1 // Copyright 2012 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 // Platform-specific code for Linux goes here. For the POSIX-compatible
6 // parts, the implementation is in platform-posix.cc.
7
8 #include <pthread.h>
9 #include <semaphore.h>
10 #include <signal.h>
11 #include <stdio.h>
12 #include <stdlib.h>
13 #include <sys/prctl.h>
14 #include <sys/resource.h>
15 #include <sys/syscall.h>
16 #include <sys/time.h>
17
18 // Ubuntu Dapper requires memory pages to be marked as
19 // executable. Otherwise, OS raises an exception when executing code
20 // in that page.
21 #include <errno.h>
22 #include <fcntl.h> // open
23 #include <stdarg.h>
24 #include <strings.h> // index
25 #include <sys/mman.h> // mmap & munmap
26 #include <sys/stat.h> // open
27 #include <sys/types.h> // mmap & munmap
28 #include <unistd.h> // sysconf
29
30 // GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
31 // Old versions of the C library <signal.h> didn't define the type.
32 #if defined(__ANDROID__) && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
33 (defined(__arm__) || defined(__aarch64__)) && \
34 !defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
35 #include <asm/sigcontext.h> // NOLINT
36 #endif
37
38 #include <cmath>
39
40 #undef MAP_TYPE
41
42 #include "src/base/macros.h"
43 #include "src/base/platform/platform-posix-time.h"
44 #include "src/base/platform/platform-posix.h"
45 #include "src/base/platform/platform.h"
46
47 namespace v8 {
48 namespace base {
49
50 #ifdef __arm__
51
ArmUsingHardFloat()52 bool OS::ArmUsingHardFloat() {
53 // GCC versions 4.6 and above define __ARM_PCS or __ARM_PCS_VFP to specify
54 // the Floating Point ABI used (PCS stands for Procedure Call Standard).
55 // We use these as well as a couple of other defines to statically determine
56 // what FP ABI used.
57 // GCC versions 4.4 and below don't support hard-fp.
58 // GCC versions 4.5 may support hard-fp without defining __ARM_PCS or
59 // __ARM_PCS_VFP.
60
61 #define GCC_VERSION \
62 (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
63 #if GCC_VERSION >= 40600 && !defined(__clang__)
64 #if defined(__ARM_PCS_VFP)
65 return true;
66 #else
67 return false;
68 #endif
69
70 #elif GCC_VERSION < 40500 && !defined(__clang__)
71 return false;
72
73 #else
74 #if defined(__ARM_PCS_VFP)
75 return true;
76 #elif defined(__ARM_PCS) || defined(__SOFTFP__) || defined(__SOFTFP) || \
77 !defined(__VFP_FP__)
78 return false;
79 #else
80 #error \
81 "Your version of compiler does not report the FP ABI compiled for." \
82 "Please report it on this issue" \
83 "http://code.google.com/p/v8/issues/detail?id=2140"
84
85 #endif
86 #endif
87 #undef GCC_VERSION
88 }
89
90 #endif // def __arm__
91
CreateTimezoneCache()92 TimezoneCache* OS::CreateTimezoneCache() {
93 return new PosixDefaultTimezoneCache();
94 }
95
GetSharedLibraryAddresses()96 std::vector<OS::SharedLibraryAddress> OS::GetSharedLibraryAddresses() {
97 std::vector<SharedLibraryAddress> result;
98 // This function assumes that the layout of the file is as follows:
99 // hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name]
100 // If we encounter an unexpected situation we abort scanning further entries.
101 FILE* fp = fopen("/proc/self/maps", "r");
102 if (fp == nullptr) return result;
103
104 // Allocate enough room to be able to store a full file name.
105 const int kLibNameLen = FILENAME_MAX + 1;
106 char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));
107
108 // This loop will terminate once the scanning hits an EOF.
109 while (true) {
110 uintptr_t start, end, offset;
111 char attr_r, attr_w, attr_x, attr_p;
112 // Parse the addresses and permission bits at the beginning of the line.
113 if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2) break;
114 if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4) break;
115 if (fscanf(fp, "%" V8PRIxPTR, &offset) != 1) break;
116
117 // Adjust {start} based on {offset}.
118 start -= offset;
119
120 int c;
121 if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') {
122 // Found a read-only executable entry. Skip characters until we reach
123 // the beginning of the filename or the end of the line.
124 do {
125 c = getc(fp);
126 } while ((c != EOF) && (c != '\n') && (c != '/') && (c != '['));
127 if (c == EOF) break; // EOF: Was unexpected, just exit.
128
129 // Process the filename if found.
130 if ((c == '/') || (c == '[')) {
131 // Push the '/' or '[' back into the stream to be read below.
132 ungetc(c, fp);
133
134 // Read to the end of the line. Exit if the read fails.
135 if (fgets(lib_name, kLibNameLen, fp) == nullptr) break;
136
137 // Drop the newline character read by fgets. We do not need to check
138 // for a zero-length string because we know that we at least read the
139 // '/' or '[' character.
140 lib_name[strlen(lib_name) - 1] = '\0';
141 } else {
142 // No library name found, just record the raw address range.
143 snprintf(lib_name, kLibNameLen, "%08" V8PRIxPTR "-%08" V8PRIxPTR, start,
144 end);
145 }
146 result.push_back(SharedLibraryAddress(lib_name, start, end));
147 } else {
148 // Entry not describing executable data. Skip to end of line to set up
149 // reading the next entry.
150 do {
151 c = getc(fp);
152 } while ((c != EOF) && (c != '\n'));
153 if (c == EOF) break;
154 }
155 }
156 free(lib_name);
157 fclose(fp);
158 return result;
159 }
160
SignalCodeMovingGC()161 void OS::SignalCodeMovingGC() {
162 // Support for ll_prof.py.
163 //
164 // The Linux profiler built into the kernel logs all mmap's with
165 // PROT_EXEC so that analysis tools can properly attribute ticks. We
166 // do a mmap with a name known by ll_prof.py and immediately munmap
167 // it. This injects a GC marker into the stream of events generated
168 // by the kernel and allows us to synchronize V8 code log and the
169 // kernel log.
170 long size = sysconf(_SC_PAGESIZE); // NOLINT(runtime/int)
171 FILE* f = fopen(OS::GetGCFakeMMapFile(), "w+");
172 if (f == nullptr) {
173 OS::PrintError("Failed to open %s\n", OS::GetGCFakeMMapFile());
174 OS::Abort();
175 }
176 void* addr = mmap(OS::GetRandomMmapAddr(), size, PROT_READ | PROT_EXEC,
177 MAP_PRIVATE, fileno(f), 0);
178 DCHECK_NE(MAP_FAILED, addr);
179 CHECK(Free(addr, size));
180 fclose(f);
181 }
182
183 } // namespace base
184 } // namespace v8
185