Re: [PATCH v2] crypto: crc32: make crc32 available in PBL

[Johannes Zink <j.zink@pengutronix.de>]

Hi Sascha,

On 9/4/23 10:19, Sascha Hauer wrote:
> On Tue, Aug 29, 2023 at 04:38:32PM +0200, Johannes Zink wrote:
>> crc32 may be required in PBL for checking data integrity. Add it to PBL
>> when CONFIG_CRC32 is enabled.
>>
>> To save some memory use a slower-but-smaller variant of the crc32 algorithm
>> in the PBL.
> 
> I've just sent an alternative patch series. Please check if that works
> for you.

What did you base the series on? Maybe I am holding it wrong, but it does 
neither apply on v2023.07.1 which I use in my customer project nor on 
upstream/next.

Johannes

> 
> Sascha
> 
> 
>>
>> Signed-off-by: Johannes Zink <j.zink@pengutronix.de>
>> ---
>> To: Barebox Mailing List <barebox@lists.infradead.org>
>> Cc: Johannes Zink <j.zink@pengutronix.de>
>> Cc: patchwork-jzi@pengutronix.de
>> ---
>>
>> Changes:
>>
>> v1->v2: Worked in Ahmad's review (thank you for reviewing my patch):
>>    - instead of using CRC32_EARLY, always add crc32.o to obj and pbl if
>>      CONFIG_CRC is set and rely on LTO to remove unused symbols instead
>>    - use a CRC32 implementation without a prepopulated Lookup Table,
>>      which trades in speed for code size in the PBL, analogously to what
>>      Sascha implemented in [1]
>>    - add hints on some of the #endifs for better readability of nested
>>      ifdef blocks
>>    - reword commit message to reflect on the changes made
>>
>>      [1] 2d13b856604b ("crc: Add PBL variant for crc_itu_t()")
>> ---
>>   crypto/Makefile |  2 +-
>>   crypto/crc32.c  | 34 ++++++++++++++++++++++++++++------
>>   2 files changed, 29 insertions(+), 7 deletions(-)
>>
>> diff --git a/crypto/Makefile b/crypto/Makefile
>> index 22035d4f69ee..4a1c7e9615b8 100644
>> --- a/crypto/Makefile
>> +++ b/crypto/Makefile
>> @@ -1,6 +1,6 @@
>>   # SPDX-License-Identifier: GPL-2.0-only
>>   
>> -obj-$(CONFIG_CRC32)	+= crc32.o
>> +obj-pbl-$(CONFIG_CRC32)	+= crc32.o
>>   obj-pbl-$(CONFIG_CRC_ITU_T)	+= crc-itu-t.o
>>   obj-$(CONFIG_CRC7)	+= crc7.o
>>   obj-$(CONFIG_DIGEST)	+= digest.o
>> diff --git a/crypto/crc32.c b/crypto/crc32.c
>> index 95cb2212db2b..2cf13144c1d2 100644
>> --- a/crypto/crc32.c
>> +++ b/crypto/crc32.c
>> @@ -22,7 +22,7 @@
>>   #define STATIC static inline
>>   #endif
>>   
>> -#ifdef CONFIG_DYNAMIC_CRC_TABLE
>> +#if defined(CONFIG_DYNAMIC_CRC_TABLE) && !defined(__PBL__)
>>   
>>   static uint32_t *crc_table;
>>   
>> @@ -73,7 +73,7 @@ static void make_crc_table(void)
>>       crc_table[n] = c;
>>     }
>>   }
>> -#else
>> +#elif !defined(__PBL__)
>>   /* ========================================================================
>>    * Table of CRC-32's of all single-byte values (made by make_crc_table)
>>    */
>> @@ -131,9 +131,30 @@ static const uint32_t crc_table[256] = {
>>     0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
>>     0x2d02ef8dL
>>   };
>> -#endif
>> +#endif /* defined(CONFIG_DYNAMIC_CRC_TABLE) && !defined(__PBL__) */
>> +
>> +
>> +
>> +#ifdef __PBL__
>> +#define CRC32_POLY 0xEDB88320L
>> +STATIC uint32_t crc32(uint32_t crc, const void *_buf, unsigned int len)
>> +{
>> +	int i, j;
>> +	const unsigned char *buf = _buf;
>>   
>> +	crc = crc ^ 0xffffffffL;
>>   
>> +	for (i=0; i< len; i++) {
>> +		crc ^= buf[i];
>> +		for (j = 0; j < 8; j++) {
>> +			crc = (crc >> 1) ^ ((crc & 1) ? CRC32_POLY : 0);
>> +		}
>> +	}
>> +
>> +	crc = crc ^ 0xffffffffL;
>> +	return crc;
>> +}
>> +#else
>>   /* ========================================================================= */
>>   #define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
>>   #define DO2(buf)  DO1(buf); DO1(buf);
>> @@ -148,7 +169,7 @@ STATIC uint32_t crc32(uint32_t crc, const void *_buf, unsigned int len)
>>   #ifdef CONFIG_DYNAMIC_CRC_TABLE
>>   	if (!crc_table)
>>   		make_crc_table();
>> -#endif
>> +#endif /* CONFIG_DYNAMIC_CRC_TABLE */
>>       crc = crc ^ 0xffffffffL;
>>       while (len >= 8)
>>       {
>> @@ -162,7 +183,7 @@ STATIC uint32_t crc32(uint32_t crc, const void *_buf, unsigned int len)
>>   }
>>   #ifdef __BAREBOX__
>>   EXPORT_SYMBOL(crc32);
>> -#endif
>> +#endif /* __BAREBOX__ */
>>   
>>   /* No ones complement version. JFFS2 (and other things ?)
>>    * don't use ones compliment in their CRC calculations.
>> @@ -174,7 +195,7 @@ STATIC uint32_t crc32_no_comp(uint32_t crc, const void *_buf, unsigned int len)
>>   #ifdef CONFIG_DYNAMIC_CRC_TABLE
>>   	if (!crc_table)
>>   		make_crc_table();
>> -#endif
>> +#endif /* CONFIG_DYNAMIC_CRC_TABLE */
>>       while (len >= 8)
>>       {
>>         DO8(buf);
>> @@ -186,6 +207,7 @@ STATIC uint32_t crc32_no_comp(uint32_t crc, const void *_buf, unsigned int len)
>>   
>>       return crc;
>>   }
>> +#endif /* __PBL__ */
>>   
>>   STATIC uint32_t crc32_be(uint32_t crc, const void *_buf, unsigned int len)
>>   {
>>
>> ---
>> base-commit: bef38b18eeb5d2f1fac334fb8b831e47261e099c
>> change-id: 20230829-crc32_in_pbl-4d824629d4e2
>>
>> Best regards,
>> -- 
>> Johannes Zink <j.zink@pengutronix.de>
>>
>>
>>
> 

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