Atmosphere/libraries/libmesosphere/source/arch/arm64/svc/kern_svc_tables.cpp

/*
 * Copyright (c) 2018-2020 Atmosphère-NX
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifdef MESOSPHERE_USE_STUBBED_SVC_TABLES
#include <mesosphere/kern_debug_log.hpp>
#endif

#include <mesosphere/svc/kern_svc_tables.hpp>
#include <vapours/svc/svc_codegen.hpp>

namespace ams::kern::svc {

    namespace {

        #ifndef MESOSPHERE_USE_STUBBED_SVC_TABLES
            #define DECLARE_SVC_STRUCT(ID, RETURN_TYPE, NAME, ...)                                                                        \
                class NAME {                                                                                                              \
                    private:                                                                                                              \
                        using Impl = ::ams::svc::codegen::KernelSvcWrapper<::ams::kern::svc::NAME##64, ::ams::kern::svc::NAME##64From32>; \
                    public:                                                                                                               \
                        static NOINLINE void       Call64() { return Impl::Call64(); }                                                    \
                        static NOINLINE void Call64From32() { return Impl::Call64From32(); }                                              \
                };
        #else
            #define DECLARE_SVC_STRUCT(ID, RETURN_TYPE, NAME, ...)                                                                        \
                class NAME {                                                                                                              \
                    public:                                                                                                               \
                        static NOINLINE void Call64()       { MESOSPHERE_PANIC("Stubbed Svc"#NAME"64 was called"); }                      \
                        static NOINLINE void Call64From32() { MESOSPHERE_PANIC("Stubbed Svc"#NAME"64From32 was called"); }                \
                };
        #endif


        /* Set omit-frame-pointer to prevent GCC from emitting MOV X29, SP instructions. */
        #pragma GCC push_options
        #pragma GCC optimize ("omit-frame-pointer")

            AMS_SVC_FOREACH_KERN_DEFINITION(DECLARE_SVC_STRUCT, _)

        #pragma GCC pop_options

        constexpr const std::array<SvcTableEntry, NumSupervisorCalls> SvcTable64From32Impl = [] {
            std::array<SvcTableEntry, NumSupervisorCalls> table = {};

            #define AMS_KERN_SVC_SET_TABLE_ENTRY(ID, RETURN_TYPE, NAME, ...) \
                if (table[ID] == nullptr) { table[ID] = NAME::Call64From32; }
            AMS_SVC_FOREACH_KERN_DEFINITION(AMS_KERN_SVC_SET_TABLE_ENTRY, _)
            #undef AMS_KERN_SVC_SET_TABLE_ENTRY

            return table;
        }();

        constexpr const std::array<SvcTableEntry, NumSupervisorCalls> SvcTable64Impl = [] {
            std::array<SvcTableEntry, NumSupervisorCalls> table = {};

            #define AMS_KERN_SVC_SET_TABLE_ENTRY(ID, RETURN_TYPE, NAME, ...) \
                if (table[ID] == nullptr) { table[ID] = NAME::Call64; }
            AMS_SVC_FOREACH_KERN_DEFINITION(AMS_KERN_SVC_SET_TABLE_ENTRY, _)
            #undef AMS_KERN_SVC_SET_TABLE_ENTRY

            return table;
        }();

        constexpr bool IsValidSvcTable(const std::array<SvcTableEntry, NumSupervisorCalls> &table) {
            for (size_t i = 0; i < NumSupervisorCalls; i++) {
                if (table[i] != nullptr) {
                    return true;
                }
            }

            return false;
        }

        static_assert(IsValidSvcTable(SvcTable64Impl));
        static_assert(IsValidSvcTable(SvcTable64From32Impl));

    }

    constinit const std::array<SvcTableEntry, NumSupervisorCalls> SvcTable64       = SvcTable64Impl;

    constinit const std::array<SvcTableEntry, NumSupervisorCalls> SvcTable64From32 = SvcTable64From32Impl;

    namespace {

        /* NOTE: Although the SVC tables are constants, our global constructor will run before .rodata is protected R--. */
        class SvcTablePatcher {
            private:
                using SvcTable = std::array<SvcTableEntry, NumSupervisorCalls>;
            private:
                static SvcTablePatcher s_instance;
            private:
                ALWAYS_INLINE volatile SvcTableEntry *GetEditableTable(const SvcTable *table) {
                    if (table != nullptr) {
                        return const_cast<volatile SvcTableEntry *>(table->data());
                    } else {
                        return nullptr;
                    }
                }

                /* TODO: This should perhaps be implemented in assembly. */
                NOINLINE void PatchTables(volatile SvcTableEntry *table_64, volatile SvcTableEntry *table_64_from_32) {
                    /* Get the target firmware. */
                    const auto target_fw = kern::GetTargetFirmware();

                    /* 10.0.0 broke the ABI for QueryIoMapping. */
                    if (target_fw < TargetFirmware_10_0_0) {
                        if (table_64)         { table_64[        svc::SvcId_QueryIoMapping] = LegacyQueryIoMapping::Call64; }
                        if (table_64_from_32) { table_64_from_32[svc::SvcId_QueryIoMapping] = LegacyQueryIoMapping::Call64From32; }
                    }

                    /* 3.0.0 broke the ABI for ContinueDebugEvent. */
                    if (target_fw < TargetFirmware_3_0_0) {
                        if (table_64)         { table_64[        svc::SvcId_ContinueDebugEvent] = LegacyContinueDebugEvent::Call64; }
                        if (table_64_from_32) { table_64_from_32[svc::SvcId_ContinueDebugEvent] = LegacyContinueDebugEvent::Call64From32; }
                    }
                }
            public:
                SvcTablePatcher(const SvcTable *table_64, const SvcTable *table_64_from_32) {
                    PatchTables(GetEditableTable(table_64), GetEditableTable(table_64_from_32));
                }
        };

        SvcTablePatcher SvcTablePatcher::s_instance(std::addressof(SvcTable64), std::addressof(SvcTable64From32));

    }

}