target/linux/ipq806x/patches-6.6/902-ARM-decompressor-support-for-ATAGs-rootblock-parsing.patch

   1 From 13bb6d8dd9138927950a520a288401db82871dc9 Mon Sep 17 00:00:00 2001
   2 From: Christian Marangi <ansuelsmth@gmail.com>
   3 Date: Sun, 21 Jan 2024 23:36:57 +0100
   4 Subject: [PATCH] ARM: decompressor: support for ATAGs rootblock parsing
   5
   6 The command-line arguments provided by the boot loader will be
   7 appended to a new device tree property: bootloader-args.
   8
   9 If there is a property "append-rootblock" in DT under /chosen
  10 and a root= option in bootloaders command line it will be parsed
  11 and added to DT bootargs with the form: <append-rootblock>XX.
  12
  13 This is usefull in dual boot systems, to get the current root partition
  14 without afecting the rest of the system.
  15
  16 Signed-off-by: Adrian Panella <ianchi74@outlook.com>
  17 [ reworked to a cleaner patch ]
  18 Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
  19 ---
  20  arch/arm/Kconfig                        |  10 +++
  21  arch/arm/boot/compressed/atags_to_fdt.c | 102 ++++++++++++++++++++++--
  22  init/main.c                             |  12 +++
  23  3 files changed, 117 insertions(+), 7 deletions(-)
  24
  25 --- a/arch/arm/Kconfig
  26 +++ b/arch/arm/Kconfig
  27 @@ -1578,6 +1578,16 @@ config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEN
  28           The command-line arguments provided by the boot loader will be
  29           appended to the the device tree bootargs property.
  30
  31 +config ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE
  32 +       bool "Append rootblock parsing bootloader's kernel arguments"
  33 +       help
  34 +         The command-line arguments provided by the boot loader will be
  35 +         appended to a new device tree property: bootloader-args.
  36 +
  37 +         If there is a property "append-rootblock" in DT under /chosen
  38 +         and a root= option in bootloaders command line it will be parsed
  39 +         and added to DT bootargs with the form: <append-rootblock>XX.
  40 +
  41  endchoice
  42
  43  config CMDLINE_OVERRIDE
  44 --- a/arch/arm/boot/compressed/atags_to_fdt.c
  45 +++ b/arch/arm/boot/compressed/atags_to_fdt.c
  46 @@ -4,7 +4,8 @@
  47  #include <libfdt.h>
  48  #include "misc.h"
  49
  50 -#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND)
  51 +#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND) || \
  52 +       defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
  53  #define do_extend_cmdline 1
  54  #else
  55  #define do_extend_cmdline 0
  56 @@ -70,6 +71,83 @@ static uint32_t get_cell_size(const void
  57         return cell_size;
  58  }
  59
  60 +/**
  61 + * taken from arch/x86/boot/string.c
  62 + * local_strstr - Find the first substring in a %NUL terminated string
  63 + * @s1: The string to be searched
  64 + * @s2: The string to search for
  65 + */
  66 +static char *local_strstr(const char *s1, const char *s2)
  67 +{
  68 +       size_t l1, l2;
  69 +
  70 +       l2 = strlen(s2);
  71 +       if (!l2)
  72 +               return (char *)s1;
  73 +       l1 = strlen(s1);
  74 +       while (l1 >= l2) {
  75 +               l1--;
  76 +               if (!memcmp(s1, s2, l2))
  77 +                       return (char *)s1;
  78 +               s1++;
  79 +       }
  80 +       return NULL;
  81 +}
  82 +
  83 +static char *append_rootblock(char *dest, const char *str, int len, void *fdt)
  84 +{
  85 +       char *ptr, *end, *tmp;
  86 +       const char *root="root=";
  87 +       const char *find_rootblock;
  88 +       int i, l;
  89 +       const char *rootblock;
  90 +
  91 +       find_rootblock = getprop(fdt, "/chosen", "find-rootblock", &l);
  92 +       if (!find_rootblock)
  93 +               find_rootblock = root;
  94 +
  95 +       /* ARM doesn't have __HAVE_ARCH_STRSTR, so it was copied from x86 */
  96 +       ptr = local_strstr(str, find_rootblock);
  97 +       if (!ptr)
  98 +               return dest;
  99 +
 100 +       end = strchr(ptr, ' ');
 101 +       end = end ? (end - 1) : (strchr(ptr, 0) - 1);
 102 +
 103 +       /* Some boards ubi.mtd=XX,ZZZZ, so let's check for '," too. */
 104 +       tmp = strchr(ptr, ',');
 105 +       if (tmp)
 106 +               end = end < tmp ? end : tmp - 1;
 107 +
 108 +       /*
 109 +        * find partition number
 110 +        * (assumes format root=/dev/mtdXX | /dev/mtdblockXX | yy:XX | ubi.mtd=XX,ZZZZ )
 111 +        */
 112 +       for (i = 0; end >= ptr && *end >= '0' && *end <= '9'; end--, i++);
 113 +
 114 +       ptr = end + 1;
 115 +
 116 +       /* if append-rootblock property is set use it to append to command line */
 117 +       rootblock = getprop(fdt, "/chosen", "append-rootblock", &l);
 118 +       if (rootblock != NULL) {
 119 +               if (*dest != ' ') {
 120 +                       *dest = ' ';
 121 +                       dest++;
 122 +                       len++;
 123 +               }
 124 +
 125 +               if (len + l + i <= COMMAND_LINE_SIZE) {
 126 +                       memcpy(dest, rootblock, l);
 127 +                       dest += l - 1;
 128 +
 129 +                       memcpy(dest, ptr, i);
 130 +                       dest += i;
 131 +               }
 132 +       }
 133 +
 134 +       return dest;
 135 +}
 136 +
 137  static void merge_fdt_bootargs(void *fdt, const char *fdt_cmdline)
 138  {
 139         char cmdline[COMMAND_LINE_SIZE];
 140 @@ -87,13 +165,23 @@ static void merge_fdt_bootargs(void *fdt
 141                         ptr += len - 1;
 142                 }
 143
 144 -       /* and append the ATAG_CMDLINE */
 145         if (fdt_cmdline) {
 146 -               len = strlen(fdt_cmdline);
 147 -               if (ptr - cmdline + len + 2 < COMMAND_LINE_SIZE) {
 148 -                       *ptr++ = ' ';
 149 -                       memcpy(ptr, fdt_cmdline, len);
 150 -                       ptr += len;
 151 +               if (IS_ENABLED(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)) {
 152 +                       /*
 153 +                       * save original bootloader args
 154 +                       * and append ubi.mtd with root partition number
 155 +                       * to current cmdline
 156 +                       */
 157 +                       setprop_string(fdt, "/chosen", "bootloader-args", fdt_cmdline);
 158 +                       ptr = append_rootblock(ptr, fdt_cmdline, len, fdt);
 159 +               } else {
 160 +                       /* and append the ATAG_CMDLINE */
 161 +                       len = strlen(fdt_cmdline);
 162 +                       if (ptr - cmdline + len + 2 < COMMAND_LINE_SIZE) {
 163 +                               *ptr++ = ' ';
 164 +                               memcpy(ptr, fdt_cmdline, len);
 165 +                               ptr += len;
 166 +                       }
 167                 }
 168         }
 169         *ptr = '\0';
 170 --- a/init/main.c
 171 +++ b/init/main.c
 172 @@ -28,6 +28,7 @@
 173  #include <linux/initrd.h>
 174  #include <linux/memblock.h>
 175  #include <linux/acpi.h>
 176 +#include <linux/of.h>
 177  #include <linux/bootconfig.h>
 178  #include <linux/console.h>
 179  #include <linux/nmi.h>
 180 @@ -929,6 +930,17 @@ void start_kernel(void)
 181         pr_notice("Kernel command line: %s\n", saved_command_line);
 182         /* parameters may set static keys */
 183         jump_label_init();
 184 +
 185 +       /* Show bootloader's original command line for reference */
 186 +       if (IS_ENABLED(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE) && of_chosen) {
 187 +               const char *prop = of_get_property(of_chosen, "bootloader-args", NULL);
 188 +
 189 +               if(prop)
 190 +                       pr_notice("Bootloader command line (ignored): %s\n", prop);
 191 +               else
 192 +                       pr_notice("Bootloader command line not present\n");
 193 +       }
 194 +
 195         parse_early_param();
 196         after_dashes = parse_args("Booting kernel",
 197                                   static_command_line, __start___param,