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kvmmake() makes a complete kernel page table, matching Figure 3.3

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This commit is contained in:
Frans Kaashoek 2020-10-14 20:03:14 -04:00
parent 21cfc97809
commit d4cecb269f
3 changed files with 47 additions and 27 deletions
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3
kernel/defs.h
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@ -86,6 +86,7 @@ int cpuid(void);
void exit(int);
int fork(void);
int growproc(int);
void proc_mapstacks(pagetable_t);
pagetable_t proc_pagetable(struct proc *);
void proc_freepagetable(pagetable_t, uint64);
int kill(int);
@ -156,7 +157,7 @@ int uartgetc(void);
// vm.c
void kvminit(void);
void kvminithart(void);
void kvmmap(uint64, uint64, uint64, int);
void kvmmap(pagetable_t, uint64, uint64, uint64, int);
int mappages(pagetable_t, uint64, uint64, uint64, int);
pagetable_t uvmcreate(void);
void uvminit(pagetable_t, uchar *, uint);

29
kernel/proc.c
View file

@ -21,6 +21,23 @@ static void freeproc(struct proc *p);
extern char trampoline[]; // trampoline.S
// Allocate a page for each process's kernel stack.
// Map it high in memory, followed by an invalid
// guard page.
void
proc_mapstacks(pagetable_t kpgtbl) {
struct proc *p;
for(p = proc; p < &proc[NPROC]; p++) {
char *pa = kalloc();
if(pa == 0)
panic("kalloc");
uint64 va = KSTACK((int) (p - proc));
kvmmap(kpgtbl, va, (uint64)pa, PGSIZE, PTE_R | PTE_W);
}
}
// initialize the proc table at boot time.
void
procinit(void)
@ -30,18 +47,8 @@ procinit(void)
initlock(&pid_lock, "nextpid");
for(p = proc; p < &proc[NPROC]; p++) {
initlock(&p->lock, "proc");
// Allocate a page for the process's kernel stack.
// Map it high in memory, followed by an invalid
// guard page.
char *pa = kalloc();
if(pa == 0)
panic("kalloc");
uint64 va = KSTACK((int) (p - proc));
kvmmap(va, (uint64)pa, PGSIZE, PTE_R | PTE_W);
p->kstack = va;
p->kstack = KSTACK((int) (p - proc));
}
kvminithart();
}
// Must be called with interrupts disabled,

42
kernel/vm.c
View file

@ -15,33 +15,45 @@ extern char etext[]; // kernel.ld sets this to end of kernel code.
extern char trampoline[]; // trampoline.S
/*
* create a direct-map page table for the kernel.
*/
void
kvminit()
// Make a direct-map page table for the kernel.
pagetable_t
kvmmake(void)
{
kernel_pagetable = (pagetable_t) kalloc();
memset(kernel_pagetable, 0, PGSIZE);
pagetable_t kpgtbl;
kpgtbl = (pagetable_t) kalloc();
memset(kpgtbl, 0, PGSIZE);
// uart registers
kvmmap(UART0, UART0, PGSIZE, PTE_R | PTE_W);
kvmmap(kpgtbl, UART0, UART0, PGSIZE, PTE_R | PTE_W);
// virtio mmio disk interface
kvmmap(VIRTIO0, VIRTIO0, PGSIZE, PTE_R | PTE_W);
kvmmap(kpgtbl, VIRTIO0, VIRTIO0, PGSIZE, PTE_R | PTE_W);
// PLIC
kvmmap(PLIC, PLIC, 0x400000, PTE_R | PTE_W);
kvmmap(kpgtbl, PLIC, PLIC, 0x400000, PTE_R | PTE_W);
// map kernel text executable and read-only.
kvmmap(KERNBASE, KERNBASE, (uint64)etext-KERNBASE, PTE_R | PTE_X);
kvmmap(kpgtbl, KERNBASE, KERNBASE, (uint64)etext-KERNBASE, PTE_R | PTE_X);
// map kernel data and the physical RAM we'll make use of.
kvmmap((uint64)etext, (uint64)etext, PHYSTOP-(uint64)etext, PTE_R | PTE_W);
kvmmap(kpgtbl, (uint64)etext, (uint64)etext, PHYSTOP-(uint64)etext, PTE_R | PTE_W);
// map the trampoline for trap entry/exit to
// the highest virtual address in the kernel.
kvmmap(TRAMPOLINE, (uint64)trampoline, PGSIZE, PTE_R | PTE_X);
kvmmap(kpgtbl, TRAMPOLINE, (uint64)trampoline, PGSIZE, PTE_R | PTE_X);
// map kernel stacks
proc_mapstacks(kpgtbl);
return kpgtbl;
}
// Initialize the one kernel_pagetable
void
kvminit(void)
{
kernel_pagetable = kvmmake();
}
// Switch h/w page table register to the kernel's page table,
@ -112,9 +124,9 @@ walkaddr(pagetable_t pagetable, uint64 va)
// only used when booting.
// does not flush TLB or enable paging.
void
kvmmap(uint64 va, uint64 pa, uint64 sz, int perm)
kvmmap(pagetable_t kpgtbl, uint64 va, uint64 pa, uint64 sz, int perm)
{
if(mappages(kernel_pagetable, va, sz, pa, perm) != 0)
if(mappages(kpgtbl, va, sz, pa, perm) != 0)
panic("kvmmap");
}