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commit 8618ddd817621c40c1f44f0ab6df7c7805234416
Author: Dave Anderson <anderson@redhat.com>
Date:   Fri Feb 1 15:01:29 2019 -0500

    First phase of support for ARM64 kernels that are configured with
    CONFIG_ARM64_USER_VA_BITS_52, which causes the PTRS_PER_PGD count
    to increase from 64 to 1024.  Without the patch, "WARNING: cannot
    access vmalloc'd module memory" will be displayed during session
    initialization, and the translation of any mapped kernel virtual
    address that requires a page table walk will fail, leading to a
    myriad of other errors.
    (anderson@redhat.com)

diff --git a/arm64.c b/arm64.c
index 45c7313..2308612 100644
--- a/arm64.c
+++ b/arm64.c
@@ -1,8 +1,8 @@
 /*
  * arm64.c - core analysis suite
  *
- * Copyright (C) 2012-2018 David Anderson
- * Copyright (C) 2012-2018 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2012-2019 David Anderson
+ * Copyright (C) 2012-2019 Red Hat, Inc. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -209,6 +209,8 @@ arm64_init(int when)
 		ms->page_offset = ARM64_PAGE_OFFSET;
 		machdep->identity_map_base = ARM64_PAGE_OFFSET;
 		machdep->kvbase = ARM64_VA_START;
+		machdep->is_kvaddr = generic_is_kvaddr;
+		machdep->kvtop = arm64_kvtop;
 		ms->userspace_top = ARM64_USERSPACE_TOP;
 		if (machdep->flags & NEW_VMEMMAP) {
 			struct syment *sp;
@@ -262,11 +264,17 @@ arm64_init(int when)
 			break;
 
 		case 65536:
+			if (kernel_symbol_exists("idmap_ptrs_per_pgd") &&
+			    readmem(symbol_value("idmap_ptrs_per_pgd"), KVADDR,
+			    &value, sizeof(ulong), "idmap_ptrs_per_pgd", RETURN_ON_ERROR))
+				machdep->ptrs_per_pgd = value;
+		
 			if (machdep->machspec->VA_BITS > PGDIR_SHIFT_L3_64K) {
 				machdep->flags |= VM_L3_64K;
-				machdep->ptrs_per_pgd = PTRS_PER_PGD_L3_64K;
+				if (!machdep->ptrs_per_pgd)
+					machdep->ptrs_per_pgd = PTRS_PER_PGD_L3_64K;
 				if ((machdep->pgd =
-				    (char *)malloc(PTRS_PER_PGD_L3_64K * 8)) == NULL)
+				    (char *)malloc(machdep->ptrs_per_pgd * 8)) == NULL)
 					error(FATAL, "cannot malloc pgd space.");
 				if ((machdep->pmd =
 				    (char *)malloc(PTRS_PER_PMD_L3_64K * 8)) == NULL)
@@ -276,9 +284,10 @@ arm64_init(int when)
 					error(FATAL, "cannot malloc ptbl space.");
 			} else {
 				machdep->flags |= VM_L2_64K;
-				machdep->ptrs_per_pgd = PTRS_PER_PGD_L2_64K;
+				if (!machdep->ptrs_per_pgd)
+					machdep->ptrs_per_pgd = PTRS_PER_PGD_L2_64K;
 				if ((machdep->pgd =
-				    (char *)malloc(PTRS_PER_PGD_L2_64K * 8)) == NULL)
+				    (char *)malloc(machdep->ptrs_per_pgd * 8)) == NULL)
 					error(FATAL, "cannot malloc pgd space.");
 				if ((machdep->ptbl =
 				    (char *)malloc(PTRS_PER_PTE_L2_64K * 8)) == NULL)
@@ -306,9 +315,11 @@ arm64_init(int when)
 		machdep->flags |= VMEMMAP;
 
 		machdep->uvtop = arm64_uvtop;
-		machdep->kvtop = arm64_kvtop;
-		machdep->is_kvaddr = generic_is_kvaddr;
 		machdep->is_uvaddr = arm64_is_uvaddr;
+		if (kernel_symbol_exists("vabits_user") && 
+		    readmem(symbol_value("vabits_user"), KVADDR,
+		    &value, sizeof(ulong), "vabits_user", RETURN_ON_ERROR))
+			machdep->machspec->vabits_user = value;
 		machdep->eframe_search = arm64_eframe_search;
 		machdep->back_trace = arm64_back_trace_cmd;
 		machdep->in_alternate_stack = arm64_in_alternate_stack;
@@ -350,10 +361,14 @@ arm64_init(int when)
 	case POST_GDB:
 		arm64_calc_virtual_memory_ranges();
 		machdep->section_size_bits = _SECTION_SIZE_BITS;
-		if (THIS_KERNEL_VERSION >= LINUX(3,17,0))
-			machdep->max_physmem_bits = _MAX_PHYSMEM_BITS_3_17;
-		else
-			machdep->max_physmem_bits = _MAX_PHYSMEM_BITS;
+		if (!machdep->max_physmem_bits) {
+			if (machdep->machspec->VA_BITS == 52)  /* guess */
+				machdep->max_physmem_bits = _MAX_PHYSMEM_BITS_52;
+			else if (THIS_KERNEL_VERSION >= LINUX(3,17,0)) 
+				machdep->max_physmem_bits = _MAX_PHYSMEM_BITS_3_17;
+			else
+				machdep->max_physmem_bits = _MAX_PHYSMEM_BITS;
+		}
 		ms = machdep->machspec;
 
 		if (THIS_KERNEL_VERSION >= LINUX(4,0,0)) {
@@ -601,6 +616,11 @@ arm64_dump_machdep_table(ulong arg)
 
 	fprintf(fp, "            machspec: %lx\n", (ulong)ms);
 	fprintf(fp, "               VA_BITS: %ld\n", ms->VA_BITS);
+	fprintf(fp, "           vabits_user: ");
+	if (ms->vabits_user)
+		fprintf(fp, "%ld\n", ms->vabits_user);
+	else
+		fprintf(fp, "(unused)\n");
 	fprintf(fp, "         userspace_top: %016lx\n", ms->userspace_top);
 	fprintf(fp, "           page_offset: %016lx\n", ms->page_offset);
 	fprintf(fp, "    vmalloc_start_addr: %016lx\n", ms->vmalloc_start_addr);
@@ -691,6 +711,8 @@ arm64_parse_machdep_arg_l(char *argstring, char *param, ulong *value)
 			*value = dtol(p, flags, &err);
 			if (!err)
 				*value = MEGABYTES(*value);
+		} else if (STRNEQ(argstring, "max_physmem_bits")) {
+			*value = dtol(p, flags, &err);
 		} else {
 			*value = htol(p, flags, &err);
 		}
@@ -750,6 +772,12 @@ arm64_parse_cmdline_args(void)
 					"setting kimage_voffset to: 0x%lx\n\n",
 					machdep->machspec->kimage_voffset);
 				continue;
+			} else if (arm64_parse_machdep_arg_l(arglist[i], "max_physmem_bits",
+			        &machdep->max_physmem_bits)) {
+				error(NOTE,
+					"setting max_physmem_bits to: %ld\n\n",
+					machdep->max_physmem_bits);
+				continue;
 			}
 
 			error(WARNING, "ignoring --machdep option: %s\n",
@@ -1065,8 +1093,8 @@ arm64_vtop_2level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose)
                 fprintf(fp, "PAGE DIRECTORY: %lx\n", pgd);
 
 	pgd_base = (ulong *)pgd;
-	FILL_PGD(pgd_base, KVADDR, PTRS_PER_PGD_L2_64K * sizeof(ulong));
-	pgd_ptr = pgd_base + (((vaddr) >> PGDIR_SHIFT_L2_64K) & (PTRS_PER_PGD_L2_64K - 1));
+	FILL_PGD(pgd_base, KVADDR, machdep->ptrs_per_pgd * sizeof(ulong));
+	pgd_ptr = pgd_base + (((vaddr) >> PGDIR_SHIFT_L2_64K) & (machdep->ptrs_per_pgd - 1));
         pgd_val = ULONG(machdep->pgd + PAGEOFFSET(pgd_ptr));
         if (verbose) 
                 fprintf(fp, "   PGD: %lx => %lx\n", (ulong)pgd_ptr, pgd_val);
@@ -1129,8 +1157,8 @@ arm64_vtop_3level_64k(ulong pgd, ulong vaddr, physaddr_t *paddr, int verbose)
                 fprintf(fp, "PAGE DIRECTORY: %lx\n", pgd);
 
 	pgd_base = (ulong *)pgd;
-	FILL_PGD(pgd_base, KVADDR, PTRS_PER_PGD_L3_64K * sizeof(ulong));
-	pgd_ptr = pgd_base + (((vaddr) >> PGDIR_SHIFT_L3_64K) & (PTRS_PER_PGD_L3_64K - 1));
+	FILL_PGD(pgd_base, KVADDR, machdep->ptrs_per_pgd * sizeof(ulong));
+	pgd_ptr = pgd_base + (((vaddr) >> PGDIR_SHIFT_L3_64K) & (machdep->ptrs_per_pgd - 1));
         pgd_val = ULONG(machdep->pgd + PGDIR_OFFSET_L3_64K(pgd_ptr));
         if (verbose)
                 fprintf(fp, "   PGD: %lx => %lx\n", (ulong)pgd_ptr, pgd_val);
diff --git a/crash.8 b/crash.8
index 8c11615..f9de36d 100644
--- a/crash.8
+++ b/crash.8
@@ -278,6 +278,7 @@ ARM:
 ARM64:  
   phys_offset=<physical-address>
   kimage_voffset=<kimage_voffset-value>
+  max_physmem_bits=<value>
 X86:
   page_offset=<CONFIG_PAGE_OFFSET-value>
 .fi
diff --git a/defs.h b/defs.h
index b473972..05f2d17 100644
--- a/defs.h
+++ b/defs.h
@@ -3049,7 +3049,7 @@ typedef signed int s32;
 #define PMD_SHIFT_L3_64K     (29)
 #define PMD_SIZE_L3_64K      (1UL << PMD_SHIFT_L3_64K)
 #define PMD_MASK_L3_64K      (~(PMD_SIZE_L3_64K-1))
-#define PGDIR_OFFSET_L3_64K(X) (((ulong)(X)) & ((PTRS_PER_PGD_L3_64K * 8) - 1))
+#define PGDIR_OFFSET_L3_64K(X) (((ulong)(X)) & ((machdep->ptrs_per_pgd * 8) - 1))
 
 /*
  * 2-levels / 64K pages
@@ -3136,6 +3136,7 @@ typedef signed int s32;
 #define _SECTION_SIZE_BITS      30
 #define _MAX_PHYSMEM_BITS       40
 #define _MAX_PHYSMEM_BITS_3_17  48
+#define _MAX_PHYSMEM_BITS_52    52
 
 typedef unsigned long long __u64;
 typedef unsigned long long u64;
@@ -3215,6 +3216,7 @@ struct machine_specific {
 	ulong kern_eframe_offset;
 	ulong machine_kexec_start;
 	ulong machine_kexec_end;
+	ulong vabits_user;
 };
 
 struct arm64_stackframe {
diff --git a/help.c b/help.c
index ff0c80b..ba15dec 100644
--- a/help.c
+++ b/help.c
@@ -179,6 +179,7 @@ char *program_usage_info[] = {
     "    ARM64:",
     "      phys_offset=<physical-address>",
     "      kimage_voffset=<kimage_voffset-value>",
+    "      max_physmem_bits=<value>",
     "    X86:",
     "      page_offset=<CONFIG_PAGE_OFFSET-value>",
     "",