91 lines
2.3 KiB
C++
91 lines
2.3 KiB
C++
/**
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* Wrappers for various syscalls.
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*
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* WARNING: This file contains code that is known to the State of California to cause birth defects or reproductive harm
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*/
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#pragma once
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#include "./metaprogramming.hxx"
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enum class LnxSystemOp : long {
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READ = 0,
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WRITE = 1,
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OPEN = 2,
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CLOSE = 3,
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EXIT = 60,
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KEXEC_FILE_LOAD = 320
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};
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template<class _Type>
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concept LnxSystemCallArgumentType = MphStaticCastableTo<_Type, long> || MphIsPointer<_Type>::value;
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/**
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* Cast something to a long for a syscall
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*
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* \internal
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*/
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template<class _Type>
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inline long LnxSystemCallCast(_Type arg) {
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if constexpr (MphIsPointer<decltype(arg)>::value) {
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return reinterpret_cast<long>(arg);
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} else {
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return static_cast<long>(arg);
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}
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}
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/**
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* Do a system call with only long arguments. This probably isn't memory safe.
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*
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* \internal
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*/
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template<MphSameAs<long>... _ArgTypes>
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[[using gnu: naked]]
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inline int LnxSystemCallInternal(long op, _ArgTypes... args) noexcept {
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// Move arguments to where they belong
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asm volatile ("mov %%rdi, %%rax" : : : "rax");
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if constexpr (sizeof...(args) >= 1) asm volatile ("mov %%rsi, %%rdi" : : : "rdi");
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if constexpr (sizeof...(args) >= 2) asm volatile ("mov %%rdx, %%rsi" : : : "rsi");
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if constexpr (sizeof...(args) >= 3) asm volatile ("mov %%rcx, %%rdx" : : : "rdx");
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if constexpr (sizeof...(args) >= 4) asm volatile ("mov %%r8, %%r10" : : : "r10");
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if constexpr (sizeof...(args) >= 5) asm volatile ("mov %%r9, %%r8" : : : "r8" );
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if constexpr (sizeof...(args) >= 6) asm volatile ("pop %%r9 " : : : "r9" );
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// Call the system
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asm volatile ("syscall");
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// Return.
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asm volatile ("ret");
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}
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/**
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* Do a system call, heavily optimized
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*
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* \param op operation
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* \param args the arguments
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* \return system call return value
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*/
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template<LnxSystemCallArgumentType... _ArgTypes>
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inline int LnxSystemCall(LnxSystemOp op, _ArgTypes... args) noexcept {
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return LnxSystemCallInternal(static_cast<long>(op), LnxSystemCallCast(args)...);
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}
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/**
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* Write to a file descriptor
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*/
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inline int LnxWrite(int fileno, const char* path, long count) noexcept {
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return LnxSystemCall(LnxSystemOp::WRITE, fileno, path, count);
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}
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/**
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* Exit.
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*/
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[[noreturn]]
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inline int LnxExitProcess(int status) noexcept {
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LnxSystemCall(LnxSystemOp::EXIT, status);
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__builtin_unreachable();
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}
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