bootloader/bios_ia32: Restore split between kernel and identity map allocation.

This mostly reverts commit 19141f2110,
thus restoring most of the changes from 8b813adf6d.

However, we keep these ranges inside the kernel args ranges for now,
as they're used in the 32-bit non-PAE case at least.

Change-Id: I966d3269414dd02713cdda9852f5a4a212d85be5
Reviewed-on: https://review.haiku-os.org/c/haiku/+/8463
Reviewed-by: waddlesplash <[email protected]>

src/system/boot/platform/bios_ia32/mmu.cpp

@@ -81,6 +81,7 @@ static uint32 *sPageDirectory = 0;
 #ifdef _PXE_ENV
 
 static addr_t sNextPhysicalAddress = 0x112000;
+static addr_t sNextPhysicalKernelAddress = kIdentityMapEnd;
 static addr_t sNextVirtualAddress = KERNEL_LOAD_BASE + kMaxKernelSize;
 
 static addr_t sNextPageTableAddress = 0x7d000;
@@ -90,6 +91,7 @@ static const uint32 kPageTableRegionEnd = 0x8b000;
 #else
 
 static addr_t sNextPhysicalAddress = 0x100000;
+static addr_t sNextPhysicalKernelAddress = kIdentityMapEnd;
 static addr_t sNextVirtualAddress = KERNEL_LOAD_BASE + kMaxKernelSize;
 
 static addr_t sNextPageTableAddress = 0x90000;
@@ -100,7 +102,7 @@ static const uint32 kPageTableRegionEnd = 0x9e000;
 
 
 static addr_t
-get_next_virtual_address(size_t size)
+allocate_virtual(size_t size)
 {
 	addr_t address = sNextVirtualAddress;
 	sNextVirtualAddress += size;
@@ -110,21 +112,29 @@ get_next_virtual_address(size_t size)
 
 
 static addr_t
-get_next_physical_address(size_t size)
+allocate_physical(size_t size, bool inIdentityMap = true)
 {
 	if ((size % B_PAGE_SIZE) != 0)
 		panic("request for non-page-aligned physical memory!");
 
-	uint64 base;
+	addr_t* nextAddress = &sNextPhysicalKernelAddress;
+	if (inIdentityMap) {
+		nextAddress = &sNextPhysicalAddress;
+		if ((*nextAddress + size) > kIdentityMapEnd) {
+			panic("request too large for identity-map physical memory!");
+			return 0;
+		}
+	}
+
+	uint64 base = *nextAddress;
 	if (!get_free_address_range(gKernelArgs.physical_allocated_range,
-			gKernelArgs.num_physical_allocated_ranges, sNextPhysicalAddress,
-			size, &base)) {
+			gKernelArgs.num_physical_allocated_ranges, base, size, &base)) {
 		panic("Out of physical memory!");
 		return 0;
 	}
 
 	insert_physical_allocated_range(base, size);
-	sNextPhysicalAddress = base + size;
+	*nextAddress = base + size;
 		// TODO: Can overflow theoretically.
 
 	return base;
@@ -134,14 +144,14 @@ get_next_physical_address(size_t size)
 static addr_t
 get_next_virtual_page()
 {
-	return get_next_virtual_address(B_PAGE_SIZE);
+	return allocate_virtual(B_PAGE_SIZE);
 }
 
 
 static addr_t
 get_next_physical_page()
 {
-	return get_next_physical_address(B_PAGE_SIZE);
+	return allocate_physical(B_PAGE_SIZE, false);
 }
 
 
@@ -154,7 +164,7 @@ get_next_page_table()
 
 	addr_t address = sNextPageTableAddress;
 	if (address >= kPageTableRegionEnd)
-		return (uint32 *)get_next_physical_page();
+		return (uint32 *)allocate_physical(B_PAGE_SIZE);
 
 	sNextPageTableAddress += B_PAGE_SIZE;
 	return (uint32 *)address;
@@ -324,7 +334,7 @@ init_page_directory(void)
 	TRACE("init_page_directory\n");
 
 	// allocate a new pgdir
-	sPageDirectory = (uint32 *)get_next_physical_page();
+	sPageDirectory = (uint32 *)allocate_physical(B_PAGE_SIZE);
 	gKernelArgs.arch_args.phys_pgdir = (uint32)sPageDirectory;
 
 	// clear out the pgdir
@@ -636,7 +646,9 @@ mmu_init(void)
 
 	gKernelArgs.physical_allocated_range[0].start = sNextPhysicalAddress;
 	gKernelArgs.physical_allocated_range[0].size = 0;
-	gKernelArgs.num_physical_allocated_ranges = 1;
+	gKernelArgs.physical_allocated_range[1].start = sNextPhysicalKernelAddress;
+	gKernelArgs.physical_allocated_range[1].size = 0;
+	gKernelArgs.num_physical_allocated_ranges = 2;
 		// remember the start of the allocated physical pages
 
 	init_page_directory();
@@ -818,13 +830,10 @@ ssize_t
 platform_allocate_heap_region(size_t size, void **_base)
 {
 	size = ROUNDUP(size, B_PAGE_SIZE);
-	addr_t base = get_next_physical_address(size);
+	addr_t base = allocate_physical(size);
 	if (base == 0)
 		return B_NO_MEMORY;
 
-	if ((base + size) > kIdentityMapEnd)
-		panic("platform_allocate_heap_region: region end is beyond identity map");
-
 	*_base = (void*)base;
 	return size;
 }