fw_setenv: lock the flash only if it was locked beforeWIP/2020-07-30-more-env-updates

With current implementation of fw_setenv, it is always locks u-boot-env
region if lock interface is implemented for such mtd device. You can
not control lock of this region with fw_setenv, there is no option for
it in config or in application itself. Because of this situation may
happen problems like in this thread on xilinx forum:
https://forums.xilinx.com/t5/Embedded-Linux/Flash-be-locked-after-use-fw-setenv-from-user-space
/td-p/1027851

A short summary of that link is: some person has issue with some spi
chip which has lock interface but doesn't locks properly which leads to
lock of whole flash memory on lock of u-boot-env region. As resulted
solution hack was added into spi-nor.c driver for this chip with lock
disablement.

Instead fix this problem by adding logic to fw_setenv only lock the
flash if it was already locked when we attempted to use it.

Signed-off-by: Ivan Mikhaylov <fr0st61te@gmail.com>

1 files changed, 19 insertions, 5 deletions

diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index c6378ecf34..3ab1ae69c7 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -995,6 +995,7 @@ static int flash_write_buf(int dev, int fd, void *buf, size_t count)
 				   of the data */
 	loff_t blockstart;	/* running start of the current block -
 				   MEMGETBADBLOCK needs 64 bits */
+	int was_locked;		/* flash lock flag */
 	int rc;
 
 	/*
@@ -1080,6 +1081,12 @@ static int flash_write_buf(int dev, int fd, void *buf, size_t count)
 	}
 
 	erase.length = erasesize;
+	if (DEVTYPE(dev) != MTD_ABSENT) {
+		was_locked = ioctl(fd, MEMISLOCKED, &erase);
+		/* treat any errors as unlocked flash */
+		if (was_locked < 0)
+			was_locked = 0;
+	}
 
 	/* This only runs once on NOR flash and SPI-dataflash */
 	while (processed < write_total) {
@@ -1099,7 +1106,8 @@ static int flash_write_buf(int dev, int fd, void *buf, size_t count)
 
 		if (DEVTYPE(dev) != MTD_ABSENT) {
 			erase.start = blockstart;
-			ioctl(fd, MEMUNLOCK, &erase);
+			if (was_locked)
+				ioctl(fd, MEMUNLOCK, &erase);
 			/* These do not need an explicit erase cycle */
 			if (DEVTYPE(dev) != MTD_DATAFLASH)
 				if (ioctl(fd, MEMERASE, &erase) != 0) {
@@ -1127,8 +1135,10 @@ static int flash_write_buf(int dev, int fd, void *buf, size_t count)
 			return -1;
 		}
 
-		if (DEVTYPE(dev) != MTD_ABSENT)
-			ioctl(fd, MEMLOCK, &erase);
+		if (DEVTYPE(dev) != MTD_ABSENT) {
+			if (was_locked)
+				ioctl(fd, MEMLOCK, &erase);
+		}
 
 		processed += erasesize;
 		block_seek = 0;
@@ -1149,7 +1159,9 @@ static int flash_flag_obsolete(int dev, int fd, off_t offset)
 	int rc;
 	struct erase_info_user erase;
 	char tmp = ENV_REDUND_OBSOLETE;
+	int was_locked;	/* flash lock flag */
 
+	was_locked = ioctl(fd, MEMISLOCKED, &erase);
 	erase.start = DEVOFFSET(dev);
 	erase.length = DEVESIZE(dev);
 	/* This relies on the fact, that ENV_REDUND_OBSOLETE == 0 */
@@ -1159,9 +1171,11 @@ static int flash_flag_obsolete(int dev, int fd, off_t offset)
 			DEVNAME(dev));
 		return rc;
 	}
-	ioctl(fd, MEMUNLOCK, &erase);
+	if (was_locked)
+		ioctl(fd, MEMUNLOCK, &erase);
 	rc = write(fd, &tmp, sizeof(tmp));
-	ioctl(fd, MEMLOCK, &erase);
+	if (was_locked)
+		ioctl(fd, MEMLOCK, &erase);
 	if (rc < 0)
 		perror("Could not set obsolete flag");