diff options
| -rw-r--r-- | runoff.spec | 10 | ||||
| -rw-r--r-- | vm.c | 264 |
2 files changed, 137 insertions, 137 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 @@ -6,33 +6,38 @@ #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() +// Set up CPU's kernel segment descriptors. +// Run once at boot time on each CPU. +void +ksegment(void) +{ + struct cpu *c; + + // Map virtual addresses to linear addresses using identity map. + // Cannot share a CODE descriptor for both kernel and user + // because it would have to have DPL_USR, but the CPU forbids + // an interrupt from CPL=0 to DPL=3. + c = &cpus[cpunum()]; + c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, 0); + c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0); + c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, DPL_USER); + c->gdt[SEG_UDATA] = SEG(STA_W, 0, 0xffffffff, DPL_USER); + + // map cpu, and curproc + c->gdt[SEG_KCPU] = SEG(STA_W, &c->cpu, 8, 0); + + lgdt(c->gdt, sizeof(c->gdt)); + loadgs(SEG_KCPU << 3); + + // Initialize cpu-local storage. + cpu = c; + 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. @@ -50,10 +55,8 @@ walkpgdir(pde_t *pgdir, const void *va, int create) 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. @@ -68,9 +71,9 @@ walkpgdir(pde_t *pgdir, const void *va, int create) static int mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm) { - char *first = PGROUNDDOWN(la); + char *a = PGROUNDDOWN(la); char *last = PGROUNDDOWN(la + size - 1); - char *a = first; + while(1){ pte_t *pte = walkpgdir(pgdir, a, 1); if(pte == 0) @@ -86,32 +89,75 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm) return 1; } -// Set up CPU's kernel segment descriptors. -// Run once at boot time on each CPU. +// 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 -ksegment(void) +kvmalloc(void) { - struct cpu *c; + kpgdir = setupkvm(); +} - // Map virtual addresses to linear addresses using identity map. - // Cannot share a CODE descriptor for both kernel and user - // because it would have to have DPL_USR, but the CPU forbids - // an interrupt from CPL=0 to DPL=3. - c = &cpus[cpunum()]; - c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, 0); - c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0); - c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, DPL_USER); - c->gdt[SEG_UDATA] = SEG(STA_W, 0, 0xffffffff, DPL_USER); +// Set up kernel part of a page table. +pde_t* +setupkvm(void) +{ + pde_t *pgdir; - // map cpu, and curproc - c->gdt[SEG_KCPU] = SEG(STA_W, &c->cpu, 8, 0); + // 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; +} - lgdt(c->gdt, sizeof(c->gdt)); - loadgs(SEG_KCPU << 3); - - // Initialize cpu-local storage. - cpu = c; - proc = 0; +// 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. @@ -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); -} - |