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authorFrans Kaashoek <[email protected]>2011-07-29 07:31:27 -0400
committerFrans Kaashoek <[email protected]>2011-07-29 07:31:27 -0400
commit9aa0337dc1452a911ac52698c833246a618fc9f3 (patch)
tree28e25817d4f7c9f7f1e6988949012f46d6c28fb7 /vm.c
parentdccb915282854476ce47752df6631dcce3b8f661 (diff)
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Map kernel high
Very important to give qemu memory through PHYSTOP :(
Diffstat (limited to 'vm.c')
-rw-r--r--vm.c127
1 files changed, 99 insertions, 28 deletions
diff --git a/vm.c b/vm.c
index 1fe64d2..b14a863 100644
--- a/vm.c
+++ b/vm.c
@@ -2,20 +2,71 @@
#include "types.h"
#include "defs.h"
#include "x86.h"
+#include "memlayout.h"
#include "mmu.h"
#include "proc.h"
#include "elf.h"
extern char data[]; // defined in data.S
-
static pde_t *kpgdir; // for use in scheduler()
+struct segdesc gdt[NSEGS];
-// Allocate one page table for the machine for the kernel address
-// space for scheduler processes.
+
+// page map for during boot
+// XXX build a static page table in assembly
+static void
+pgmap(void *va, void *last, uint pa)
+{
+ pde_t *pde;
+ pte_t *pgtab;
+ pte_t *pte;
+
+ for(;;){
+ pde = &kpgdir[PDX(va)];
+ pde_t pdev = *pde;
+ if (pdev == 0) {
+ pgtab = (pte_t *) pgalloc();
+ *pde = v2p(pgtab) | PTE_P | PTE_W;
+ } else {
+ pgtab = (pte_t*)p2v(PTE_ADDR(pdev));
+ }
+ pte = &pgtab[PTX(va)];
+ *pte = pa | PTE_W | PTE_P;
+ if(va == last)
+ break;
+ va += PGSIZE;
+ pa += PGSIZE;
+ }
+}
+
+// set up a page table to get off the ground
void
-kvmalloc(void)
+pginit(char* (*alloc)(void))
{
- kpgdir = setupkvm();
+ uint cr0;
+
+ kpgdir = (pde_t *) alloc();
+ pgmap((void *) 0, (void *) PHYSTOP, 0); // map pa 0 at va 0
+ pgmap((void *) KERNBASE, (void *) (KERNBASE+PHYSTOP), 0); // map pa 0 at va KERNBASE
+ pgmap((void*)0xFE000000, 0, 0xFE000000);
+
+ switchkvm(); // load kpgdir into cr3
+
+ cr0 = rcr0();
+ cr0 |= CR0_PG;
+ lcr0(cr0); // paging on
+
+ // new gdt
+ gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, 0);
+ gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
+ lgdt((void *)v2p(gdt), sizeof(gdt));
+ loadgs(SEG_KDATA << 3);
+ loadfs(SEG_KDATA << 3);
+ loades(SEG_KDATA << 3);
+ loadds(SEG_KDATA << 3);
+ loadss(SEG_KDATA << 3);
+
+ __asm volatile("ljmp %0,$1f\n 1:\n" :: "i" (SEG_KCODE << 3)); // reload cs
}
// Set up CPU's kernel segment descriptors.
@@ -57,7 +108,7 @@ walkpgdir(pde_t *pgdir, const void *va, int create)
pde = &pgdir[PDX(va)];
if(*pde & PTE_P){
- pgtab = (pte_t*)PTE_ADDR(*pde);
+ pgtab = (pte_t*)p2v(PTE_ADDR(*pde));
} else {
if(!create || (pgtab = (pte_t*)kalloc()) == 0)
return 0;
@@ -66,7 +117,7 @@ walkpgdir(pde_t *pgdir, const void *va, int create)
// The permissions here are overly generous, but they can
// be further restricted by the permissions in the page table
// entries, if necessary.
- *pde = PADDR(pgtab) | PTE_P | PTE_W | PTE_U;
+ *pde = v2p(pgtab) | PTE_P | PTE_W | PTE_U;
}
return &pgtab[PTX(va)];
}
@@ -105,29 +156,30 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm)
// 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)
+// 0..KERNBASE : user memory (text, data, stack, heap), mapped to some phys mem
+// KERNBASE+640K..KERNBASE+1M: mapped to 640K..1M
+// KERNBASE+1M..KERNBASE+end : mapped to 1M..end
+// KERNBASE+end..KERBASE+PHYSTOP : mapped to end..PHYSTOP (free memory)
// 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).
+// (which is inaccessible in user mode). The user program sits in
+// the bottom of the address space, and the kernel at the top at KERNBASE.
static struct kmap {
- void *p;
- void *e;
+ void *l;
+ uint p;
+ uint e;
int perm;
} kmap[] = {
- {(void*)USERTOP, (void*)0x100000, PTE_W}, // I/O space
- {(void*)0x100000, data, 0 }, // kernel text, rodata
- {data, (void*)PHYSTOP, PTE_W}, // kernel data, memory
- {(void*)0xFE000000, 0, PTE_W}, // device mappings
+ { (void *)IOSPACEB, IOSPACEB, IOSPACEE, PTE_W}, // I/O space
+ { P2V(IOSPACEB), IOSPACEB, IOSPACEE, PTE_W}, // I/O space
+ { (void *)KERNLINK, V2P(KERNLINK), V2P(data), 0}, // kernel text, rodata
+ { data, V2P(data), PHYSTOP, PTE_W}, // kernel data, memory
+ { (void*)0xFE000000, 0xFE000000, 0, PTE_W}, // device mappings
};
// Set up kernel part of a page table.
@@ -142,12 +194,21 @@ setupkvm(void)
memset(pgdir, 0, PGSIZE);
k = kmap;
for(k = kmap; k < &kmap[NELEM(kmap)]; k++)
- if(mappages(pgdir, k->p, k->e - k->p, (uint)k->p, k->perm) < 0)
+ if(mappages(pgdir, k->l, k->e - k->p, (uint)k->p, k->perm) < 0)
return 0;
return pgdir;
}
+// Allocate one page table for the machine for the kernel address
+// space for scheduler processes.
+void
+kvmalloc(void)
+{
+ kpgdir = setupkvm();
+ switchkvm();
+}
+
// Turn on paging.
void
vmenable(void)
@@ -158,6 +219,16 @@ vmenable(void)
cr0 = rcr0();
cr0 |= CR0_PG;
lcr0(cr0);
+
+ struct cpu *c = &cpus[0];
+ lgdt((void *)v2p((void *)(c->gdt)), sizeof(c->gdt));
+ loadgs(SEG_KCPU << 3);
+ loadfs(SEG_KDATA << 3);
+ loades(SEG_KDATA << 3);
+ loadds(SEG_KDATA << 3);
+ loadss(SEG_KDATA << 3);
+
+ __asm volatile("ljmp %0,$1f\n 1:\n" :: "i" (SEG_KCODE << 3)); // reload cs
}
// Switch h/w page table register to the kernel-only page table,
@@ -165,7 +236,7 @@ vmenable(void)
void
switchkvm(void)
{
- lcr3(PADDR(kpgdir)); // switch to the kernel page table
+ lcr3(v2p(kpgdir)); // switch to the kernel page table
}
// Switch TSS and h/w page table to correspond to process p.
@@ -180,7 +251,7 @@ switchuvm(struct proc *p)
ltr(SEG_TSS << 3);
if(p->pgdir == 0)
panic("switchuvm: no pgdir");
- lcr3(PADDR(p->pgdir)); // switch to new address space
+ lcr3(v2p(p->pgdir)); // switch to new address space
popcli();
}
@@ -195,7 +266,7 @@ inituvm(pde_t *pgdir, char *init, uint sz)
panic("inituvm: more than a page");
mem = kalloc();
memset(mem, 0, PGSIZE);
- mappages(pgdir, 0, PGSIZE, PADDR(mem), PTE_W|PTE_U);
+ mappages(pgdir, 0, PGSIZE, v2p(mem), PTE_W|PTE_U);
memmove(mem, init, sz);
}
@@ -245,7 +316,7 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
return 0;
}
memset(mem, 0, PGSIZE);
- mappages(pgdir, (char*)a, PGSIZE, PADDR(mem), PTE_W|PTE_U);
+ mappages(pgdir, (char*)a, PGSIZE, v2p(mem), PTE_W|PTE_U);
}
return newsz;
}
@@ -289,7 +360,7 @@ freevm(pde_t *pgdir)
deallocuvm(pgdir, USERTOP, 0);
for(i = 0; i < NPDENTRIES; i++){
if(pgdir[i] & PTE_P)
- kfree((char*)PTE_ADDR(pgdir[i]));
+ kfree(p2v(PTE_ADDR(pgdir[i])));
}
kfree((char*)pgdir);
}
@@ -315,7 +386,7 @@ copyuvm(pde_t *pgdir, uint sz)
if((mem = kalloc()) == 0)
goto bad;
memmove(mem, (char*)pa, PGSIZE);
- if(mappages(d, (void*)i, PGSIZE, PADDR(mem), PTE_W|PTE_U) < 0)
+ if(mappages(d, (void*)i, PGSIZE, v2p(mem), PTE_W|PTE_U) < 0)
goto bad;
}
return d;