1 //===-- fuchsia.cpp ---------------------------------------------*- 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 "platform.h"
10 
11 #if SCUDO_FUCHSIA
12 
13 #include "common.h"
14 #include "mutex.h"
15 #include "string_utils.h"
16 
17 #include <lib/sync/mutex.h> // for sync_mutex_t
18 #include <stdlib.h>         // for getenv()
19 #include <zircon/compiler.h>
20 #include <zircon/process.h>
21 #include <zircon/sanitizer.h>
22 #include <zircon/syscalls.h>
23 
24 namespace scudo {
25 
26 uptr getPageSize() { return _zx_system_get_page_size(); }
27 
28 void NORETURN die() { __builtin_trap(); }
29 
30 // We zero-initialize the Extra parameter of map(), make sure this is consistent
31 // with ZX_HANDLE_INVALID.
32 static_assert(ZX_HANDLE_INVALID == 0, "");
33 
34 static void *allocateVmar(uptr Size, MapPlatformData *Data, bool AllowNoMem) {
35   // Only scenario so far.
36   DCHECK(Data);
37   DCHECK_EQ(Data->Vmar, ZX_HANDLE_INVALID);
38 
39   const zx_status_t Status = _zx_vmar_allocate(
40       _zx_vmar_root_self(),
41       ZX_VM_CAN_MAP_READ | ZX_VM_CAN_MAP_WRITE | ZX_VM_CAN_MAP_SPECIFIC, 0,
42       Size, &Data->Vmar, &Data->VmarBase);
43   if (UNLIKELY(Status != ZX_OK)) {
44     if (Status != ZX_ERR_NO_MEMORY || !AllowNoMem)
45       dieOnMapUnmapError(Status == ZX_ERR_NO_MEMORY ? Size : 0);
46     return nullptr;
47   }
48   return reinterpret_cast<void *>(Data->VmarBase);
49 }
50 
51 void *map(void *Addr, uptr Size, const char *Name, uptr Flags,
52           MapPlatformData *Data) {
53   DCHECK_EQ(Size % getPageSizeCached(), 0);
54   const bool AllowNoMem = !!(Flags & MAP_ALLOWNOMEM);
55 
56   // For MAP_NOACCESS, just allocate a Vmar and return.
57   if (Flags & MAP_NOACCESS)
58     return allocateVmar(Size, Data, AllowNoMem);
59 
60   const zx_handle_t Vmar = (Data && Data->Vmar != ZX_HANDLE_INVALID)
61                                ? Data->Vmar
62                                : _zx_vmar_root_self();
63 
64   zx_status_t Status;
65   zx_handle_t Vmo;
66   uint64_t VmoSize = 0;
67   if (Data && Data->Vmo != ZX_HANDLE_INVALID) {
68     // If a Vmo was specified, it's a resize operation.
69     CHECK(Addr);
70     DCHECK(Flags & MAP_RESIZABLE);
71     Vmo = Data->Vmo;
72     VmoSize = Data->VmoSize;
73     Status = _zx_vmo_set_size(Vmo, VmoSize + Size);
74     if (Status != ZX_OK) {
75       if (Status != ZX_ERR_NO_MEMORY || !AllowNoMem)
76         dieOnMapUnmapError(Status == ZX_ERR_NO_MEMORY ? Size : 0);
77       return nullptr;
78     }
79   } else {
80     // Otherwise, create a Vmo and set its name.
81     Status = _zx_vmo_create(Size, ZX_VMO_RESIZABLE, &Vmo);
82     if (UNLIKELY(Status != ZX_OK)) {
83       if (Status != ZX_ERR_NO_MEMORY || !AllowNoMem)
84         dieOnMapUnmapError(Status == ZX_ERR_NO_MEMORY ? Size : 0);
85       return nullptr;
86     }
87     _zx_object_set_property(Vmo, ZX_PROP_NAME, Name, strlen(Name));
88   }
89 
90   uintptr_t P;
91   zx_vm_option_t MapFlags =
92       ZX_VM_PERM_READ | ZX_VM_PERM_WRITE | ZX_VM_ALLOW_FAULTS;
93   if (Addr)
94     DCHECK(Data);
95   const uint64_t Offset =
96       Addr ? reinterpret_cast<uintptr_t>(Addr) - Data->VmarBase : 0;
97   if (Offset)
98     MapFlags |= ZX_VM_SPECIFIC;
99   Status = _zx_vmar_map(Vmar, MapFlags, Offset, Vmo, VmoSize, Size, &P);
100   if (UNLIKELY(Status != ZX_OK)) {
101     if (Status != ZX_ERR_NO_MEMORY || !AllowNoMem)
102       dieOnMapUnmapError(Status == ZX_ERR_NO_MEMORY ? Size : 0);
103     return nullptr;
104   }
105 
106   if (Flags & MAP_PRECOMMIT) {
107     Status = _zx_vmar_op_range(Vmar, ZX_VMAR_OP_COMMIT, P, Size,
108                                /*buffer=*/nullptr, /*buffer_size=*/0);
109   }
110 
111   // No need to track the Vmo if we don't intend on resizing it. Close it.
112   if (Flags & MAP_RESIZABLE) {
113     DCHECK(Data);
114     if (Data->Vmo == ZX_HANDLE_INVALID)
115       Data->Vmo = Vmo;
116     else
117       DCHECK_EQ(Data->Vmo, Vmo);
118   } else {
119     CHECK_EQ(_zx_handle_close(Vmo), ZX_OK);
120   }
121   if (UNLIKELY(Status != ZX_OK)) {
122     if (Status != ZX_ERR_NO_MEMORY || !AllowNoMem)
123       dieOnMapUnmapError(Status == ZX_ERR_NO_MEMORY ? Size : 0);
124     return nullptr;
125   }
126 
127   if (Data)
128     Data->VmoSize += Size;
129 
130   return reinterpret_cast<void *>(P);
131 }
132 
133 void unmap(void *Addr, uptr Size, uptr Flags, MapPlatformData *Data) {
134   if (Flags & UNMAP_ALL) {
135     DCHECK_NE(Data, nullptr);
136     const zx_handle_t Vmar = Data->Vmar;
137     DCHECK_NE(Vmar, _zx_vmar_root_self());
138     // Destroying the vmar effectively unmaps the whole mapping.
139     CHECK_EQ(_zx_vmar_destroy(Vmar), ZX_OK);
140     CHECK_EQ(_zx_handle_close(Vmar), ZX_OK);
141   } else {
142     const zx_handle_t Vmar = (Data && Data->Vmar != ZX_HANDLE_INVALID)
143                                  ? Data->Vmar
144                                  : _zx_vmar_root_self();
145     const zx_status_t Status =
146         _zx_vmar_unmap(Vmar, reinterpret_cast<uintptr_t>(Addr), Size);
147     if (UNLIKELY(Status != ZX_OK))
148       dieOnMapUnmapError();
149   }
150   if (Data) {
151     if (Data->Vmo != ZX_HANDLE_INVALID)
152       CHECK_EQ(_zx_handle_close(Data->Vmo), ZX_OK);
153     memset(Data, 0, sizeof(*Data));
154   }
155 }
156 
157 void setMemoryPermission(UNUSED uptr Addr, UNUSED uptr Size, UNUSED uptr Flags,
158                          UNUSED MapPlatformData *Data) {
159   const zx_vm_option_t Prot =
160       (Flags & MAP_NOACCESS) ? 0 : (ZX_VM_PERM_READ | ZX_VM_PERM_WRITE);
161   DCHECK(Data);
162   DCHECK_NE(Data->Vmar, ZX_HANDLE_INVALID);
163   if (_zx_vmar_protect(Data->Vmar, Prot, Addr, Size) != ZX_OK)
164     dieOnMapUnmapError();
165 }
166 
167 void releasePagesToOS(UNUSED uptr BaseAddress, uptr Offset, uptr Size,
168                       MapPlatformData *Data) {
169   DCHECK(Data);
170   DCHECK_NE(Data->Vmar, ZX_HANDLE_INVALID);
171   DCHECK_NE(Data->Vmo, ZX_HANDLE_INVALID);
172   const zx_status_t Status =
173       _zx_vmo_op_range(Data->Vmo, ZX_VMO_OP_DECOMMIT, Offset, Size, NULL, 0);
174   CHECK_EQ(Status, ZX_OK);
175 }
176 
177 const char *getEnv(const char *Name) { return getenv(Name); }
178 
179 // Note: we need to flag these methods with __TA_NO_THREAD_SAFETY_ANALYSIS
180 // because the Fuchsia implementation of sync_mutex_t has clang thread safety
181 // annotations. Were we to apply proper capability annotations to the top level
182 // HybridMutex class itself, they would not be needed. As it stands, the
183 // thread analysis thinks that we are locking the mutex and accidentally leaving
184 // it locked on the way out.
185 bool HybridMutex::tryLock() __TA_NO_THREAD_SAFETY_ANALYSIS {
186   // Size and alignment must be compatible between both types.
187   return sync_mutex_trylock(&M) == ZX_OK;
188 }
189 
190 void HybridMutex::lockSlow() __TA_NO_THREAD_SAFETY_ANALYSIS {
191   sync_mutex_lock(&M);
192 }
193 
194 void HybridMutex::unlock() __TA_NO_THREAD_SAFETY_ANALYSIS {
195   sync_mutex_unlock(&M);
196 }
197 
198 u64 getMonotonicTime() { return _zx_clock_get_monotonic(); }
199 
200 u32 getNumberOfCPUs() { return _zx_system_get_num_cpus(); }
201 
202 u32 getThreadID() { return 0; }
203 
204 bool getRandom(void *Buffer, uptr Length, UNUSED bool Blocking) {
205   static_assert(MaxRandomLength <= ZX_CPRNG_DRAW_MAX_LEN, "");
206   if (UNLIKELY(!Buffer || !Length || Length > MaxRandomLength))
207     return false;
208   _zx_cprng_draw(Buffer, Length);
209   return true;
210 }
211 
212 void outputRaw(const char *Buffer) {
213   __sanitizer_log_write(Buffer, strlen(Buffer));
214 }
215 
216 void setAbortMessage(const char *Message) {}
217 
218 } // namespace scudo
219 
220 #endif // SCUDO_FUCHSIA
221