6c1f56fdb5
This patch lifts aux vector related definitions to app.h. Because startup's refactoring is in progress, this patch still contains duplicated changes. This problem will be addressed very soon in an incoming patch.
125 lines
4.0 KiB
C++
125 lines
4.0 KiB
C++
//===-- Classes to capture properites of linux applications -----*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_CONFIG_LINUX_APP_H
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#define LLVM_LIBC_CONFIG_LINUX_APP_H
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#include "src/__support/macros/properties/architectures.h"
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#include <stdint.h>
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namespace LIBC_NAMESPACE {
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// Data structure to capture properties of the linux/ELF TLS image.
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struct TLSImage {
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// The load address of the TLS.
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uintptr_t address;
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// The byte size of the TLS image consisting of both initialized and
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// uninitialized memory. In ELF executables, it is size of .tdata + size of
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// .tbss. Put in another way, it is the memsz field of the PT_TLS header.
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uintptr_t size;
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// The byte size of initialized memory in the TLS image. In ELF exectubles,
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// this is the size of .tdata. Put in another way, it is the filesz of the
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// PT_TLS header.
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uintptr_t init_size;
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// The alignment of the TLS layout. It assumed that the alignment
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// value is a power of 2.
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uintptr_t align;
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};
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#if defined(LIBC_TARGET_ARCH_IS_X86_64) || \
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defined(LIBC_TARGET_ARCH_IS_AARCH64) || \
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defined(LIBC_TARGET_ARCH_IS_ANY_RISCV)
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// At the language level, argc is an int. But we use uint64_t as the x86_64
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// ABI specifies it as an 8 byte value. Likewise, in the ARM64 ABI, arguments
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// are usually passed in registers. x0 is a doubleword register, so this is
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// 64 bit for aarch64 as well.
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typedef uintptr_t ArgcType;
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// At the language level, argv is a char** value. However, we use uint64_t as
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// ABIs specify the argv vector be an |argc| long array of 8-byte values.
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typedef uintptr_t ArgVEntryType;
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typedef uintptr_t EnvironType;
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#else
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#error "argc and argv types are not defined for the target platform."
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#endif
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// Linux manpage on `proc(5)` says that the aux vector is an array of
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// unsigned long pairs.
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// (see: https://man7.org/linux/man-pages/man5/proc.5.html)
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using AuxEntryType = unsigned long;
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// Using the naming convention from `proc(5)`.
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// TODO: Would be nice to use the aux entry structure from elf.h when available.
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struct AuxEntry {
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AuxEntryType id;
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AuxEntryType value;
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};
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struct Args {
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ArgcType argc;
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// A flexible length array would be more suitable here, but C++ doesn't have
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// flexible arrays: P1039 proposes to fix this. So, for now we just fake it.
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// Even if argc is zero, "argv[argc] shall be a null pointer"
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// (ISO C 5.1.2.2.1) so one is fine. Also, length of 1 is not really wrong as
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// |argc| is guaranteed to be atleast 1, and there is an 8-byte null entry at
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// the end of the argv array.
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ArgVEntryType argv[1];
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};
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// Data structure which captures properties of a linux application.
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struct AppProperties {
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// Page size used for the application.
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uintptr_t page_size;
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Args *args;
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// The properties of an application's TLS image.
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TLSImage tls;
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// Environment data.
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EnvironType *env_ptr;
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// Auxiliary vector data.
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AuxEntry *auxv_ptr;
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};
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extern AppProperties app;
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// The descriptor of a thread's TLS area.
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struct TLSDescriptor {
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// The size of the TLS area.
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uintptr_t size = 0;
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// The address of the TLS area. This address can be passed to cleanup
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// functions like munmap.
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uintptr_t addr = 0;
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// The value the thread pointer register should be initialized to.
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// Note that, dependending the target architecture ABI, it can be the
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// same as |addr| or something else.
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uintptr_t tp = 0;
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constexpr TLSDescriptor() = default;
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};
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// Create and initialize the TLS area for the current thread. Should not
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// be called before app.tls has been initialized.
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void init_tls(TLSDescriptor &tls);
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// Cleanup the TLS area as described in |tls_descriptor|.
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void cleanup_tls(uintptr_t tls_addr, uintptr_t tls_size);
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} // namespace LIBC_NAMESPACE
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#endif // LLVM_LIBC_CONFIG_LINUX_APP_H
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