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MIPS: cmdline: Clean up boot_command_line initialization

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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
This commit is contained in:
Paul Burton 2019-10-09 23:09:45 +00:00
parent c85ac57ce2
commit 7784cac697
No known key found for this signature in database
GPG Key ID: 3EA79FACB57500DD
1 changed files with 83 additions and 42 deletions
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125
arch/mips/kernel/setup.c
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@ -538,11 +538,88 @@ static void __init check_kernel_sections_mem(void)
}
}
#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 **cmdline_p)
{
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();