b0df5186e6
1) The PML2 was not initialized to zeroes, thus leaving some bits behind that caused the fork code to go crazy, forking the unforkable, and mapping addresses that never, ever, should have been mapped, leaving behind a trail of page faults and general protection faults on some computers, while other computers worked because the uninitalized memory just wasn't uninitialized enough. Yep, this was a schrödinbug! 2) Fixed a time bomb. The kernel heap was accidentally put such that whenever a few megabytes were allocated, it would begin overwriting the physical page stack causing unthinkable events to unfold and would probably be even more obscure to debug than 1). Oh, and some string errors fixed and removed RunApplication from kernel.cpp, funny thing that even linked in the first place. Guess, the optimizer actually did work for once. :)
105 lines
3.2 KiB
C++
105 lines
3.2 KiB
C++
/******************************************************************************
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COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
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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
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with Sortix. If not, see <http://www.gnu.org/licenses/>.
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memorymanagement.cpp
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Handles memory for the x86 architecture.
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******************************************************************************/
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#include "platform.h"
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#include <libmaxsi/memory.h>
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#include "multiboot.h"
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#include "panic.h"
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#include "../memorymanagement.h"
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#include "x86-family/memorymanagement.h"
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namespace Sortix
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{
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namespace Page
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{
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extern size_t stackused;
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extern size_t stacklength;
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}
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namespace Memory
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{
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extern addr_t currentdir;
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void InitCPU()
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{
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PML* const BOOTPML2 = (PML* const) 0x01000UL;
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PML* const BOOTPML1 = (PML* const) 0x02000UL;
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PML* const FORKPML1 = (PML* const) 0x03000UL;
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PML* const IDENPML1 = (PML* const) 0x04000UL;
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// Initialize the memory structures with zeroes.
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Maxsi::Memory::Set((PML* const) 0x01000UL, 0, 0x6000UL);
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// Identity map the first 4 MiB.
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addr_t flags = PML_PRESENT | PML_WRITABLE;
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BOOTPML2->entry[0] = ((addr_t) IDENPML1) | flags;
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for ( size_t i = 0; i < ENTRIES; i++ )
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{
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IDENPML1->entry[i] = (i * 4096UL) | flags;
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}
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// Next order of business is to map the virtual memory structures
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// to the pre-defined locations in the virtual address space.
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// Fractal map the PML1s.
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BOOTPML2->entry[1023] = (addr_t) BOOTPML2 | flags;
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// Fractal map the PML2s.
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BOOTPML2->entry[1022] = (addr_t) BOOTPML1 | flags | PML_FORK;
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BOOTPML1->entry[1023] = (addr_t) BOOTPML2 | flags;
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// Add some predefined room for forking address spaces.
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BOOTPML1->entry[0] = (addr_t) FORKPML1 | flags | PML_FORK;
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// The virtual memory structures are now available on the predefined
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// locations. This means the virtual memory code is bootstrapped. Of
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// course, we still have no physical page allocator, so that's the
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// next step.
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PML* const PHYSPML1 = (PML* const) 0x05000UL;
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PML* const PHYSPML0 = (PML* const) 0x06000UL;
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BOOTPML2->entry[1021] = (addr_t) PHYSPML1 | flags;
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PHYSPML1->entry[0] = (addr_t) PHYSPML0 | flags;
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// Alright, enable virtual memory!
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SwitchAddressSpace((addr_t) BOOTPML2);
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size_t cr0;
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asm volatile("mov %%cr0, %0": "=r"(cr0));
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cr0 |= 0x80000000UL; /* Enable paging! */
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asm volatile("mov %0, %%cr0":: "r"(cr0));
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Page::stackused = 0;
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Page::stacklength = 4096UL / sizeof(addr_t);
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// The physical memory allocator should now be ready for use. Next
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// up, the calling function will fill up the physical allocator with
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// plenty of nice physical pages. (see Page::InitPushRegion)
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}
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}
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}
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