arch/x86/mmuContext.c

@@ -77,3 +77,24 @@ struct mmu_context *mmuContextCreate()
 
     return ctx;
 }
+
+int mmuContextSyncKernelPDE(int pdEntry, void * pde, size_t pdeSize)
+{
+    uint32_t flags;
+    struct mmu_context *destContext;
+    int nbContexts;
+
+    disable_IRQs(flags);
+    list_foreach_forward(listContext, destContext, nbContexts)
+    {
+        void *dest_pd;
+
+        assert(destContext->ref > 0);
+
+        dest_pd          = (void *)destContext->vaddr_PD;
+        memcpy(dest_pd + pdEntry *pdeSize, pde, pdeSize);
+    }
+    restore_IRQs(flags);
+
+    return 0;
+}

arch/x86/paging.c

@@ -1,7 +1,9 @@
 #include "paging.h"
 #include "errno.h"
+#include "kernel.h"
 #include "klibc.h"
 #include "mem.h"
+#include "mmuContext.h"
 #include "stdarg.h"
 
 // In a Vaddr, 10 first bit (MSB) are the index in the Page Directory. A Page Directory Entry
@@ -23,6 +25,20 @@
 #define PD_SHIFT 22
 #define PD_MIRROR_PAGE_IDX 1023U
 
+/** Frontier between kernel and user space virtual addresses */
+#define PAGING_BASE_USER_ADDRESS (0x40000000) /* 1GB (must be 4MB-aligned) */
+#define PAGING_TOP_USER_ADDRESS  (0xFFFFFFFF) /* 4GB - 1B */
+#define PAGING_USER_SPACE_SIZE   (0xc0000000) /* 3GB */
+
+/** Length of the space reserved for the mirroring in the kernel
+    virtual space */
+#define PAGING_MIRROR_SIZE  (PAGE_SIZE << 10)  /* 1 PD = 1024 Page Tables = 4MB */
+
+/** Virtual address where the mirroring takes place */
+#define PAGING_MIRROR_VADDR \
+   (PAGING_BASE_USER_ADDRESS - PAGING_MIRROR_SIZE)
+
+
 static unsigned long mappedPage = 0;
 
 struct pde {
@@ -107,9 +123,10 @@ int pagingSetup(paddr_t lowerKernelAddr, paddr_t upperKernelAddr)
     }
 
     // Setup mirroring
-    pd[PD_MIRROR_PAGE_IDX].present = 1;
+    pd[PAGING_MIRROR_VADDR >> PD_SHIFT].present = 1;
-    pd[PD_MIRROR_PAGE_IDX].write   = 1;
+    pd[PAGING_MIRROR_VADDR >> PD_SHIFT].write   = 1;
-    pd[PD_MIRROR_PAGE_IDX].pt_addr = ((paddr_t)pd >> PT_SHIFT);
+    pd[PAGING_MIRROR_VADDR >> PD_SHIFT].pt_addr = ((paddr_t)pd >> PT_SHIFT);
+    pd[PAGING_MIRROR_VADDR >> PD_SHIFT].user    = 0;
 
     // Loading of the PDBR in the MMU:
     asm volatile("movl %0,%%cr3\n\t"
@@ -130,22 +147,34 @@ int pageMap(vaddr_t vaddr, paddr_t paddr, int flags)
     uint pdEntry = vaddr >> (PD_SHIFT);
     uint ptEntry = (vaddr >> PT_SHIFT) & PTE_MASK;
 
+    if ((vaddr >= PAGING_MIRROR_VADDR) &&
+        (vaddr < PAGING_MIRROR_VADDR + PAGING_MIRROR_SIZE))
+        return -EINVAL;
+
     // Thank to mirroring, we can access the PD
     struct pde *pd =
-        (struct pde *)((PD_MIRROR_PAGE_IDX << PD_SHIFT) + (PD_MIRROR_PAGE_IDX << PT_SHIFT));
+        (struct pde *)(PAGING_MIRROR_VADDR + PAGE_SIZE*(PAGING_MIRROR_VADDR>>PD_SHIFT));
+
+    struct pte *pt = (struct pte *)((PAGING_MIRROR_VADDR) + (pdEntry * PAGE_SIZE));
 
-    struct pte *pt = (struct pte *)((PD_MIRROR_PAGE_IDX << PD_SHIFT) + (pdEntry << PT_SHIFT));
 
     if (!pd[pdEntry].present) {
         paddr_t ptPhy = allocPhyPage(1);
         if (ptPhy == (vaddr_t)NULL)
             return -ENOMEM;
 
-        pd[pdEntry].user    = (flags & PAGING_MEM_USER) ? 1 : 0;
         pd[pdEntry].present = 1;
         pd[pdEntry].write   = 1;
         pd[pdEntry].pt_addr = (ptPhy >> PT_SHIFT);
 
+        if(vaddr < PAGING_BASE_USER_ADDRESS){
+            pd[pdEntry].user   = 0;
+            mmuContextSyncKernelPDE(pdEntry, &pd[pdEntry], sizeof(struct pde));
+        }else{
+            assert(flags & PAGING_MEM_USER);
+            pd[pdEntry].user   = 1;
+        }
+
         __native_flush_tlb_single((vaddr_t)pt);
         memset((void *)pt, 0, PAGE_SIZE);
     } else {
@@ -175,11 +204,15 @@ int pageUnmap(vaddr_t vaddr)
     uint pdEntry = vaddr >> (PD_SHIFT);
     uint ptEntry = (vaddr >> PT_SHIFT) & PTE_MASK;
 
+    if ((vaddr >= PAGING_MIRROR_VADDR) &&
+        (vaddr < PAGING_MIRROR_VADDR + PAGING_MIRROR_SIZE))
+        return -EINVAL;
+
     // Thank to mirroring, we can access the PD
     struct pde *pd =
-        (struct pde *)((PD_MIRROR_PAGE_IDX << PD_SHIFT) + (PD_MIRROR_PAGE_IDX << PT_SHIFT));
+        (struct pde *)(PAGING_MIRROR_VADDR + PAGE_SIZE*(PAGING_MIRROR_VADDR>>PD_SHIFT));
 
-    struct pte *pt = (struct pte *)((PD_MIRROR_PAGE_IDX << PD_SHIFT) + (pdEntry << PT_SHIFT));
+    struct pte *pt = (struct pte *)((PAGING_MIRROR_VADDR) + (pdEntry * PAGE_SIZE));
     if (!pd[pdEntry].present)
         return -EINVAL;
     if (!pt[ptEntry].present)
@@ -191,6 +224,9 @@ int pageUnmap(vaddr_t vaddr)
     // PTE not used. Decrease refcount on it. Is PT not used anymore ?
     if (unrefPhyPage(pd[pdEntry].pt_addr << PT_SHIFT) == 0) {
         pd[pdEntry].present = 0;
+        if (vaddr < PAGING_BASE_USER_ADDRESS) {
+            mmuContextSyncKernelPDE(pdEntry, &pd[pdEntry], sizeof(struct pde));
+        }
         __native_flush_tlb_single((vaddr_t)pt);
     }
     __native_flush_tlb_single(vaddr);
@@ -206,12 +242,11 @@ paddr_t pagingGetPaddr(vaddr_t vaddr)
     unsigned ptEntry    = vaddr >> PT_SHIFT;
     unsigned pageOffset = vaddr & PAGE_MASK;
 
-    /* Get the PD of the current context */
+    // Thank to mirroring, we can access the PD
     struct pde *pd =
-        (struct pde *)((PD_MIRROR_PAGE_IDX << PD_SHIFT) + (PD_MIRROR_PAGE_IDX << PT_SHIFT));
+        (struct pde *)(PAGING_MIRROR_VADDR + PAGE_SIZE*(PAGING_MIRROR_VADDR>>PD_SHIFT));
 
-    /* Address of the PT in the mirroring */
+    struct pte *pt = (struct pte *)((PAGING_MIRROR_VADDR) + (pdEntry * PAGE_SIZE));
-    struct pte *pt = (struct pte *)((PD_MIRROR_PAGE_IDX << PD_SHIFT) + (pdEntry << PT_SHIFT));
 
     /* No page mapped at this address ? */
     if (!pd[pdEntry].present)
@@ -233,3 +268,21 @@ paddr_t pagingGetCurrentPDPaddr()
   asm volatile("movl %%cr3, %0\n": "=r"(pdbr));
   return (pdbr.pd_paddr << 12);
 }
+
+int pagingSetCurrentPDPaddr(paddr_t paddrPD)
+{
+  struct pdbr pdbr;
+
+  assert(paddrPD != 0);
+  assert(IS_ALIGNED(paddrPD, PAGE_SIZE));
+
+  /* Setup the value of the PDBR */
+  memset(& pdbr, 0x0, sizeof(struct pdbr)); /* Reset the PDBR */
+  pdbr.pd_paddr = (paddrPD >> 12);
+
+  /* Configure the MMU according to the PDBR */
+  asm volatile ("movl %0,%%cr3\n" ::"r"(pdbr));
+
+  return 0;
+}
+

arch/x86/paging.h

@@ -11,5 +11,6 @@ int pageMap(vaddr_t vaddr, paddr_t paddr, int flags);
 int pageUnmap(vaddr_t vaddr);
 unsigned long getNbMappedPage(void);
 
+int pagingSetCurrentPDPaddr(paddr_t paddrPD);
 paddr_t pagingGetPaddr(vaddr_t vaddr);
 paddr_t pagingGetCurrentPDPaddr();

core/mmuContext.h

@@ -1,5 +1,8 @@
 #pragma once
+#include "stdarg.h"
 
 struct mmu_context;
+
 int mmuContextSetup();
 struct mmu_context *mmuContextCreate();
+int mmuContextSyncKernelPDE(int pdEntry, void *pde, size_t pdeSize);