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

[Nikolai Artemiev (Code Review)]

Attention is currently required from: Edward O'Callaghan.

Hello Edward O'Callaghan,

I'd like you to do a code review.
Please visit

https://review.coreboot.org/c/flashrom/+/70515

to review the following change.

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 
---
M flashrom.c
1 file changed, 68 insertions(+), 7 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/15/70515/1

diff --git a/flashrom.c b/flashrom.c
index 19068a7..76a2801 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -582,15 +582,49 @@
    	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;