linux-kernel - Re: [PATCH v3] nvmem: u-boot-env: align endianness of crc32 values

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Date:   Mon, 20 Feb 2023 22:34:10 +0900
From:   INAGAKI Hiroshi <musashino.open@...il.com>
To:     Rafał Miłecki <rafal@...ecki.pl>,
        srinivas.kandagatla@...aro.org
Cc:     chunkeey@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] nvmem: u-boot-env: align endianness of crc32 values

Hi Rafał,

On 2023/02/20 17:01, Rafał Miłecki wrote:
> On 13.02.2023 14:23, INAGAKI Hiroshi wrote:
>> @@ -117,8 +117,8 @@ static int u_boot_env_parse(struct u_boot_env 
>> *priv)
>>       size_t crc32_offset;
>>       size_t data_offset;
>>       size_t data_len;
>> -    uint32_t crc32;
>> -    uint32_t calc;
>> +    __le32 crc32;
>> +    __le32 calc;
>>       size_t bytes;
>>       uint8_t *buf;
>>       int err;
>> @@ -152,11 +152,11 @@ static int u_boot_env_parse(struct u_boot_env 
>> *priv)
>>           data_offset = offsetof(struct u_boot_env_image_broadcom, 
>> data);
>>           break;
>>       }
>> -    crc32 = le32_to_cpu(*(__le32 *)(buf + crc32_offset));
>> +    crc32 = cpu_to_le32(*(uint32_t *)(buf + crc32_offset));
>>       crc32_data_len = priv->mtd->size - crc32_data_offset;
>>       data_len = priv->mtd->size - data_offset;
>>   -    calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ 
>> ~0L;
>> +    calc = cpu_to_le32(crc32(~0, buf + crc32_data_offset, 
>> crc32_data_len) ^ ~0L);
>
> Can you see what happens on BE device if instead of this whole patch 
> you
> just replace crc32() in above line with crc32_le()?

Thank you for your suggestion.
I tried it, but "calc" still has big-endianness value and needs to be 
converted to little-endianness value.

log:

[    8.725024] u_boot_env 
18001200.spi:flash@0:partitions:partition@...00: Invalid calculated 
CRC32: 0x88cd6f09 (expected: 0x096fcd88)

"crc32()" seems to be the same as "crc32_le()" [0].

[0]: 
https://elixir.bootlin.com/linux/v5.15.94/source/include/linux/crc32.h#L66

>
>
>>       if (calc != crc32) {
>>           dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 
>> 0x%08x)\n", calc, crc32);
>>           err = -EINVAL;

Thanks,
Hiroshi