arch/x86/exception.c

@@ -45,9 +45,9 @@ int exceptionSetRoutine(int exception, exception_handler handler)
 
 void print_handler(struct cpu_state *frame, ulong intr)
 {
-    int intNbInt = intr;
-    VGAPrintf(RED, BLACK, 0, VGA_HEIGHT - 1, "EXCEPTION %d", intNbInt);
+    VGAPrintf(RED, BLACK, 0, VGA_HEIGHT - 1, "EXCEPTION %lu", intr);
     printf("Exception %lu at 0x%p\n", intr, (void *)cpu_context_get_PC(frame));
+
     asm("hlt");
 }
 
@@ -55,17 +55,26 @@ void pagefault_handler(struct cpu_state *frame, ulong intr)
 {
 
     struct thread *current = getCurrentThread();
-    struct uAddrSpace *as = processGetAddrSpace(current->process);
-    vaddr_t faultAddr = cpu_context_get_EX_faulting_vaddr(frame);
+    assert(frame == current->cpuState);
+    if (cpu_context_is_in_user_mode(current->cpuState)) {
+        struct uAddrSpace *as = processGetAddrSpace(current->process);
+        vaddr_t faultAddr     = cpu_context_get_EX_faulting_vaddr(frame);
 
-    if(!uAddrSpaceCheckNAlloc(as, faultAddr))
-        return;
+        if (!uAddrSpaceHeapCheckNAlloc(as, faultAddr))
+            return;
 
-    printf("page fault while in thread [%s] at 0x%p when trying to access 0x%p err_code 0x%x\n", current->name,
-           (void *)cpu_context_get_PC(frame), (void *)faultAddr, cpu_context_get_EX_err(frame));
-    if (cpu_context_is_in_user_mode(frame)) {
+        // PAGE_FAULT is a interrupt with an error code (see exception_wrapper.S)
+        uint32_t error_code = cpu_context_get_EX_err(frame);
+
+        if (!uAddrSpaceSolvePageFault(as, faultAddr, error_code & 0x2))
+            return;
+
+        printf(
+            "page fault while in thread [%s] at 0x%p when trying to access 0x%p err_code 0x%x\n",
+            current->name, (void *)cpu_context_get_PC(frame), (void *)faultAddr, error_code);
         printf("Killing User Thread\n");
         threadExit();
+        return;
     }
     VGAPrintf(RED, BLACK, 0, VGA_HEIGHT - 1, "PAGE FAULT %d", intr);
     (void)intr;
@@ -79,5 +88,6 @@ int exceptionSetup()
         exceptionSetRoutine(i, print_handler);
     }
     exceptionSetRoutine(EXCEPTION_PAGE_FAULT, pagefault_handler);
+
     return 0;
 }

arch/x86/exception_wrappers.S

@@ -165,7 +165,7 @@
         iret
 .endm
 
-/*List of exception w or w/o err codehttps://wiki.osdev.org/Exceptions*/
+/* List of exception w or w/o err code https://wiki.osdev.org/Exceptions */
 .irp exception_id, 8, 10, 11, 12, 13, 14, 17, 30
     exception_mac_with_errcode exception_id
 .endr

core/syscall.c

@@ -61,6 +61,7 @@ int syscallExecute(int syscallId, const struct cpu_state *userCtx)
         case SYSCALL_ID_MMAP: {
             struct uAddrSpace *as;
             uaddr_t uaddr;
+            uaddr_t uaddr_ptr;
             size_t size;
             uint32_t rights;
             uint32_t flags;
@@ -69,15 +70,26 @@ int syscallExecute(int syscallId, const struct cpu_state *userCtx)
             char path[256];
 
             as  = processGetAddrSpace(getCurrentThread()->process);
-            ret = syscallGet5args(userCtx, (unsigned int *)&uaddr, (unsigned int *)&size, (unsigned int *)&rights,
+            ret = syscallGet5args(userCtx, (unsigned int *)&uaddr_ptr, (unsigned int *)&size, (unsigned int *)&rights,
                                   (unsigned int *)&flags, (unsigned int *)&userPath);
+
+            if (memcpyFromUser((vaddr_t)&uaddr, uaddr_ptr, sizeof(uaddr)) != sizeof(uaddr)) {
+                ret = -EFAULT;
+                break;
+            }
+
             strzcpyFromUser((vaddr_t *)path, (uaddr_t *)userPath, sizeof(path));
-            printf("Trying mmap for device %s\n", path);
+
+            printf("Trying mmap for device %s at %lu\n", path, (vaddr_t)uaddr);
             if(strcmp(path, "/dev/zero") == 0){
                 ret = zeroMmap(as, &uaddr, size, rights,flags);
             }
-            printf("ret %d\n", ret);
-            (void)as;
+            if(!ret){
+                if(memcpyToUser(uaddr_ptr, (vaddr_t)&uaddr, sizeof(uaddr)) != sizeof(uaddr)){
+                    ret = -EFAULT;
+                    break;
+                }
+            }
             break;
         }
         default:

core/uaccess.c

@@ -44,6 +44,17 @@ static int memcpyUserMemNoCheck(vaddr_t dest, vaddr_t src, size_t size)
     return size;
 }
 
+int memcpyToUser(uaddr_t to, vaddr_t from, size_t size)
+{
+
+    if ((uint)to < PAGING_BASE_USER_ADDRESS)
+        return -EPERM;
+    if ((uint)to > PAGING_TOP_USER_ADDRESS - size)
+        return -EPERM;
+
+    return memcpyUserMemNoCheck(to, from, size);
+}
+
 int memcpyFromUser(vaddr_t to, uaddr_t from, size_t size)
 {
 

core/uaccess.h

@@ -4,4 +4,5 @@
 #include "stdarg.h"
 
 int memcpyFromUser(vaddr_t to, uaddr_t from, size_t size);
+int memcpyToUser(uaddr_t to, vaddr_t from, size_t size);
 int strzcpyFromUser(vaddr_t *to, uaddr_t *from, size_t size);

core/uaddrspace.c

@@ -250,7 +250,7 @@ uaddr_t sysBrk(struct uAddrSpace *as, uaddr_t newHeapTop)
     incSize = ALIGN(newHeapTop - (as->heapStart + as->heapSize), PAGE_SIZE);
 
     if (incSize < 0){
-        //TODO how to free allocated page by uAddrSpaceCheckNAlloc
+        //TODO how to free allocated page by uAddrSpaceHeapCheckNAlloc
         return as->heapStart + as->heapSize;
     }
 
@@ -259,7 +259,7 @@ uaddr_t sysBrk(struct uAddrSpace *as, uaddr_t newHeapTop)
     return as->heapStart + as->heapSize;
 }
 
-int uAddrSpaceCheckNAlloc(struct uAddrSpace *as, vaddr_t addr)
+int uAddrSpaceHeapCheckNAlloc(struct uAddrSpace *as, vaddr_t addr)
 {
     struct uAddrVirtualReg *newReg;
     int right = PAGING_MEM_USER | PAGING_MEM_WRITE | PAGING_MEM_READ;
@@ -372,3 +372,28 @@ free_reg:
     free(reg);
     return ret;
 }
+
+/**
+ * Check if @param faultAddr could be managed by the uAddrVirtualReg from @param as
+ **/
+int uAddrSpaceSolvePageFault(struct uAddrSpace *as, vaddr_t faultAddr, int isWriteAccess)
+{
+    struct uAddrVirtualReg *reg;
+    int rights = PAGING_MEM_READ;
+
+    reg = findVirtualRegionFromAddr(as, faultAddr, 1);
+
+    if (reg == NULL)
+        return -EFAULT;
+
+    if (isWriteAccess && !(reg->right & PAGING_MEM_WRITE))
+        return -EFAULT;
+
+    if (isWriteAccess)
+        rights |= PAGING_MEM_WRITE;
+
+    if (reg->res->ops->nopage(reg, faultAddr, rights))
+        return -EFAULT;
+
+    return 0;
+}

core/uaddrspace.h

@@ -43,9 +43,10 @@ struct uAddrSpace * uAddrSpaceCreate(struct process *proc);
 int uAddrSpaceDelete(struct uAddrSpace *addr);
 struct mmu_context * uAddrSpaceGetMMUContext(struct uAddrSpace *addr);
 int uAddrSpaceSetHeap(struct uAddrSpace *as, uaddr_t addr, size_t size);
-int uAddrSpaceCheckNAlloc(struct uAddrSpace *as, vaddr_t addr);
+int uAddrSpaceHeapCheckNAlloc(struct uAddrSpace *as, vaddr_t addr);
 uaddr_t sysBrk(struct uAddrSpace *as, uaddr_t newHeapTop);
 
 int uAddrSpaceMmap(struct uAddrSpace *as, uaddr_t *uaddr, size_t size, uint32_t rights,
                    uint32_t flags, struct mappedRessource *res, uint32_t offset);
 int uAddrSpaceUnmap(struct uAddrSpace *as, uaddr_t uaddr, size_t size);
+int uAddrSpaceSolvePageFault(struct uAddrSpace *as, vaddr_t faultAddr, int isWriteAccess);

userspace/libc.c

@@ -4,6 +4,7 @@
 #include "swintr.h"
 #include "syscall.h"
 
+int errno = 0;
 int memcmp(const void *aptr, const void *bptr, size_t size)
 {
     const unsigned char *a = (const unsigned char *)aptr;
@@ -725,7 +726,11 @@ void *realloc(void *ptr, size_t size)
     return new_ptr;
 }
 
-void *mmap(void *addr, size_t len, int prot, int flags, char *path){
+void *mmap(void *addr, size_t len, int prot, int flags, char *path) {
 
-    return (void *)syscall5(SYSCALL_ID_MMAP, (unsigned int)addr, len, prot, flags, (unsigned int)path);
+    int ret = syscall5(SYSCALL_ID_MMAP, (unsigned int)&addr, len, prot, flags, (unsigned int)path);
+    if(!ret)
+        return addr;
+    errno = ret;
+    return (void *)-1;
 }