1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
2 * vim: set ts=8 sts=2 et sw=2 tw=80:
3 * This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7 #include "util/NativeStack.h"
8
9 #include "mozilla/Assertions.h" // MOZ_ASSERT, MOZ_RELEASE_ASSERT, MOZ_CRASH
10
11 #ifdef XP_WIN
12 # include "util/Windows.h"
13 #elif defined(__wasi__)
14 // Nothing
15 #elif defined(XP_DARWIN) || defined(DARWIN) || defined(XP_UNIX)
16 # include <pthread.h>
17 # if defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
18 # include <pthread_np.h>
19 # endif
20 # if defined(SOLARIS) || defined(AIX)
21 # include <ucontext.h>
22 # endif
23 # if defined(ANDROID) && !defined(__aarch64__)
24 # include <sys/types.h>
25 # include <unistd.h>
26 # endif
27 # if defined(XP_LINUX) && !defined(ANDROID) && defined(__GLIBC__)
28 # include <dlfcn.h>
29 # include <sys/syscall.h>
30 # include <sys/types.h>
31 # include <unistd.h>
32 # define gettid() static_cast<pid_t>(syscall(__NR_gettid))
33 # endif
34 #else
35 # error "Unsupported platform"
36 #endif
37
38 #include "js/friend/StackLimits.h" // JS_STACK_GROWTH_DIRECTION
39
40 #if defined(XP_WIN)
41
GetNativeStackBaseImpl()42 void* js::GetNativeStackBaseImpl() {
43 PNT_TIB pTib = reinterpret_cast<PNT_TIB>(NtCurrentTeb());
44 return static_cast<void*>(pTib->StackBase);
45 }
46
47 #elif defined(SOLARIS)
48
49 static_assert(JS_STACK_GROWTH_DIRECTION < 0);
50
GetNativeStackBaseImpl()51 void* js::GetNativeStackBaseImpl() {
52 stack_t st;
53 stack_getbounds(&st);
54 return static_cast<char*>(st.ss_sp) + st.ss_size;
55 }
56
57 #elif defined(AIX)
58
59 static_assert(JS_STACK_GROWTH_DIRECTION < 0);
60
GetNativeStackBaseImpl()61 void* js::GetNativeStackBaseImpl() {
62 ucontext_t context;
63 getcontext(&context);
64 return static_cast<char*>(context.uc_stack.ss_sp) + context.uc_stack.ss_size;
65 }
66
67 #elif defined(XP_LINUX) && !defined(ANDROID) && defined(__GLIBC__)
GetNativeStackBaseImpl()68 void* js::GetNativeStackBaseImpl() {
69 // On the main thread, get stack base from glibc's __libc_stack_end rather
70 // than pthread APIs to avoid filesystem calls /proc/self/maps. Non-main
71 // threads spawned with pthreads can read this information directly from their
72 // pthread struct, but the main thread must go parse /proc/self/maps to figure
73 // the mapped stack address space ranges. We want to avoid reading from
74 // /proc/ so that firefox can run in sandboxed environments where /proc may
75 // not be mounted.
76 if (gettid() == getpid()) {
77 void** pLibcStackEnd = (void**)dlsym(RTLD_DEFAULT, "__libc_stack_end");
78
79 // If __libc_stack_end is not found, architecture specific frame pointer
80 // hopping will need to be implemented.
81 MOZ_RELEASE_ASSERT(
82 pLibcStackEnd,
83 "__libc_stack_end unavailable, unable to setup stack range for JS");
84 void* stackBase = *pLibcStackEnd;
85 MOZ_RELEASE_ASSERT(
86 stackBase, "invalid stack base, unable to setup stack range for JS");
87
88 // We don't need to fix stackBase, as it already roughly points to beginning
89 // of the stack
90 return stackBase;
91 }
92
93 // Non-main threads have the required info stored in memory, so no filesystem
94 // calls are made.
95 pthread_t thread = pthread_self();
96 pthread_attr_t sattr;
97 pthread_attr_init(&sattr);
98 pthread_getattr_np(thread, &sattr);
99
100 // stackBase will be the *lowest* address on all architectures.
101 void* stackBase = nullptr;
102 size_t stackSize = 0;
103 int rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
104 if (rc) {
105 MOZ_CRASH(
106 "call to pthread_attr_getstack failed, unable to setup stack range for "
107 "JS");
108 }
109 MOZ_RELEASE_ASSERT(stackBase,
110 "invalid stack base, unable to setup stack range for JS");
111 pthread_attr_destroy(&sattr);
112
113 # if JS_STACK_GROWTH_DIRECTION > 0
114 return stackBase;
115 # else
116 return static_cast<char*>(stackBase) + stackSize;
117 # endif
118 }
119
120 #elif defined(__wasi__)
121
122 // Since we rearrange the layout for wasi via --stack-first flag for the linker
123 // the final layout is: 0x00 | <- stack | data | heap -> |.
124 static void* const NativeStackBase = __builtin_frame_address(0);
125
GetNativeStackBaseImpl()126 void* js::GetNativeStackBaseImpl() {
127 MOZ_ASSERT(JS_STACK_GROWTH_DIRECTION < 0);
128 return NativeStackBase;
129 }
130
131 #else // __wasi__
132
GetNativeStackBaseImpl()133 void* js::GetNativeStackBaseImpl() {
134 pthread_t thread = pthread_self();
135 # if defined(XP_DARWIN) || defined(DARWIN)
136 return pthread_get_stackaddr_np(thread);
137
138 # else
139 pthread_attr_t sattr;
140 pthread_attr_init(&sattr);
141 # if defined(__OpenBSD__)
142 stack_t ss;
143 # elif defined(PTHREAD_NP_H) || defined(_PTHREAD_NP_H_) || defined(NETBSD)
144 /* e.g. on FreeBSD 4.8 or newer, neundorf@kde.org */
145 pthread_attr_get_np(thread, &sattr);
146 # else
147 /*
148 * FIXME: this function is non-portable;
149 * other POSIX systems may have different np alternatives
150 */
151 pthread_getattr_np(thread, &sattr);
152 # endif
153
154 void* stackBase = 0;
155 size_t stackSize = 0;
156 int rc;
157 # if defined(__OpenBSD__)
158 rc = pthread_stackseg_np(pthread_self(), &ss);
159 stackBase = (void*)((size_t)ss.ss_sp - ss.ss_size);
160 stackSize = ss.ss_size;
161 # elif defined(ANDROID) && !defined(__aarch64__)
162 if (gettid() == getpid()) {
163 // bionic's pthread_attr_getstack prior to API 21 doesn't tell the truth
164 // for the main thread (see bug 846670). So we scan /proc/self/maps to
165 // find the segment which contains the stack.
166 rc = -1;
167
168 // Put the string on the stack, otherwise there is the danger that it
169 // has not been decompressed by the the on-demand linker. Bug 1165460.
170 //
171 // The volatile keyword should stop the compiler from trying to omit
172 // the stack copy in the future (hopefully).
173 volatile char path[] = "/proc/self/maps";
174 FILE* fs = fopen((const char*)path, "r");
175
176 if (fs) {
177 char line[100];
178 unsigned long stackAddr = (unsigned long)&sattr;
179 while (fgets(line, sizeof(line), fs) != nullptr) {
180 unsigned long stackStart;
181 unsigned long stackEnd;
182 if (sscanf(line, "%lx-%lx ", &stackStart, &stackEnd) == 2 &&
183 stackAddr >= stackStart && stackAddr < stackEnd) {
184 stackBase = (void*)stackStart;
185 stackSize = stackEnd - stackStart;
186 rc = 0;
187 break;
188 }
189 }
190 fclose(fs);
191 }
192 } else {
193 // For non main-threads pthread allocates the stack itself so it tells
194 // the truth.
195 rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
196 }
197 # else
198 rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
199 # endif
200 if (rc) {
201 MOZ_CRASH();
202 }
203 MOZ_ASSERT(stackBase);
204 pthread_attr_destroy(&sattr);
205
206 # if JS_STACK_GROWTH_DIRECTION > 0
207 return stackBase;
208 # else
209 return static_cast<char*>(stackBase) + stackSize;
210 # endif
211 # endif
212 }
213
214 #endif /* !XP_WIN */
215