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Kernel/riscv64: Don't use the memory before .text as the initial stack

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This new stack has the same size as the x86_64 prekernel stack (32K).
This commit is contained in:
Sönke Holz 2024-02-15 21:12:06 +01:00 • committed by Jelle Raaijmakers
parent 3b6a300ed7
commit 227818de9b
3 changed files with 8 additions and 10 deletions
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8
Kernel/Arch/riscv64/MMU.cpp
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@ -150,20 +150,12 @@ static UNMAP_AFTER_INIT void build_mappings(PageBumpAllocator& allocator, u64* r
auto start_of_kernel_range = VirtualAddress { bit_cast<FlatPtr>(+start_of_kernel_image) };
auto end_of_kernel_range = VirtualAddress { bit_cast<FlatPtr>(+end_of_kernel_image) };
// FIXME: don't use the memory before `start` as the stack
auto start_of_stack_range = VirtualAddress { bit_cast<FlatPtr>(+start_of_kernel_image) }.offset(-64 * KiB);
auto end_of_stack_range = VirtualAddress { bit_cast<FlatPtr>(+start_of_kernel_image) };
auto start_of_physical_kernel_range = PhysicalAddress { start_of_kernel_range.get() }.offset(-calculate_physical_to_link_time_address_offset());
auto start_of_physical_stack_range = PhysicalAddress { start_of_stack_range.get() }.offset(-calculate_physical_to_link_time_address_offset());
// FIXME: dont map everything RWX
// Map kernel into high virtual memory
insert_entries_for_memory_range(allocator, root_table, start_of_kernel_range, end_of_kernel_range, start_of_physical_kernel_range, PageTableEntryBits::Readable | PageTableEntryBits::Writeable | PageTableEntryBits::Executable);
// Map the stack
insert_entries_for_memory_range(allocator, root_table, start_of_stack_range, end_of_stack_range, start_of_physical_stack_range, PageTableEntryBits::Readable | PageTableEntryBits::Writeable);
}
static UNMAP_AFTER_INIT void setup_kernel_page_directory(u64* root_table)

4
Kernel/Arch/riscv64/boot.S
View file

@ -35,8 +35,8 @@ Lclear_bss_loop:
bltu t0, t1, Lclear_bss_loop
Lclear_bss_done:
// Let the stack start before .text for now.
lla sp, start
// Set the stack pointer register to the location defined in the linker script.
lla sp, end_of_initial_stack
// Zero all registers except sp, a0 and a1.
li ra, 0

6
Kernel/Arch/riscv64/linker.ld
View file

@ -98,6 +98,12 @@ SECTIONS
*(.heap)
} :bss
. = ALIGN(4K);
start_of_initial_stack = .;
. += 32K;
end_of_initial_stack = .;
/*
FIXME: 8MB is enough space for all of the tables required to identity map
physical memory. 8M is wasteful, so this should be properly calculated.