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sortix--sortix/kernel/x64/memorymanagement.cpp
2014-05-16 14:48:27 +02:00

218 lines
7 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2014.
This file is part of Sortix.
Sortix is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.
Sortix is distributed in the hope that 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
Sortix. If not, see <http://www.gnu.org/licenses/>.
x64/memorymanagement.cpp
Handles memory for the x64 architecture.
*******************************************************************************/
#include <string.h>
#include <sortix/kernel/interrupt.h>
#include <sortix/kernel/kernel.h>
#include <sortix/kernel/memorymanagement.h>
#include "multiboot.h"
#include "x86-family/memorymanagement.h"
namespace Sortix {
namespace Page {
extern size_t stackused;
extern size_t stacklength;
void ExtendStack();
} // namespace Page
} // namespace Sortix
namespace Sortix {
namespace Memory {
extern addr_t currentdir;
void InitCPU()
{
// The x64 boot code already set up virtual memory and identity
// mapped the first 2 MiB. This code finishes the job such that
// virtual memory is fully usable and manageable.
// boot.s already initialized everything from 0x21000UL to 0x2F000UL to
// zeroes. Since these structures are already used, doing it here would
// destroying the existing data.
PML* const BOOTPML4 = (PML* const) 0x21000UL;
PML* const BOOTPML3 = (PML* const) 0x26000UL;
PML* const BOOTPML2 = (PML* const) 0x27000UL;
PML* const BOOTPML1 = (PML* const) 0x28000UL;
// First order of business is to map the virtual memory structures
// to the pre-defined locations in the virtual address space.
addr_t flags = PML_PRESENT | PML_WRITABLE;
// Fractal map the PML1s.
BOOTPML4->entry[511] = (addr_t) BOOTPML4 | flags;
// Fractal map the PML2s.
BOOTPML4->entry[510] = (addr_t) BOOTPML3 | flags | PML_FORK;
BOOTPML3->entry[511] = (addr_t) BOOTPML4 | flags;
// Fractal map the PML3s.
BOOTPML3->entry[510] = (addr_t) BOOTPML2 | flags | PML_FORK;
BOOTPML2->entry[511] = (addr_t) BOOTPML4 | flags;
// Fractal map the PML4s.
BOOTPML2->entry[510] = (addr_t) BOOTPML1 | flags | PML_FORK;
BOOTPML1->entry[511] = (addr_t) BOOTPML4 | flags;
// Add some predefined room for forking address spaces.
PML* const FORKPML2 = (PML* const) 0x29000UL;
PML* const FORKPML1 = (PML* const) 0x2A000UL;
BOOTPML3->entry[0] = (addr_t) FORKPML2 | flags | PML_FORK;
FORKPML2->entry[0] = (addr_t) FORKPML1 | flags | PML_FORK;
currentdir = (addr_t) BOOTPML4;
// The virtual memory structures are now available on the predefined
// locations. This means the virtual memory code is bootstrapped. Of
// course, we still have no physical page allocator, so that's the
// next step.
PML* const PHYSPML3 = (PML* const) 0x2B000UL;
PML* const PHYSPML2 = (PML* const) 0x2C000UL;
PML* const PHYSPML1 = (PML* const) 0x2D000UL;
PML* const PHYSPML0 = (PML* const) 0x2E000UL;
BOOTPML4->entry[509] = (addr_t) PHYSPML3 | flags;
PHYSPML3->entry[0] = (addr_t) PHYSPML2 | flags;
PHYSPML2->entry[0] = (addr_t) PHYSPML1 | flags;
PHYSPML1->entry[0] = (addr_t) PHYSPML0 | flags;
Page::stackused = 0;
Page::stacklength = 4096UL / sizeof(addr_t);
// The physical memory allocator should now be ready for use. Next
// up, the calling function will fill up the physical allocator with
// plenty of nice physical pages. (see Page::InitPushRegion)
}
// Please note that even if this function exists, you should still clean
// up the address space of a process _before_ calling
// DestroyAddressSpace. This is just a hack because it currently is
// impossible to clean up PLM1's using the MM api!
// ---
// TODO: This function is duplicated in {x86,x64}/memorymanagement.cpp!
// ---
void RecursiveFreeUserspacePages(size_t level, size_t offset)
{
PML* pml = PMLS[level] + offset;
for ( size_t i = 0; i < ENTRIES; i++ )
{
addr_t entry = pml->entry[i];
if ( !(entry & PML_PRESENT) )
continue;
if ( !(entry & PML_USERSPACE) )
continue;
if ( !(entry & PML_FORK) )
continue;
if ( 1 < level )
RecursiveFreeUserspacePages(level-1, offset * ENTRIES + i);
addr_t addr = pml->entry[i] & PML_ADDRESS;
// No need to unmap the page, we just need to mark it as unused.
Page::PutUnlocked(addr);
}
}
void DestroyAddressSpace(addr_t fallback, void (*func)(addr_t, void*), void* user)
{
// Look up the last few entries used for the fractal mapping. These
// cannot be unmapped as that would destroy the world. Instead, we
// will remember them, switch to another adress space, and safely
// mark them as unused. Also handling the forking related pages.
addr_t fractal3 = (PMLS[4] + 0)->entry[510UL];
addr_t fork2 = (PMLS[3] + 510UL)->entry[0];
addr_t fractal2 = (PMLS[3] + 510UL)->entry[510];
addr_t fork1 = (PMLS[2] + 510UL * 512UL + 0)->entry[0];
addr_t fractal1 = (PMLS[2] + 510UL * 512UL + 510UL)->entry[510];
addr_t dir = currentdir;
// We want to free the pages, but we are still using them ourselves,
// so lock the page allocation structure until we are done.
Page::Lock();
// In case any pages wasn't cleaned at this point.
// TODO: Page::Put calls may internally Page::Get and then reusing pages we are not done with just yet
RecursiveFreeUserspacePages(TOPPMLLEVEL, 0);
// Switch to the address space from when the world was originally
// created. It should contain the kernel, the whole kernel, and
// nothing but the kernel.
PML* const BOOTPML4 = (PML* const) 0x21000UL;
if ( !fallback )
fallback = (addr_t) BOOTPML4;
if ( func )
func(fallback, user);
else
SwitchAddressSpace(fallback);
// Ok, now we got marked everything left behind as unused, we can
// now safely let another thread use the pages.
Page::Unlock();
// These are safe to free since we switched address space.
Page::Put(fractal3 & PML_ADDRESS);
Page::Put(fractal2 & PML_ADDRESS);
Page::Put(fractal1 & PML_ADDRESS);
Page::Put(fork2 & PML_ADDRESS);
Page::Put(fork1 & PML_ADDRESS);
Page::Put(dir & PML_ADDRESS);
}
const size_t KERNEL_STACK_SIZE = 256UL * 1024UL;
const addr_t KERNEL_STACK_END = 0xFFFF800000001000UL;
const addr_t KERNEL_STACK_START = KERNEL_STACK_END + KERNEL_STACK_SIZE;
const addr_t VIRTUAL_AREA_LOWER = KERNEL_STACK_START;
const addr_t VIRTUAL_AREA_UPPER = 0xFFFFFE8000000000UL;
void GetKernelVirtualArea(addr_t* from, size_t* size)
{
*from = KERNEL_STACK_END;
*size = VIRTUAL_AREA_UPPER - VIRTUAL_AREA_LOWER;
}
void GetUserVirtualArea(uintptr_t* from, size_t* size)
{
*from = 0x400000; // 4 MiB.
*size = 0x800000000000 - *from; // 128 TiB - 4 MiB.
}
addr_t GetKernelStack()
{
return KERNEL_STACK_START;
}
size_t GetKernelStackSize()
{
return KERNEL_STACK_SIZE;
}
} // namespace Memory
} // namespace Sortix