189 lines
7.8 KiB
C
189 lines
7.8 KiB
C
#ifndef JOS_INC_MEMLAYOUT_H
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#define JOS_INC_MEMLAYOUT_H
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#ifndef __ASSEMBLER__
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#include <inc/types.h>
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#include <inc/mmu.h>
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#endif /* not __ASSEMBLER__ */
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/*
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* This file contains definitions for memory management in our OS,
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* which are relevant to both the kernel and user-mode software.
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*/
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// Global descriptor numbers
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#define GD_KT 0x08 // kernel text
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#define GD_KD 0x10 // kernel data
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#define GD_UT 0x18 // user text
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#define GD_UD 0x20 // user data
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#define GD_TSS0 0x28 // Task segment selector for CPU 0
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/*
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* Virtual memory map: Permissions
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* kernel/user
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*
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* 4 Gig --------> +------------------------------+
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* | | RW/--
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* : . :
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* : . :
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* : . :
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* |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| RW/--
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* | | RW/--
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* | Remapped Physical Memory | RW/--
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* | | RW/--
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* KERNBASE, ----> +------------------------------+ 0xf0000000 --+
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* KSTACKTOP | CPU0's Kernel Stack | RW/-- KSTKSIZE |
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* | - - - - - - - - - - - - - - -| |
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* | Invalid Memory (*) | --/-- KSTKGAP |
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* +------------------------------+ |
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* | CPU1's Kernel Stack | RW/-- KSTKSIZE |
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* | - - - - - - - - - - - - - - -| PTSIZE
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* | Invalid Memory (*) | --/-- KSTKGAP |
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* +------------------------------+ |
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* : . : |
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* : . : |
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* MMIOLIM ------> +------------------------------+ 0xefc00000 --+
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* | Memory-mapped I/O | RW/-- PTSIZE
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* ULIM, MMIOBASE --> +------------------------------+ 0xef800000
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* | Cur. Page Table (User R-) | R-/R- PTSIZE
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* UVPT ----> +------------------------------+ 0xef400000
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* | RO PAGES | R-/R- PTSIZE
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* UPAGES ----> +------------------------------+ 0xef000000
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* | RO ENVS | R-/R- PTSIZE
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* UTOP,UENVS ------> +------------------------------+ 0xeec00000
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* UXSTACKTOP -/ | User Exception Stack | RW/RW PGSIZE
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* +------------------------------+ 0xeebff000
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* | Empty Memory (*) | --/-- PGSIZE
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* USTACKTOP ---> +------------------------------+ 0xeebfe000
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* | Normal User Stack | RW/RW PGSIZE
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* +------------------------------+ 0xeebfd000
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* | |
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* | |
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* . .
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* . .
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* . .
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* |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|
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* | Program Data & Heap |
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* UTEXT --------> +------------------------------+ 0x00800000
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* PFTEMP -------> | Empty Memory (*) | PTSIZE
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* | |
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* UTEMP --------> +------------------------------+ 0x00400000 --+
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* | Empty Memory (*) | |
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* | - - - - - - - - - - - - - - -| |
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* | User STAB Data (optional) | PTSIZE
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* USTABDATA ----> +------------------------------+ 0x00200000 |
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* | Empty Memory (*) | |
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* 0 ------------> +------------------------------+ --+
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*
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* (*) Note: The kernel ensures that "Invalid Memory" is *never* mapped.
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* "Empty Memory" is normally unmapped, but user programs may map pages
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* there if desired. JOS user programs map pages temporarily at UTEMP.
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*/
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// All physical memory mapped at this address
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#define KERNBASE 0xF0000000
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// At IOPHYSMEM (640K) there is a 384K hole for I/O. From the kernel,
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// IOPHYSMEM can be addressed at KERNBASE + IOPHYSMEM. The hole ends
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// at physical address EXTPHYSMEM.
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#define IOPHYSMEM 0x0A0000
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#define EXTPHYSMEM 0x100000
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// Kernel stack.
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#define KSTACKTOP KERNBASE
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#define KSTKSIZE (8*PGSIZE) // size of a kernel stack
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#define KSTKGAP (8*PGSIZE) // size of a kernel stack guard
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// Memory-mapped IO.
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#define MMIOLIM (KSTACKTOP - PTSIZE)
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#define MMIOBASE (MMIOLIM - PTSIZE)
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#define ULIM (MMIOBASE)
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/*
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* User read-only mappings! Anything below here til UTOP are readonly to user.
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* They are global pages mapped in at env allocation time.
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*/
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// User read-only virtual page table (see 'uvpt' below)
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#define UVPT (ULIM - PTSIZE)
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// Read-only copies of the Page structures
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#define UPAGES (UVPT - PTSIZE)
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// Read-only copies of the global env structures
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#define UENVS (UPAGES - PTSIZE)
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/*
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* Top of user VM. User can manipulate VA from UTOP-1 and down!
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*/
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// Top of user-accessible VM
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#define UTOP UENVS
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// Top of one-page user exception stack
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#define UXSTACKTOP UTOP
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// Next page left invalid to guard against exception stack overflow; then:
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// Top of normal user stack
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#define USTACKTOP (UTOP - 2*PGSIZE)
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// Where user programs generally begin
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#define UTEXT (2*PTSIZE)
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// Used for temporary page mappings. Typed 'void*' for convenience
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#define UTEMP ((void*) PTSIZE)
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// Used for temporary page mappings for the user page-fault handler
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// (should not conflict with other temporary page mappings)
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#define PFTEMP (UTEMP + PTSIZE - PGSIZE)
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// The location of the user-level STABS data structure
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#define USTABDATA (PTSIZE / 2)
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#ifndef __ASSEMBLER__
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typedef uint32_t pte_t;
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typedef uint32_t pde_t;
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#if JOS_USER
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/*
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* The page directory entry corresponding to the virtual address range
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* [UVPT, UVPT + PTSIZE) points to the page directory itself. Thus, the page
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* directory is treated as a page table as well as a page directory.
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*
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* One result of treating the page directory as a page table is that all PTEs
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* can be accessed through a "virtual page table" at virtual address UVPT (to
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* which uvpt is set in lib/entry.S). The PTE for page number N is stored in
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* uvpt[N]. (It's worth drawing a diagram of this!)
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*
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* A second consequence is that the contents of the current page directory
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* will always be available at virtual address (UVPT + (UVPT >> PGSHIFT)), to
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* which uvpd is set in lib/entry.S.
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*/
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extern volatile pte_t uvpt[]; // VA of "virtual page table"
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extern volatile pde_t uvpd[]; // VA of current page directory
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#endif
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/*
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* Page descriptor structures, mapped at UPAGES.
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* Read/write to the kernel, read-only to user programs.
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*
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* Each struct PageInfo stores metadata for one physical page.
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* Is it NOT the physical page itself, but there is a one-to-one
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* correspondence between physical pages and struct PageInfo's.
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* You can map a struct PageInfo * to the corresponding physical address
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* with page2pa() in kern/pmap.h.
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*/
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struct PageInfo {
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// Next page on the free list.
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struct PageInfo *pp_link;
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// pp_ref is the count of pointers (usually in page table entries)
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// to this page, for pages allocated using page_alloc.
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// Pages allocated at boot time using pmap.c's
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// boot_alloc do not have valid reference count fields.
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uint16_t pp_ref;
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};
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#endif /* !__ASSEMBLER__ */
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#endif /* !JOS_INC_MEMLAYOUT_H */
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