It is now permission-oriented, not just user/kernel oriented. Added <sys/mman.h> with nice PROT_{READ,WRITE,EXEC,FORK} constants.
707 lines
19 KiB
C++
707 lines
19 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
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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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memorymanagement.cpp
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Handles memory for the x86 family of architectures.
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*******************************************************************************/
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#include <sortix/kernel/platform.h>
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#include <libmaxsi/error.h>
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#include <libmaxsi/memory.h>
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#include "multiboot.h"
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#include <sortix/kernel/panic.h>
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#include <sortix/mman.h>
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#include <sortix/kernel/memorymanagement.h>
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#include "memorymanagement.h"
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#include "syscall.h"
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#include "msr.h"
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using namespace Maxsi;
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namespace Sortix
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{
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extern size_t end;
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namespace Page
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{
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void InitPushRegion(addr_t position, size_t length);
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size_t pagesnotonstack;
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size_t stackused;
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size_t stackreserved;
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size_t stacklength;
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size_t totalmem;
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}
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namespace Memory
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{
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addr_t currentdir;
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void InitCPU();
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void AllocateKernelPMLs();
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int SysMemStat(size_t* memused, size_t* memtotal);
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addr_t PAT2PMLFlags[PAT_NUM];
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void InitCPU(multiboot_info_t* bootinfo)
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{
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const size_t MAXKERNELEND = 0x400000UL; /* 4 MiB */
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addr_t kernelend = Page::AlignUp((addr_t) &end);
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if ( MAXKERNELEND < kernelend )
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{
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Log::PrintF("Warning: The kernel is too big! It ends at 0x%zx, "
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"but the highest ending address supported is 0x%zx. "
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"The system may not boot correctly.\n", kernelend,
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MAXKERNELEND);
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}
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Page::stackreserved = 0;
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Page::pagesnotonstack = 0;
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Page::totalmem = 0;
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if ( !( bootinfo->flags & MULTIBOOT_INFO_MEM_MAP ) )
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{
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Panic("memorymanagement.cpp: The memory map flag was't set in "
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"the multiboot structure. Are your bootloader multiboot "
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"specification compliant?");
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}
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// If supported, setup the Page Attribute Table feature that allows
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// us to control the memory type (caching) of memory more precisely.
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if ( MSR::IsPATSupported() )
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{
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MSR::InitializePAT();
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for ( addr_t i = 0; i < PAT_NUM; i++ )
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PAT2PMLFlags[i] = EncodePATAsPMLFlag(i);
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}
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// Otherwise, reroute all requests to the backwards compatible
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// scheme. TODO: Not all early 32-bit x86 CPUs supports these
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// values, so we need yet another fallback.
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else
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{
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PAT2PMLFlags[PAT_UC] = PML_WRTHROUGH | PML_NOCACHE;
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PAT2PMLFlags[PAT_WC] = PML_WRTHROUGH | PML_NOCACHE; // Approx.
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PAT2PMLFlags[2] = 0; // No such flag.
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PAT2PMLFlags[3] = 0; // No such flag.
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PAT2PMLFlags[PAT_WT] = PML_WRTHROUGH;
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PAT2PMLFlags[PAT_WP] = PML_WRTHROUGH; // Approx.
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PAT2PMLFlags[PAT_WB] = 0;
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PAT2PMLFlags[PAT_UCM] = PML_NOCACHE;
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}
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// Initialize CPU-specific things.
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InitCPU();
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typedef const multiboot_memory_map_t* mmap_t;
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// Loop over every detected memory region.
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for (
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mmap_t mmap = (mmap_t) (addr_t) bootinfo->mmap_addr;
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(addr_t) mmap < bootinfo->mmap_addr + bootinfo->mmap_length;
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mmap = (mmap_t) ((addr_t) mmap + mmap->size + sizeof(mmap->size))
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)
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{
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// Check that we can use this kind of RAM.
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if ( mmap->type != 1 ) { continue; }
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// The kernel's code may split this memory area into multiple pieces.
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addr_t base = (addr_t) mmap->addr;
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size_t length = Page::AlignDown(mmap->len);
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#ifdef PLATFORM_X86
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// Figure out if the memory area is addressable (are our pointers big enough?)
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if ( 0xFFFFFFFFULL < mmap->addr ) { continue; }
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if ( 0xFFFFFFFFULL < mmap->addr + mmap->len ) { length = 0x100000000ULL - mmap->addr; }
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#endif
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// Count the amount of usable RAM (even if reserved for kernel).
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Page::totalmem += length;
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// Give all the physical memory to the physical memory allocator
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// but make sure not to give it things we already use.
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addr_t regionstart = mmap->addr;
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addr_t regionend = mmap->addr + mmap->len;
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addr_t processed = regionstart;
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while ( processed < regionend )
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{
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addr_t lowest = processed;
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addr_t highest = regionend;
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// Don't allocate the kernel.
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if ( lowest < kernelend ) { processed = kernelend; continue; }
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// Don't give any of our modules to the physical page
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// allocator, we'll need them.
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bool continuing = false;
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uint32_t* modules = (uint32_t*) (addr_t) bootinfo->mods_addr;
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for ( uint32_t i = 0; i < bootinfo->mods_count; i++ )
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{
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size_t modsize = (size_t) (modules[2*i+1] - modules[2*i+0]);
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addr_t modstart = (addr_t) modules[2*i+0];
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addr_t modend = modstart + modsize;
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if ( modstart <= processed && processed < modend )
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{
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processed = modend;
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continuing = true;
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break;
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}
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if ( lowest <= modstart && modstart < highest )
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{
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highest = modstart;
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}
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}
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if ( continuing ) { continue; }
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if ( highest <= lowest ) { break; }
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// Now that we have a continious area not used by anything,
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// let's forward it to the physical page allocator.
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lowest = Page::AlignUp(lowest);
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highest = Page::AlignUp(highest);
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size_t size = highest - lowest;
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Page::InitPushRegion(lowest, size);
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processed = highest;
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}
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}
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// If the physical allocator couldn't handle the vast amount of
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// physical pages, it may decide to drop some. This shouldn't happen
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// until the pebibyte era of RAM.
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if ( 0 < Page::pagesnotonstack )
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{
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Log::PrintF("%zu bytes of RAM aren't used due to technical "
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"restrictions.\n", Page::pagesnotonstack * 0x1000UL);
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}
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// Finish allocating the top level PMLs for the kernels use.
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AllocateKernelPMLs();
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}
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void Statistics(size_t* amountused, size_t* totalmem)
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{
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size_t memfree = (Page::stackused - Page::stackreserved) << 12UL;
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size_t memused = Page::totalmem - memfree;
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if ( amountused ) { *amountused = memused; }
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if ( totalmem ) { *totalmem = Page::totalmem; }
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}
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// Prepare the non-forkable kernel PMLs such that forking the kernel
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// address space will always keep the kernel mapped.
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void AllocateKernelPMLs()
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{
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const addr_t flags = PML_PRESENT | PML_WRITABLE;
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PML* const pml = PMLS[TOPPMLLEVEL];
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size_t start = ENTRIES / 2;
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size_t end = ENTRIES;
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for ( size_t i = start; i < end; i++ )
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{
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if ( pml->entry[i] & PML_PRESENT ) { continue; }
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addr_t page = Page::Get();
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if ( !page ) { Panic("out of memory allocating boot PMLs"); }
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pml->entry[i] = page | flags;
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// Invalidate the new PML and reset it to zeroes.
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addr_t pmladdr = (addr_t) (PMLS[TOPPMLLEVEL-1] + i);
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InvalidatePage(pmladdr);
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Maxsi::Memory::Set((void*) pmladdr, 0, sizeof(PML));
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}
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}
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}
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namespace Page
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{
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void ExtendStack()
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{
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// This call will always succeed, if it didn't, then the stack
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// wouldn't be full, and thus this function won't be called.
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addr_t page = Get();
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// This call will also succeed, since there are plenty of physical
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// pages available and it might need some.
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addr_t virt = (addr_t) (STACK + stacklength);
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if ( !Memory::Map(page, virt, PROT_KREAD | PROT_KWRITE) )
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{
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Panic("Unable to extend page stack, which should have worked");
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}
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// TODO: This may not be needed during the boot process!
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//Memory::InvalidatePage((addr_t) (STACK + stacklength));
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stacklength += 4096UL / sizeof(addr_t);
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}
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void InitPushRegion(addr_t position, size_t length)
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{
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// Align our entries on page boundaries.
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addr_t newposition = Page::AlignUp(position);
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length = Page::AlignDown((position + length) - newposition);
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position = newposition;
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while ( length )
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{
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if ( unlikely(stackused == stacklength) )
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{
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if ( stackused == MAXSTACKLENGTH )
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{
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pagesnotonstack += length / 4096UL;
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return;
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}
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ExtendStack();
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}
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addr_t* stackentry = &(STACK[stackused++]);
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*stackentry = position;
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length -= 4096UL;
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position += 4096UL;
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}
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}
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bool Reserve(size_t* counter, size_t least, size_t ideal)
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{
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ASSERT(least < ideal);
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size_t available = stackused - stackreserved;
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if ( least < available ) { Error::Set(ENOMEM); return false; }
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if ( available < ideal ) { ideal = available; }
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stackreserved += ideal;
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*counter += ideal;
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return true;
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}
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bool Reserve(size_t* counter, size_t amount)
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{
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return Reserve(counter, amount, amount);
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}
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addr_t GetReserved(size_t* counter)
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{
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if ( !*counter ) { return false; }
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ASSERT(stackused); // After all, we did _reserve_ the memory.
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addr_t result = STACK[--stackused];
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ASSERT(result == AlignDown(result));
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stackreserved--;
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(*counter)--;
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return result;
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}
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addr_t Get()
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{
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ASSERT(stackreserved <= stackused);
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if ( unlikely(stackreserved == stackused) )
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{
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Error::Set(ENOMEM);
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return 0;
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}
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addr_t result = STACK[--stackused];
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ASSERT(result == AlignDown(result));
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return result;
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}
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void Put(addr_t page)
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{
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ASSERT(page == AlignDown(page));
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ASSERT(stackused < MAXSTACKLENGTH);
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STACK[stackused++] = page;
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}
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}
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namespace Memory
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{
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addr_t ProtectionToPMLFlags(int prot)
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{
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addr_t result = 0;
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if ( prot & PROT_EXEC ) { result |= PML_USERSPACE; }
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if ( prot & PROT_READ ) { result |= PML_USERSPACE; }
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if ( prot & PROT_WRITE ) { result |= PML_USERSPACE | PML_WRITABLE; }
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if ( prot & PROT_KEXEC ) { result |= 0; }
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if ( prot & PROT_KREAD ) { result |= 0; }
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if ( prot & PROT_KWRITE ) { result |= PML_WRITABLE; }
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if ( prot & PROT_FORK ) { result |= PML_FORK; }
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return result;
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}
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int PMLFlagsToProtection(addr_t flags)
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{
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int prot = PROT_KREAD | PROT_KEXEC;
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bool user = flags & PML_USERSPACE;
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bool write = flags & PML_WRITABLE;
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if ( user ) { prot |= PROT_EXEC | PROT_READ; }
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if ( user && write ) { prot |= PROT_WRITE; }
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return prot;
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}
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int ProvidedProtection(int prot)
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{
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addr_t flags = ProtectionToPMLFlags(prot);
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return PMLFlagsToProtection(flags);
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}
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bool LookUp(addr_t mapto, addr_t* physical, int* protection)
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{
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// Translate the virtual address into PML indexes.
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const size_t MASK = (1<<TRANSBITS)-1;
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size_t pmlchildid[TOPPMLLEVEL + 1];
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for ( size_t i = 1; i <= TOPPMLLEVEL; i++ )
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{
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pmlchildid[i] = (mapto >> (12+(i-1)*TRANSBITS)) & MASK;
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}
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int prot = PROT_USER | PROT_KERNEL | PROT_FORK;
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// For each PML level, make sure it exists.
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size_t offset = 0;
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for ( size_t i = TOPPMLLEVEL; i > 1; i-- )
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{
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size_t childid = pmlchildid[i];
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PML* pml = PMLS[i] + offset;
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addr_t entry = pml->entry[childid];
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if ( !(entry & PML_PRESENT) ) { return false; }
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int entryflags = entry & PML_ADDRESS;
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int entryprot = PMLFlagsToProtection(entryflags);
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prot &= entryprot;
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// Find the index of the next PML in the fractal mapped memory.
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offset = offset * ENTRIES + childid;
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}
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addr_t entry = (PMLS[1] + offset)->entry[pmlchildid[1]];
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int entryflags = entry & PML_ADDRESS;
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int entryprot = PMLFlagsToProtection(entryflags);
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prot &= entryprot;
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addr_t phys = entry & PML_ADDRESS;
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if ( physical ) { *physical = phys; }
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if ( protection ) { *protection = prot; }
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return true;
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}
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void InvalidatePage(addr_t /*addr*/)
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{
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// TODO: Actually just call the instruction.
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Flush();
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}
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// Flushes the Translation Lookaside Buffer (TLB).
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void Flush()
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{
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asm volatile("mov %0, %%cr3":: "r"(currentdir));
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}
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addr_t SwitchAddressSpace(addr_t addrspace)
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{
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// Have fun debugging this.
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if ( currentdir != Page::AlignDown(currentdir) )
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{
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PanicF("The variable containing the current address space "
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"contains garbage all of sudden: it isn't page-aligned. "
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"It contains the value 0x%zx.", currentdir);
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}
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// Don't switch if we are already there.
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if ( addrspace == currentdir ) { return currentdir; }
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if ( addrspace & 0xFFFUL ) { PanicF("addrspace 0x%zx was not page-aligned!", addrspace); }
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addr_t previous = currentdir;
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// Switch and flush the TLB.
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asm volatile("mov %0, %%cr3":: "r"(addrspace));
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currentdir = addrspace;
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return previous;
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}
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bool MapRange(addr_t where, size_t bytes, int protection)
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{
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for ( addr_t page = where; page < where + bytes; page += 4096UL )
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{
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addr_t physicalpage = Page::Get();
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if ( physicalpage == 0 )
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{
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while ( where < page )
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{
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page -= 4096UL;
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physicalpage = Unmap(page);
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Page::Put(physicalpage);
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}
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return false;
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}
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Map(physicalpage, page, protection);
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}
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return true;
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}
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bool UnmapRange(addr_t where, size_t bytes)
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{
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for ( addr_t page = where; page < where + bytes; page += 4096UL )
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{
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addr_t physicalpage = Unmap(page);
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Page::Put(physicalpage);
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}
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return true;
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}
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static bool MapInternal(addr_t physical, addr_t mapto, int prot, addr_t extraflags = 0)
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{
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addr_t flags = ProtectionToPMLFlags(prot) | PML_PRESENT;
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// Translate the virtual address into PML indexes.
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const size_t MASK = (1<<TRANSBITS)-1;
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size_t pmlchildid[TOPPMLLEVEL + 1];
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for ( size_t i = 1; i <= TOPPMLLEVEL; i++ )
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{
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pmlchildid[i] = (mapto >> (12+(i-1)*TRANSBITS)) & MASK;
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}
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// For each PML level, make sure it exists.
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size_t offset = 0;
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for ( size_t i = TOPPMLLEVEL; i > 1; i-- )
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{
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size_t childid = pmlchildid[i];
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PML* pml = PMLS[i] + offset;
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addr_t& entry = pml->entry[childid];
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// Find the index of the next PML in the fractal mapped memory.
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size_t childoffset = offset * ENTRIES + childid;
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if ( !(entry & PML_PRESENT) )
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{
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// TODO: Possible memory leak when page allocation fails.
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addr_t page = Page::Get();
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if ( !page ) { return false; }
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addr_t pmlflags = PML_PRESENT | PML_WRITABLE | PML_USERSPACE
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| PML_FORK;
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entry = page | pmlflags;
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// Invalidate the new PML and reset it to zeroes.
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addr_t pmladdr = (addr_t) (PMLS[i-1] + childoffset);
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InvalidatePage(pmladdr);
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Maxsi::Memory::Set((void*) pmladdr, 0, sizeof(PML));
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}
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offset = childoffset;
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}
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// Actually map the physical page to the virtual page.
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const addr_t entry = physical | flags | extraflags;
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(PMLS[1] + offset)->entry[pmlchildid[1]] = entry;
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return true;
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}
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bool Map(addr_t physical, addr_t mapto, int prot)
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{
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|
return MapInternal(physical, mapto, prot);
|
|
}
|
|
|
|
void PageProtect(addr_t mapto, int protection)
|
|
{
|
|
addr_t phys;
|
|
LookUp(mapto, &phys, NULL);
|
|
Map(phys, mapto, protection);
|
|
}
|
|
|
|
void PageProtectAdd(addr_t mapto, int protection)
|
|
{
|
|
addr_t phys;
|
|
int prot;
|
|
LookUp(mapto, &phys, &prot);
|
|
prot |= protection;
|
|
Map(phys, mapto, prot);
|
|
}
|
|
|
|
void PageProtectSub(addr_t mapto, int protection)
|
|
{
|
|
addr_t phys;
|
|
int prot;
|
|
LookUp(mapto, &phys, &prot);
|
|
prot &= ~protection;
|
|
Map(phys, mapto, prot);
|
|
}
|
|
|
|
addr_t Unmap(addr_t mapto)
|
|
{
|
|
// Translate the virtual address into PML indexes.
|
|
const size_t MASK = (1<<TRANSBITS)-1;
|
|
size_t pmlchildid[TOPPMLLEVEL + 1];
|
|
for ( size_t i = 1; i <= TOPPMLLEVEL; i++ )
|
|
{
|
|
pmlchildid[i] = (mapto >> (12+(i-1)*TRANSBITS)) & MASK;
|
|
}
|
|
|
|
// For each PML level, make sure it exists.
|
|
size_t offset = 0;
|
|
for ( size_t i = TOPPMLLEVEL; i > 1; i-- )
|
|
{
|
|
size_t childid = pmlchildid[i];
|
|
PML* pml = PMLS[i] + offset;
|
|
|
|
addr_t& entry = pml->entry[childid];
|
|
|
|
if ( !(entry & PML_PRESENT) )
|
|
{
|
|
PanicF("Attempted to unmap virtual page %p, but the virtual"
|
|
" page was wasn't mapped. This is a bug in the code "
|
|
"code calling this function", mapto);
|
|
}
|
|
|
|
// Find the index of the next PML in the fractal mapped memory.
|
|
offset = offset * ENTRIES + childid;
|
|
}
|
|
|
|
addr_t& entry = (PMLS[1] + offset)->entry[pmlchildid[1]];
|
|
addr_t result = entry & PML_ADDRESS;
|
|
entry = 0;
|
|
|
|
// TODO: If all the entries in PML[N] are not-present, then who
|
|
// unmaps its entry from PML[N-1]?
|
|
|
|
return result;
|
|
}
|
|
|
|
bool MapPAT(addr_t physical, addr_t mapto, int prot, addr_t mtype)
|
|
{
|
|
addr_t extraflags = PAT2PMLFlags[mtype];
|
|
return MapInternal(physical, mapto, prot, extraflags);
|
|
}
|
|
|
|
void ForkCleanup(size_t i, size_t level)
|
|
{
|
|
PML* destpml = FORKPML + level;
|
|
if ( !i ) { return; }
|
|
for ( size_t n = 0; n < i-1; n++ )
|
|
{
|
|
addr_t entry = destpml->entry[i];
|
|
if ( !(entry & PML_FORK ) ) { continue; }
|
|
addr_t phys = entry & PML_ADDRESS;
|
|
if ( 1 < level )
|
|
{
|
|
addr_t destaddr = (addr_t) (FORKPML + level-1);
|
|
Map(phys, destaddr, PROT_KREAD | PROT_KWRITE);
|
|
InvalidatePage(destaddr);
|
|
ForkCleanup(ENTRIES+1UL, level-1);
|
|
}
|
|
Page::Put(phys);
|
|
}
|
|
}
|
|
|
|
// TODO: Copying every frame is endlessly useless in many uses. It'd be
|
|
// nice to upgrade this to a copy-on-write algorithm.
|
|
bool Fork(size_t level, size_t pmloffset)
|
|
{
|
|
PML* destpml = FORKPML + level;
|
|
for ( size_t i = 0; i < ENTRIES; i++ )
|
|
{
|
|
addr_t entry = (PMLS[level] + pmloffset)->entry[i];
|
|
|
|
// Link the entry if it isn't supposed to be forked.
|
|
if ( !(entry & PML_FORK ) )
|
|
{
|
|
destpml->entry[i] = entry;
|
|
continue;
|
|
}
|
|
|
|
addr_t phys = Page::Get();
|
|
if ( unlikely(!phys) ) { ForkCleanup(i, level); return false; }
|
|
|
|
addr_t flags = entry & PML_FLAGS;
|
|
destpml->entry[i] = phys | flags;
|
|
|
|
// Map the destination page.
|
|
addr_t destaddr = (addr_t) (FORKPML + level-1);
|
|
Map(phys, destaddr, PROT_KREAD | PROT_KWRITE);
|
|
InvalidatePage(destaddr);
|
|
|
|
size_t offset = pmloffset * ENTRIES + i;
|
|
|
|
if ( 1 < level )
|
|
{
|
|
if ( !Fork(level-1, offset) )
|
|
{
|
|
Page::Put(phys);
|
|
ForkCleanup(i, level);
|
|
return false;
|
|
}
|
|
continue;
|
|
}
|
|
|
|
// Determine the source page's address.
|
|
const void* src = (const void*) (offset * 4096UL);
|
|
|
|
// Determine the destination page's address.
|
|
void* dest = (void*) (FORKPML + level - 1);
|
|
|
|
Maxsi::Memory::Copy(dest, src, 4096UL);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool Fork(addr_t dir, size_t level, size_t pmloffset)
|
|
{
|
|
PML* destpml = FORKPML + level;
|
|
|
|
// This call always succeeds.
|
|
Map(dir, (addr_t) destpml, PROT_KREAD | PROT_KWRITE);
|
|
InvalidatePage((addr_t) destpml);
|
|
|
|
return Fork(level, pmloffset);
|
|
}
|
|
|
|
// Create an exact copy of the current address space.
|
|
addr_t Fork()
|
|
{
|
|
addr_t dir = Page::Get();
|
|
if ( dir == 0 ) { return 0; }
|
|
if ( !Fork(dir, TOPPMLLEVEL, 0) ) { Page::Put(dir); return 0; }
|
|
|
|
// Now, the new top pml needs to have its fractal memory fixed.
|
|
const addr_t flags = PML_PRESENT | PML_WRITABLE;
|
|
addr_t mapto;
|
|
addr_t childaddr;
|
|
|
|
(FORKPML + TOPPMLLEVEL)->entry[ENTRIES-1] = dir | flags;
|
|
childaddr = (FORKPML + TOPPMLLEVEL)->entry[ENTRIES-2] & PML_ADDRESS;
|
|
|
|
for ( size_t i = TOPPMLLEVEL-1; i > 0; i-- )
|
|
{
|
|
mapto = (addr_t) (FORKPML + i);
|
|
Map(childaddr, mapto, PROT_KREAD | PROT_KWRITE);
|
|
InvalidatePage(mapto);
|
|
(FORKPML + i)->entry[ENTRIES-1] = dir | flags;
|
|
childaddr = (FORKPML + i)->entry[ENTRIES-2] & PML_ADDRESS;
|
|
}
|
|
return dir;
|
|
}
|
|
}
|
|
}
|
|
|