package/boot/uboot-lantiq/patches/0030-lzma-force-8bit-reads.patch

   1 From a40a6e16ed76e5e26a0f60226b64c311d4a62c9f Mon Sep 17 00:00:00 2001
   2 From: Mathias Kresin <dev@kresin.me>
   3 Date: Sun, 31 Oct 2021 23:04:54 +0100
   4 Subject: [PATCH] lzma: force 8bit reads
   5
   6 At least since gcc 7.3.0 (OpenWrt 18.06) lwr/lwl are used in the
   7 assembly of LzmaProps_Decode. While the decission made by the compiler
   8 looks perfect fine, it triggers some obscure hang on lantiq danube-s
   9 v1.5 with MX29LV640EB NOR flash chips.
  10
  11 Only if the offset 1 is used, the hang can be observed. Using any other
  12 offset works fine:
  13
  14   lwl s0,0(a1) - s0 == 0x6d000080
  15   lwl s0,1(a1) - hangs
  16   lwl s0,2(a1) - s0 == 0x0080xxxx
  17   lwl s0,3(a1) - s0 == 0x80xxxxxx
  18
  19 It isn't clear whether it is a limitation of the flash chip, the EBU or
  20 something else.
  21
  22 Force 8bit reads to prevent gcc optimizing the read with lwr/lwl
  23 instructions.
  24
  25 Signed-off-by: Mathias Kresin <dev@kresin.me>
  26 ---
  27  lib/lzma/LzmaDec.c | 3 ++-
  28  1 file changed, 2 insertions(+), 1 deletion(-)
  29
  30 --- a/lib/lzma/LzmaDec.c
  31 +++ b/lib/lzma/LzmaDec.c
  32 @@ -7,6 +7,7 @@
  33  #include "LzmaDec.h"
  34
  35  #include <linux/string.h>
  36 +#include <asm/io.h>
  37
  38  #define kNumTopBits 24
  39  #define kTopValue ((UInt32)1 << kNumTopBits)
  40 @@ -929,7 +930,7 @@ SRes LzmaProps_Decode(CLzmaProps *p, con
  41    if (size < LZMA_PROPS_SIZE)
  42      return SZ_ERROR_UNSUPPORTED;
  43    else
  44 -    dicSize = data[1] | ((UInt32)data[2] << 8) | ((UInt32)data[3] << 16) | ((UInt32)data[4] << 24);
  45 +    dicSize = readb(&data[1]) | ((UInt32)readb(&data[2]) << 8) | ((UInt32)readb(&data[3]) << 16) | ((UInt32)readb(&data[4]) << 24);
  46
  47    if (dicSize < LZMA_DIC_MIN)
  48      dicSize = LZMA_DIC_MIN;