[tip: x86/boot] x86/boot: Move kernel cmdline setup earlier in the boot process (again)

[tip-bot2 for Julian Stecklina]

The following commit has been merged into the x86/boot branch of tip:

Commit-ID:     4faa0e5d6d79fc4c6e1943e8b62a65744d8439a0
Gitweb:        https://git.kernel.org/tip/4faa0e5d6d79fc4c6e1943e8b62a65744d8439a0
Author:        Julian Stecklina <julian.stecklina@xxxxxxxxxxxxxxxxxxxxx>
AuthorDate:    Thu, 28 Mar 2024 16:42:12 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 29 Mar 2024 08:19:12 +01:00

x86/boot: Move kernel cmdline setup earlier in the boot process (again)

When split_lock_detect=off (or similar) is specified in
CONFIG_CMDLINE, its effect is lost. The flow is currently this:

	setup_arch():
	  -> early_cpu_init()
	    -> early_identify_cpu()
	      -> sld_setup()
		-> sld_state_setup()
		  -> Looks for split_lock_detect in boot_command_line

	  -> e820__memory_setup()

	  -> Assemble final command line:
	     boot_command_line = builtin_cmdline + boot_cmdline

	  -> parse_early_param()

There were earlier attempts at fixing this in:

  8d48bf8206f7 ("x86/boot: Pull up cmdline preparation and early param parsing")

later reverted in:

  fbe618399854 ("Revert "x86/boot: Pull up cmdline preparation and early param parsing"")

.. because parse_early_param() can't be called before
e820__memory_setup().

In this patch, we just move the command line concatenation to the
beginning of early_cpu_init(). This should fix sld_state_setup(), while
not running in the same issues as the earlier attempt.

The order is now:

	setup_arch():
	  -> Assemble final command line:
	     boot_command_line = builtin_cmdline + boot_cmdline

	  -> early_cpu_init()
	    -> early_identify_cpu()
	      -> sld_setup()
		-> sld_state_setup()
		  -> Looks for split_lock_detect in boot_command_line

	  -> e820__memory_setup()

	  -> parse_early_param()

Signed-off-by: Julian Stecklina <julian.stecklina@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 arch/x86/kernel/setup.c | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 3e1e96e..4c35f1b 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -753,6 +753,22 @@ void __init setup_arch(char **cmdline_p)
 	boot_cpu_data.x86_phys_bits = MAX_PHYSMEM_BITS;
 #endif
 
+#ifdef CONFIG_CMDLINE_BOOL
+#ifdef CONFIG_CMDLINE_OVERRIDE
+	strscpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+#else
+	if (builtin_cmdline[0]) {
+		/* append boot loader cmdline to builtin */
+		strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
+		strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
+		strscpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+	}
+#endif
+#endif
+
+	strscpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
+	*cmdline_p = command_line;
+
 	/*
 	 * If we have OLPC OFW, we might end up relocating the fixmap due to
 	 * reserve_top(), so do this before touching the ioremap area.
@@ -832,22 +848,6 @@ void __init setup_arch(char **cmdline_p)
 	bss_resource.start = __pa_symbol(__bss_start);
 	bss_resource.end = __pa_symbol(__bss_stop)-1;
 
-#ifdef CONFIG_CMDLINE_BOOL
-#ifdef CONFIG_CMDLINE_OVERRIDE
-	strscpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
-#else
-	if (builtin_cmdline[0]) {
-		/* append boot loader cmdline to builtin */
-		strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
-		strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
-		strscpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
-	}
-#endif
-#endif
-
-	strscpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
-	*cmdline_p = command_line;
-
 	/*
 	 * x86_configure_nx() is called before parse_early_param() to detect
 	 * whether hardware doesn't support NX (so that the early EHCI debug