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 bytes size of the TLS. 24 uintptr_t size; 25 26 // The alignment of the TLS layout. It assumed that the alignment 27 // value is a power of 2. 28 uintptr_t align; 29 }; 30 31 #if defined(LLVM_LIBC_ARCH_X86_64) || defined(LLVM_LIBC_ARCH_AARCH64) 32 // At the language level, argc is an int. But we use uint64_t as the x86_64 33 // ABI specifies it as an 8 byte value. Likewise, in the ARM64 ABI, arguments 34 // are usually passed in registers. x0 is a doubleword register, so this is 35 // 64 bit for aarch64 as well. 36 typedef uint64_t ArgcType; 37 38 // At the language level, argv is a char** value. However, we use uint64_t as 39 // ABIs specify the argv vector be an |argc| long array of 8-byte values. 40 typedef uint64_t ArgVEntryType; 41 #else 42 #error "argc and argv types are not defined for the target platform." 43 #endif 44 45 struct Args { 46 ArgcType argc; 47 48 // A flexible length array would be more suitable here, but C++ doesn't have 49 // flexible arrays: P1039 proposes to fix this. So, for now we just fake it. 50 // Even if argc is zero, "argv[argc] shall be a null pointer" 51 // (ISO C 5.1.2.2.1) so one is fine. Also, length of 1 is not really wrong as 52 // |argc| is guaranteed to be atleast 1, and there is an 8-byte null entry at 53 // the end of the argv array. 54 ArgVEntryType argv[1]; 55 }; 56 57 // Data structure which captures properties of a linux application. 58 struct AppProperties { 59 // Page size used for the application. 60 uintptr_t pageSize; 61 62 Args *args; 63 64 // The properties of an application's TLS. 65 TLS tls; 66 67 // Environment data. 68 uint64_t *envPtr; 69 }; 70 71 extern AppProperties app; 72 73 // Creates and initializes the TLS area for the current thread. Should not 74 // be called before app.tls has been initialized. 75 void initTLS(); 76 77 } // namespace __llvm_libc 78 79 #endif // LLVM_LIBC_CONFIG_LINUX_APP_H 80