Kernel+Userland: Remove loadable kernel moduless

These interfaces are broken for about 9 months, maybe longer than that.
At this point, this is just a dead code nobody tests or tries to use, so
let's remove it instead of keeping a stale code just for the sake of
keeping it and hoping someone will fix it.

To better justify this, I read that OpenBSD removed loadable kernel
modules in 5.7 release (2014), mainly for the same reason we do -
nobody used it so they had no good reason to maintain it.
Still, OpenBSD had LKMs being effectively working, which is not the
current state in our project for a long time.
An arguably better approach to minimize the Kernel image size is to
allow dropping drivers and features while compiling a new image.

1 files changed, 0 insertions, 168 deletions

diff --git a/Kernel/Syscalls/module.cpp b/Kernel/Syscalls/module.cpp
deleted file mode 100644
index 538c6846d8..0000000000
--- a/Kernel/Syscalls/module.cpp
+++ /dev/null
@@ -1,168 +0,0 @@
-/*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#include <Kernel/FileSystem/OpenFileDescription.h>
-#include <Kernel/FileSystem/VirtualFileSystem.h>
-#include <Kernel/KSyms.h>
-#include <Kernel/Module.h>
-#include <Kernel/Process.h>
-#include <LibELF/Image.h>
-
-namespace Kernel {
-
-extern HashMap<String, OwnPtr<Module>>* g_modules;
-
-KResultOr<FlatPtr> Process::sys$module_load(Userspace<const char*> user_path, size_t path_length)
-{
-    VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
-    if (!is_superuser())
-        return EPERM;
-
-    REQUIRE_NO_PROMISES;
-
-    auto path = TRY(get_syscall_path_argument(user_path, path_length));
-    auto description = TRY(VirtualFileSystem::the().open(path->view(), O_RDONLY, 0, current_directory()));
-    auto payload = TRY(description->read_entire_file());
-
-    auto storage = TRY(KBuffer::try_create_with_bytes(payload->bytes()));
-
-    auto elf_image = try_make<ELF::Image>(storage->data(), storage->size());
-    if (!elf_image)
-        return ENOMEM;
-    if (!elf_image->parse())
-        return ENOEXEC;
-
-    HashMap<String, u8*> section_storage_by_name;
-
-    auto module = try_make<Module>();
-    if (!module)
-        return ENOMEM;
-
-    KResult section_loading_result = KSuccess;
-    elf_image->for_each_section_of_type(SHT_PROGBITS, [&](const ELF::Image::Section& section) {
-        if (!section.size() || !section_loading_result.is_error())
-            return;
-        auto section_storage_or_error = KBuffer::try_create_with_bytes(ReadonlyBytes { section.raw_data(), section.size() }, Memory::Region::Access::ReadWriteExecute);
-        if (section_storage_or_error.is_error()) {
-            section_loading_result = section_storage_or_error.error();
-            return;
-        }
-        auto section_storage = section_storage_or_error.release_value();
-        section_storage_by_name.set(section.name(), section_storage->data());
-        module->sections.append(move(section_storage));
-    });
-    if (section_loading_result.is_error())
-        return section_loading_result;
-
-    bool missing_symbols = false;
-
-    elf_image->for_each_section_of_type(SHT_PROGBITS, [&](const ELF::Image::Section& section) {
-        if (!section.size())
-            return;
-
-        auto* section_storage = section_storage_by_name.get(section.name()).value_or(nullptr);
-        VERIFY(section_storage);
-        auto relocations = section.relocations();
-        VERIFY(relocations.has_value());
-        relocations->for_each_relocation([&](const ELF::Image::Relocation& relocation) {
-            auto& patch_ptr = *reinterpret_cast<ptrdiff_t*>(section_storage + relocation.offset());
-            switch (relocation.type()) {
-            case R_386_PC32: {
-                // PC-relative relocation
-                dbgln("PC-relative relocation: {}", relocation.symbol().name());
-                auto symbol_address = address_for_kernel_symbol(relocation.symbol().name());
-                if (symbol_address == 0)
-                    missing_symbols = true;
-                dbgln("   Symbol address: {:p}", symbol_address);
-                ptrdiff_t relative_offset = (FlatPtr)symbol_address - ((FlatPtr)&patch_ptr + 4);
-                patch_ptr = relative_offset;
-                break;
-            }
-            case R_386_32: // Absolute relocation
-                dbgln("Absolute relocation: '{}' value={}, index={}", relocation.symbol().name(), relocation.symbol().value(), relocation.symbol_index());
-
-                if (relocation.symbol().bind() == STB_LOCAL) {
-                    auto* section_storage_containing_symbol = section_storage_by_name.get(relocation.symbol().section().name()).value_or(nullptr);
-                    VERIFY(section_storage_containing_symbol);
-                    u32 symbol_address = (ptrdiff_t)(section_storage_containing_symbol + relocation.symbol().value());
-                    if (symbol_address == 0)
-                        missing_symbols = true;
-                    dbgln("   Symbol address: {:p}", symbol_address);
-                    patch_ptr += symbol_address;
-                } else if (relocation.symbol().bind() == STB_GLOBAL) {
-                    u32 symbol_address = address_for_kernel_symbol(relocation.symbol().name());
-                    if (symbol_address == 0)
-                        missing_symbols = true;
-                    dbgln("   Symbol address: {:p}", symbol_address);
-                    patch_ptr += symbol_address;
-                } else {
-                    VERIFY_NOT_REACHED();
-                }
-                break;
-            }
-        });
-    });
-
-    if (missing_symbols)
-        return EINVAL;
-
-    auto* text_base = section_storage_by_name.get(".text").value_or(nullptr);
-    if (!text_base) {
-        dbgln("No .text section found in module!");
-        return EINVAL;
-    }
-
-    elf_image->for_each_symbol([&](const ELF::Image::Symbol& symbol) {
-        dbgln(" - {} '{}' @ {:p}, size={}", symbol.type(), symbol.name(), symbol.value(), symbol.size());
-        if (symbol.name() == "module_init") {
-            module->module_init = (ModuleInitPtr)(text_base + symbol.value());
-        } else if (symbol.name() == "module_fini") {
-            module->module_fini = (ModuleFiniPtr)(text_base + symbol.value());
-        } else if (symbol.name() == "module_name") {
-            const u8* storage = section_storage_by_name.get(symbol.section().name()).value_or(nullptr);
-            if (storage)
-                module->name = String((const char*)(storage + symbol.value()));
-        }
-    });
-
-    if (!module->module_init)
-        return EINVAL;
-
-    if (g_modules->contains(module->name)) {
-        dbgln("a module with the name {} is already loaded; please unload it first", module->name);
-        return EEXIST;
-    }
-
-    module->module_init();
-
-    auto name = module->name;
-    g_modules->set(name, move(module));
-
-    return 0;
-}
-
-KResultOr<FlatPtr> Process::sys$module_unload(Userspace<const char*> user_name, size_t name_length)
-{
-    VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
-    if (!is_superuser())
-        return EPERM;
-
-    REQUIRE_NO_PROMISES;
-
-    auto module_name = TRY(try_copy_kstring_from_user(user_name, name_length));
-
-    auto it = g_modules->find(module_name->view());
-    if (it == g_modules->end())
-        return ENOENT;
-
-    if (it->value->module_fini)
-        it->value->module_fini();
-
-    g_modules->remove(it);
-    return 0;
-}
-
-}