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9d4bc2a15f
Previously the kernel heap grew downwards for historical reasons. There is no reason for this and it simplifies the heap implementation if it only grows upwards. This also rearranges how the kernel virtual memory is allocated to suit an upwards-growing heap.
124 lines
3.5 KiB
C++
124 lines
3.5 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2013.
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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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addralloc.cpp
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Class to keep track of mount points.
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*******************************************************************************/
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#include <assert.h>
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#include <errno.h>
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#include <stddef.h>
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#include <sortix/kernel/platform.h>
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#include <sortix/kernel/addralloc.h>
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#include <sortix/kernel/kthread.h>
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#include <sortix/kernel/memorymanagement.h>
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namespace Sortix {
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size_t aux_allocated = 0;
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size_t heap_allocated = 0;
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kthread_mutex_t alloc_lock = KTHREAD_MUTEX_INITIALIZER;
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// TODO: Kernel address space is allocated simply by increasing the pointer,
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// with no support for freeing it. This is not that big a problem at this point,
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// since address space is consumed at boot and then used forever. When it
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// becomes normal for devices to come and go, just recode these functions and
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// everyone should do the right thing.
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bool AllocateKernelAddress(addralloc_t* ret, size_t size)
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{
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size = Page::AlignUp(size);
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ScopedLock lock(&alloc_lock);
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addr_t kmem_from;
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size_t kmem_size;
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Memory::GetKernelVirtualArea(&kmem_from, &kmem_size);
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addr_t aux_reached = kmem_from + kmem_size - aux_allocated;
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size_t heap_reached = kmem_from + heap_allocated;
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size_t unused_left = aux_reached - heap_reached;
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if ( unused_left < size )
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return errno = ENOMEM, false;
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aux_allocated += size;
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ret->from = kmem_from + kmem_size - aux_allocated;
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ret->size = size;
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return true;
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}
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void FreeKernelAddress(addralloc_t* alloc)
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{
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if ( !alloc->from )
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return;
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// Currently, nothing to do here.
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alloc->from = 0;
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alloc->size = 0;
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}
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size_t ExpandHeap(size_t increase)
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{
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increase = Page::AlignUp(increase);
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ScopedLock lock(&alloc_lock);
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addr_t kmem_from;
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size_t kmem_size;
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Memory::GetKernelVirtualArea(&kmem_from, &kmem_size);
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addr_t aux_reached = kmem_from + kmem_size - aux_allocated;
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size_t heap_reached = kmem_from + heap_allocated;
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size_t unused_left = aux_reached - heap_reached;
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if ( unused_left < increase )
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return errno = ENOMEM, 0;
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heap_allocated += increase;
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return increase;
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}
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void ShrinkHeap(size_t decrease)
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{
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assert(decrease == Page::AlignUp(decrease));
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ScopedLock lock(&alloc_lock);
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assert(decrease <= heap_allocated);
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heap_allocated -= decrease;
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}
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// No need for locks in these three functions, since only the heap calls these
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// and it already uses an internal lock, and heap_allocated will not change
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// unless the heap calls ExpandHeap.
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addr_t GetHeapLower()
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{
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addr_t kmem_from;
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size_t kmem_size;
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Memory::GetKernelVirtualArea(&kmem_from, &kmem_size);
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(void) kmem_size;
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return kmem_from;
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}
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addr_t GetHeapUpper()
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{
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addr_t kmem_from;
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size_t kmem_size;
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Memory::GetKernelVirtualArea(&kmem_from, &kmem_size);
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(void) kmem_size;
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return kmem_from + heap_allocated;
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}
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size_t GetHeapSize()
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{
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return heap_allocated;
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}
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} // namespace Sortix
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