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Kernel: Add fast page to page table

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Add "fast page" to KERNEL_OFFSET. This is always present in page
tables and only requires changing the page table entry to map. This
requires no interrupts since it should only be for very operations
like memcpy.

I used to map all temporary mappings to vaddr 0, but this is much
better. C++ standard always says that nullptr access is undefined
and this gets rid of it.

Fixed some bugs I found along the way
This commit is contained in:
Bananymous
2023-10-30 19:02:09 +02:00
parent 6e676ee8c5
commit 42772611ce
9 changed files with 193 additions and 134 deletions
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10
LibELF/LibELF/LoadableELF.cpp
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@@ -1,4 +1,5 @@
#include <BAN/ScopeGuard.h>
#include <kernel/CriticalScope.h>
#include <kernel/Memory/Heap.h>
#include <kernel/LockGuard.h>
#include <LibELF/LoadableELF.h>
@@ -306,9 +307,12 @@ namespace LibELF
if (paddr == 0)
return BAN::Error::from_errno(ENOMEM);
m_page_table.map_page_at(paddr, 0, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
memcpy((void*)0, (void*)(start + i * PAGE_SIZE), PAGE_SIZE);
m_page_table.unmap_page(0);
{
CriticalScope _;
PageTable::map_fast_page(paddr);
memcpy(PageTable::fast_page_as_ptr(), (void*)(start + i * PAGE_SIZE), PAGE_SIZE);
PageTable::unmap_fast_page();
}
new_page_table.map_page_at(paddr, start + i * PAGE_SIZE, flags);
elf->m_physical_page_count++;