boot/efi/arm: remove identity mapping for EFI code and data segments

All the regions allocated via platform_allocate_region() are mapped to a
high virtual address so there's no need to do identity mapping for them
any more.

Copy kernel_args to a region allocated via platform_allocate_region() so it
will be mapped similarly.

Identity mapping is still needed for trampoline code for jumping to the kernel

Change-Id: I844a7a789b440a38521db49adc077bb77e658ddf
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4865
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: Fredrik Holmqvist <[email protected]>
Reviewed-by: Alex von Gluck IV <[email protected]>

src/system/boot/platform/efi/arch/arm/arch_mmu.cpp

@@ -27,6 +27,10 @@ static uint32_t *sNextPageTable = NULL;
 static uint32_t *sLastPageTable = NULL;
 
 
+extern "C" void arch_enter_kernel(uint32_t ttbr, struct kernel_args *kernelArgs,
+	addr_t kernelEntry, addr_t kernelStackTop);
+
+
 static void
 dump_page_dir(void)
 {
@@ -153,8 +157,6 @@ build_physical_memory_list(size_t memory_map_size,
 		switch (entry->Type) {
 		case EfiLoaderCode:
 		case EfiLoaderData:
-			entry->VirtualStart = entry->PhysicalStart;
-			break;
 		case EfiBootServicesCode:
 		case EfiBootServicesData:
 		case EfiConventionalMemory: {
@@ -308,21 +310,6 @@ arch_mmu_generate_post_efi_page_tables(size_t memory_map_size,
 	build_physical_memory_list(memory_map_size, memory_map,
 		descriptor_size, descriptor_version);
 
-	for (size_t i = 0; i < memory_map_size / descriptor_size; ++i) {
-		efi_memory_descriptor* entry =
-			(efi_memory_descriptor *)(memory_map_addr + i * descriptor_size);
-		switch (entry->Type) {
-		case EfiLoaderCode:
-		case EfiLoaderData:
-			map_range(entry->VirtualStart, entry->PhysicalStart,
-				entry->NumberOfPages * B_PAGE_SIZE,
-				ARM_MMU_L2_FLAG_B | ARM_MMU_L2_FLAG_C | ARM_MMU_L2_FLAG_AP_RW);
-			break;
-		default:
-			;
-		}
-	}
-
 	for (size_t i = 0; i < memory_map_size / descriptor_size; ++i) {
 		efi_memory_descriptor* entry =
 			(efi_memory_descriptor *)(memory_map_addr + i * descriptor_size);
@@ -341,6 +328,10 @@ arch_mmu_generate_post_efi_page_tables(size_t memory_map_size,
 			ARM_MMU_L2_FLAG_B | ARM_MMU_L2_FLAG_C | ARM_MMU_L2_FLAG_AP_RW);
 	}
 
+	// identity mapping for entry.S trampoline
+	map_range((uint32_t)arch_enter_kernel, (uint32_t)arch_enter_kernel, B_PAGE_SIZE,
+		ARM_MMU_L2_FLAG_B | ARM_MMU_L2_FLAG_C | ARM_MMU_L2_FLAG_AP_RW);
+
 	map_range_to_new_area(gKernelArgs.arch_args.uart.regs, ARM_MMU_L2_FLAG_B);
 
 	sort_address_ranges(gKernelArgs.virtual_allocated_range,

src/system/boot/platform/efi/arch/arm/arch_start.cpp

@@ -16,7 +16,7 @@
 #define ALIGN_MEMORY_MAP	4
 
 
-extern "C" void arch_enter_kernel(uint32_t ttbr, struct kernel_args *kernelArgs,
+extern "C" void arch_enter_kernel(uint32_t ttbr, addr_t kernelArgs,
 	addr_t kernelEntry, addr_t kernelStackTop);
 
 // From arch_mmu.cpp
@@ -79,6 +79,16 @@ memory_region_type_str(int type)
 void
 arch_start_kernel(addr_t kernelEntry)
 {
+	// Allocate virtual memory for kernel args
+	struct kernel_args *kernelArgs = NULL;
+	if (platform_allocate_region((void **)&kernelArgs,
+			sizeof(struct kernel_args), 0, false) != B_OK)
+		panic("Failed to allocate kernel args.");
+
+	addr_t virtKernelArgs;
+	platform_bootloader_address_to_kernel_address((void*)kernelArgs,
+		&virtKernelArgs);
+
 	// Prepare to exit EFI boot services.
 	// Read the memory map.
 	// First call is to determine the buffer size.
@@ -164,14 +174,19 @@ arch_start_kernel(addr_t kernelEntry)
 	arch_mmu_post_efi_setup(memory_map_size, memory_map,
 			descriptor_size, descriptor_version);
 
+	// Copy final kernel args
+	// This should be the last step before jumping to the kernel
+	// as there are some fixups happening to kernel_args even in the last minute
+	memcpy(kernelArgs, &gKernelArgs, sizeof(struct kernel_args));
+
 	//smp_boot_other_cpus(final_pml4, kernelEntry);
 
 	// Enter the kernel!
 	dprintf("arch_enter_kernel(ttbr0: 0x%08x, kernelArgs: 0x%08x, "
 		"kernelEntry: 0x%08x, sp: 0x%08x)\n",
-		final_ttbr0, (uint32_t)&gKernelArgs, (uint32_t)kernelEntry,
+		final_ttbr0, (uint32_t)virtKernelArgs, (uint32_t)kernelEntry,
 		(uint32_t)(gKernelArgs.cpu_kstack[0].start + gKernelArgs.cpu_kstack[0].size));
 
-	arch_enter_kernel(final_ttbr0, &gKernelArgs, kernelEntry,
+	arch_enter_kernel(final_ttbr0, virtKernelArgs, kernelEntry,
 		gKernelArgs.cpu_kstack[0].start + gKernelArgs.cpu_kstack[0].size);
 }