1 //===-- PlatformLinux.cpp -------------------------------------------------===//
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 "PlatformLinux.h"
10 #include "lldb/Host/Config.h"
11 
12 #include <cstdio>
13 #if LLDB_ENABLE_POSIX
14 #include <sys/utsname.h>
15 #endif
16 
17 #include "Utility/ARM64_DWARF_Registers.h"
18 #include "lldb/Core/Debugger.h"
19 #include "lldb/Core/PluginManager.h"
20 #include "lldb/Host/HostInfo.h"
21 #include "lldb/Symbol/UnwindPlan.h"
22 #include "lldb/Target/Process.h"
23 #include "lldb/Target/Target.h"
24 #include "lldb/Utility/FileSpec.h"
25 #include "lldb/Utility/Log.h"
26 #include "lldb/Utility/State.h"
27 #include "lldb/Utility/Status.h"
28 #include "lldb/Utility/StreamString.h"
29 
30 // Define these constants from Linux mman.h for use when targeting remote linux
31 // systems even when host has different values.
32 #define MAP_PRIVATE 2
33 #define MAP_ANON 0x20
34 
35 using namespace lldb;
36 using namespace lldb_private;
37 using namespace lldb_private::platform_linux;
38 
39 LLDB_PLUGIN_DEFINE(PlatformLinux)
40 
41 static uint32_t g_initialize_count = 0;
42 
43 
44 PlatformSP PlatformLinux::CreateInstance(bool force, const ArchSpec *arch) {
45   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PLATFORM));
46   LLDB_LOG(log, "force = {0}, arch=({1}, {2})", force,
47            arch ? arch->GetArchitectureName() : "<null>",
48            arch ? arch->GetTriple().getTriple() : "<null>");
49 
50   bool create = force;
51   if (!create && arch && arch->IsValid()) {
52     const llvm::Triple &triple = arch->GetTriple();
53     switch (triple.getOS()) {
54     case llvm::Triple::Linux:
55       create = true;
56       break;
57 
58 #if defined(__linux__)
59     // Only accept "unknown" for the OS if the host is linux and it "unknown"
60     // wasn't specified (it was just returned because it was NOT specified)
61     case llvm::Triple::OSType::UnknownOS:
62       create = !arch->TripleOSWasSpecified();
63       break;
64 #endif
65     default:
66       break;
67     }
68   }
69 
70   LLDB_LOG(log, "create = {0}", create);
71   if (create) {
72     return PlatformSP(new PlatformLinux(false));
73   }
74   return PlatformSP();
75 }
76 
77 llvm::StringRef PlatformLinux::GetPluginDescriptionStatic(bool is_host) {
78   if (is_host)
79     return "Local Linux user platform plug-in.";
80   return "Remote Linux user platform plug-in.";
81 }
82 
83 void PlatformLinux::Initialize() {
84   PlatformPOSIX::Initialize();
85 
86   if (g_initialize_count++ == 0) {
87 #if defined(__linux__) && !defined(__ANDROID__)
88     PlatformSP default_platform_sp(new PlatformLinux(true));
89     default_platform_sp->SetSystemArchitecture(HostInfo::GetArchitecture());
90     Platform::SetHostPlatform(default_platform_sp);
91 #endif
92     PluginManager::RegisterPlugin(
93         PlatformLinux::GetPluginNameStatic(false),
94         PlatformLinux::GetPluginDescriptionStatic(false),
95         PlatformLinux::CreateInstance, nullptr);
96   }
97 }
98 
99 void PlatformLinux::Terminate() {
100   if (g_initialize_count > 0) {
101     if (--g_initialize_count == 0) {
102       PluginManager::UnregisterPlugin(PlatformLinux::CreateInstance);
103     }
104   }
105 
106   PlatformPOSIX::Terminate();
107 }
108 
109 /// Default Constructor
110 PlatformLinux::PlatformLinux(bool is_host)
111     : PlatformPOSIX(is_host) // This is the local host platform
112 {}
113 
114 bool PlatformLinux::GetSupportedArchitectureAtIndex(uint32_t idx,
115                                                     ArchSpec &arch) {
116   if (IsHost()) {
117     ArchSpec hostArch = HostInfo::GetArchitecture(HostInfo::eArchKindDefault);
118     if (hostArch.GetTriple().isOSLinux()) {
119       if (idx == 0) {
120         arch = hostArch;
121         return arch.IsValid();
122       } else if (idx == 1) {
123         // If the default host architecture is 64-bit, look for a 32-bit
124         // variant
125         if (hostArch.IsValid() && hostArch.GetTriple().isArch64Bit()) {
126           arch = HostInfo::GetArchitecture(HostInfo::eArchKind32);
127           return arch.IsValid();
128         }
129       }
130     }
131   } else {
132     if (m_remote_platform_sp)
133       return m_remote_platform_sp->GetSupportedArchitectureAtIndex(idx, arch);
134 
135     llvm::Triple triple;
136     // Set the OS to linux
137     triple.setOS(llvm::Triple::Linux);
138     // Set the architecture
139     switch (idx) {
140     case 0:
141       triple.setArchName("x86_64");
142       break;
143     case 1:
144       triple.setArchName("i386");
145       break;
146     case 2:
147       triple.setArchName("arm");
148       break;
149     case 3:
150       triple.setArchName("aarch64");
151       break;
152     case 4:
153       triple.setArchName("mips64");
154       break;
155     case 5:
156       triple.setArchName("hexagon");
157       break;
158     case 6:
159       triple.setArchName("mips");
160       break;
161     case 7:
162       triple.setArchName("mips64el");
163       break;
164     case 8:
165       triple.setArchName("mipsel");
166       break;
167     case 9:
168       triple.setArchName("s390x");
169       break;
170     default:
171       return false;
172     }
173     // Leave the vendor as "llvm::Triple:UnknownVendor" and don't specify the
174     // vendor by calling triple.SetVendorName("unknown") so that it is a
175     // "unspecified unknown". This means when someone calls
176     // triple.GetVendorName() it will return an empty string which indicates
177     // that the vendor can be set when two architectures are merged
178 
179     // Now set the triple into "arch" and return true
180     arch.SetTriple(triple);
181     return true;
182   }
183   return false;
184 }
185 
186 void PlatformLinux::GetStatus(Stream &strm) {
187   Platform::GetStatus(strm);
188 
189 #if LLDB_ENABLE_POSIX
190   // Display local kernel information only when we are running in host mode.
191   // Otherwise, we would end up printing non-Linux information (when running on
192   // Mac OS for example).
193   if (IsHost()) {
194     struct utsname un;
195 
196     if (uname(&un))
197       return;
198 
199     strm.Printf("    Kernel: %s\n", un.sysname);
200     strm.Printf("   Release: %s\n", un.release);
201     strm.Printf("   Version: %s\n", un.version);
202   }
203 #endif
204 }
205 
206 uint32_t
207 PlatformLinux::GetResumeCountForLaunchInfo(ProcessLaunchInfo &launch_info) {
208   uint32_t resume_count = 0;
209 
210   // Always resume past the initial stop when we use eLaunchFlagDebug
211   if (launch_info.GetFlags().Test(eLaunchFlagDebug)) {
212     // Resume past the stop for the final exec into the true inferior.
213     ++resume_count;
214   }
215 
216   // If we're not launching a shell, we're done.
217   const FileSpec &shell = launch_info.GetShell();
218   if (!shell)
219     return resume_count;
220 
221   std::string shell_string = shell.GetPath();
222   // We're in a shell, so for sure we have to resume past the shell exec.
223   ++resume_count;
224 
225   // Figure out what shell we're planning on using.
226   const char *shell_name = strrchr(shell_string.c_str(), '/');
227   if (shell_name == nullptr)
228     shell_name = shell_string.c_str();
229   else
230     shell_name++;
231 
232   if (strcmp(shell_name, "csh") == 0 || strcmp(shell_name, "tcsh") == 0 ||
233       strcmp(shell_name, "zsh") == 0 || strcmp(shell_name, "sh") == 0) {
234     // These shells seem to re-exec themselves.  Add another resume.
235     ++resume_count;
236   }
237 
238   return resume_count;
239 }
240 
241 bool PlatformLinux::CanDebugProcess() {
242   if (IsHost()) {
243     return true;
244   } else {
245     // If we're connected, we can debug.
246     return IsConnected();
247   }
248 }
249 
250 void PlatformLinux::CalculateTrapHandlerSymbolNames() {
251   m_trap_handlers.push_back(ConstString("_sigtramp"));
252   m_trap_handlers.push_back(ConstString("__kernel_rt_sigreturn"));
253   m_trap_handlers.push_back(ConstString("__restore_rt"));
254 }
255 
256 static lldb::UnwindPlanSP GetAArch64TrapHanlderUnwindPlan(ConstString name) {
257   UnwindPlanSP unwind_plan_sp;
258   if (name != "__kernel_rt_sigreturn")
259     return unwind_plan_sp;
260 
261   UnwindPlan::RowSP row = std::make_shared<UnwindPlan::Row>();
262   row->SetOffset(0);
263 
264   // In the signal trampoline frame, sp points to an rt_sigframe[1], which is:
265   //  - 128-byte siginfo struct
266   //  - ucontext struct:
267   //     - 8-byte long (uc_flags)
268   //     - 8-byte pointer (uc_link)
269   //     - 24-byte stack_t
270   //     - 128-byte signal set
271   //     - 8 bytes of padding because sigcontext has 16-byte alignment
272   //     - sigcontext/mcontext_t
273   // [1]
274   // https://github.com/torvalds/linux/blob/master/arch/arm64/kernel/signal.c
275   int32_t offset = 128 + 8 + 8 + 24 + 128 + 8;
276   // Then sigcontext[2] is:
277   // - 8 byte fault address
278   // - 31 8 byte registers
279   // - 8 byte sp
280   // - 8 byte pc
281   // [2]
282   // https://github.com/torvalds/linux/blob/master/arch/arm64/include/uapi/asm/sigcontext.h
283 
284   // Skip fault address
285   offset += 8;
286   row->GetCFAValue().SetIsRegisterPlusOffset(arm64_dwarf::sp, offset);
287 
288   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x0, 0 * 8, false);
289   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x1, 1 * 8, false);
290   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x2, 2 * 8, false);
291   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x3, 3 * 8, false);
292   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x4, 4 * 8, false);
293   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x5, 5 * 8, false);
294   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x6, 6 * 8, false);
295   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x7, 7 * 8, false);
296   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x8, 8 * 8, false);
297   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x9, 9 * 8, false);
298   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x10, 10 * 8, false);
299   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x11, 11 * 8, false);
300   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x12, 12 * 8, false);
301   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x13, 13 * 8, false);
302   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x14, 14 * 8, false);
303   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x15, 15 * 8, false);
304   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x16, 16 * 8, false);
305   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x17, 17 * 8, false);
306   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x18, 18 * 8, false);
307   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x19, 19 * 8, false);
308   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x20, 20 * 8, false);
309   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x21, 21 * 8, false);
310   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x22, 22 * 8, false);
311   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x23, 23 * 8, false);
312   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x24, 24 * 8, false);
313   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x25, 25 * 8, false);
314   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x26, 26 * 8, false);
315   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x27, 27 * 8, false);
316   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x28, 28 * 8, false);
317   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::fp, 29 * 8, false);
318   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::x30, 30 * 8, false);
319   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::sp, 31 * 8, false);
320   row->SetRegisterLocationToAtCFAPlusOffset(arm64_dwarf::pc, 32 * 8, false);
321 
322   // The sigcontext may also contain floating point and SVE registers.
323   // However this would require a dynamic unwind plan so they are not included
324   // here.
325 
326   unwind_plan_sp = std::make_shared<UnwindPlan>(eRegisterKindDWARF);
327   unwind_plan_sp->AppendRow(row);
328   unwind_plan_sp->SetSourceName("AArch64 Linux sigcontext");
329   unwind_plan_sp->SetSourcedFromCompiler(eLazyBoolYes);
330   // Because sp is the same throughout the function
331   unwind_plan_sp->SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
332   unwind_plan_sp->SetUnwindPlanForSignalTrap(eLazyBoolYes);
333 
334   return unwind_plan_sp;
335 }
336 
337 lldb::UnwindPlanSP
338 PlatformLinux::GetTrapHandlerUnwindPlan(const llvm::Triple &triple,
339                                         ConstString name) {
340   if (triple.isAArch64())
341     return GetAArch64TrapHanlderUnwindPlan(name);
342 
343   return {};
344 }
345 
346 MmapArgList PlatformLinux::GetMmapArgumentList(const ArchSpec &arch,
347                                                addr_t addr, addr_t length,
348                                                unsigned prot, unsigned flags,
349                                                addr_t fd, addr_t offset) {
350   uint64_t flags_platform = 0;
351   uint64_t map_anon = arch.IsMIPS() ? 0x800 : MAP_ANON;
352 
353   if (flags & eMmapFlagsPrivate)
354     flags_platform |= MAP_PRIVATE;
355   if (flags & eMmapFlagsAnon)
356     flags_platform |= map_anon;
357 
358   MmapArgList args({addr, length, prot, flags_platform, fd, offset});
359   return args;
360 }
361 
362