From f25a3f9a41de02116c39b0e65243d111e1cb1026 Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Thu, 2 Sep 2010 16:23:15 -0400 Subject: [PATCH] Rearrange vm.c so it's in logical order and prints nicely. Shorten a few functions in uninteresting ways to make them fit. --- runoff.spec | 10 +- vm.c | 320 ++++++++++++++++++++++++++-------------------------- 2 files changed, 165 insertions(+), 165 deletions(-) diff --git a/runoff.spec b/runoff.spec index 9d87528..d5b5334 100644 --- a/runoff.spec +++ b/runoff.spec @@ -42,8 +42,14 @@ odd: proc.h left: proc.c # VERY important odd: proc.c # VERY important -# setjmp.S either -# vm.c either +# A few more action packed spreads +# page table creation and process loading +# walkpgdir mappages setupkvm vmenable switch[ku]vm inituvm loaduvm +# process memory management +# allocuvm deallocuvm freevm +right: vm.c +odd: vm.c + # kalloc.c either # syscall.h either diff --git a/vm.c b/vm.c index 9c0783d..f3436b7 100644 --- a/vm.c +++ b/vm.c @@ -6,86 +6,10 @@ #include "proc.h" #include "elf.h" -// The mappings from logical to linear are one to one (i.e., -// segmentation doesn't do anything). -// There is one page table per process, plus one that's used -// when a CPU is not running any process (kpgdir). -// A user process uses the same page table as the kernel; the -// page protection bits prevent it from using anything other -// than its memory. -// -// setupkvm() and exec() set up every page table like this: -// 0..640K : user memory (text, data, stack, heap) -// 640K..1M : mapped direct (for IO space) -// 1M..end : mapped direct (for the kernel's text and data) -// end..PHYSTOP : mapped direct (kernel heap and user pages) -// 0xfe000000..0 : mapped direct (devices such as ioapic) -// -// The kernel allocates memory for its heap and for user memory -// between kernend and the end of physical memory (PHYSTOP). -// The virtual address space of each user program includes the kernel -// (which is inaccessible in user mode). The user program addresses -// range from 0 till 640KB (USERTOP), which where the I/O hole starts -// (both in physical memory and in the kernel's virtual address -// space). - #define USERTOP 0xA0000 static pde_t *kpgdir; // for use in scheduler() -// return the address of the PTE in page table pgdir -// that corresponds to linear address va. if create!=0, -// create any required page table pages. -static pte_t * -walkpgdir(pde_t *pgdir, const void *va, int create) -{ - uint r; - pde_t *pde; - pte_t *pgtab; - - pde = &pgdir[PDX(va)]; - if(*pde & PTE_P){ - pgtab = (pte_t*) PTE_ADDR(*pde); - } else if(!create || !(r = (uint) kalloc())) - return 0; - else { - pgtab = (pte_t*) r; - - // Make sure all those PTE_P bits are zero. - memset(pgtab, 0, PGSIZE); - - // The permissions here are overly generous, but they can - // be further restricted by the permissions in the page table - // entries, if necessary. - *pde = PADDR(r) | PTE_P | PTE_W | PTE_U; - } - return &pgtab[PTX(va)]; -} - -// create PTEs for linear addresses starting at la that refer to -// physical addresses starting at pa. la and size might not -// be page-aligned. -static int -mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm) -{ - char *first = PGROUNDDOWN(la); - char *last = PGROUNDDOWN(la + size - 1); - char *a = first; - while(1){ - pte_t *pte = walkpgdir(pgdir, a, 1); - if(pte == 0) - return 0; - if(*pte & PTE_P) - panic("remap"); - *pte = pa | perm | PTE_P; - if(a == last) - break; - a += PGSIZE; - pa += PGSIZE; - } - return 1; -} - // Set up CPU's kernel segment descriptors. // Run once at boot time on each CPU. void @@ -114,6 +38,128 @@ ksegment(void) proc = 0; } +// return the address of the PTE in page table pgdir +// that corresponds to linear address va. if create!=0, +// create any required page table pages. +static pte_t * +walkpgdir(pde_t *pgdir, const void *va, int create) +{ + uint r; + pde_t *pde; + pte_t *pgtab; + + pde = &pgdir[PDX(va)]; + if(*pde & PTE_P){ + pgtab = (pte_t*) PTE_ADDR(*pde); + } else if(!create || !(r = (uint) kalloc())) + return 0; + else { + pgtab = (pte_t*) r; + // Make sure all those PTE_P bits are zero. + memset(pgtab, 0, PGSIZE); + // The permissions here are overly generous, but they can + // be further restricted by the permissions in the page table + // entries, if necessary. + *pde = PADDR(r) | PTE_P | PTE_W | PTE_U; + } + return &pgtab[PTX(va)]; +} + +// create PTEs for linear addresses starting at la that refer to +// physical addresses starting at pa. la and size might not +// be page-aligned. +static int +mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm) +{ + char *a = PGROUNDDOWN(la); + char *last = PGROUNDDOWN(la + size - 1); + + while(1){ + pte_t *pte = walkpgdir(pgdir, a, 1); + if(pte == 0) + return 0; + if(*pte & PTE_P) + panic("remap"); + *pte = pa | perm | PTE_P; + if(a == last) + break; + a += PGSIZE; + pa += PGSIZE; + } + return 1; +} + +// The mappings from logical to linear are one to one (i.e., +// segmentation doesn't do anything). +// There is one page table per process, plus one that's used +// when a CPU is not running any process (kpgdir). +// A user process uses the same page table as the kernel; the +// page protection bits prevent it from using anything other +// than its memory. +// +// setupkvm() and exec() set up every page table like this: +// 0..640K : user memory (text, data, stack, heap) +// 640K..1M : mapped direct (for IO space) +// 1M..end : mapped direct (for the kernel's text and data) +// end..PHYSTOP : mapped direct (kernel heap and user pages) +// 0xfe000000..0 : mapped direct (devices such as ioapic) +// +// The kernel allocates memory for its heap and for user memory +// between kernend and the end of physical memory (PHYSTOP). +// The virtual address space of each user program includes the kernel +// (which is inaccessible in user mode). The user program addresses +// range from 0 till 640KB (USERTOP), which where the I/O hole starts +// (both in physical memory and in the kernel's virtual address +// space). + +// Allocate one page table for the machine for the kernel address +// space for scheduler processes. +void +kvmalloc(void) +{ + kpgdir = setupkvm(); +} + +// Set up kernel part of a page table. +pde_t* +setupkvm(void) +{ + pde_t *pgdir; + + // Allocate page directory + if(!(pgdir = (pde_t *) kalloc())) + return 0; + memset(pgdir, 0, PGSIZE); + if(// Map IO space from 640K to 1Mbyte + !mappages(pgdir, (void *)USERTOP, 0x60000, USERTOP, PTE_W) || + // Map kernel and free memory pool + !mappages(pgdir, (void *)0x100000, PHYSTOP-0x100000, 0x100000, PTE_W) || + // Map devices such as ioapic, lapic, ... + !mappages(pgdir, (void *)0xFE000000, 0x2000000, 0xFE000000, PTE_W)) + return 0; + return pgdir; +} + +// Turn on paging. +void +vmenable(void) +{ + uint cr0; + + switchkvm(); // load kpgdir into cr3 + cr0 = rcr0(); + cr0 |= CR0_PG; + lcr0(cr0); +} + +// Switch h/w page table register to the kernel-only page table, for when +// no process is running. +void +switchkvm() +{ + lcr3(PADDR(kpgdir)); // Switch to the kernel page table +} + // Switch h/w page table and TSS registers to point to process p. void switchuvm(struct proc *p) @@ -134,36 +180,6 @@ switchuvm(struct proc *p) popcli(); } -// Switch h/w page table register to the kernel-only page table, for when -// no process is running. -void -switchkvm() -{ - lcr3(PADDR(kpgdir)); // Switch to the kernel page table -} - -// Set up kernel part of a page table. -pde_t* -setupkvm(void) -{ - pde_t *pgdir; - - // Allocate page directory - if(!(pgdir = (pde_t *) kalloc())) - return 0; - memset(pgdir, 0, PGSIZE); - // Map IO space from 640K to 1Mbyte - if(!mappages(pgdir, (void *)USERTOP, 0x60000, USERTOP, PTE_W)) - return 0; - // Map kernel and free memory pool - if(!mappages(pgdir, (void *)0x100000, PHYSTOP-0x100000, 0x100000, PTE_W)) - return 0; - // Map devices such as ioapic, lapic, ... - if(!mappages(pgdir, (void *)0xFE000000, 0x2000000, 0xFE000000, PTE_W)) - return 0; - return pgdir; -} - // return the physical address that a given user address // maps to. the result is also a kernel logical address, // since the kernel maps the physical memory allocated to user @@ -177,6 +193,37 @@ uva2ka(pde_t *pgdir, char *uva) return (char *)pa; } +void +inituvm(pde_t *pgdir, char *init, uint sz) +{ + char *mem = kalloc(); + if (sz >= PGSIZE) + panic("inituvm: more than a page"); + memset(mem, 0, PGSIZE); + mappages(pgdir, 0, PGSIZE, PADDR(mem), PTE_W|PTE_U); + memmove(mem, init, sz); +} + +int +loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz) +{ + uint i, pa, n; + pte_t *pte; + + if((uint)addr % PGSIZE != 0) + panic("loaduvm: addr must be page aligned\n"); + for(i = 0; i < sz; i += PGSIZE){ + if(!(pte = walkpgdir(pgdir, addr+i, 0))) + panic("loaduvm: address should exist\n"); + pa = PTE_ADDR(*pte); + if(sz - i < PGSIZE) n = sz - i; + else n = PGSIZE; + if(readi(ip, (char *)pa, offset+i, n) != n) + return 0; + } + return 1; +} + // allocate sz bytes more memory for a process starting at the // given user address; allocates physical memory and page // table entries. addr and sz need not be page-aligned. @@ -187,10 +234,9 @@ allocuvm(pde_t *pgdir, char *addr, uint sz) { if(addr + sz > (char*)USERTOP) return 0; - char *first = PGROUNDDOWN(addr); + char *a = PGROUNDDOWN(addr); char *last = PGROUNDDOWN(addr + sz - 1); - char *a; - for(a = first; a <= last; a += PGSIZE){ + for(; a <= last; a += PGSIZE){ pte_t *pte = walkpgdir(pgdir, a, 0); if(pte == 0 || (*pte & PTE_P) == 0){ char *mem = kalloc(); @@ -213,10 +259,9 @@ deallocuvm(pde_t *pgdir, char *addr, uint sz) { if(addr + sz > (char*)USERTOP) return 0; - char *first = (char*) PGROUNDUP((uint)addr); + char *a = (char *)PGROUNDUP((uint)addr); char *last = PGROUNDDOWN(addr + sz - 1); - char *a; - for(a = first; a <= last; a += PGSIZE){ + for(; a <= last; a += PGSIZE){ pte_t *pte = walkpgdir(pgdir, a, 0); if(pte && (*pte & PTE_P) != 0){ uint pa = PTE_ADDR(*pte); @@ -246,37 +291,6 @@ freevm(pde_t *pgdir) kfree((void *) pgdir); } -int -loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz) -{ - uint i, pa, n; - pte_t *pte; - - if((uint)addr % PGSIZE != 0) - panic("loaduvm: addr must be page aligned\n"); - for(i = 0; i < sz; i += PGSIZE){ - if(!(pte = walkpgdir(pgdir, addr+i, 0))) - panic("loaduvm: address should exist\n"); - pa = PTE_ADDR(*pte); - if(sz - i < PGSIZE) n = sz - i; - else n = PGSIZE; - if(readi(ip, (char *)pa, offset+i, n) != n) - return 0; - } - return 1; -} - -void -inituvm(pde_t *pgdir, char *init, uint sz) -{ - char *mem = kalloc(); - if (sz >= PGSIZE) - panic("inituvm: more than a page"); - memset(mem, 0, PGSIZE); - mappages(pgdir, 0, PGSIZE, PADDR(mem), PTE_W|PTE_U); - memmove(mem, init, sz); -} - // given a parent process's page table, create a copy // of it for a child. pde_t* @@ -307,23 +321,3 @@ bad: return 0; } -// Allocate one page table for the machine for the kernel address -// space for scheduler processes. -void -kvmalloc(void) -{ - kpgdir = setupkvm(); -} - -// Turn on paging. -void -vmenable(void) -{ - uint cr0; - - switchkvm(); // load kpgdir into cr3 - cr0 = rcr0(); - cr0 |= CR0_PG; - lcr0(cr0); -} -