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MIPS: cmdline: Clean up boot_command_line initialization
Our current code to initialize boot_command_line is a mess. Some of this is due to the addition of too many options over the years, and some of this is due to workarounds for early_init_dt_scan_chosen() performing actions specific to options from other architectures that probably shouldn't be in generic code. Clean this up by introducing a new bootcmdline_init() function that simplifies the initialization somewhat. The major changes are: - Because bootcmdline_init() is a function it can return early in the CONFIG_CMDLINE_OVERRIDE case. - We clear boot_command_line rather than inheriting whatever early_init_dt_scan_chosen() may have left us. This means we no longer need to set boot_command_line to a space character in an attempt to prevent early_init_dt_scan_chosen() from copying CONFIG_CMDLINE into boot_command_line without us knowing about it. - Indirection via USE_PROM_CMDLINE, USE_DTB_CMDLINE, EXTEND_WITH_PROM & BUILTIN_EXTEND_WITH_PROM macros is removed; they seemingly served only to obfuscate the code. - The logic is cleaner, clearer & commented. Two minor drawbacks of this approach are: 1) We call of_scan_flat_dt(), which means we scan through the DT again. The overhead is fairly minimal & shouldn't be noticeable. 2) cmdline_scan_chosen() duplicates a small amount of the logic from early_init_dt_scan_chosen(). Alternatives might be to allow the generic FDT code to keep & expose a copy of the arguments taken from the /chosen node's bootargs property, or to introduce a function like early_init_dt_scan_chosen() that retrieves them without modification to handle CONFIG_CMDLINE. Neither of these sounds particularly cleaner though, and this way we at least keep the extra work in arch/mips. Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: linux-mips@vger.kernel.org
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@ -538,11 +538,88 @@ static void __init check_kernel_sections_mem(void)
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}
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}
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#define USE_PROM_CMDLINE IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_BOOTLOADER)
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#define USE_DTB_CMDLINE IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_DTB)
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#define EXTEND_WITH_PROM IS_ENABLED(CONFIG_MIPS_CMDLINE_DTB_EXTEND)
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#define BUILTIN_EXTEND_WITH_PROM \
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IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND)
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static void __init bootcmdline_append(const char *s, size_t max)
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{
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if (!s[0] || !max)
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return;
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if (boot_command_line[0])
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strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
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strlcat(boot_command_line, s, max);
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}
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static int __init bootcmdline_scan_chosen(unsigned long node, const char *uname,
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int depth, void *data)
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{
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bool *dt_bootargs = data;
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const char *p;
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int l;
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if (depth != 1 || !data ||
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(strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
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return 0;
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p = of_get_flat_dt_prop(node, "bootargs", &l);
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if (p != NULL && l > 0) {
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bootcmdline_append(p, min(l, COMMAND_LINE_SIZE));
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*dt_bootargs = true;
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}
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return 1;
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}
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static void __init bootcmdline_init(char **cmdline_p)
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{
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bool dt_bootargs = false;
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/*
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* If CMDLINE_OVERRIDE is enabled then initializing the command line is
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* trivial - we simply use the built-in command line unconditionally &
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* unmodified.
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*/
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if (IS_ENABLED(CONFIG_CMDLINE_OVERRIDE)) {
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strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
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return;
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}
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/*
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* If the user specified a built-in command line &
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* MIPS_CMDLINE_BUILTIN_EXTEND, then the built-in command line is
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* prepended to arguments from the bootloader or DT so we'll copy them
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* to the start of boot_command_line here. Otherwise, empty
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* boot_command_line to undo anything early_init_dt_scan_chosen() did.
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*/
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if (IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND))
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strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
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else
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boot_command_line[0] = 0;
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/*
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* If we're configured to take boot arguments from DT, look for those
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* now.
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*/
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if (IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_DTB))
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of_scan_flat_dt(bootcmdline_scan_chosen, &dt_bootargs);
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/*
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* If we didn't get any arguments from DT (regardless of whether that's
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* because we weren't configured to look for them, or because we looked
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* & found none) then we'll take arguments from the bootloader.
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* plat_mem_setup() should have filled arcs_cmdline with arguments from
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* the bootloader.
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*/
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if (IS_ENABLED(CONFIG_MIPS_CMDLINE_DTB_EXTEND) || !dt_bootargs)
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bootcmdline_append(arcs_cmdline, COMMAND_LINE_SIZE);
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/*
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* If the user specified a built-in command line & we didn't already
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* prepend it, we append it to boot_command_line here.
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*/
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if (IS_ENABLED(CONFIG_CMDLINE_BOOL) &&
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!IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND))
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bootcmdline_append(builtin_cmdline, COMMAND_LINE_SIZE);
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}
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/*
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* arch_mem_init - initialize memory management subsystem
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@ -570,48 +647,12 @@ static void __init arch_mem_init(char **cmdline_p)
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{
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extern void plat_mem_setup(void);
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/*
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* Initialize boot_command_line to an innocuous but non-empty string in
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* order to prevent early_init_dt_scan_chosen() from copying
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* CONFIG_CMDLINE into it without our knowledge. We handle
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* CONFIG_CMDLINE ourselves below & don't want to duplicate its
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* content because repeating arguments can be problematic.
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*/
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strlcpy(boot_command_line, " ", COMMAND_LINE_SIZE);
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/* call board setup routine */
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plat_mem_setup();
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memblock_set_bottom_up(true);
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#if defined(CONFIG_CMDLINE_BOOL) && defined(CONFIG_CMDLINE_OVERRIDE)
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strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
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#else
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if ((USE_PROM_CMDLINE && arcs_cmdline[0]) ||
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(USE_DTB_CMDLINE && !boot_command_line[0]))
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strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
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if (EXTEND_WITH_PROM && arcs_cmdline[0]) {
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if (boot_command_line[0])
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strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
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strlcat(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
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}
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#if defined(CONFIG_CMDLINE_BOOL)
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if (builtin_cmdline[0]) {
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if (boot_command_line[0])
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strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
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strlcat(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
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}
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if (BUILTIN_EXTEND_WITH_PROM && arcs_cmdline[0]) {
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if (boot_command_line[0])
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strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
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strlcat(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
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}
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#endif
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#endif
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bootcmdline_init(cmdline_p);
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strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
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*cmdline_p = command_line;
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parse_early_param();
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