[M] Change in flashrom[master]: flashrom: Check for flash access restricitons in verify_range()

[Edward O'Callaghan (Code Review)]

Edward O'Callaghan has submitted this change. ( https://review.coreboot.org/c/flashrom/+/70515 )

(

3 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the submitted one.
 )Change subject: flashrom: Check for flash access restricitons in verify_range()
......................................................................

flashrom: Check for flash access restricitons in verify_range()

Make verify_flash() skip read/write-protected regions based on the
FLASHROM_FLAG_SKIP_UNREADABLE and FLASHROM_FLAG_SKIP_UNWRITABLE flags.

If FLASHROM_FLAG_SKIP_UNREADABLE is false, read-protected regions will cause
verification to fail.

If FLASHROM_FLAG_SKIP_UNWRITABLE is false, read-only regions will still
be verified and any mismatch will cause verification to fail. It can be
useful to set the flag to true so that expected mismatches in read-only
regions are ignored by verify_range() after flashing.

BUG=b:260440773
BRANCH=none
TEST=flashrom -v on dedede (JSL)

Change-Id: I61dfadd3c75365f2e55abeea75f673ab791ca5cc
CoAuthored-by: Edward O'Callaghan 
Signed-off-by: Edward O'Callaghan 
Signed-off-by: Nikolai Artemiev 
Reviewed-on: https://review.coreboot.org/c/flashrom/+/70515
Reviewed-by: Edward O'Callaghan 
Tested-by: build bot (Jenkins) 
Reviewed-by: Angel Pons 
---
M flashrom.c
1 file changed, 72 insertions(+), 7 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Angel Pons: Looks good to me, but someone else must approve
  Edward O'Callaghan: Looks good to me, approved

diff --git a/flashrom.c b/flashrom.c
index d036b5c..573f10b 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -604,15 +604,49 @@
    	return -1;
    }

-	int ret = read_flash(flash, readbuf, start, len);
-	if (ret) {
-		msg_gerr("Verification impossible because read failed "
-			 "at 0x%x (len 0x%x)\n", start, len);
-		ret = -1;
-		goto out_free;
+	int ret = 0;
+
+	msg_gdbg("%#06x..%#06x ", start, start + len - 1);
+
+	unsigned int read_len;
+	for (size_t addr = start; addr < start + len; addr += read_len) {
+		struct flash_region region;
+		get_flash_region(flash, addr, &region);
+		read_len = min(start + len, region.end) - addr;
+
+		if ((region.write_prot && flash->flags.skip_unwritable_regions) ||
+		    (region.read_prot  && flash->flags.skip_unreadable_regions)) {
+			msg_gdbg("%s: Skipping verification of %s region (%#08x..%#08x)\n",
+				 __func__, region.name, region.start, region.end - 1);
+			free(region.name);
+			continue;
+		}
+
+		if (region.read_prot) {
+			msg_gerr("%s: Verification imposible because %s region (%#08x..%#08x) is unreadable.\n",
+				 __func__, region.name, region.start, region.end - 1);
+			free(region.name);
+			goto out_free;
+		}
+
+		msg_gdbg("%s: Verifying %s region (%#08x..%#08x)\n",
+			 __func__, region.name, region.start, region.end - 1);
+		free(region.name);
+
+		ret = read_flash(flash, readbuf, addr, read_len);
+		if (ret) {
+			msg_gerr("Verification impossible because read failed "
+				 "at 0x%x (len 0x%x)\n", start, len);
+			ret = -1;
+			goto out_free;
+		}
+
+		ret = compare_range(cmpbuf + (addr - start), readbuf, addr, read_len);
+		if (ret)
+			goto out_free;
+
    }

-	ret = compare_range(cmpbuf, readbuf, start, len);
 out_free:
    free(readbuf);
    return ret;