[flashrom-gerrit] [M] Change in flashrom[master]: flashrom.c: squash subregion fix

[Edward O'Callaghan (Code Review)]

Edward O'Callaghan has uploaded this change for review. ( https://review.coreboot.org/c/flashrom/+/71680 )

Change subject: flashrom.c: squash subregion fix
......................................................................

flashrom.c: squash subregion fix

Change-Id: I0cce707ed88f6c4b600ba76926bb9e60b93e066b
Signed-off-by: Edward O'Callaghan 
---
M flashrom.c
1 file changed, 82 insertions(+), 6 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/80/71680/1

diff --git a/flashrom.c b/flashrom.c
index 62f38f8..6f5d54c 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -1187,6 +1187,65 @@
    return chip - flashchips;
 }

+/*
+ * Gets the lowest erase granularity; it is used when
+ * deciding if the layout map needs to be adjusted such that erase boundaries
+ * match this granularity. Returns -1 if unsuccessful.
+ */
+static int get_required_erase_size(struct flashctx *flash)
+{
+	int i, erase_size_found = 0;
+	unsigned int required_erase_size;
+	/*
+	 * Find eraseable block size for read alignment.
+	 * FIXME: This assumes the smallest block erase size is useable
+	 * by erase_and_write_flash().
+	 */
+	required_erase_size = ~0;
+	for (i = 0; i < NUM_ERASEFUNCTIONS; i++) {
+		struct block_eraser eraser = flash->chip->block_erasers[i];
+		int j;
+		for (j = 0; j < NUM_ERASEREGIONS; j++) {
+			unsigned int size = eraser.eraseblocks[j].size;
+			if (size && (size < required_erase_size)) {
+				required_erase_size = size;
+				erase_size_found = 1;
+			}
+		}
+	}
+	/* likely an error in flashchips[] */
+	if (!erase_size_found) {
+		msg_cerr("%s: No usable erase size found.\n", __func__);
+		return -1;
+	}
+	return required_erase_size;
+}
+static int round_to_erasable_block_boundary(const int required_erase_size,
+					    const struct romentry *entry,
+					    chipoff_t *rounded_start,
+					    chipsize_t* rounded_len) {
+	unsigned int start_align, len_align;
+	const struct flash_region *region = &entry->region;
+	if (required_erase_size < 0)
+		return 1;
+	/* round down to nearest eraseable block boundary */
+	start_align = region->start % required_erase_size;
+	*rounded_start = region->start - start_align;
+	/* round up to nearest eraseable block boundary */
+	*rounded_len = region->end - *rounded_start + 1;
+	len_align = *rounded_len % required_erase_size;
+	if (len_align)
+		*rounded_len = *rounded_len + required_erase_size - len_align;
+	if (start_align || len_align) {
+		msg_gdbg("\n%s: Re-aligned partial read due to eraseable "
+			 "block size requirement:\n\tstart: 0x%06x, "
+			 "len: 0x%06x, aligned start: 0x%06x, len: 0x%06x\n",
+			 __func__, region->start, region->end - region->start + 1,
+			 *rounded_start, *rounded_len);
+	}
+	return 0;
+}
+
 /**
  * @brief Reads the included layout regions into a buffer.
  *
@@ -1198,15 +1257,22 @@
  * @return 0 on success,
  *	   1 if any read fails.
  */
-static int read_by_layout(struct flashctx *const flashctx, uint8_t *const buffer)
+static int read_by_layout(struct flashctx *const flashctx, uint8_t *const buffer,
+                          bool align_to_erasable_block_boundary)
 {
    const struct flashrom_layout *const layout = get_layout(flashctx);
    const struct romentry *entry = NULL;
+	const int required_erase_size = get_required_erase_size(flashctx);

while ((entry = layout_next_included(layout, entry))) {
    	const struct flash_region *region = &entry->region;
-		const chipoff_t region_start	= region->start;
-		const chipsize_t region_len	= region->end - region->start + 1;
+		chipoff_t region_start	= region->start;
+		chipsize_t region_len	= region->end - region->start + 1;
+
+		if (align_to_erasable_block_boundary &&
+		    round_to_erasable_block_boundary(required_erase_size, entry,
+						     &region_start, &region_len))
+			return 1;

if (read_flash(flashctx, buffer + region_start, region_start, region_len))
    		return 1;
@@ -1386,7 +1452,7 @@

if (info->curcontents) {
    			msg_cinfo("Reading current flash chip contents... ");
-				if (read_by_layout(flashctx, info->curcontents)) {
+				if (read_by_layout(flashctx, info->curcontents, true)) {
    				/* Now we are truly screwed. Read failed as well. */
    				msg_cerr("Can't read anymore! Aborting.\n");
    				/* We have no idea about the flash chip contents, so
@@ -1990,7 +2056,7 @@
    msg_cinfo("Reading flash... ");

int ret = 1;
-	if (read_by_layout(flashctx, buffer)) {
+	if (read_by_layout(flashctx, buffer, false)) {
    	msg_cerr("Read operation failed!\n");
    	msg_cinfo("FAILED.\n");
    	goto _finalize_ret;
@@ -2089,7 +2155,7 @@
    		}
    		memcpy(curcontents, oldcontents, flash_size);
    	} else {
-			if (read_by_layout(flashctx, curcontents)) {
+			if (read_by_layout(flashctx, curcontents, true)) {
    			msg_cinfo("FAILED.\n");
    			goto _finalize_ret;
    		}