From 1f46427d16f0f099ae2acf98680f81295d6fa895 Mon Sep 17 00:00:00 2001
From: David Karoly <karolyd577@gmail.com>
Date: Sun, 28 Nov 2021 16:13:11 +0100
Subject: [PATCH] kernel/arch/arm: introduce virtual_ranges_to_keep

Change-Id: I36b8b871a103f2be87c600fc0b0a12f7ceff0ae4
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4743
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
---
 .../kernel/arch/arm/arch_kernel_args.h        |  6 ++++
 src/system/kernel/arch/arm/arch_vm.cpp        | 34 +++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/headers/private/kernel/arch/arm/arch_kernel_args.h b/headers/private/kernel/arch/arm/arch_kernel_args.h
index 78b34058d7..513848004b 100644
--- a/headers/private/kernel/arch/arm/arch_kernel_args.h
+++ b/headers/private/kernel/arch/arm/arch_kernel_args.h
@@ -16,6 +16,8 @@
 
 #define _PACKED __attribute__((packed))
 
+#define MAX_VIRTUAL_RANGES_TO_KEEP	32
+
 
 // kernel args
 typedef struct {
@@ -30,6 +32,10 @@ typedef struct {
 	uint32	vir_pgdir;
 	uint32	next_pagetable;
 
+	// The virtual ranges we want to keep in the kernel.
+	uint32		num_virtual_ranges_to_keep;
+	addr_range	virtual_ranges_to_keep[MAX_VIRTUAL_RANGES_TO_KEEP];
+
 	// needed for UEFI, otherwise kernel acpi support can't find ACPI root
 	FixedWidthPointer<void> acpi_root;
 	FixedWidthPointer<void> fdt;
diff --git a/src/system/kernel/arch/arm/arch_vm.cpp b/src/system/kernel/arch/arm/arch_vm.cpp
index a17f317d70..22610da76c 100644
--- a/src/system/kernel/arch/arm/arch_vm.cpp
+++ b/src/system/kernel/arch/arm/arch_vm.cpp
@@ -16,6 +16,7 @@
 #include <boot/kernel_args.h>
 
 #include <vm/vm.h>
+#include <vm/VMAddressSpace.h>
 #include <vm/vm_types.h>
 #include <arch/vm.h>
 //#include <arch_mmu.h>
@@ -55,6 +56,39 @@ arch_vm_init_post_area(kernel_args *args)
 status_t
 arch_vm_init_end(kernel_args *args)
 {
+	TRACE(("arch_vm_init_end(): %" B_PRIu32 " virtual ranges to keep:\n",
+		args->arch_args.num_virtual_ranges_to_keep));
+
+	for (int i = 0; i < (int)args->arch_args.num_virtual_ranges_to_keep; i++) {
+		addr_range &range = args->arch_args.virtual_ranges_to_keep[i];
+
+		TRACE(("  start: %p, size: %#" B_PRIxSIZE "\n", (void*)range.start, range.size));
+
+		// skip ranges outside the kernel address space
+		if (!IS_KERNEL_ADDRESS(range.start)) {
+			TRACE(("    no kernel address, skipping...\n"));
+			continue;
+		}
+
+		phys_addr_t physicalAddress;
+		void *address = (void*)range.start;
+		if (vm_get_page_mapping(VMAddressSpace::KernelID(), range.start,
+			&physicalAddress) != B_OK)
+			panic("arch_vm_init_end(): No page mapping for %p\n", address);
+
+		area_id area = vm_map_physical_memory(VMAddressSpace::KernelID(),
+			"boot loader reserved area", &address,
+			B_EXACT_ADDRESS, range.size,
+			B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA,
+			physicalAddress, true);
+
+		if (area < 0) {
+			panic("arch_vm_init_end(): Failed to create area for boot loader "
+				"reserved area: %p - %p\n", (void*)range.start,
+				(void*)(range.start + range.size));
+		}
+	}
+
 	// Throw away all mappings that are unused by the kernel
 	vm_free_unused_boot_loader_range(KERNEL_LOAD_BASE, KERNEL_SIZE);