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