[PATCH] x86_64_init: Refresh vmalloc region addresses in POST_RELOC instead of POST_GDB phase

[Tao Liu <ltao@xxxxxxxxxx>]

Previously for x86_64, when memory is randomized, the region addresses
such as vmalloc_start_addr/vmemmap_vaddr/modules_vaddr are firstly set
to a default value before POST_RELOC phase, then get refreshed with the
actual value in POST_GDB phase.

However for crash mininal mode, POST_GDB phase is not called, which
leaving the region addresses unrefreshed and incorrect. As a consequence,
the x86_64_IS_VMALLOC_ADDR check will give a faulty result when
value_search tries to search a symbol by address.

For example, in crash minimal mode we can observe the following issue:

    crash> dis -f panic
    dis: cannot resolve address: ffffffffb20e0d30

    crash> sym panic
    ffffffffb20e0d30 (T) panic /usr/src/debug/kernel-4.18.0-290/linux-4.18.0-290/kernel/panic.c: 168
    crash> sym ffffffffb20e0d30
    symbol not found: ffffffffb20e0d30

In this patch, we will move the code which update the region addresses into
POST_RELOC phase, so in mininal mode the regions can get the correct
addresses.

Signed-off-by: Tao Liu <ltao@xxxxxxxxxx>
---
 x86_64.c | 52 ++++++++++++++++++++++++++--------------------------
 1 file changed, 26 insertions(+), 26 deletions(-)

diff --git a/x86_64.c b/x86_64.c
index 552d619..2fb1277 100644
--- a/x86_64.c
+++ b/x86_64.c
@@ -384,6 +384,31 @@ x86_64_init(int when)
 				"page_offset_base", QUIET|FAULT_ON_ERROR);
 			machdep->kvbase = machdep->machspec->page_offset;
 			machdep->identity_map_base = machdep->machspec->page_offset;
+
+			readmem(symbol_value("vmalloc_base"), KVADDR,
+					&machdep->machspec->vmalloc_start_addr,
+					sizeof(ulong), "vmalloc_base", FAULT_ON_ERROR);
+			if (machdep->flags & VM_5LEVEL)
+				machdep->machspec->vmalloc_end =
+					machdep->machspec->vmalloc_start_addr + TERABYTES(1280) - 1;
+			else
+				machdep->machspec->vmalloc_end =
+					machdep->machspec->vmalloc_start_addr + TERABYTES(32) - 1;
+			if (kernel_symbol_exists("vmemmap_base")) {
+				readmem(symbol_value("vmemmap_base"), KVADDR,
+					&machdep->machspec->vmemmap_vaddr, sizeof(ulong),
+					"vmemmap_base", FAULT_ON_ERROR);
+				machdep->machspec->vmemmap_end = 
+					machdep->machspec->vmemmap_vaddr +
+					TERABYTES(1) - 1;
+			} else {
+				machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_2_6_31;
+				machdep->machspec->vmemmap_end = VMEMMAP_END_2_6_31;
+			}
+			machdep->machspec->modules_vaddr = __START_KERNEL_map + 
+				(machdep->machspec->kernel_image_size ?
+				machdep->machspec->kernel_image_size : GIGABYTES(1));
+			machdep->machspec->modules_end = MODULES_END_2_6_31;
 		}
 		break;
 
@@ -414,32 +439,7 @@ x86_64_init(int when)
 			machdep->machspec->modules_end = MODULES_END_2_6_27;
 		}
 		if (THIS_KERNEL_VERSION >= LINUX(2,6,31)) {
-			if (machdep->flags & RANDOMIZED) {
-				readmem(symbol_value("vmalloc_base"), KVADDR,
-					&machdep->machspec->vmalloc_start_addr,
-					sizeof(ulong), "vmalloc_base", FAULT_ON_ERROR);
-				if (machdep->flags & VM_5LEVEL)
-					machdep->machspec->vmalloc_end =
-						machdep->machspec->vmalloc_start_addr + TERABYTES(1280) - 1;
-				else
-					machdep->machspec->vmalloc_end =
-						machdep->machspec->vmalloc_start_addr + TERABYTES(32) - 1;
-				if (kernel_symbol_exists("vmemmap_base")) {
-					readmem(symbol_value("vmemmap_base"), KVADDR,
-						&machdep->machspec->vmemmap_vaddr, sizeof(ulong),
-						"vmemmap_base", FAULT_ON_ERROR);
-					machdep->machspec->vmemmap_end = 
-						machdep->machspec->vmemmap_vaddr +
-						TERABYTES(1) - 1;
-				} else {
-					machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_2_6_31;
-					machdep->machspec->vmemmap_end = VMEMMAP_END_2_6_31;
-				}
-				machdep->machspec->modules_vaddr = __START_KERNEL_map + 
-					(machdep->machspec->kernel_image_size ?
-					machdep->machspec->kernel_image_size : GIGABYTES(1));
-				machdep->machspec->modules_end = MODULES_END_2_6_31;
-			} else {
+			if (!(machdep->flags & RANDOMIZED)) {
 				machdep->machspec->vmalloc_start_addr = VMALLOC_START_ADDR_2_6_31;
 				machdep->machspec->vmalloc_end = VMALLOC_END_2_6_31;
 				machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_2_6_31;
-- 
2.33.1

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