File 0009-arm64-use-dedicated-bits-to-record-the-VA-space-layo.patch of Package crash.24895

From bf1379a8b6ff8d6a8fa12978f7194f15f85c4380 Mon Sep 17 00:00:00 2001
From: Pingfan Liu <piliu@redhat.com>
Date: Fri, 2 Jul 2021 10:14:23 +0800
Subject: [PATCH] arm64: use dedicated bits to record the VA space layout
 changes

arm64 memory layout experiences big changes due to the following kernel
commits in date descending order:
  5. 7bc1a0f9e176 arm64: mm: use single quantity to represent the PA to VA translation
  4. b6d00d47e81a arm64: mm: Introduce 52-bit Kernel VAs
  3. 5383cc6efed1 arm64: mm: Introduce vabits_actual
  2. 14c127c957c1 arm64: mm: Flip kernel VA space
  1. f80fb3a3d508 arm64: add support for kernel ASLR

For 1, crash has already used NEW_VMEMMAP to trace it.
For 2, crash lacks a flag to tag it and handle it differently.
For 3, two important kernel variables vabits_actual and physvirt_offset
are introduced.
For 4, since it comes immediately after 3, crash-utility does not need
to distinguish it.
For 5, kernel variable phyvirt_offset is removed

These changes have effects on PTOV()/VTOP() formula. So introducing
two bits HAS_PHYSVIRT_OFFSET and FLIPPED_VM as hint to apply different
formula.

Signed-off-by: Pingfan Liu <piliu@redhat.com>
---
 arm64.c | 10 ++++++++++
 defs.h  |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/arm64.c b/arm64.c
index 149db36..b04369f 100644
--- a/arm64.c
+++ b/arm64.c
@@ -563,6 +563,10 @@ arm64_dump_machdep_table(ulong arg)
 		fprintf(fp, "%sMACHDEP_BT_TEXT", others++ ? "|" : "");
 	if (machdep->flags & NEW_VMEMMAP)
 		fprintf(fp, "%sNEW_VMEMMAP", others++ ? "|" : "");
+	if (machdep->flags & FLIPPED_VM)
+		fprintf(fp, "%sFLIPPED_VM", others++ ? "|" : "");
+	if (machdep->flags & HAS_PHYSVIRT_OFFSET)
+		fprintf(fp, "%sHAS_PHYSVIRT_OFFSET", others++ ? "|" : "");
 	fprintf(fp, ")\n");
 
 	fprintf(fp, "              kvbase: %lx\n", machdep->kvbase);
@@ -997,6 +1001,7 @@ arm64_calc_physvirt_offset(void)
 		if (READMEM(pc->mfd, &physvirt_offset, sizeof(physvirt_offset),
 			sp->value, sp->value -
 			machdep->machspec->kimage_voffset) > 0) {
+				machdep->flags |= HAS_PHYSVIRT_OFFSET;
 				ms->physvirt_offset = physvirt_offset;
 		}
 	}
@@ -3963,6 +3968,11 @@ arm64_calc_VA_BITS(void)
 				error(FATAL, "cannot determine VA_BITS_ACTUAL\n");
 		}
 
+		/*
+		 * The mm flip commit is introduced before 52-bits VA, which is before the
+		 * commit to export NUMBER(TCR_EL1_T1SZ)
+		 */
+		machdep->flags |= FLIPPED_VM;
 		return;
 	}
 
diff --git a/defs.h b/defs.h
index b7b20af..eca145c 100644
--- a/defs.h
+++ b/defs.h
@@ -3214,6 +3214,8 @@ typedef signed int s32;
 #define NEW_VMEMMAP   (0x80)
 #define VM_L4_4K      (0x100)
 #define UNW_4_14      (0x200)
+#define FLIPPED_VM    (0x400)
+#define HAS_PHYSVIRT_OFFSET (0x800)
 
 /*
  * Get kimage_voffset from /dev/crash
-- 
2.33.1