target/linux/ipq806x/patches-6.6/901-02-ARM-decompressor-add-option-to-ignore-MEM-ATAGs.patch

   1 From 781d7cd4c3364e9d38fa12a342c5ad4c7e33a5ba Mon Sep 17 00:00:00 2001
   2 From: Christian Marangi <ansuelsmth@gmail.com>
   3 Date: Fri, 19 Jan 2024 20:33:10 +0100
   4 Subject: [PATCH v2 2/2] ARM: decompressor: add option to ignore MEM ATAGs
   5
   6 Some bootloaders can pass broken MEM ATAGs that provide hardcoded
   7 information about mounted RAM size and physical location.
   8 Example booloader provide RAM of size 1.7Gb but actual mounted RAM
   9 size is 512Mb causing kernel panic.
  10
  11 Add option CONFIG_ARM_ATAG_DTB_COMPAT_IGNORE_MEM to ignore these ATAG
  12 and not augument appended DTB memory node.
  13
  14 Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
  15 Acked-by: Linus Walleij <linus.walleij@linaro.org>
  16 ---
  17  arch/arm/Kconfig                        | 12 ++++++++++++
  18  arch/arm/boot/compressed/atags_to_fdt.c |  4 ++++
  19  2 files changed, 16 insertions(+)
  20
  21 --- a/arch/arm/Kconfig
  22 +++ b/arch/arm/Kconfig
  23 @@ -1570,6 +1570,18 @@ config ARM_ATAG_DTB_COMPAT
  24           bootloaders, this option allows zImage to extract the information
  25           from the ATAG list and store it at run time into the appended DTB.
  26
  27 +config ARM_ATAG_DTB_COMPAT_IGNORE_MEM
  28 +       bool "Ignore MEM ATAG information from bootloader"
  29 +       depends on ARM_ATAG_DTB_COMPAT
  30 +       help
  31 +         Some bootloaders can pass broken MEM ATAGs that provide hardcoded
  32 +         information about mounted RAM size and physical location.
  33 +         Example booloader provide RAM of size 1.7Gb but actual mounted RAM
  34 +         size is 512Mb causing kernel panic.
  35 +
  36 +         Enable this option if MEM ATAGs should be ignored and the memory
  37 +         node in the appended DTB should NOT be augumented.
  38 +
  39  choice
  40         prompt "Kernel command line type" if ARM_ATAG_DTB_COMPAT
  41         default ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER
  42 --- a/arch/arm/boot/compressed/atags_to_fdt.c
  43 +++ b/arch/arm/boot/compressed/atags_to_fdt.c
  44 @@ -169,6 +169,10 @@ int atags_to_fdt(void *atag_list, void *
  45                                 setprop_string(fdt, "/chosen", "bootargs",
  46                                                atag->u.cmdline.cmdline);
  47                 } else if (atag->hdr.tag == ATAG_MEM) {
  48 +                       /* Bootloader MEM ATAG are broken and should be ignored */
  49 +                       if (IS_ENABLED(CONFIG_ARM_ATAG_DTB_COMPAT_IGNORE_MEM))
  50 +                               continue;
  51 +
  52                         if (memcount >= sizeof(mem_reg_property)/4)
  53                                 continue;
  54                         if (!atag->u.mem.size)