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 diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
  48 index b8884de89c81e1b444b218a15519556b4a374089..e56dd6c25d46336fcb9af21326f697d0c37aac1c 100644
  49 --- a/arch/mips/kernel/setup.c
  50 +++ b/arch/mips/kernel/setup.c
  51 @@ -538,11 +538,88 @@ static void __init check_kernel_sections_mem(void)
  52         }
  53  }
  54
  55 -#define USE_PROM_CMDLINE       IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_BOOTLOADER)
  56 -#define USE_DTB_CMDLINE                IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_DTB)
  57 -#define EXTEND_WITH_PROM       IS_ENABLED(CONFIG_MIPS_CMDLINE_DTB_EXTEND)
  58 -#define BUILTIN_EXTEND_WITH_PROM       \
  59 -       IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND)
  60 +static void __init bootcmdline_append(const char *s, size_t max)
  61 +{
  62 +       if (!s[0] || !max)
  63 +               return;
  64 +
  65 +       if (boot_command_line[0])
  66 +               strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
  67 +
  68 +       strlcat(boot_command_line, s, max);
  69 +}
  70 +
  71 +static int __init bootcmdline_scan_chosen(unsigned long node, const char *uname,
  72 +                                         int depth, void *data)
  73 +{
  74 +       bool *dt_bootargs = data;
  75 +       const char *p;
  76 +       int l;
  77 +
  78 +       if (depth != 1 || !data ||
  79 +           (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
  80 +               return 0;
  81 +
  82 +       p = of_get_flat_dt_prop(node, "bootargs", &l);
  83 +       if (p != NULL && l > 0) {
  84 +               bootcmdline_append(p, min(l, COMMAND_LINE_SIZE));
  85 +               *dt_bootargs = true;
  86 +       }
  87 +
  88 +       return 1;
  89 +}
  90 +
  91 +static void __init bootcmdline_init(char **cmdline_p)
  92 +{
  93 +       bool dt_bootargs = false;
  94 +
  95 +       /*
  96 +        * If CMDLINE_OVERRIDE is enabled then initializing the command line is
  97 +        * trivial - we simply use the built-in command line unconditionally &
  98 +        * unmodified.
  99 +        */
 100 +       if (IS_ENABLED(CONFIG_CMDLINE_OVERRIDE)) {
 101 +               strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
 102 +               return;
 103 +       }
 104 +
 105 +       /*
 106 +        * If the user specified a built-in command line &
 107 +        * MIPS_CMDLINE_BUILTIN_EXTEND, then the built-in command line is
 108 +        * prepended to arguments from the bootloader or DT so we'll copy them
 109 +        * to the start of boot_command_line here. Otherwise, empty
 110 +        * boot_command_line to undo anything early_init_dt_scan_chosen() did.
 111 +        */
 112 +       if (IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND))
 113 +               strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
 114 +       else
 115 +               boot_command_line[0] = 0;
 116 +
 117 +       /*
 118 +        * If we're configured to take boot arguments from DT, look for those
 119 +        * now.
 120 +        */
 121 +       if (IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_DTB))
 122 +               of_scan_flat_dt(bootcmdline_scan_chosen, &dt_bootargs);
 123 +
 124 +       /*
 125 +        * If we didn't get any arguments from DT (regardless of whether that's
 126 +        * because we weren't configured to look for them, or because we looked
 127 +        * & found none) then we'll take arguments from the bootloader.
 128 +        * plat_mem_setup() should have filled arcs_cmdline with arguments from
 129 +        * the bootloader.
 130 +        */
 131 +       if (IS_ENABLED(CONFIG_MIPS_CMDLINE_DTB_EXTEND) || !dt_bootargs)
 132 +               bootcmdline_append(arcs_cmdline, COMMAND_LINE_SIZE);
 133 +
 134 +       /*
 135 +        * If the user specified a built-in command line & we didn't already
 136 +        * prepend it, we append it to boot_command_line here.
 137 +        */
 138 +       if (IS_ENABLED(CONFIG_CMDLINE_BOOL) &&
 139 +           !IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND))
 140 +               bootcmdline_append(builtin_cmdline, COMMAND_LINE_SIZE);
 141 +}
 142
 143  /*
 144   * arch_mem_init - initialize memory management subsystem
 145 @@ -570,48 +647,12 @@ static void __init arch_mem_init(char **cmdline_p)
 146  {
 147         extern void plat_mem_setup(void);
 148
 149 -       /*
 150 -        * Initialize boot_command_line to an innocuous but non-empty string in
 151 -        * order to prevent early_init_dt_scan_chosen() from copying
 152 -        * CONFIG_CMDLINE into it without our knowledge. We handle
 153 -        * CONFIG_CMDLINE ourselves below & don't want to duplicate its
 154 -        * content because repeating arguments can be problematic.
 155 -        */
 156 -       strlcpy(boot_command_line, " ", COMMAND_LINE_SIZE);
 157 -
 158         /* call board setup routine */
 159         plat_mem_setup();
 160         memblock_set_bottom_up(true);
 161
 162 -#if defined(CONFIG_CMDLINE_BOOL) && defined(CONFIG_CMDLINE_OVERRIDE)
 163 -       strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
 164 -#else
 165 -       if ((USE_PROM_CMDLINE && arcs_cmdline[0]) ||
 166 -           (USE_DTB_CMDLINE && !boot_command_line[0]))
 167 -               strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
 168 -
 169 -       if (EXTEND_WITH_PROM && arcs_cmdline[0]) {
 170 -               if (boot_command_line[0])
 171 -                       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
 172 -               strlcat(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
 173 -       }
 174 -
 175 -#if defined(CONFIG_CMDLINE_BOOL)
 176 -       if (builtin_cmdline[0]) {
 177 -               if (boot_command_line[0])
 178 -                       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
 179 -               strlcat(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
 180 -       }
 181 -
 182 -       if (BUILTIN_EXTEND_WITH_PROM && arcs_cmdline[0]) {
 183 -               if (boot_command_line[0])
 184 -                       strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
 185 -               strlcat(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
 186 -       }
 187 -#endif
 188 -#endif
 189 +       bootcmdline_init(cmdline_p);
 190         strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
 191 -
 192         *cmdline_p = command_line;
 193
 194         parse_early_param();