70 lines
2.2 KiB
C++
70 lines
2.2 KiB
C++
//===-- Implementation of crt for aarch64 ---------------------------------===//
|
|
//
|
|
// 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
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "config/linux/app.h"
|
|
#include "src/__support/OSUtil/syscall.h"
|
|
|
|
#include <linux/auxvec.h>
|
|
#include <linux/elf.h>
|
|
#include <stdint.h>
|
|
#include <sys/syscall.h>
|
|
|
|
extern "C" int main(int, char **, char **);
|
|
|
|
// Source documentation:
|
|
// https://github.com/ARM-software/abi-aa/tree/main/sysvabi64
|
|
|
|
namespace __llvm_libc {
|
|
|
|
AppProperties app;
|
|
|
|
} // namespace __llvm_libc
|
|
|
|
using __llvm_libc::app;
|
|
|
|
// TODO: Would be nice to use the aux entry structure from elf.h when available.
|
|
struct AuxEntry {
|
|
uint64_t type;
|
|
uint64_t value;
|
|
};
|
|
|
|
extern "C" void _start() {
|
|
// Skip the Frame Pointer and the Link Register
|
|
// https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst
|
|
// Section 6.2.3
|
|
app.args = reinterpret_cast<__llvm_libc::Args *>(
|
|
reinterpret_cast<uintptr_t *>(__builtin_frame_address(0)) + 2);
|
|
|
|
// After the argv array, is a 8-byte long NULL value before the array of env
|
|
// values. The end of the env values is marked by another 8-byte long NULL
|
|
// value. We step over it (the "+ 1" below) to get to the env values.
|
|
uint64_t *env_ptr = app.args->argv + app.args->argc + 1;
|
|
uint64_t *env_end_marker = env_ptr;
|
|
while (*env_end_marker)
|
|
++env_end_marker;
|
|
|
|
// After the env array, is the aux-vector. The end of the aux-vector is
|
|
// denoted by an AT_NULL entry.
|
|
for (AuxEntry *aux_entry = reinterpret_cast<AuxEntry *>(env_end_marker + 1);
|
|
aux_entry->type != AT_NULL; ++aux_entry) {
|
|
switch (aux_entry->type) {
|
|
case AT_PAGESZ:
|
|
app.pageSize = aux_entry->value;
|
|
break;
|
|
default:
|
|
break; // TODO: Read other useful entries from the aux vector.
|
|
}
|
|
}
|
|
|
|
// TODO: Init TLS
|
|
|
|
__llvm_libc::syscall(SYS_exit, main(app.args->argc,
|
|
reinterpret_cast<char **>(app.args->argv),
|
|
reinterpret_cast<char **>(env_ptr)));
|
|
}
|