[PATCH v2] RISC-V: Add address map dumper

[Yash Shah]

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@xxxxxxxxxx>
---
This patch is based on Linux 5.4-rc6 and tested on SiFive HiFive
Unleashed board.

Changes in v2:
- Avoid #ifdefs inside functions
- Helper functions instead of macros
- Drop newly added CONFIG_DEBUG_VM_LAYOUT, instead use CONFIG_DEBUG_VM
---
 arch/riscv/mm/init.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 573463d..7828136 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -45,6 +45,41 @@ 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("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);
+	print_mlk(".init", (unsigned long)__init_begin,
+		  (unsigned long)__init_end);
+	print_mlk(".text", (unsigned long)_text, (unsigned long)_etext);
+	print_mlk(".data", (unsigned long)_sdata, (unsigned long)_edata);
+	print_mlk(".bss", (unsigned long)__bss_start,
+		  (unsigned long)__bss_stop);
+}
+#else
+static void print_vm_layout(void) { }
+#endif /* CONFIG_DEBUG_VM */
+
 void __init mem_init(void)
 {
 #ifdef CONFIG_FLATMEM
@@ -55,6 +90,7 @@ void __init mem_init(void)
 	memblock_free_all();
 
 	mem_init_print_info(NULL);
+	print_vm_layout();
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD
-- 
2.7.4