RISC-V: Add address map dumper

Add support for dumping the kernel address space layout to the console.
User can enable CONFIG_DEBUG_VM to dump the virtual memory region into
dmesg buffer during boot-up.

Signed-off-by: Yash Shah <yash.shah@sifive.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
[paul.walmsley@sifive.com: dropped .init/.text/.data/.bss prints;
 added PCI legacy I/O region display]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/mm/init.c

@@ -45,6 +45,37 @@ void setup_zero_page(void)
 	memset((void *)empty_zero_page, 0, PAGE_SIZE);
 }
 
+#ifdef CONFIG_DEBUG_VM
+static inline void print_mlk(char *name, unsigned long b, unsigned long t)
+{
+	pr_notice("%12s : 0x%08lx - 0x%08lx   (%4ld kB)\n", name, b, t,
+		  (((t) - (b)) >> 10));
+}
+
+static inline void print_mlm(char *name, unsigned long b, unsigned long t)
+{
+	pr_notice("%12s : 0x%08lx - 0x%08lx   (%4ld MB)\n", name, b, t,
+		  (((t) - (b)) >> 20));
+}
+
+static void print_vm_layout(void)
+{
+	pr_notice("Virtual kernel memory layout:\n");
+	print_mlk("fixmap", (unsigned long)FIXADDR_START,
+		  (unsigned long)FIXADDR_TOP);
+	print_mlm("pci io", (unsigned long)PCI_IO_START,
+		  (unsigned long)PCI_IO_END);
+	print_mlm("vmemmap", (unsigned long)VMEMMAP_START,
+		  (unsigned long)VMEMMAP_END);
+	print_mlm("vmalloc", (unsigned long)VMALLOC_START,
+		  (unsigned long)VMALLOC_END);
+	print_mlm("lowmem", (unsigned long)PAGE_OFFSET,
+		  (unsigned long)high_memory);
+}
+#else
+static void print_vm_layout(void) { }
+#endif /* CONFIG_DEBUG_VM */
+
 void __init mem_init(void)
 {
 #ifdef CONFIG_FLATMEM
@@ -55,6 +86,7 @@ void __init mem_init(void)
 	memblock_free_all();
 
 	mem_init_print_info(NULL);
+	print_vm_layout();
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD