[PATCH] 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_LAYOUT 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.
---
 arch/riscv/Kconfig.debug |  9 +++++++++
 arch/riscv/mm/init.c     | 30 ++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/arch/riscv/Kconfig.debug b/arch/riscv/Kconfig.debug
index e69de29..cdedfd3 100644
--- a/arch/riscv/Kconfig.debug
+++ b/arch/riscv/Kconfig.debug
@@ -0,0 +1,9 @@
+config DEBUG_VM_LAYOUT
+	bool "Print virtual memory layout on boot up"
+	depends on DEBUG_KERNEL
+	help
+	  Say Y here if you want to dump the kernel virtual memory layout to
+	  dmesg log on boot up. This information is only useful for kernel
+	  developers who are working in architecture specific areas of the
+	  kernel. It is probably not a good idea to enable this feature in a
+	  production kernel.
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 79cfb35..fcb8144 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -55,6 +55,36 @@ void __init mem_init(void)
 	memblock_free_all();
 
 	mem_init_print_info(NULL);
+#ifdef CONFIG_DEBUG_VM_LAYOUT
+#define MLK(b, t) b, t, (((t) - (b)) >> 10)
+#define MLM(b, t) b, t, (((t) - (b)) >> 20)
+#define MLK_ROUNDUP(b, t) b, t, DIV_ROUND_UP(((t) - (b)), SZ_1K)
+
+
+	pr_notice("Virtual kernel memory layout:\n"
+			"    fixmap  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
+			"    vmemmap : 0x%08lx - 0x%08lx   (%4ld MB)\n"
+			"    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
+			"    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
+			"      .init : 0x%px - 0x%px   (%4td kB)\n"
+			"      .text : 0x%px - 0x%px   (%4td kB)\n"
+			"      .data : 0x%px - 0x%px   (%4td kB)\n"
+			"       .bss : 0x%px - 0x%px   (%4td kB)\n",
+
+			MLK(FIXADDR_START, FIXADDR_TOP),
+			MLM(VMEMMAP_START, VMEMMAP_END),
+			MLM(VMALLOC_START, VMALLOC_END),
+			MLM(PAGE_OFFSET, (unsigned long)high_memory),
+
+			MLK_ROUNDUP(__init_begin, __init_end),
+			MLK_ROUNDUP(_text, _etext),
+			MLK_ROUNDUP(_sdata, _edata),
+			MLK_ROUNDUP(__bss_start, __bss_stop));
+
+#undef MLK
+#undef MLM
+#undef MLK_ROUNDUP
+#endif
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD
-- 
2.7.4