Change in flashrom[master]: cbtable.c: don't assume high addresses can fully map 1MB

[Edward O'Callaghan (Code Review)]

Edward O'Callaghan has uploaded this change for review. ( https://review.coreboot.org/c/flashrom/+/45521 )

Change subject: cbtable.c: don't assume high addresses can fully map 1MB
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cbtable.c: don't assume high addresses can fully map 1MB

I do not know a clean way to compose find_lb_table() and
find_lb_table_remap() or why this cannot always been done.

However this is a fix ported from downstream found here:
 https://chromium-review.googlesource.com/685608

Change-Id: Ibf2323a0a793f693928b81c64acd09bb932a6b98
Signed-off-by: Edward O'Callaghan 
---
M cbtable.c
1 file changed, 61 insertions(+), 7 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/21/45521/1

diff --git a/cbtable.c b/cbtable.c
index 6185f12..6dd4059 100644
--- a/cbtable.c
+++ b/cbtable.c
@@ -205,8 +205,68 @@
    	msg_pdbg("Found coreboot table at 0x%08lx.\n", addr);
    	return head;

+	};
+
+	return NULL;
+}
+
+static struct lb_header *find_lb_table_remap(unsigned long start_addr,
+					     uint8_t **table_area)
+{
+	size_t offset;
+	unsigned long addr, end;
+	size_t mapping_size;
+	void *base;
+
+	mapping_size = getpagesize();
+	offset = start_addr % getpagesize();
+	start_addr -= offset;
+
+	base = physmap_ro("high tables", start_addr, mapping_size);
+	if (ERROR_PTR == base) {
+		msg_perr("Failed getting access to coreboot high tables.\n");
+		return NULL;
    }

+	for (addr = offset, end = getpagesize(); addr < end; addr += 16) {
+		struct lb_record *recs;
+		struct lb_header *head;
+
+		/* No more headers to check. */
+		if (end - addr < sizeof(*head))
+			return NULL;
+
+		head = (struct lb_header *)(((char *)base) + addr);
+
+		if (!lb_header_valid(head, addr))
+			continue;
+
+		if (mapping_size - addr < head->table_bytes + sizeof(*head)) {
+			size_t prev_mapping_size = mapping_size;
+			mapping_size = head->table_bytes + sizeof(*head);
+			mapping_size += addr;
+			mapping_size += getpagesize() -
+				(mapping_size % getpagesize());
+			physunmap(base, prev_mapping_size);
+			base = physmap_ro("high tables", start_addr,
+						mapping_size);
+			if (ERROR_PTR == base) {
+				msg_perr("Failed getting access to coreboot high tables.\n");
+				return NULL;
+			}
+		}
+
+		head = (struct lb_header *)(((char *)base) + addr);
+		recs =
+		    (struct lb_record *)(((char *)base) + addr + sizeof(*head));
+		if (!lb_table_valid(head, recs))
+			continue;
+		msg_pdbg("Found coreboot table at 0x%08lx.\n", addr);
+		*table_area = base;
+		return head;
+	}
+
+	physunmap(base, mapping_size);
    return NULL;
 }

@@ -283,15 +343,9 @@
    		(((char *)lb_table) + lb_table->header_bytes);
    	if (forward->tag == LB_TAG_FORWARD) {
    		start = forward->forward;
-			start &= ~(getpagesize() - 1);
    		physunmap_unaligned(table_area, BYTES_TO_MAP);
    		// FIXME: table_area is never unmapped below, nor is it unmapped above in the no-forward case
-			table_area = physmap_ro_unaligned("high tables", start, BYTES_TO_MAP);
-			if (ERROR_PTR == table_area) {
-				msg_perr("Failed getting access to coreboot high tables.\n");
-				return -1;
-			}
-			lb_table = find_lb_table(table_area, 0x00000, 0x1000);
+			lb_table = find_lb_table_remap(start, &table_area);
    	}
    }

[Edward O'Callaghan (Code Review)]

Edward O'Callaghan has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/45521 )

Change subject: cbtable.c: don't assume high addresses can fully map 1MB
......................................................................

Patch Set 1: Code-Review-2

[Edward O'Callaghan (Code Review)]

Edward O'Callaghan has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/45521 )

Change subject: cbtable.c: don't assume high addresses can fully map 1MB
......................................................................

Patch Set 1:

I honestly think there is room to clean this up however this is directly pulled out of what the Chromium fork is doing.