citra/src/core/hle/kernel/svc_wrapper.h
2018-11-12 13:59:34 -05:00

294 lines
12 KiB
C++

// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <array>
#include <cstring>
#include <type_traits>
#include "common/common_types.h"
namespace Kernel {
/*
* This class defines the SVC ABI, and provides a wrapper template for translating between ARM
* registers and SVC parameters and return value. The SVC context class should inherit from this
* class using CRTP (`class SVC : public SVCWrapper<SVC> {...}`), and use the Wrap() template to
* convert a SVC function interface to a void()-type function that interacts with registers
* interface GetReg() and SetReg().
*/
template <typename Context>
class SVCWrapper {
protected:
template <auto F>
void Wrap() {
WrapHelper<decltype(F)>::Call(*static_cast<Context*>(this), F);
};
private:
// A special param index represents the return value
static constexpr std::size_t INDEX_RETURN = ~(std::size_t)0;
struct ParamSlot {
// whether the slot is used for a param
bool used;
// index of a param in the function signature, starting from 0, or special value
// INDEX_RETURN
std::size_t param_index;
// index of a 32-bit word within the param
std::size_t word_index;
};
// Size in words of the given type in ARM ABI
template <typename T>
static constexpr std::size_t WordSize() {
static_assert(std::is_trivially_copyable_v<T>);
if constexpr (std::is_pointer_v<T>) {
return 1;
} else if constexpr (std::is_same_v<T, bool>) {
return 1;
} else {
return (sizeof(T) - 1) / 4 + 1;
}
}
// Size in words of the given type in ARM ABI with pointer removed
template <typename T>
static constexpr std::size_t OutputWordSize() {
if constexpr (std::is_pointer_v<T>) {
return WordSize<std::remove_pointer_t<T>>();
} else {
return 0;
}
}
// Describes the register assignments of a SVC
struct SVCABI {
static constexpr std::size_t RegCount = 8;
// Register assignments for input params.
// For example, in[0] records which input param and word r0 stores
std::array<ParamSlot, RegCount> in{};
// Register assignments for output params.
// For example, out[0] records which output param (with pointer removed) and word r0 stores
std::array<ParamSlot, RegCount> out{};
// Search the register assignments for a word of a param
constexpr std::size_t GetRegisterIndex(std::size_t param_index,
std::size_t word_index) const {
for (std::size_t slot = 0; slot < RegCount; ++slot) {
if (in[slot].used && in[slot].param_index == param_index &&
in[slot].word_index == word_index) {
return slot;
}
if (out[slot].used && out[slot].param_index == param_index &&
out[slot].word_index == word_index) {
return slot;
}
}
// should throw, but gcc bugs out here
return 0x12345678;
}
};
// Generates ABI info for a given SVC signature R(Context::)(T...)
template <typename R, typename... T>
static constexpr SVCABI GetSVCABI() {
constexpr std::size_t param_count = sizeof...(T);
std::array<bool, param_count> param_is_output{{std::is_pointer_v<T>...}};
std::array<std::size_t, param_count> param_size{{WordSize<T>()...}};
std::array<std::size_t, param_count> output_param_size{{OutputWordSize<T>()...}};
std::array<bool, param_count> param_need_align{
{(std::is_same_v<T, u64> || std::is_same_v<T, s64>)...}};
// derives ARM ABI, which assigns all params to r0~r3 and then stack
std::array<ParamSlot, 4> armabi_reg{};
std::array<ParamSlot, 4> armabi_stack{};
std::size_t reg_pos = 0;
std::size_t stack_pos = 0;
for (std::size_t i = 0; i < param_count; ++i) {
if (param_need_align[i]) {
reg_pos += reg_pos % 2;
}
for (std::size_t j = 0; j < param_size[i]; ++j) {
if (reg_pos == 4) {
armabi_stack[stack_pos++] = ParamSlot{true, i, j};
} else {
armabi_reg[reg_pos++] = ParamSlot{true, i, j};
}
}
}
// now derives SVC ABI which is a modified version of ARM ABI
SVCABI mod_abi{};
std::size_t out_pos = 0; // next available output register
// assign return value to output registers
if constexpr (!std::is_void_v<R>) {
for (std::size_t j = 0; j < WordSize<R>(); ++j) {
mod_abi.out[out_pos++] = {true, INDEX_RETURN, j};
}
}
// assign output params (pointer-type params) to output registers
for (std::size_t i = 0; i < param_count; ++i) {
if (param_is_output[i]) {
for (std::size_t j = 0; j < output_param_size[i]; ++j) {
mod_abi.out[out_pos++] = ParamSlot{true, i, j};
}
}
}
// assign input params (non-pointer-type params) to input registers
stack_pos = 0; // next available stack param
for (std::size_t k = 0; k < mod_abi.in.size(); ++k) {
if (k < armabi_reg.size() && armabi_reg[k].used &&
!param_is_output[armabi_reg[k].param_index]) {
// If this is within the ARM ABI register range and it is a used input param, use
// the same register position
mod_abi.in[k] = armabi_reg[k];
} else {
// Otherwise, assign it with the next available stack input
// If all stack inputs have been allocated, this would do nothing
// and leaves the slot unused.
// Loop until an input stack param is found
while (stack_pos < armabi_stack.size() &&
(!armabi_stack[stack_pos].used ||
param_is_output[armabi_stack[stack_pos].param_index])) {
++stack_pos;
}
// Reassign the stack param to the free register
if (stack_pos < armabi_stack.size()) {
mod_abi.in[k] = armabi_stack[stack_pos++];
}
}
}
return mod_abi;
}
template <std::size_t param_index, std::size_t word_size, std::size_t... indices>
static constexpr std::array<std::size_t, word_size> GetRegIndicesImpl(
SVCABI abi, std::index_sequence<indices...>) {
return {{abi.GetRegisterIndex(param_index, indices)...}};
}
// Gets assigned register index for the param_index-th param of word_size in a function with
// signature R(Context::)(Ts...)
template <std::size_t param_index, std::size_t word_size, typename R, typename... Ts>
static constexpr std::array<std::size_t, word_size> GetRegIndices() {
constexpr SVCABI abi = GetSVCABI<R, Ts...>();
return GetRegIndicesImpl<param_index, word_size>(abi,
std::make_index_sequence<word_size>{});
}
// Gets the value for the param_index-th param of word_size in a function with signature
// R(Context::)(Ts...)
// T is the param type, which must be a non-pointer as it is an input param.
// Must hold: Ts[param_index] == T
template <std::size_t param_index, typename T, typename R, typename... Ts>
static void GetParam(Context& context, T& value) {
static_assert(!std::is_pointer_v<T>, "T should not be a pointer");
constexpr auto regi = GetRegIndices<param_index, WordSize<T>(), R, Ts...>();
if constexpr (std::is_class_v<T> || std::is_union_v<T>) {
std::array<u32, WordSize<T>()> buf;
for (std::size_t i = 0; i < WordSize<T>(); ++i) {
buf[i] = context.GetReg(regi[i]);
}
std::memcpy(&value, &buf, sizeof(T));
} else if constexpr (WordSize<T>() == 2) {
u64 l = context.GetReg(regi[0]);
u64 h = context.GetReg(regi[1]);
value = static_cast<T>(l | (h << 32));
} else if constexpr (std::is_same_v<T, bool>) {
// TODO: Is this correct or should only test the lowest byte?
value = context.GetReg(regi[0]) != 0;
} else {
value = static_cast<T>(context.GetReg(regi[0]));
}
}
// Sets the value for the param_index-th param of word_size in a function with signature
// R(Context::)(Ts...)
// T is the param type with pointer removed, which was originally a pointer-type output param
// Must hold: (Ts[param_index] == T*) || (R==T && param_index == INDEX_RETURN)
template <std::size_t param_index, typename T, typename R, typename... Ts>
static void SetParam(Context& context, const T& value) {
static_assert(!std::is_pointer_v<T>, "T should have pointer removed before passing in");
constexpr auto regi = GetRegIndices<param_index, WordSize<T>(), R, Ts...>();
if constexpr (std::is_class_v<T> || std::is_union_v<T>) {
std::array<u32, WordSize<T>()> buf;
std::memcpy(&buf, &value, sizeof(T));
for (std::size_t i = 0; i < WordSize<T>(); ++i) {
context.SetReg(regi[i], buf[i]);
}
} else if constexpr (WordSize<T>() == 2) {
u64 u = static_cast<u64>(value);
context.SetReg(regi[0], static_cast<u32>(u & 0xFFFFFFFF));
context.SetReg(regi[1], static_cast<u32>(u >> 32));
} else {
u32 u = static_cast<u32>(value);
context.SetReg(regi[0], u);
}
}
template <typename SVCT, typename R, typename... Ts>
struct WrapPass;
template <typename SVCT, typename R, typename T, typename... Ts>
struct WrapPass<SVCT, R, T, Ts...> {
// Do I/O for the param T in function R(Context::svc)(Us..., T, Ts...) and then move on to
// the next param.
// Us are params whose I/O is already handled.
// T is the current param to do I/O.
// Ts are params whose I/O is not handled yet.
template <typename... Us>
static void Call(Context& context, SVCT svc, Us... u) {
static_assert(std::is_same_v<SVCT, R (Context::*)(Us..., T, Ts...)>);
constexpr std::size_t current_param_index = sizeof...(Us);
if constexpr (std::is_pointer_v<T>) {
using OutputT = std::remove_pointer_t<T>;
OutputT output;
WrapPass<SVCT, R, Ts...>::Call(context, svc, u..., &output);
SetParam<current_param_index, OutputT, R, Us..., T, Ts...>(context, output);
} else {
T input;
GetParam<current_param_index, T, R, Us..., T, Ts...>(context, input);
WrapPass<SVCT, R, Ts...>::Call(context, svc, u..., input);
}
}
};
template <typename SVCT, typename R>
struct WrapPass<SVCT, R /*empty for T, Ts...*/> {
// Call function R(Context::svc)(Us...) and transfer the return value to registers
template <typename... Us>
static void Call(Context& context, SVCT svc, Us... u) {
static_assert(std::is_same_v<SVCT, R (Context::*)(Us...)>);
if constexpr (std::is_void_v<R>) {
(context.*svc)(u...);
} else {
R r = (context.*svc)(u...);
SetParam<INDEX_RETURN, R, R, Us...>(context, r);
}
}
};
template <typename T>
struct WrapHelper;
template <typename R, typename... T>
struct WrapHelper<R (Context::*)(T...)> {
static void Call(Context& context, R (Context::*svc)(T...)) {
WrapPass<decltype(svc), R, T...>::Call(context, svc /*Empty for Us*/);
}
};
};
} // namespace Kernel