[RESEND PATCH V2 5/5] riscv: crash_core: Export kernel vm layout, phys_ram_base

[Xianting Tian]

These infos are needed by the kdump crash tool. Since these values change
from time to time, it is preferable to export them via vmcoreinfo than to
change the crash's code frequently.

Signed-off-by: Xianting Tian <xianting.tian at linux.alibaba.com>
---
 .../admin-guide/kdump/vmcoreinfo.rst          | 31 +++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst
index 8419019b6a88..6b76284a503c 100644
--- a/Documentation/admin-guide/kdump/vmcoreinfo.rst
+++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst
@@ -595,3 +595,34 @@ X2TLB
 -----
 
 Indicates whether the crashed kernel enabled SH extended mode.
+
+RISCV64
+=======
+
+VA_BITS
+-------
+
+The maximum number of bits for virtual addresses. Used to compute the
+virtual memory ranges.
+
+PAGE_OFFSET
+-----------
+
+Indicates the virtual kernel start address of direct-mapped RAM region.
+
+phys_ram_base
+-------------
+
+Indicates the start physical RAM address.
+
+MODULES_VADDR|MODULES_END|VMALLOC_START|VMALLOC_END|VMEMMAP_START|VMEMMAP_END
+-----------------------------------------------------------------------------
+KASAN_SHADOW_START|KASAN_SHADOW_END|KERNEL_LINK_ADDR|ADDRESS_SPACE_END
+----------------------------------------------------------------------
+
+Used to get the correct ranges:
+	MODULES_VADDR ~ MODULES_END : Kernel module space.
+	VMALLOC_START ~ VMALLOC_END : vmalloc() / ioremap() space.
+	VMEMMAP_START ~ VMEMMAP_END : vmemmap region, used for struct page array.
+	KASAN_SHADOW_START ~ KASAN_SHADOW_END : kasan shadow space.
+	KERNEL_LINK_ADDR ~ ADDRESS_SPACE_END : Kernel link and BPF space.
-- 
2.17.1