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

3 files changed, 47 insertions, 27 deletions

diff --git a/kernel/defs.h b/kernel/defs.h
index 49aafdd..41098f4 100644
--- a/kernel/defs.h
+++ b/kernel/defs.h
@@ -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);
diff --git a/kernel/proc.c b/kernel/proc.c
index 56314e5..d847c43 100644
--- a/kernel/proc.c
+++ b/kernel/proc.c
@@ -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,
diff --git a/kernel/vm.c b/kernel/vm.c
index bd53fd7..b47f111 100644
--- a/kernel/vm.c
+++ b/kernel/vm.c
@@ -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");
 }