[PATCH] uboot-lantiq: danube: fix hanging lzma kernel uncompression

[Mathias Kresin]

11/2/21 11:52 PM, Hauke Mehrtens:
> On 11/2/21 11:35 PM, Mathias Kresin wrote:
>> At least since gcc 7.3.0 (OpenWrt 18.06) lwr/lwl are used in the
>> assembly  of LzmaProps_Decode. The instructions are using unaligned
>> access, which locks up danube boards using memory mapped NOR flash.
>>
>> It isn't clear whether it is a limitation of the flash chip or a
>> limitation of the EBU.
>>
>> Moving the pointer to the next int position and accessing accessing just
>> the first byte, let gcc use sll instead of lwr/lwl and prevents the
>> unaligned access.
>>
>> Signed-off-by: Mathias Kresin <dev at kresin.me>
>> ---
>>   .../0030-lzma-fix-unaligned-access.patch      | 32 +++++++++++++++++++
>>   1 file changed, 32 insertions(+)
>>   create mode 100644 
>> package/boot/uboot-lantiq/patches/0030-lzma-fix-unaligned-access.patch
>>
>> diff --git 
>> a/package/boot/uboot-lantiq/patches/0030-lzma-fix-unaligned-access.patch 
>> b/package/boot/uboot-lantiq/patches/0030-lzma-fix-unaligned-access.patch
>> new file mode 100644
>> index 0000000000..de9afe0bf5
>> --- /dev/null
>> +++ 
>> b/package/boot/uboot-lantiq/patches/0030-lzma-fix-unaligned-access.patch
>> @@ -0,0 +1,32 @@
>> +From a335c4c0532cf0d09b31e73f8461d3b4d0ce6f9a Mon Sep 17 00:00:00 2001
>> +From: Mathias Kresin <dev at kresin.me>
>> +Date: Sun, 31 Oct 2021 23:04:54 +0100
>> +Subject: [PATCH] lzma: fix unaligned access
>> +
>> +At least since gcc 7.3.0 (OpenWrt 18.06) lwr/lwl are used in the
>> +assembly  of LzmaProps_Decode. The instructions are using unaligned
>> +access, which locks up danube boards using memory mapped NOR flash.
>> +
>> +It isn't clear whether it is a limitation of the flash chip or a
>> +limitation of the EBU.
>> +
>> +Moving the pointer to the next int position and accessing accessing just
>> +the first byte, let gcc use sll instead of lwr/lwl and prevents the
>> +unaligned access.
>> +
>> +Signed-off-by: Mathias Kresin <dev at kresin.me>
>> +---
>> + lib/lzma/LzmaDec.c | 2 +-
>> + 1 file changed, 1 insertion(+), 1 deletion(-)
>> +
>> +--- a/lib/lzma/LzmaDec.c
>> ++++ b/lib/lzma/LzmaDec.c
>> +@@ -929,7 +929,7 @@ SRes LzmaProps_Decode(CLzmaProps *p, con
>> +   if (size < LZMA_PROPS_SIZE)
>> +     return SZ_ERROR_UNSUPPORTED;
>> +   else
>> +-    dicSize = data[1] | ((UInt32)data[2] << 8) | ((UInt32)data[3] << 
>> 16) | ((UInt32)data[4] << 24);
>> ++    dicSize = data[1] | ((UInt32)data[2] << 8) | ((UInt32)data[3] << 
>> 16) | ((UInt32)(data+1)[0] << 24);
> 
> Please add a small comment on top of this line in case someone applies 
> these patches to a git tree and looks only at this code.

Sorry, I don't get it. Why should such a comment be required?

0030-lzma-fix-unaligned-access.patch can be applied to an u-boot git 
repository as it is using "git am". It has a proper commit text which 
describes the change as well.

Mathias

> 
>> +
>> +   if (dicSize < LZMA_DIC_MIN)
>> +     dicSize = LZMA_DIC_MIN;
>>
>