Unmap(),Protect(): Removed goto programming by a do {} while loop. Also fixed

problem with potential integer overflow at the end of the address space.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@37190 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/arch/x86/paging/32bit/X86VMTranslationMap32Bit.cpp

@@ -211,24 +211,21 @@ X86VMTranslationMap32Bit::Map(addr_t va, phys_addr_t pa, uint32 attributes,
 status_t
 X86VMTranslationMap32Bit::Unmap(addr_t start, addr_t end)
 {
-	page_directory_entry *pd = fPagingStructures->pgdir_virt;
-
 	start = ROUNDDOWN(start, B_PAGE_SIZE);
-	end = ROUNDUP(end, B_PAGE_SIZE);
-
-	TRACE("unmap_tmap: asked to free pages 0x%lx to 0x%lx\n", start, end);
-
-restart:
 	if (start >= end)
 		return B_OK;
 
+	TRACE("unmap_tmap: asked to free pages 0x%lx to 0x%lx\n", start, end);
+
+	page_directory_entry *pd = fPagingStructures->pgdir_virt;
+
+	do {
 		int index = VADDR_TO_PDENT(start);
 		if ((pd[index] & X86_PDE_PRESENT) == 0) {
-		// no pagetable here, move the start up to access the next page table
+			// no page table here, move the start up to access the next page
-		start = ROUNDUP(start + 1, B_PAGE_SIZE * 1024);
+			// table
-		if (start == 0)
+			start = ROUNDUP(start + 1, kPageTableAlignment);
-			return B_OK;
+			continue;
-		goto restart;
 		}
 
 		struct thread* thread = thread_get_current_thread();
@@ -253,15 +250,14 @@ restart:
 
 			if ((oldEntry & X86_PTE_ACCESSED) != 0) {
 				// Note, that we only need to invalidate the address, if the
-			// accessed flags was set, since only then the entry could have been
+				// accessed flags was set, since only then the entry could have
-			// in any TLB.
+				// been in any TLB.
 				InvalidatePage(start);
 			}
 		}
+	} while (start != 0 && start < end);
 
-	pinner.Unlock();
+	return B_OK;
-
-	goto restart;
 }
 
 
@@ -641,9 +637,9 @@ status_t
 X86VMTranslationMap32Bit::Protect(addr_t start, addr_t end, uint32 attributes,
 	uint32 memoryType)
 {
-	page_directory_entry *pd = fPagingStructures->pgdir_virt;
-
 	start = ROUNDDOWN(start, B_PAGE_SIZE);
+	if (start >= end)
+		return B_OK;
 
 	TRACE("protect_tmap: pages 0x%lx to 0x%lx, attributes %lx\n", start, end,
 		attributes);
@@ -657,17 +653,15 @@ X86VMTranslationMap32Bit::Protect(addr_t start, addr_t end, uint32 attributes,
 	} else if ((attributes & B_KERNEL_WRITE_AREA) != 0)
 		newProtectionFlags = X86_PTE_WRITABLE;
 
-restart:
+	page_directory_entry *pd = fPagingStructures->pgdir_virt;
-	if (start >= end)
-		return B_OK;
 
+	do {
 		int index = VADDR_TO_PDENT(start);
 		if ((pd[index] & X86_PDE_PRESENT) == 0) {
-		// no pagetable here, move the start up to access the next page table
+			// no page table here, move the start up to access the next page
-		start = ROUNDUP(start + 1, B_PAGE_SIZE * 1024);
+			// table
-		if (start == 0)
+			start = ROUNDUP(start + 1, kPageTableAlignment);
-			return B_OK;
+			continue;
-		goto restart;
 		}
 
 		struct thread* thread = thread_get_current_thread();
@@ -692,7 +686,8 @@ restart:
 			while (true) {
 				oldEntry = X86PagingMethod32Bit::TestAndSetPageTableEntry(
 					&pt[index],
-				(entry & ~(X86_PTE_PROTECTION_MASK | X86_PTE_MEMORY_TYPE_MASK))
+					(entry & ~(X86_PTE_PROTECTION_MASK
+							| X86_PTE_MEMORY_TYPE_MASK))
 						| newProtectionFlags
 						| X86PagingMethod32Bit::MemoryTypeToPageTableEntryFlags(
 							memoryType),
@@ -704,15 +699,14 @@ restart:
 
 			if ((oldEntry & X86_PTE_ACCESSED) != 0) {
 				// Note, that we only need to invalidate the address, if the
-			// accessed flag was set, since only then the entry could have been
+				// accessed flag was set, since only then the entry could have
-			// in any TLB.
+				// been in any TLB.
 				InvalidatePage(start);
 			}
 		}
+	} while (start != 0 && start < end);
 
-	pinner.Unlock();
+	return B_OK;
-
-	goto restart;
 }