target/linux/ath79/patches-5.4/0001-MIPS-cmdline-Clean-up-boot_command_line-initializati.patch

   1 From: Paul Burton <paul.burton@mips.com>
   2 Date: Wed, 9 Oct 2019 23:09:45 +0000
   3 Subject: MIPS: cmdline: Clean up boot_command_line initialization
   4
   5 Our current code to initialize boot_command_line is a mess. Some of this
   6 is due to the addition of too many options over the years, and some of
   7 this is due to workarounds for early_init_dt_scan_chosen() performing
   8 actions specific to options from other architectures that probably
   9 shouldn't be in generic code.
  10
  11 Clean this up by introducing a new bootcmdline_init() function that
  12 simplifies the initialization somewhat. The major changes are:
  13
  14 - Because bootcmdline_init() is a function it can return early in the
  15   CONFIG_CMDLINE_OVERRIDE case.
  16
  17 - We clear boot_command_line rather than inheriting whatever
  18   early_init_dt_scan_chosen() may have left us. This means we no longer
  19   need to set boot_command_line to a space character in an attempt to
  20   prevent early_init_dt_scan_chosen() from copying CONFIG_CMDLINE into
  21   boot_command_line without us knowing about it.
  22
  23 - Indirection via USE_PROM_CMDLINE, USE_DTB_CMDLINE, EXTEND_WITH_PROM &
  24   BUILTIN_EXTEND_WITH_PROM macros is removed; they seemingly served only
  25   to obfuscate the code.
  26
  27 - The logic is cleaner, clearer & commented.
  28
  29 Two minor drawbacks of this approach are:
  30
  31 1) We call of_scan_flat_dt(), which means we scan through the DT again.
  32    The overhead is fairly minimal & shouldn't be noticeable.
  33
  34 2) cmdline_scan_chosen() duplicates a small amount of the logic from
  35    early_init_dt_scan_chosen(). Alternatives might be to allow the
  36    generic FDT code to keep & expose a copy of the arguments taken from
  37    the /chosen node's bootargs property, or to introduce a function like
  38    early_init_dt_scan_chosen() that retrieves them without modification
  39    to handle CONFIG_CMDLINE. Neither of these sounds particularly
  40    cleaner though, and this way we at least keep the extra work in
  41    arch/mips.
  42
  43 Origin: upstream, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7784cac697351f0cc0a4bb619594c0c99348c5aa
  44 Signed-off-by: Paul Burton <paul.burton@mips.com>
  45 Cc: linux-mips@vger.kernel.org
  46
  47 --- a/arch/mips/kernel/setup.c
  48 +++ b/arch/mips/kernel/setup.c
  49 @@ -538,11 +538,88 @@ static void __init check_kernel_sections
  50         }
  51  }
  52
  53 -#define USE_PROM_CMDLINE       IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_BOOTLOADER)
  54 -#define USE_DTB_CMDLINE                IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_DTB)
  55 -#define EXTEND_WITH_PROM       IS_ENABLED(CONFIG_MIPS_CMDLINE_DTB_EXTEND)
  56 -#define BUILTIN_EXTEND_WITH_PROM       \
  57 -       IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND)
  58 +static void __init bootcmdline_append(const char *s, size_t max)
  59 +{
  60 +       if (!s[0] || !max)
  61 +               return;
  62 +
  63 +       if (boot_command_line[0])
  64 +               strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
  65 +
  66 +       strlcat(boot_command_line, s, max);
  67 +}
  68 +
  69 +static int __init bootcmdline_scan_chosen(unsigned long node, const char *uname,
  70 +                                         int depth, void *data)
  71 +{
  72 +       bool *dt_bootargs = data;
  73 +       const char *p;
  74 +       int l;
  75 +
  76 +       if (depth != 1 || !data ||
  77 +           (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
  78 +               return 0;
  79 +
  80 +       p = of_get_flat_dt_prop(node, "bootargs", &l);
  81 +       if (p != NULL && l > 0) {
  82 +               bootcmdline_append(p, min(l, COMMAND_LINE_SIZE));
  83 +               *dt_bootargs = true;
  84 +       }
  85 +
  86 +       return 1;
  87 +}
  88 +
  89 +static void __init bootcmdline_init(char **cmdline_p)
  90 +{
  91 +       bool dt_bootargs = false;
  92 +
  93 +       /*
  94 +        * If CMDLINE_OVERRIDE is enabled then initializing the command line is
  95 +        * trivial - we simply use the built-in command line unconditionally &
  96 +        * unmodified.
  97 +        */
  98 +       if (IS_ENABLED(CONFIG_CMDLINE_OVERRIDE)) {
  99 +               strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
 100 +               return;
 101 +       }
 102 +
 103 +       /*
 104 +        * If the user specified a built-in command line &
 105 +        * MIPS_CMDLINE_BUILTIN_EXTEND, then the built-in command line is
 106 +        * prepended to arguments from the bootloader or DT so we'll copy them
 107 +        * to the start of boot_command_line here. Otherwise, empty
 108 +        * boot_command_line to undo anything early_init_dt_scan_chosen() did.
 109 +        */
 110 +       if (IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND))
 111 +               strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
 112 +       else
 113 +               boot_command_line[0] = 0;
 114 +
 115 +       /*
 116 +        * If we're configured to take boot arguments from DT, look for those
 117 +        * now.
 118 +        */
 119 +       if (IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_DTB))
 120 +               of_scan_flat_dt(bootcmdline_scan_chosen, &dt_bootargs);
 121 +
 122 +       /*
 123 +        * If we didn't get any arguments from DT (regardless of whether that's
 124 +        * because we weren't configured to look for them, or because we looked
 125 +        * & found none) then we'll take arguments from the bootloader.
 126 +        * plat_mem_setup() should have filled arcs_cmdline with arguments from
 127 +        * the bootloader.
 128 +        */
 129 +       if (IS_ENABLED(CONFIG_MIPS_CMDLINE_DTB_EXTEND) || !dt_bootargs)
 130 +               bootcmdline_append(arcs_cmdline, COMMAND_LINE_SIZE);
 131 +
 132 +       /*
 133 +        * If the user specified a built-in command line & we didn't already
 134 +        * prepend it, we append it to boot_command_line here.
 135 +        */
 136 +       if (IS_ENABLED(CONFIG_CMDLINE_BOOL) &&
 137 +           !IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND))
 138 +               bootcmdline_append(builtin_cmdline, COMMAND_LINE_SIZE);
 139 +}
 140
 141  /*
 142   * arch_mem_init - initialize memory management subsystem
 143 @@ -570,48 +647,12 @@ static void __init arch_mem_init(char **
 144  {
 145         extern void plat_mem_setup(void);
 146
 147 -       /*
 148 -        * Initialize boot_command_line to an innocuous but non-empty string in
 149 -        * order to prevent early_init_dt_scan_chosen() from copying
 150 -        * CONFIG_CMDLINE into it without our knowledge. We handle
 151 -        * CONFIG_CMDLINE ourselves below & don't want to duplicate its
 152 -        * content because repeating arguments can be problematic.
 153 -        */
 154 -       strlcpy(boot_command_line, " ", COMMAND_LINE_SIZE);
 155 -
 156         /* call board setup routine */
 157         plat_mem_setup();
 158         memblock_set_bottom_up(true);
 159
 160 -#if defined(CONFIG_CMDLINE_BOOL) && defined(CONFIG_CMDLINE_OVERRIDE)
 161 -       strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
 162 -#else
 163 -       if ((USE_PROM_CMDLINE && arcs_cmdline[0]) ||
 164 -           (USE_DTB_CMDLINE && !boot_command_line[0]))
 165 -               strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
 166 -
 167 -       if (EXTEND_WITH_PROM && arcs_cmdline[0]) {
 168 -               if (boot_command_line[0])
 169 -                       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
 170 -               strlcat(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
 171 -       }
 172 -
 173 -#if defined(CONFIG_CMDLINE_BOOL)
 174 -       if (builtin_cmdline[0]) {
 175 -               if (boot_command_line[0])
 176 -                       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
 177 -               strlcat(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
 178 -       }
 179 -
 180 -       if (BUILTIN_EXTEND_WITH_PROM && arcs_cmdline[0]) {
 181 -               if (boot_command_line[0])
 182 -                       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
 183 -               strlcat(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
 184 -       }
 185 -#endif
 186 -#endif
 187 +       bootcmdline_init(cmdline_p);
 188         strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
 189 -
 190         *cmdline_p = command_line;
 191
 192         parse_early_param();