move McKernel out of Linux kernel virtual

arch/x86_64/kernel/include/arch-memory.h

@@ -42,10 +42,24 @@
 
 #define USER_END           0x0000800000000000UL
 #define TASK_UNMAPPED_BASE 0x00002AAAAAA00000UL
+
+/*
+ * Canonical negative addresses (i.e., the smallest kernel virtual address)
+ * on x86 64 bit mode (in its most restricted 48 bit format) starts from
+ * 0xffff800000000000, but Linux starts mapping physical memory at 0xffff880000000000.
+ * The 0x80000000000 long gap (8TBs, i.e., 16 PGD level entries in the page tables)
+ * is used for Xen hyervisor (see arch/x86/include/asm/page.h) and that is
+ * what we utilize for McKernel.
+ * This gives us the benefit of being able to use Linux kernel virtual
+ * addresses identically as in Linux.
+ *
+ * NOTE: update these also in eclair.c when modified!
+ */
 #define MAP_ST_START       0xffff800000000000UL
-#define MAP_VMAP_START     0xfffff00000000000UL
+#define MAP_VMAP_START     0xffff850000000000UL
-#define MAP_FIXED_START    0xffffffff70000000UL
+#define MAP_FIXED_START    0xffff860000000000UL
-#define MAP_KERNEL_START   0xffffffff80000000UL
+#define MAP_KERNEL_START   0xffff870000000000UL
+#define LINUX_PAGE_OFFSET  0xffff880000000000UL
 #define STACK_TOP(region)  ((region)->user_end)
 
 #define MAP_VMAP_SIZE      0x0000000100000000UL

arch/x86_64/kernel/memory.c

@@ -2539,6 +2539,30 @@ static void init_normal_area(struct page_table *pt)
 		virt += LARGE_PAGE_SIZE;
 	}
 }
+
+static void init_linux_kernel_mapping(struct page_table *pt)
+{
+	unsigned long map_start, map_end, phys;
+	void *virt;
+
+	/* Map 2 TB for now */
+	map_start = 0;
+	map_end = 0x20000000000;
+
+	virt = (void *)LINUX_PAGE_OFFSET;
+
+	kprintf("Linux kernel virtual: 0x%lx - 0x%lx -> 0x%lx - 0x%lx\n",
+		LINUX_PAGE_OFFSET, LINUX_PAGE_OFFSET + map_end, 0, map_end);
+
+	for (phys = map_start; phys < map_end; phs += LARGE_PAGE_SIZE) {
+		if (set_pt_large_page(pt, virt, phys, PTATTR_WRITABLE) != 0) {
+			kprintf("%s: error setting mapping for 0x%lx\n",
+				__func__, virt);
+		}
+		virt += LARGE_PAGE_SIZE;
+	}
+}
+
 void init_text_area(struct page_table *pt)
 {
 	unsigned long __end, phys, virt;
@@ -2627,6 +2651,7 @@ void init_page_table(void)
 
 	/* Normal memory area */
 	init_normal_area(init_pt);
+	init_linux_kernel_mapping(init_pt);
 	init_fixed_area(init_pt);
 	init_low_area(init_pt);
 	init_text_area(init_pt);

kernel/config/smp-x86.lds

@@ -5,7 +5,7 @@ PHDRS
 }
 SECTIONS
 {
-	. = 0xffffffff80001000;
+	. = 0xffff870000001000;
 	_head = .;
 
 	.text : {