package/boot/kexec-tools/patches/001-arm-do-not-copy-magic-4-bytes-of-appended-DTB-in-zIm.patch

   1 From 9817ec81968a5eec7863902833fb77680544eae4 Mon Sep 17 00:00:00 2001
   2 From: Alexander Egorenkov <egorenar-dev@posteo.net>
   3 Date: Mon, 12 Apr 2021 13:18:05 +0200
   4 Subject: [PATCH 1/1] arm: do not copy magic 4 bytes of appended DTB in zImage
   5
   6 If the passed zImage happens to have a DTB appended, then the magic 4 bytes
   7 of the DTB are copied together with the kernel image. This leads to
   8 failed kexec boots because the decompressor finds the aforementioned
   9 DTB magic and falsely tries to replace the DTB passed in the register r2
  10 with the non-existent appended one.
  11
  12 Signed-off-by: Alexander Egorenkov <egorenar-dev@posteo.net>
  13 Signed-off-by: Simon Horman <horms@verge.net.au>
  14 ---
  15  kexec/arch/arm/kexec-zImage-arm.c | 12 +++++++++++-
  16  1 file changed, 11 insertions(+), 1 deletion(-)
  17
  18 --- a/kexec/arch/arm/kexec-zImage-arm.c
  19 +++ b/kexec/arch/arm/kexec-zImage-arm.c
  20 @@ -382,6 +382,7 @@ int zImage_arm_load(int argc, char **arg
  21         unsigned int atag_offset = 0x1000; /* 4k offset from memory start */
  22         unsigned int extra_size = 0x8000; /* TEXT_OFFSET */
  23         const struct zimage_tag *tag;
  24 +       size_t kernel_buf_size;
  25         size_t kernel_mem_size;
  26         const char *command_line;
  27         char *modified_cmdline = NULL;
  28 @@ -538,6 +539,15 @@ int zImage_arm_load(int argc, char **arg
  29         }
  30
  31         /*
  32 +        * Save the length of the compressed kernel image w/o the appended DTB.
  33 +        * This will be required later on when the kernel image contained
  34 +        * in the zImage will be loaded into a kernel memory segment.
  35 +        * And we want to load ONLY the compressed kernel image from the zImage
  36 +        * and discard the appended DTB.
  37 +        */
  38 +       kernel_buf_size = len;
  39 +
  40 +       /*
  41          * Always extend the zImage by four bytes to ensure that an appended
  42          * DTB image always sees an initialised value after _edata.
  43          */
  44 @@ -759,7 +769,7 @@ int zImage_arm_load(int argc, char **arg
  45                 add_segment(info, dtb_buf, dtb_length, dtb_offset, dtb_length);
  46         }
  47
  48 -       add_segment(info, buf, len, kernel_base, kernel_mem_size);
  49 +       add_segment(info, buf, kernel_buf_size, kernel_base, kernel_mem_size);
  50
  51         info->entry = (void*)kernel_base;
  52