1 //===-- Classes to capture properites of linux applications -----*- 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 #ifndef LLVM_LIBC_CONFIG_LINUX_APP_H 10 #define LLVM_LIBC_CONFIG_LINUX_APP_H 11 12 #include "src/__support/architectures.h" 13 14 #include <stdint.h> 15 16 namespace __llvm_libc { 17 18 // Data structure to capture properties of the linux/ELF TLS. 19 struct TLS { 20 // The load address of the TLS. 21 uintptr_t address; 22 23 // The byte size of the TLS image consisting of both initialized and 24 // uninitialized memory. In ELF executables, it is size of .tdata + size of 25 // .tbss. Put in another way, it is the memsz field of the PT_TLS header. 26 uintptr_t size; 27 28 // The byte size of initialized memory in the TLS image. In ELF exectubles, 29 // this is the size of .tdata. Put in another way, it is the filesz of the 30 // PT_TLS header. 31 uintptr_t init_size; 32 33 // The alignment of the TLS layout. It assumed that the alignment 34 // value is a power of 2. 35 uintptr_t align; 36 }; 37 38 #if defined(LLVM_LIBC_ARCH_X86_64) || defined(LLVM_LIBC_ARCH_AARCH64) 39 // At the language level, argc is an int. But we use uint64_t as the x86_64 40 // ABI specifies it as an 8 byte value. Likewise, in the ARM64 ABI, arguments 41 // are usually passed in registers. x0 is a doubleword register, so this is 42 // 64 bit for aarch64 as well. 43 typedef uint64_t ArgcType; 44 45 // At the language level, argv is a char** value. However, we use uint64_t as 46 // ABIs specify the argv vector be an |argc| long array of 8-byte values. 47 typedef uint64_t ArgVEntryType; 48 #else 49 #error "argc and argv types are not defined for the target platform." 50 #endif 51 52 struct Args { 53 ArgcType argc; 54 55 // A flexible length array would be more suitable here, but C++ doesn't have 56 // flexible arrays: P1039 proposes to fix this. So, for now we just fake it. 57 // Even if argc is zero, "argv[argc] shall be a null pointer" 58 // (ISO C 5.1.2.2.1) so one is fine. Also, length of 1 is not really wrong as 59 // |argc| is guaranteed to be atleast 1, and there is an 8-byte null entry at 60 // the end of the argv array. 61 ArgVEntryType argv[1]; 62 }; 63 64 // Data structure which captures properties of a linux application. 65 struct AppProperties { 66 // Page size used for the application. 67 uintptr_t pageSize; 68 69 Args *args; 70 71 // The properties of an application's TLS. 72 TLS tls; 73 74 // Environment data. 75 uint64_t *envPtr; 76 }; 77 78 extern AppProperties app; 79 80 // Creates and initializes the TLS area for the current thread. Should not 81 // be called before app.tls has been initialized. 82 void initTLS(); 83 84 } // namespace __llvm_libc 85 86 #endif // LLVM_LIBC_CONFIG_LINUX_APP_H 87