futility: flashrom_drv: Support partial read for multiple regions

Similar to CL:3490388, support flashrom read for multiple regions.

BUG=b:260531154
TEST=emerge-corsola vboot_reference
BRANCH=none

Change-Id: I1f75832f882004e879bc299be6862db089c2b71d
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/4251503
Reviewed-by: Hung-Te Lin <hungte@chromium.org>

3 files changed, 42 insertions, 23 deletions

diff --git a/futility/cmd_gbb_utility.c b/futility/cmd_gbb_utility.c
index a34e9aa4..95c1a47d 100644
--- a/futility/cmd_gbb_utility.c
+++ b/futility/cmd_gbb_utility.c
@@ -417,8 +417,9 @@ static void teardown_flash(struct updater_config *cfg,
 static uint8_t *read_from_flash(struct updater_config *cfg, off_t *filesize)
 {
 #ifdef USE_FLASHROM
-	if (flashrom_read_image(&cfg->image_current, FMAP_RO_GBB,
-				 cfg->verbosity + 1))
+	const char * const regions[] = {FMAP_RO_GBB, NULL};
+	if (flashrom_read_image(&cfg->image_current, regions,
+				cfg->verbosity + 1))
 		return NULL;
 	uint8_t *ret = cfg->image_current.data;
 	cfg->image_current.data = NULL;
diff --git a/host/lib/flashrom_drv.c b/host/lib/flashrom_drv.c
index d30d1dec..8acd3be7 100644
--- a/host/lib/flashrom_drv.c
+++ b/host/lib/flashrom_drv.c
@@ -46,13 +46,19 @@ static char *flashrom_extract_params(const char *str, char **prog, char **params
 	return tmp;
 }
 
+/*
+ * NOTE: When `regions` contains multiple regions, `region_start` and
+ * `region_len` will be filled with the data of the first region.
+ */
 static int flashrom_read_image_impl(struct firmware_image *image,
-				    const char *region,
+				    const char * const regions[],
 				    unsigned int *region_start,
 				    unsigned int *region_len, int verbosity)
 {
 	int r = 0;
 	size_t len = 0;
+	*region_start = 0;
+	*region_len = 0;
 
 	g_verbose_screen = (verbosity == -1) ? FLASHROM_MSG_INFO : verbosity;
 
@@ -79,7 +85,8 @@ static int flashrom_read_image_impl(struct firmware_image *image,
 
 	flashrom_flag_set(flashctx, FLASHROM_FLAG_SKIP_UNREADABLE_REGIONS, true);
 
-	if (region) {
+	if (regions) {
+		int i;
 		r = flashrom_layout_read_fmap_from_rom(
 			&layout, flashctx, 0, len);
 		if (r > 0) {
@@ -87,12 +94,15 @@ static int flashrom_read_image_impl(struct firmware_image *image,
 			r = -1;
 			goto err_cleanup;
 		}
-		// empty region causes seg fault in API.
-		r |= flashrom_layout_include_region(layout, region);
-		if (r > 0) {
-			ERROR("could not include region = '%s'\n", region);
-			r = -1;
-			goto err_cleanup;
+		for (i = 0; regions[i]; i++) {
+			// empty region causes seg fault in API.
+			r |= flashrom_layout_include_region(layout, regions[i]);
+			if (r > 0) {
+				ERROR("could not include region = '%s'\n",
+				      regions[i]);
+				r = -1;
+				goto err_cleanup;
+			}
 		}
 		flashrom_layout_set(flashctx, layout);
 	}
@@ -103,8 +113,8 @@ static int flashrom_read_image_impl(struct firmware_image *image,
 
 	r |= flashrom_image_read(flashctx, image->data, len);
 
-	if (r == 0 && region)
-		r |= flashrom_layout_get_region_range(layout, region,
+	if (r == 0 && regions && regions[0])
+		r |= flashrom_layout_get_region_range(layout, regions[0],
 						      region_start, region_len);
 
 err_cleanup:
@@ -119,18 +129,21 @@ err_init:
 	return r;
 }
 
-int flashrom_read_image(struct firmware_image *image, const char *region,
+int flashrom_read_image(struct firmware_image *image,
+			const char * const regions[],
 			int verbosity)
 {
 	unsigned int start, len;
-	return flashrom_read_image_impl(image, region, &start, &len, verbosity);
+	return flashrom_read_image_impl(image, regions, &start, &len,
+					verbosity);
 }
 
 int flashrom_read_region(struct firmware_image *image, const char *region,
 			 int verbosity)
 {
+	const char * const regions[] = {region, NULL};
 	unsigned int start, len;
-	int r = flashrom_read_image_impl(image, region, &start, &len,
+	int r = flashrom_read_image_impl(image, regions, &start, &len,
 					 verbosity);
 	if (r != 0)
 		return r;
diff --git a/host/lib/include/flashrom.h b/host/lib/include/flashrom.h
index e7eda28a..0c1b3716 100644
--- a/host/lib/include/flashrom.h
+++ b/host/lib/include/flashrom.h
@@ -30,21 +30,26 @@ struct firmware_image {
 };
 
 /**
- * Read using flashrom into an allocated buffer. flashrom_read subprocesses the
- * flashrom binary and returns a buffer truncated to the region.
- * flashrom_read_image will read the return a full sized buffer with only the
- * region filled with data. flashrom_read_region will return the buffer
- * truncated to the region.
+ * Read using flashrom into an allocated buffer.
+ *
+ * flashrom_read subprocesses the flashrom binary and returns a buffer truncated
+ * to the region.
+ *
+ * flashrom_read_image reads the returns a full sized buffer with only the
+ * regions filled with data.
+ *
+ * flashrom_read_region returns the buffer truncated to the region.
  *
  * @param image		The parameter that contains the programmer, buffer and
  *			size to use in the read operation.
- * @param region	The name of the fmap region to read, or NULL to
- *			read the entire flash chip.
+ * @param regions	A list of the names of the fmap regions to read, or NULL
+ *			to read the entire flash chip.
  *
  * @return VB2_SUCCESS on success, or a relevant error.
  */
 vb2_error_t flashrom_read(struct firmware_image *image, const char *region);
-int flashrom_read_image(struct firmware_image *image, const char *region,
+int flashrom_read_image(struct firmware_image *image,
+			const char * const regions[],
 			int verbosity);
 int flashrom_read_region(struct firmware_image *image, const char *region,
 			 int verbosity);