kexec-tools: add patch to fix issue with appended DTB and zImage on ARM

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

diff --git a/package/boot/kexec-tools/patches/001-arm-do-not-copy-magic-4-bytes-of-appended-DTB-in-zIm.patch b/package/boot/kexec-tools/patches/001-arm-do-not-copy-magic-4-bytes-of-appended-DTB-in-zIm.patch
new file mode 100644 (file)
index 0000000..82bdd4e
--- /dev/null
+++ b/package/boot/kexec-tools/patches/001-arm-do-not-copy-magic-4-bytes-of-appended-DTB-in-zIm.patch
@@ -0,0 +1,52 @@
+From 9817ec81968a5eec7863902833fb77680544eae4 Mon Sep 17 00:00:00 2001
+From: Alexander Egorenkov <egorenar-dev@posteo.net>
+Date: Mon, 12 Apr 2021 13:18:05 +0200
+Subject: [PATCH 1/1] arm: do not copy magic 4 bytes of appended DTB in zImage
+
+If the passed zImage happens to have a DTB appended, then the magic 4 bytes
+of the DTB are copied together with the kernel image. This leads to
+failed kexec boots because the decompressor finds the aforementioned
+DTB magic and falsely tries to replace the DTB passed in the register r2
+with the non-existent appended one.
+
+Signed-off-by: Alexander Egorenkov <egorenar-dev@posteo.net>
+Signed-off-by: Simon Horman <horms@verge.net.au>
+---
+ kexec/arch/arm/kexec-zImage-arm.c | 12 +++++++++++-
+ 1 file changed, 11 insertions(+), 1 deletion(-)
+
+--- a/kexec/arch/arm/kexec-zImage-arm.c
++++ b/kexec/arch/arm/kexec-zImage-arm.c
+@@ -382,6 +382,7 @@ int zImage_arm_load(int argc, char **arg
+       unsigned int atag_offset = 0x1000; /* 4k offset from memory start */
+       unsigned int extra_size = 0x8000; /* TEXT_OFFSET */
+       const struct zimage_tag *tag;
++      size_t kernel_buf_size;
+       size_t kernel_mem_size;
+       const char *command_line;
+       char *modified_cmdline = NULL;
+@@ -538,6 +539,15 @@ int zImage_arm_load(int argc, char **arg
+       }
+ 
+       /*
++       * Save the length of the compressed kernel image w/o the appended DTB.
++       * This will be required later on when the kernel image contained
++       * in the zImage will be loaded into a kernel memory segment.
++       * And we want to load ONLY the compressed kernel image from the zImage
++       * and discard the appended DTB.
++       */
++      kernel_buf_size = len;
++
++      /*
+        * Always extend the zImage by four bytes to ensure that an appended
+        * DTB image always sees an initialised value after _edata.
+        */
+@@ -759,7 +769,7 @@ int zImage_arm_load(int argc, char **arg
+               add_segment(info, dtb_buf, dtb_length, dtb_offset, dtb_length);
+       }
+ 
+-      add_segment(info, buf, len, kernel_base, kernel_mem_size);
++      add_segment(info, buf, kernel_buf_size, kernel_base, kernel_mem_size);
+ 
+       info->entry = (void*)kernel_base;
+