From 890e35e73a9634129a09527b07e8e8dbc85fd366 Mon Sep 17 00:00:00 2001
From: markj <markj@FreeBSD.org>
Date: Fri, 24 Apr 2020 18:47:57 +0000
Subject: [PATCH] Fix handling of 1GB mappings in the arm64 minidump code.

For such mappings we need to dump 512 page table pages, not one, and
they need to be included in the pmap size recorded in the minidump
header.

MFC after:	2 weeks
Sponsored by:	Juniper Networks, Klara Inc.
---
 sys/arm64/arm64/minidump_machdep.c | 52 ++++++++++++++++--------------
 1 file changed, 28 insertions(+), 24 deletions(-)

diff --git a/sys/arm64/arm64/minidump_machdep.c b/sys/arm64/arm64/minidump_machdep.c
index 1bf2b01b9af5..ba22f7dfc16f 100644
--- a/sys/arm64/arm64/minidump_machdep.c
+++ b/sys/arm64/arm64/minidump_machdep.c
@@ -34,8 +34,6 @@ __FBSDID("$FreeBSD$");
 
 #include "opt_watchdog.h"
 
-#include "opt_watchdog.h"
-
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/conf.h>
@@ -68,7 +66,7 @@ static size_t fragsz;
 static void *dump_va;
 static size_t counter, progress, dumpsize;
 
-static uint64_t tmpbuffer[PAGE_SIZE / sizeof(uint64_t)];
+static uint64_t tmpbuffer[Ln_ENTRIES];
 
 CTASSERT(sizeof(*vm_page_dump) == 8);
 
@@ -210,16 +208,14 @@ blk_write(struct dumperinfo *di, char *ptr, vm_paddr_t pa, size_t sz)
 int
 minidumpsys(struct dumperinfo *di)
 {
+	struct minidumphdr mdhdr;
 	pd_entry_t *l0, *l1, *l2;
 	pt_entry_t *l3;
-	uint32_t pmapsize;
 	vm_offset_t va;
 	vm_paddr_t pa;
-	int error;
 	uint64_t bits;
-	int i, bit;
-	int retry_count;
-	struct minidumphdr mdhdr;
+	uint32_t pmapsize;
+	int bit, error, i, j, retry_count;
 
 	retry_count = 0;
  retry:
@@ -231,11 +227,15 @@ minidumpsys(struct dumperinfo *di)
 		if (!pmap_get_tables(pmap_kernel(), va, &l0, &l1, &l2, &l3))
 			continue;
 
-		/* We should always be using the l2 table for kvm */
-		if (l2 == NULL)
-			continue;
-
-		if ((*l2 & ATTR_DESCR_MASK) == L2_BLOCK) {
+		if ((*l1 & ATTR_DESCR_MASK) == L1_BLOCK) {
+			pa = *l1 & ~ATTR_MASK;
+			for (i = 0; i < Ln_ENTRIES * Ln_ENTRIES;
+			    i++, pa += PAGE_SIZE)
+				if (is_dumpable(pa))
+					dump_add_page(pa);
+			pmapsize += (Ln_ENTRIES - 1) * PAGE_SIZE;
+			va += L1_SIZE - L2_SIZE;
+		} else if ((*l2 & ATTR_DESCR_MASK) == L2_BLOCK) {
 			pa = *l2 & ~ATTR_MASK;
 			for (i = 0; i < Ln_ENTRIES; i++, pa += PAGE_SIZE) {
 				if (is_dumpable(pa))
@@ -327,25 +327,31 @@ minidumpsys(struct dumperinfo *di)
 			error = blk_flush(di);
 			if (error)
 				goto fail;
-		} else if (l2 == NULL) {
+		} else if ((*l1 & ATTR_DESCR_MASK) == L1_BLOCK) {
+			/*
+			 * Handle a 1GB block mapping: write out 512 fake L2
+			 * pages.
+			 */
 			pa = (*l1 & ~ATTR_MASK) | (va & L1_OFFSET);
 
-			/* Generate fake l3 entries based upon the l1 entry */
 			for (i = 0; i < Ln_ENTRIES; i++) {
-				tmpbuffer[i] = pa + (i * PAGE_SIZE) |
-				    ATTR_DEFAULT | L3_PAGE;
+				for (j = 0; j < Ln_ENTRIES; j++) {
+					tmpbuffer[j] = pa + i * L2_SIZE +
+					    j * PAGE_SIZE | ATTR_DEFAULT |
+					    L3_PAGE;
+				}
+				error = blk_write(di, (char *)&tmpbuffer, 0,
+				    PAGE_SIZE);
+				if (error)
+					goto fail;
 			}
-			/* We always write a page, even if it is zero */
-			error = blk_write(di, (char *)&tmpbuffer, 0, PAGE_SIZE);
-			if (error)
-				goto fail;
 			/* flush, in case we reuse tmpbuffer in the same block*/
 			error = blk_flush(di);
 			if (error)
 				goto fail;
 			bzero(&tmpbuffer, sizeof(tmpbuffer));
+			va += L1_SIZE - L2_SIZE;
 		} else if ((*l2 & ATTR_DESCR_MASK) == L2_BLOCK) {
-			/* TODO: Handle an invalid L2 entry */
 			pa = (*l2 & ~ATTR_MASK) | (va & L2_OFFSET);
 
 			/* Generate fake l3 entries based upon the l1 entry */
@@ -353,7 +359,6 @@ minidumpsys(struct dumperinfo *di)
 				tmpbuffer[i] = pa + (i * PAGE_SIZE) |
 				    ATTR_DEFAULT | L3_PAGE;
 			}
-			/* We always write a page, even if it is zero */
 			error = blk_write(di, (char *)&tmpbuffer, 0, PAGE_SIZE);
 			if (error)
 				goto fail;
@@ -366,7 +371,6 @@ minidumpsys(struct dumperinfo *di)
 		} else {
 			pa = *l2 & ~ATTR_MASK;
 
-			/* We always write a page, even if it is zero */
 			error = blk_write(di, NULL, pa, PAGE_SIZE);
 			if (error)
 				goto fail;