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//===-- Classes to capture properites of linux applications -----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_CONFIG_LINUX_APP_H
#define LLVM_LIBC_CONFIG_LINUX_APP_H
#include "src/__support/macros/properties/architectures.h"
#include <stdint.h>
namespace __llvm_libc {
// Data structure to capture properties of the linux/ELF TLS image.
struct TLSImage {
// The load address of the TLS.
uintptr_t address;
// The byte size of the TLS image consisting of both initialized and
// uninitialized memory. In ELF executables, it is size of .tdata + size of
// .tbss. Put in another way, it is the memsz field of the PT_TLS header.
uintptr_t size;
// The byte size of initialized memory in the TLS image. In ELF exectubles,
// this is the size of .tdata. Put in another way, it is the filesz of the
// PT_TLS header.
uintptr_t init_size;
// The alignment of the TLS layout. It assumed that the alignment
// value is a power of 2.
uintptr_t align;
};
#if defined(LIBC_TARGET_ARCH_IS_X86_64) || \
defined(LIBC_TARGET_ARCH_IS_AARCH64) || \
defined(LIBC_TARGET_ARCH_IS_RISCV64)
// At the language level, argc is an int. But we use uint64_t as the x86_64
// ABI specifies it as an 8 byte value. Likewise, in the ARM64 ABI, arguments
// are usually passed in registers. x0 is a doubleword register, so this is
// 64 bit for aarch64 as well.
typedef uintptr_t ArgcType;
// At the language level, argv is a char** value. However, we use uint64_t as
// ABIs specify the argv vector be an |argc| long array of 8-byte values.
typedef uintptr_t ArgVEntryType;
typedef uintptr_t EnvironType;
typedef uintptr_t AuxEntryType;
#else
#error "argc and argv types are not defined for the target platform."
#endif
struct Args {
ArgcType argc;
// A flexible length array would be more suitable here, but C++ doesn't have
// flexible arrays: P1039 proposes to fix this. So, for now we just fake it.
// Even if argc is zero, "argv[argc] shall be a null pointer"
// (ISO C 5.1.2.2.1) so one is fine. Also, length of 1 is not really wrong as
// |argc| is guaranteed to be atleast 1, and there is an 8-byte null entry at
// the end of the argv array.
ArgVEntryType argv[1];
};
// Data structure which captures properties of a linux application.
struct AppProperties {
// Page size used for the application.
uintptr_t pageSize;
Args *args;
// The properties of an application's TLS image.
TLSImage tls;
// Environment data.
EnvironType *envPtr;
};
extern AppProperties app;
// The descriptor of a thread's TLS area.
struct TLSDescriptor {
// The size of the TLS area.
uintptr_t size = 0;
// The address of the TLS area. This address can be passed to cleanup
// functions like munmap.
uintptr_t addr = 0;
// The value the thread pointer register should be initialized to.
// Note that, dependending the target architecture ABI, it can be the
// same as |addr| or something else.
uintptr_t tp = 0;
constexpr TLSDescriptor() = default;
};
// Create and initialize the TLS area for the current thread. Should not
// be called before app.tls has been initialized.
void init_tls(TLSDescriptor &tls);
// Cleanup the TLS area as described in |tls_descriptor|.
void cleanup_tls(uintptr_t tls_addr, uintptr_t tls_size);
} // namespace __llvm_libc
#endif // LLVM_LIBC_CONFIG_LINUX_APP_H
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