1//=-- lsan_common_mac.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// This file is a part of LeakSanitizer.
10// Implementation of common leak checking functionality. Darwin-specific code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "sanitizer_common/sanitizer_platform.h"
15#include "sanitizer_common/sanitizer_libc.h"
16#include "lsan_common.h"
17
18#if CAN_SANITIZE_LEAKS && SANITIZER_APPLE
19
20# include <mach/mach.h>
21# include <mach/vm_statistics.h>
22# include <pthread.h>
23
24# include "lsan_allocator.h"
25# include "sanitizer_common/sanitizer_allocator_internal.h"
26namespace __lsan {
27
28class ThreadContextLsanBase;
29
30enum class SeenRegion {
31 None = 0,
32 AllocOnce = 1 << 0,
33 LibDispatch = 1 << 1,
34 Foundation = 1 << 2,
35 All = AllocOnce | LibDispatch | Foundation
36};
37
38inline SeenRegion operator|(SeenRegion left, SeenRegion right) {
39 return static_cast<SeenRegion>(static_cast<int>(left) |
40 static_cast<int>(right));
41}
42
43inline SeenRegion &operator|=(SeenRegion &left, const SeenRegion &right) {
44 left = left | right;
45 return left;
46}
47
48struct RegionScanState {
49 SeenRegion seen_regions = SeenRegion::None;
50 bool in_libdispatch = false;
51};
52
53typedef struct {
54 int disable_counter;
55 ThreadContextLsanBase *current_thread;
56 AllocatorCache cache;
57} thread_local_data_t;
58
59static pthread_key_t key;
60static pthread_once_t key_once = PTHREAD_ONCE_INIT;
61
62// The main thread destructor requires the current thread,
63// so we can't destroy it until it's been used and reset.
64void restore_tid_data(void *ptr) {
65 thread_local_data_t *data = (thread_local_data_t *)ptr;
66 if (data->current_thread)
67 pthread_setspecific(key, data);
68}
69
70static void make_tls_key() {
71 CHECK_EQ(pthread_key_create(&key, restore_tid_data), 0);
72}
73
74static thread_local_data_t *get_tls_val(bool alloc) {
75 pthread_once(&key_once, make_tls_key);
76
77 thread_local_data_t *ptr = (thread_local_data_t *)pthread_getspecific(key);
78 if (ptr == NULL && alloc) {
79 ptr = (thread_local_data_t *)InternalAlloc(sizeof(*ptr));
80 ptr->disable_counter = 0;
81 ptr->current_thread = nullptr;
82 ptr->cache = AllocatorCache();
83 pthread_setspecific(key, ptr);
84 }
85
86 return ptr;
87}
88
89bool DisabledInThisThread() {
90 thread_local_data_t *data = get_tls_val(false);
91 return data ? data->disable_counter > 0 : false;
92}
93
94void DisableInThisThread() { ++get_tls_val(true)->disable_counter; }
95
96void EnableInThisThread() {
97 int *disable_counter = &get_tls_val(true)->disable_counter;
98 if (*disable_counter == 0) {
99 DisableCounterUnderflow();
100 }
101 --*disable_counter;
102}
103
104ThreadContextLsanBase *GetCurrentThread() {
105 thread_local_data_t *data = get_tls_val(false);
106 return data ? data->current_thread : nullptr;
107}
108
109void SetCurrentThread(ThreadContextLsanBase *tctx) {
110 get_tls_val(true)->current_thread = tctx;
111}
112
113AllocatorCache *GetAllocatorCache() { return &get_tls_val(true)->cache; }
114
115LoadedModule *GetLinker() { return nullptr; }
116
117// Required on Linux for initialization of TLS behavior, but should not be
118// required on Darwin.
119void InitializePlatformSpecificModules() {}
120
121// Sections which can't contain contain global pointers. This list errs on the
122// side of caution to avoid false positives, at the expense of performance.
123//
124// Other potentially safe sections include:
125// __all_image_info, __crash_info, __const, __got, __interpose, __objc_msg_break
126//
127// Sections which definitely cannot be included here are:
128// __objc_data, __objc_const, __data, __bss, __common, __thread_data,
129// __thread_bss, __thread_vars, __objc_opt_rw, __objc_opt_ptrs
130static const char *kSkippedSecNames[] = {
131 "__cfstring", "__la_symbol_ptr", "__mod_init_func",
132 "__mod_term_func", "__nl_symbol_ptr", "__objc_classlist",
133 "__objc_classrefs", "__objc_imageinfo", "__objc_nlclslist",
134 "__objc_protolist", "__objc_selrefs", "__objc_superrefs"};
135
136// Scans global variables for heap pointers.
137void ProcessGlobalRegions(Frontier *frontier) {
138 for (auto name : kSkippedSecNames)
139 CHECK(internal_strnlen(name, kMaxSegName + 1) <= kMaxSegName);
140
141 MemoryMappingLayout memory_mapping(false);
142 InternalMmapVector<LoadedModule> modules;
143 modules.reserve(128);
144 memory_mapping.DumpListOfModules(&modules);
145 for (uptr i = 0; i < modules.size(); ++i) {
146 // Even when global scanning is disabled, we still need to scan
147 // system libraries for stashed pointers
148 if (!flags()->use_globals && modules[i].instrumented()) continue;
149
150 for (const __sanitizer::LoadedModule::AddressRange &range :
151 modules[i].ranges()) {
152 // Sections storing global variables are writable and non-executable
153 if (range.executable || !range.writable) continue;
154
155 for (auto name : kSkippedSecNames) {
156 if (!internal_strcmp(range.name, name)) continue;
157 }
158
159 ScanGlobalRange(range.beg, range.end, frontier);
160 }
161 }
162}
163
164void ProcessPlatformSpecificAllocations(Frontier *frontier) {
165 vm_address_t address = 0;
166 kern_return_t err = KERN_SUCCESS;
167
168 InternalMmapVector<Region> mapped_regions;
169 bool use_root_regions = flags()->use_root_regions && HasRootRegions();
170
171 RegionScanState scan_state;
172 while (err == KERN_SUCCESS) {
173 vm_size_t size = 0;
174 unsigned depth = 1;
175 struct vm_region_submap_info_64 info;
176 mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;
177 err = vm_region_recurse_64(mach_task_self(), &address, &size, &depth,
178 (vm_region_info_t)&info, &count);
179
180 uptr end_address = address + size;
181 if (info.user_tag == VM_MEMORY_OS_ALLOC_ONCE) {
182 // libxpc stashes some pointers in the Kernel Alloc Once page,
183 // make sure not to report those as leaks.
184 scan_state.seen_regions |= SeenRegion::AllocOnce;
185 ScanRangeForPointers(address, end_address, frontier, "GLOBAL",
186 kReachable);
187 } else if (info.user_tag == VM_MEMORY_FOUNDATION) {
188 // Objective-C block trampolines use the Foundation region.
189 scan_state.seen_regions |= SeenRegion::Foundation;
190 ScanRangeForPointers(address, end_address, frontier, "GLOBAL",
191 kReachable);
192 } else if (info.user_tag == VM_MEMORY_LIBDISPATCH) {
193 // Dispatch continuations use the libdispatch region. Empirically, there
194 // can be more than one region with this tag, so we'll optimistically
195 // assume that they're continguous. Otherwise, we would need to scan every
196 // region to ensure we find them all.
197 scan_state.in_libdispatch = true;
198 ScanRangeForPointers(address, end_address, frontier, "GLOBAL",
199 kReachable);
200 } else if (scan_state.in_libdispatch) {
201 scan_state.seen_regions |= SeenRegion::LibDispatch;
202 scan_state.in_libdispatch = false;
203 }
204
205 // Recursing over the full memory map is very slow, break out
206 // early if we don't need the full iteration.
207 if (scan_state.seen_regions == SeenRegion::All && !use_root_regions) {
208 break;
209 }
210
211 // This additional root region scan is required on Darwin in order to
212 // detect root regions contained within mmap'd memory regions, because
213 // the Darwin implementation of sanitizer_procmaps traverses images
214 // as loaded by dyld, and not the complete set of all memory regions.
215 //
216 // TODO(fjricci) - remove this once sanitizer_procmaps_mac has the same
217 // behavior as sanitizer_procmaps_linux and traverses all memory regions
218 if (use_root_regions && (info.protection & kProtectionRead))
219 mapped_regions.push_back({address, end_address});
220
221 address = end_address;
222 }
223 ScanRootRegions(frontier, mapped_regions);
224}
225
226// On darwin, we can intercept _exit gracefully, and return a failing exit code
227// if required at that point. Calling Die() here is undefined behavior and
228// causes rare race conditions.
229void HandleLeaks() {}
230
231void LockStuffAndStopTheWorld(StopTheWorldCallback callback,
232 CheckForLeaksParam *argument) {
233 ScopedStopTheWorldLock lock;
234 StopTheWorld(callback, argument);
235}
236
237} // namespace __lsan
238
239#endif // CAN_SANITIZE_LEAKS && SANITIZER_APPLE
240