1 | // Copyright 2019 The SwiftShader Authors. All Rights Reserved. |
2 | // |
3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
4 | // you may not use this file except in compliance with the License. |
5 | // You may obtain a copy of the License at |
6 | // |
7 | // http://www.apache.org/licenses/LICENSE-2.0 |
8 | // |
9 | // Unless required by applicable law or agreed to in writing, software |
10 | // distributed under the License is distributed on an "AS IS" BASIS, |
11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
12 | // See the License for the specific language governing permissions and |
13 | // limitations under the License. |
14 | |
15 | #include "MemFd.hpp" |
16 | #include "../Debug.hpp" |
17 | |
18 | #include <errno.h> |
19 | #include <fcntl.h> |
20 | #include <string.h> |
21 | #include <sys/mman.h> |
22 | #include <unistd.h> |
23 | |
24 | #ifndef MFD_CLOEXEC |
25 | #define MFD_CLOEXEC 0x0001U |
26 | #endif |
27 | |
28 | #if __aarch64__ |
29 | #define __NR_memfd_create 279 |
30 | #elif __arm__ |
31 | #define __NR_memfd_create 279 |
32 | #elif __powerpc64__ |
33 | #define __NR_memfd_create 360 |
34 | #elif __i386__ |
35 | #define __NR_memfd_create 356 |
36 | #elif __x86_64__ |
37 | #define __NR_memfd_create 319 |
38 | #endif /* __NR_memfd_create__ */ |
39 | |
40 | LinuxMemFd::~LinuxMemFd() |
41 | { |
42 | close(); |
43 | } |
44 | |
45 | void LinuxMemFd::importFd(int fd) |
46 | { |
47 | close(); |
48 | fd_ = fd; |
49 | } |
50 | |
51 | int LinuxMemFd::exportFd() const |
52 | { |
53 | if (fd_ < 0) |
54 | { |
55 | return fd_; |
56 | } |
57 | |
58 | // Duplicate file descriptor while setting the clo-on-exec flag (Linux specific). |
59 | return ::fcntl(fd_, F_DUPFD_CLOEXEC, 0); |
60 | } |
61 | |
62 | bool LinuxMemFd::allocate(const char* name, size_t size) |
63 | { |
64 | close(); |
65 | |
66 | #ifndef __NR_memfd_create |
67 | TRACE("memfd_create() not supported on this system!" ); |
68 | return false; |
69 | #else |
70 | // In the event of no system call this returns -1 with errno set |
71 | // as ENOSYS. |
72 | fd_ = syscall(__NR_memfd_create, name, MFD_CLOEXEC); |
73 | if (fd_ < 0) |
74 | { |
75 | TRACE("memfd_create() returned %d: %s" , errno, strerror(errno)); |
76 | return false; |
77 | } |
78 | // Ensure there is enough space. |
79 | if (size > 0 && ::ftruncate(fd_, size) < 0) |
80 | { |
81 | TRACE("ftruncate() %lld returned %d: %s" , (long long)size, errno, strerror(errno)); |
82 | close(); |
83 | return false; |
84 | } |
85 | #endif |
86 | return true; |
87 | } |
88 | |
89 | void LinuxMemFd::close() |
90 | { |
91 | if (fd_ >= 0) |
92 | { |
93 | // WARNING: Never retry on close() failure, even with EINTR, see |
94 | // https://lwn.net/Articles/576478/ for example. |
95 | int ret = ::close(fd_); |
96 | if (ret < 0) { |
97 | TRACE("LinuxMemFd::close() failed with: %s" , strerror(errno)); |
98 | assert(false); |
99 | } |
100 | fd_ = -1; |
101 | } |
102 | } |
103 | |
104 | void* LinuxMemFd::mapReadWrite(size_t offset, size_t size) |
105 | { |
106 | void* addr = ::mmap(nullptr, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd_, |
107 | static_cast<off_t>(offset)); |
108 | return (addr == MAP_FAILED) ? nullptr : addr; |
109 | } |
110 | |
111 | bool LinuxMemFd::unmap(void* addr, size_t size) |
112 | { |
113 | return ::munmap(addr, size) == 0; |
114 | } |
115 | |