Implemented syscalls and jump to usermode.

targets/_any/include/os/cpu.hpp

@@ -0,0 +1,57 @@
+
+#pragma once
+
+#if !defined(BAD_APPLE_OS_CPU_HPP_INCLUDED)
+#define BAD_APPLE_OS_CPU_HPP_INCLUDED
+
+#include <cstdint>
+
+namespace baos::cpu
+{
+enum class MSR : std::uint32_t
+{
+    IA32_EFER = 0xC000'0080,
+    STAR = 0xC000'0081,  // segments for syscall
+    LSTAR = 0xC000'0082, // instruction pointer for syscall
+};
+inline constexpr std::uint64_t IA32_EFER_SYSTEM_CALL_EXTENSIONS_BIT = (1 << 0);
+inline constexpr std::uint64_t IA32_EFER_LONG_MODE_ENABLE_BIT = (1 << 8);
+inline constexpr std::uint64_t IA32_EFER_LONG_MODE_ACTIVE_BIT = (1 << 10);
+inline constexpr std::uint64_t IA32_EFER_NO_EXECUTE_ENABLE_BIT = (1 << 11);
+// ...
+
+inline std::uint64_t readMSR(MSR msr) noexcept
+{
+    std::uint32_t lowHalf = 0;
+    std::uint32_t highHalf = 0;
+    __asm__ __volatile__(
+          "rdmsr"
+        : "=a"(lowHalf), "=d"(highHalf)
+        : "c"(msr)
+    );
+    return static_cast<std::uint64_t>(highHalf) << 32 | lowHalf;
+}
+
+inline void writeMSR(MSR msr, std::uint64_t value) noexcept
+{
+    std::uint32_t lowHalf = static_cast<std::uint32_t>(value & 0xFFFFFFFF);
+    std::uint32_t highHalf = static_cast<std::uint32_t>(value >> 32);
+    __asm__ __volatile__(
+          "wrmsr"
+        :
+        : "a"(lowHalf), "d"(highHalf), "c"(msr)
+    );
+}
+
+inline void setMSRBits(MSR msr, std::uint64_t bits) noexcept
+{
+    writeMSR(msr, readMSR(msr) | bits);
+}
+
+inline void unsetMSRBits(MSR msr, std::uint64_t bits) noexcept
+{
+    writeMSR(msr, readMSR(msr) & ~bits);
+}
+}
+
+#endif // !defined(BAD_APPLE_OS_CPU_HPP_INCLUDED)

targets/_any/include/os/segments.hpp

@@ -0,0 +1,18 @@
+
+#pragma once
+
+#if !defined(BAD_APPLE_OS_SEGMENTS_HPP_INCLUDED)
+#define BAD_APPLE_OS_SEGMENTS_HPP_INCLUDED
+
+#include <cstdint>
+
+namespace baos
+{
+inline constexpr std::uint16_t SEGIDX_KERNEL_CODE = 1 << 3;
+inline constexpr std::uint16_t SEGIDX_KERNEL_DATA = 2 << 3;
+inline constexpr std::uint16_t SEGIDX_USER_CODE   = 4 << 3;
+inline constexpr std::uint16_t SEGIDX_USER_DATA   = 3 << 3;
+inline constexpr std::uint16_t SEGIDX_TSS         = 5 << 3;
+}
+
+#endif // !defined(BAD_APPLE_OS_SEGMENTS_HPP_INCLUDED)

targets/_any/include/os/syscall.hpp

@@ -0,0 +1,33 @@
+
+#pragma once
+
+#if !defined(BAD_APPLE_OS_SYSCALL_HPP_INCLUDED)
+#define BAD_APPLE_OS_SYSCALL_HPP_INCLUDED
+
+#include <bit>
+#include <cstdint>
+
+namespace baos
+{
+enum class Syscall : std::uint64_t
+{
+    FILE_READ = 0,
+    FILE_WRITE = 1
+};
+
+void setupSyscall() noexcept;
+
+template<typename TParam0, typename TParam1, typename TParam2>
+inline void doSyscall(Syscall cmd, TParam0 param0 = 0, TParam1 param1 = 0, TParam2 param2 = 0) noexcept
+{
+    register std::uint64_t r8 asm("r8") = param2;
+    __asm__ __volatile__(
+          "syscall"
+        :
+        : "D"(cmd), "S"(param0), "d"(param1)
+        : "%rcx"
+    );
+}
+}
+
+#endif // !defined(BAD_APPLE_OS_SYSCALL_HPP_INCLUDED)