134 lines
4.0 KiB
C++
134 lines
4.0 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2014, 2015.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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x86/memorymanagement.cpp
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Handles memory for the x86 architecture.
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*******************************************************************************/
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#include <string.h>
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#include <sortix/kernel/kernel.h>
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#include <sortix/kernel/memorymanagement.h>
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#include <sortix/kernel/panic.h>
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#include "x86-family/memorymanagement.h"
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#include "multiboot.h"
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namespace Sortix {
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namespace Page {
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extern size_t stackused;
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extern size_t stacklength;
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void ExtendStack();
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} // namespace Page
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} // namespace Sortix
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namespace Sortix {
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namespace Memory {
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// Please note that even if this function exists, you should still clean
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// up the address space of a process _before_ calling
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// DestroyAddressSpace. This is just a hack because it currently is
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// impossible to clean up PLM1's using the MM api!
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// ---
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// TODO: This function is duplicated in {x86,x64}/memorymanagement.cpp!
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// ---
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void RecursiveFreeUserspacePages(size_t level, size_t offset)
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{
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PML* pml = PMLS[level] + offset;
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for ( size_t i = 0; i < ENTRIES; i++ )
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{
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addr_t entry = pml->entry[i];
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if ( !(entry & PML_PRESENT) )
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continue;
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if ( !(entry & PML_USERSPACE) )
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continue;
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if ( !(entry & PML_FORK) )
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continue;
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if ( 1 < level )
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RecursiveFreeUserspacePages(level-1, offset * ENTRIES + i);
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addr_t addr = pml->entry[i] & PML_ADDRESS;
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// No need to unmap the page, we just need to mark it as unused.
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Page::PutUnlocked(addr, PAGE_USAGE_PAGING_OVERHEAD);
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}
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}
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void DestroyAddressSpace(addr_t fallback)
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{
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// Look up the last few entries used for the fractal mapping. These
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// cannot be unmapped as that would destroy the world. Instead, we
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// will remember them, switch to another adress space, and safely
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// mark them as unused. Also handling the forking related pages.
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addr_t fractal1 = PMLS[2]->entry[1022];
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addr_t dir = GetAddressSpace();
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// We want to free the pages, but we are still using them ourselves,
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// so lock the page allocation structure until we are done.
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Page::Lock();
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// In case any pages wasn't cleaned at this point.
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// TODO: Page::Put calls may internally Page::Get and then reusing pages we are not done with just yet
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RecursiveFreeUserspacePages(TOPPMLLEVEL, 0);
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SwitchAddressSpace(fallback);
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// Ok, now we got marked everything left behind as unused, we can
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// now safely let another thread use the pages.
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Page::Unlock();
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// These are safe to free since we switched address space.
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Page::Put(fractal1 & PML_ADDRESS, PAGE_USAGE_PAGING_OVERHEAD);
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Page::Put(dir & PML_ADDRESS, PAGE_USAGE_PAGING_OVERHEAD);
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}
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const size_t KERNEL_STACK_SIZE = 256UL * 1024UL;
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const addr_t KERNEL_STACK_END = 0x80001000UL;
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const addr_t KERNEL_STACK_START = KERNEL_STACK_END + KERNEL_STACK_SIZE;
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const addr_t VIRTUAL_AREA_LOWER = KERNEL_STACK_START;
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const addr_t VIRTUAL_AREA_UPPER = 0xFF400000UL;
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void GetKernelVirtualArea(addr_t* from, size_t* size)
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{
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*from = KERNEL_STACK_END;
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*size = VIRTUAL_AREA_UPPER - VIRTUAL_AREA_LOWER;
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}
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void GetUserVirtualArea(uintptr_t* from, size_t* size)
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{
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*from = 0x400000; // 4 MiB.
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*size = 0x80000000 - *from; // 2 GiB - 4 MiB.
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}
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addr_t GetKernelStack()
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{
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return KERNEL_STACK_START;
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}
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size_t GetKernelStackSize()
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{
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return KERNEL_STACK_SIZE;
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}
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} // namespace Memory
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} // namespace Sortix
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