openwrt/package/base-files/files/lib/functions/caldata.sh
Thibaut VARÈNE 7557e7f267 package/base-files: caldata: work around dd's limitation
tl;dr: dd will silently truncate the output if reading from special
files (e.g. sysfs attributes) with a too large bs parameter.

This problem was exposed on some RouterBOARD ipq40xx devices which use a
caldata payload which is larger than PAGE_SIZE, contrary to all other
currently supported RouterBOARD devices: the caldata would fail to
properly load with the current scripts.

Background: dd doesn't seem to correctly handle read() results that
return less than requested data. sysfs attributes have a kernel exchange
buffer which is at most PAGE_SIZE big, so only 1 page can be read() at a
time. In this case, if bs is larger than PAGE_SIZE, dd will silently
truncate blocks to PAGE_SIZE. With the current scripts using bs=<size>
count=1, the data is truncated to PAGE_SIZE as soon as the requested
<size> exceeds this value.

This commit works around this problem by using `cat` in the caldata
routines that can read from a file (routines that read from mtd devices
are untouched). cat correctly handles partial read requests. The output
is then piped to dd with the same parameters as before, to ensure that
the resulting file remains exactly the same.

This is a simple workaround, the downside is that it uses a pipe and one
more executable, and therefore has a larger memory footprint and is
slower. This is deemed acceptable considering these routines are only
used at boot time.

Tested-by: Robert Marko <robimarko@gmail.com>
Signed-off-by: Thibaut VARÈNE <hacks@slashdirt.org>
2020-05-28 11:22:22 +02:00

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# Copyright (C) 2019 OpenWrt.org
. /lib/functions.sh
. /lib/functions/system.sh
caldata_die() {
echo "caldata: " "$*"
exit 1
}
caldata_extract() {
local part=$1
local offset=$(($2))
local count=$(($3))
local mtd
mtd=$(find_mtd_chardev $part)
[ -n "$mtd" ] || caldata_die "no mtd device found for partition $part"
dd if=$mtd of=/lib/firmware/$FIRMWARE iflag=skip_bytes bs=$count skip=$offset count=1 2>/dev/null || \
caldata_die "failed to extract calibration data from $mtd"
}
caldata_extract_ubi() {
local part=$1
local offset=$(($2))
local count=$(($3))
local ubidev
local ubi
. /lib/upgrade/nand.sh
ubidev=$(nand_find_ubi $CI_UBIPART)
ubi=$(nand_find_volume $ubidev $part)
[ -n "$ubi" ] || caldata_die "no UBI volume found for $part"
dd if=/dev/$ubi of=/lib/firmware/$FIRMWARE iflag=skip_bytes bs=$count skip=$offset count=1 2>/dev/null || \
caldata_die "failed to extract calibration data from $ubi"
}
caldata_extract_reverse() {
local part=$1
local offset=$2
local count=$(($3))
local mtd
local reversed
local caldata
mtd=$(find_mtd_chardev "$part")
reversed=$(hexdump -v -s $offset -n $count -e '/1 "%02x "' $mtd)
for byte in $reversed; do
caldata="\x${byte}${caldata}"
done
printf "%b" "$caldata" > /lib/firmware/$FIRMWARE
}
caldata_from_file() {
local source=$1
local offset=$(($2))
local count=$(($3))
local target=$4
[ -n "$target" ] || target=/lib/firmware/$FIRMWARE
# dd doesn't handle partial reads from special files: use cat
cat $source | dd of=$target iflag=skip_bytes bs=$count skip=$offset count=1 2>/dev/null || \
caldata_die "failed to extract calibration data from $source"
}
caldata_sysfsload_from_file() {
local source=$1
local offset=$(($2))
local count=$(($3))
# dd doesn't handle partial reads from special files: use cat
# test extract to /dev/null first
cat $source | dd of=/dev/null iflag=skip_bytes bs=$count skip=$offset count=1 2>/dev/null || \
caldata_die "failed to extract calibration data from $source"
# can't fail now
echo 1 > /sys/$DEVPATH/loading
cat $source | dd of=/sys/$DEVPATH/data iflag=skip_bytes bs=$count skip=$offset count=1 2>/dev/null
echo 0 > /sys/$DEVPATH/loading
}
caldata_valid() {
local expected="$1"
local target=$2
[ -n "$target" ] || target=/lib/firmware/$FIRMWARE
magic=$(hexdump -v -n 2 -e '1/1 "%02x"' $target)
[ "$magic" = "$expected" ]
return $?
}
caldata_patch_chksum() {
local mac=$1
local mac_offset=$(($2))
local chksum_offset=$(($3))
local target=$4
local xor_mac
local xor_fw_mac
local xor_fw_chksum
xor_mac=${mac//:/}
xor_mac="${xor_mac:0:4} ${xor_mac:4:4} ${xor_mac:8:4}"
xor_fw_mac=$(hexdump -v -n 6 -s $mac_offset -e '/1 "%02x"' /lib/firmware/$FIRMWARE)
xor_fw_mac="${xor_fw_mac:0:4} ${xor_fw_mac:4:4} ${xor_fw_mac:8:4}"
xor_fw_chksum=$(hexdump -v -n 2 -s $chksum_offset -e '/1 "%02x"' /lib/firmware/$FIRMWARE)
xor_fw_chksum=$(xor $xor_fw_chksum $xor_fw_mac $xor_mac)
printf "%b" "\x${xor_fw_chksum:0:2}\x${xor_fw_chksum:2:2}" | \
dd of=$target conv=notrunc bs=1 seek=$chksum_offset count=2
}
caldata_patch_mac() {
local mac=$1
local mac_offset=$(($2))
local chksum_offset=$3
local target=$4
[ -z "$mac" -o -z "$mac_offset" ] && return
[ -n "$target" ] || target=/lib/firmware/$FIRMWARE
[ -n "$chksum_offset" ] && caldata_patch_chksum "$mac" "$mac_offset" "$chksum_offset" "$target"
macaddr_2bin $mac | dd of=$target conv=notrunc oflag=seek_bytes bs=6 seek=$mac_offset count=1 || \
caldata_die "failed to write MAC address to eeprom file"
}
ath9k_patch_mac() {
local mac=$1
local target=$2
caldata_patch_mac "$mac" 0x2 "" "$target"
}
ath9k_patch_mac_crc() {
local mac=$1
local mac_offset=$2
local chksum_offset=$((mac_offset - 10))
local target=$4
caldata_patch_mac "$mac" "$mac_offset" "$chksum_offset" "$target"
}
ath10k_patch_mac() {
local mac=$1
local target=$2
caldata_patch_mac "$mac" 0x6 0x2 "$target"
}