const& lib) {
74 lib.debug_info->elf().for_each_section_of_type(SHT_PROGBITS, [&](const ELF::Image::Section& section) {
75 if (section.name() != ".text")
76 return IterationDecision::Continue;
77
78 X86::SimpleInstructionStream stream((const u8*)((uintptr_t)lib.file->data() + section.offset()), section.size());
79 X86::Disassembler disassembler(stream);
80 for (;;) {
81 auto offset = stream.offset();
82 auto instruction_address = section.address() + offset + lib.base_address;
83 auto insn = disassembler.next();
84 if (!insn.has_value())
85 break;
86 if (insn.value().mnemonic() == "RET" || insn.value().mnemonic() == "CALL") {
87 g_debug_session->insert_breakpoint(instruction_address);
88 instrumented->set(instruction_address, insn.value());
89 }
90 }
91 return IterationDecision::Continue;
92 });
93 return IterationDecision::Continue;
94 });
95 return instrumented;
96}
97
98ErrorOr<int> serenity_main(Main::Arguments arguments)
99{
100 TRY(Core::System::pledge("stdio proc exec rpath sigaction ptrace"));
101
102 if (isatty(STDOUT_FILENO))
103 g_should_output_color = true;
104
105 StringView command;
106 Core::ArgsParser args_parser;
107 args_parser.add_positional_argument(command,
108 "The program to be traced, along with its arguments",
109 "program", Core::ArgsParser::Required::Yes);
110 args_parser.parse(arguments);
111
112 auto result = Debug::DebugSession::exec_and_attach(command);
113 if (!result) {
114 warnln("Failed to start debugging session for: \"{}\"", command);
115 exit(1);
116 }
117 g_debug_session = result.release_nonnull();
118
119 auto instrumented = instrument_code();
120
121 struct sigaction sa;
122 memset(&sa, 0, sizeof(struct sigaction));
123 sa.sa_handler = handle_sigint;
124 TRY(Core::System::sigaction(SIGINT, &sa, nullptr));
125
126 size_t depth = 0;
127 bool new_function = true;
128
129 g_debug_session->run(Debug::DebugSession::DesiredInitialDebugeeState::Running, [&](Debug::DebugSession::DebugBreakReason reason, Optional<PtraceRegisters> regs) {
130 if (reason == Debug::DebugSession::DebugBreakReason::Exited) {
131 outln("Program exited.");
132 return Debug::DebugSession::DebugDecision::Detach;
133 }
134
135 if (reason == Debug::DebugSession::DebugBreakReason::Syscall) {
136 print_syscall(regs.value(), depth + 1);
137 return Debug::DebugSession::DebugDecision::ContinueBreakAtSyscall;
138 }
139
140#if ARCH(X86_64)
141 const FlatPtr ip = regs.value().rip;
142#elif ARCH(AARCH64)
143 const FlatPtr ip = 0; // FIXME
144 TODO_AARCH64();
145#else
146# error Unknown architecture
147#endif
148
149 if (new_function) {
150 auto function_name = g_debug_session->symbolicate(ip);
151 print_function_call(function_name.value().symbol, depth);
152 new_function = false;
153 return Debug::DebugSession::ContinueBreakAtSyscall;
154 }
155 auto instruction = instrumented->get(ip).value();
156
157 if (instruction.mnemonic() == "RET") {
158 if (depth != 0)
159 --depth;
160 return Debug::DebugSession::ContinueBreakAtSyscall;
161 }
162
163 // FIXME: we could miss some leaf functions that were called with a jump
164 VERIFY(instruction.mnemonic() == "CALL");
165
166 ++depth;
167 new_function = true;
168
169 return Debug::DebugSession::DebugDecision::SingleStep;
170 });
171
172 return 0;
173}