target/linux/generic/pending-4.19/920-mangle_bootargs.patch

   1 From: Imre Kaloz <kaloz@openwrt.org>
   2 Subject: init: add CONFIG_MANGLE_BOOTARGS and disable it by default
   3
   4 Enabling this option renames the bootloader supplied root=
   5 and rootfstype= variables, which might have to be know but
   6 would break the automatisms OpenWrt uses.
   7
   8 Signed-off-by: Imre Kaloz <kaloz@openwrt.org>
   9 ---
  10  init/Kconfig |  9 +++++++++
  11  init/main.c  | 24 ++++++++++++++++++++++++
  12  2 files changed, 33 insertions(+)
  13
  14 --- a/init/Kconfig
  15 +++ b/init/Kconfig
  16 @@ -1528,6 +1528,15 @@ config EMBEDDED
  17           an embedded system so certain expert options are available
  18           for configuration.
  19
  20 +config MANGLE_BOOTARGS
  21 +       bool "Rename offending bootargs"
  22 +       depends on EXPERT
  23 +       help
  24 +         Sometimes the bootloader passed bogus root= and rootfstype=
  25 +         parameters to the kernel, and while you want to ignore them,
  26 +         you need to know the values f.e. to support dual firmware
  27 +         layouts on the flash.
  28 +
  29  config HAVE_PERF_EVENTS
  30         bool
  31         help
  32 --- a/init/main.c
  33 +++ b/init/main.c
  34 @@ -366,6 +366,29 @@ static inline void setup_nr_cpu_ids(void
  35  static inline void smp_prepare_cpus(unsigned int maxcpus) { }
  36  #endif
  37
  38 +#ifdef CONFIG_MANGLE_BOOTARGS
  39 +static void __init mangle_bootargs(char *command_line)
  40 +{
  41 +       char *rootdev;
  42 +       char *rootfs;
  43 +
  44 +       rootdev = strstr(command_line, "root=/dev/mtdblock");
  45 +
  46 +       if (rootdev)
  47 +               strncpy(rootdev, "mangled_rootblock=", 18);
  48 +
  49 +       rootfs = strstr(command_line, "rootfstype");
  50 +
  51 +       if (rootfs)
  52 +               strncpy(rootfs, "mangled_fs", 10);
  53 +
  54 +}
  55 +#else
  56 +static void __init mangle_bootargs(char *command_line)
  57 +{
  58 +}
  59 +#endif
  60 +
  61  /*
  62   * We need to store the untouched command line for future reference.
  63   * We also need to store the touched command line since the parameter
  64 @@ -558,6 +581,7 @@ asmlinkage __visible void __init start_k
  65         add_device_randomness(command_line, strlen(command_line));
  66         boot_init_stack_canary();
  67         mm_init_cpumask(&init_mm);
  68 +       mangle_bootargs(command_line);
  69         setup_command_line(command_line);
  70         setup_nr_cpu_ids();
  71         setup_per_cpu_areas();