kernel/{x86, vm}: Add more error checks in VM initialization

src/system/kernel/arch/x86/paging/32bit/X86PagingMethod32Bit.cpp

@@ -101,6 +101,11 @@ X86PagingMethod32Bit::PhysicalPageSlotPool::InitInitial(kernel_args* args)
 	size_t areaSize = B_PAGE_SIZE + sizeof(PhysicalPageSlot[1024]);
 	page_table_entry* pageTable = (page_table_entry*)vm_allocate_early(args,
 		areaSize, ~0L, B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA, 0);
+	if (pageTable == 0) {
+		panic("X86PagingMethod32Bit::PhysicalPageSlotPool::InitInitial(): "
+			"Failed to allocate memory for page table!");
+		return B_ERROR;
+	}
 
 	// prepare the page table
 	_EarlyPreparePageTables(pageTable, virtualBase, 1024 * B_PAGE_SIZE);

src/system/kernel/arch/x86/paging/pae/X86PagingMethodPAE.cpp

@@ -409,6 +409,11 @@ X86PagingMethodPAE::PhysicalPageSlotPool::InitInitial(
 		+ sizeof(PhysicalPageSlot[kPAEPageTableEntryCount]);
 	pae_page_table_entry* pageTable = (pae_page_table_entry*)vm_allocate_early(
 		args, areaSize, ~0L, B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA, 0);
+	if (pageTable == 0) {
+		panic("X86PagingMethodPAE::PhysicalPageSlotPool::InitInitial(): Failed "
+			"to allocate memory for page table!");
+		return B_ERROR;
+	}
 
 	// clear the page table and put it in the page dir
 	memset(pageTable, 0, B_PAGE_SIZE);

src/system/kernel/vm/vm.cpp

@@ -3910,6 +3910,10 @@ vm_allocate_early(kernel_args* args, size_t virtualSize, size_t physicalSize,
 	// find the vaddr to allocate at
 	addr_t virtualBase = allocate_early_virtual(args, virtualSize, alignment);
 	//dprintf("vm_allocate_early: vaddr 0x%lx\n", virtualBase);
+	if (virtualBase == 0) {
+		panic("vm_allocate_early: could not allocate virtual address\n");
+		return 0;
+	}
 
 	// map the pages
 	for (uint32 i = 0; i < PAGE_ALIGN(physicalSize) / B_PAGE_SIZE; i++) {