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https://github.com/RGBCube/serenity
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da33e2a564
We initialize the MMU by first setting up the page tables for the kernel image and the initial kernel stack. Then we jump to a identity mapped page which makes the newly created kernel root page table active by setting `satp` and then jumps to `init`.
57 lines
1.6 KiB
C++
57 lines
1.6 KiB
C++
/*
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* Copyright (c) 2023, Sönke Holz <sholz8530@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Arch/riscv64/pre_init.h>
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#include <Kernel/Arch/Processor.h>
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#include <Kernel/Arch/riscv64/MMU.h>
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#include <Kernel/Arch/riscv64/SBI.h>
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#include <Kernel/Sections.h>
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namespace Kernel {
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UNMAP_AFTER_INIT void dbgln_without_mmu(StringView message)
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{
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auto probe_result = SBI::Base::probe_extension(SBI::EID::DebugConsole);
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if (probe_result.is_error() || probe_result.value() == 0) {
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for (auto const ch : message.bytes())
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(void)SBI::Legacy::console_putchar(ch);
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(void)SBI::Legacy::console_putchar('\n');
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} else {
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for (auto const ch : message.bytes())
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(void)SBI::DBCN::debug_console_write_byte(ch);
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(void)SBI::DBCN::debug_console_write_byte('\n');
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}
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}
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[[noreturn]] UNMAP_AFTER_INIT void panic_without_mmu(StringView message)
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{
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dbgln_without_mmu("KERNEL PANIC in pre_init :^("sv);
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dbgln_without_mmu(message);
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// We can't use Processor::halt() here, as that would result in an absolute jump.
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RISCV64::CSR::write(RISCV64::CSR::Address::SIE, 0);
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for (;;)
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asm volatile("wfi");
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}
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[[gnu::aligned(4)]] [[noreturn]] UNMAP_AFTER_INIT static void early_trap_handler()
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{
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panic_without_mmu("Unexpected trap"sv);
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}
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extern "C" [[noreturn]] UNMAP_AFTER_INIT void pre_init(FlatPtr mhartid, PhysicalPtr fdt_phys_addr)
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{
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(void)mhartid;
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(void)fdt_phys_addr;
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// Catch traps in pre_init
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RISCV64::CSR::write(RISCV64::CSR::Address::STVEC, bit_cast<FlatPtr>(&early_trap_handler));
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Memory::init_page_tables_and_jump_to_init();
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}
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}
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