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From: Paul Burton <paul.burton@mips.com>
Date: Wed, 9 Oct 2019 23:09:45 +0000
Subject: 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.
Origin: upstream, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7784cac697351f0cc0a4bb619594c0c99348c5aa
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -538,11 +538,88 @@ static void __init check_kernel_sections
}
}
-#define USE_PROM_CMDLINE IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_BOOTLOADER)
-#define USE_DTB_CMDLINE IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_DTB)
-#define EXTEND_WITH_PROM IS_ENABLED(CONFIG_MIPS_CMDLINE_DTB_EXTEND)
-#define BUILTIN_EXTEND_WITH_PROM \
- IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND)
+static void __init bootcmdline_append(const char *s, size_t max)
+{
+ if (!s[0] || !max)
+ return;
+
+ if (boot_command_line[0])
+ strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
+
+ strlcat(boot_command_line, s, max);
+}
+
+static int __init bootcmdline_scan_chosen(unsigned long node, const char *uname,
+ int depth, void *data)
+{
+ bool *dt_bootargs = data;
+ const char *p;
+ int l;
+
+ if (depth != 1 || !data ||
+ (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
+ return 0;
+
+ p = of_get_flat_dt_prop(node, "bootargs", &l);
+ if (p != NULL && l > 0) {
+ bootcmdline_append(p, min(l, COMMAND_LINE_SIZE));
+ *dt_bootargs = true;
+ }
+
+ return 1;
+}
+
+static void __init bootcmdline_init(char **cmdline_p)
+{
+ bool dt_bootargs = false;
+
+ /*
+ * If CMDLINE_OVERRIDE is enabled then initializing the command line is
+ * trivial - we simply use the built-in command line unconditionally &
+ * unmodified.
+ */
+ if (IS_ENABLED(CONFIG_CMDLINE_OVERRIDE)) {
+ strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+ return;
+ }
+
+ /*
+ * If the user specified a built-in command line &
+ * MIPS_CMDLINE_BUILTIN_EXTEND, then the built-in command line is
+ * prepended to arguments from the bootloader or DT so we'll copy them
+ * to the start of boot_command_line here. Otherwise, empty
+ * boot_command_line to undo anything early_init_dt_scan_chosen() did.
+ */
+ if (IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND))
+ strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+ else
+ boot_command_line[0] = 0;
+
+ /*
+ * If we're configured to take boot arguments from DT, look for those
+ * now.
+ */
+ if (IS_ENABLED(CONFIG_MIPS_CMDLINE_FROM_DTB))
+ of_scan_flat_dt(bootcmdline_scan_chosen, &dt_bootargs);
+
+ /*
+ * If we didn't get any arguments from DT (regardless of whether that's
+ * because we weren't configured to look for them, or because we looked
+ * & found none) then we'll take arguments from the bootloader.
+ * plat_mem_setup() should have filled arcs_cmdline with arguments from
+ * the bootloader.
+ */
+ if (IS_ENABLED(CONFIG_MIPS_CMDLINE_DTB_EXTEND) || !dt_bootargs)
+ bootcmdline_append(arcs_cmdline, COMMAND_LINE_SIZE);
+
+ /*
+ * If the user specified a built-in command line & we didn't already
+ * prepend it, we append it to boot_command_line here.
+ */
+ if (IS_ENABLED(CONFIG_CMDLINE_BOOL) &&
+ !IS_ENABLED(CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND))
+ bootcmdline_append(builtin_cmdline, COMMAND_LINE_SIZE);
+}
/*
* arch_mem_init - initialize memory management subsystem
@@ -570,48 +647,12 @@ static void __init arch_mem_init(char **
{
extern void plat_mem_setup(void);
- /*
- * Initialize boot_command_line to an innocuous but non-empty string in
- * order to prevent early_init_dt_scan_chosen() from copying
- * CONFIG_CMDLINE into it without our knowledge. We handle
- * CONFIG_CMDLINE ourselves below & don't want to duplicate its
- * content because repeating arguments can be problematic.
- */
- strlcpy(boot_command_line, " ", COMMAND_LINE_SIZE);
-
/* call board setup routine */
plat_mem_setup();
memblock_set_bottom_up(true);
-#if defined(CONFIG_CMDLINE_BOOL) && defined(CONFIG_CMDLINE_OVERRIDE)
- strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
-#else
- if ((USE_PROM_CMDLINE && arcs_cmdline[0]) ||
- (USE_DTB_CMDLINE && !boot_command_line[0]))
- strlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
-
- if (EXTEND_WITH_PROM && arcs_cmdline[0]) {
- if (boot_command_line[0])
- strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
- strlcat(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
- }
-
-#if defined(CONFIG_CMDLINE_BOOL)
- if (builtin_cmdline[0]) {
- if (boot_command_line[0])
- strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
- strlcat(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
- }
-
- if (BUILTIN_EXTEND_WITH_PROM && arcs_cmdline[0]) {
- if (boot_command_line[0])
- strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
- strlcat(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);
- }
-#endif
-#endif
+ bootcmdline_init(cmdline_p);
strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
-
*cmdline_p = command_line;
parse_early_param();
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