linux-kernel - [PATCH] x86/setup: Parse the builtin command line before merging

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Message-ID: <20240730152108.GAZqkE5Dfi9AuKllRw@fat_crate.local>
Date: Tue, 30 Jul 2024 17:21:08 +0200
From: Borislav Petkov <bp@...en8.de>
To: Mike Lothian <mike@...eburn.co.uk>
Cc: x86-ml <x86@...nel.org>, lkml <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86/setup: Parse the builtin command line before merging

On Mon, Jul 22, 2024 at 05:56:08PM +0100, Mike Lothian wrote:
> That patch does indeed make the warning go away :D
> 
> Is there anything else you need from me?

Nah, all good.

Thanks for reporting and testing.

From: "Borislav Petkov (AMD)" <bp@...en8.de>
Date: Tue, 30 Jul 2024 16:15:12 +0200
Subject: [PATCH] x86/setup: Parse the builtin command line before merging

Commit in Fixes was added as a catch-all for cases where the cmdline is
parsed before being merged with the builtin one.

And promptly one issue appeared, see Link below. And the microcode
loader really needs to parse it that early. And the merging happens
late. Reshuffling the early boot nightmare^W code to handle that
properly would be a painful exercise for another day so do the chicken
thing and parse the builtin cmdline too before it has been merged.

Fixes: 0c40b1c7a897 ("x86/setup: Warn when option parsing is done too early")
Reported-by: Mike Lothian <mike@...eburn.co.uk>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20240722152330.GCZp55ck8E_FT4kPnC@fat_crate.local
---
 arch/x86/include/asm/cmdline.h |  4 ++++
 arch/x86/kernel/setup.c        |  2 +-
 arch/x86/lib/cmdline.c         | 29 ++++++++++++++++++++++-------
 3 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/cmdline.h b/arch/x86/include/asm/cmdline.h
index 6faaf27e8899..6cbd9ae58b21 100644
--- a/arch/x86/include/asm/cmdline.h
+++ b/arch/x86/include/asm/cmdline.h
@@ -2,6 +2,10 @@
 #ifndef _ASM_X86_CMDLINE_H
 #define _ASM_X86_CMDLINE_H
 
+#include <asm/setup.h>
+
+extern char builtin_cmdline[COMMAND_LINE_SIZE];
+
 int cmdline_find_option_bool(const char *cmdline_ptr, const char *option);
 int cmdline_find_option(const char *cmdline_ptr, const char *option,
 			char *buffer, int bufsize);
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 5d34cad9b7b1..6129dc2ba784 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -164,7 +164,7 @@ unsigned long saved_video_mode;
 
 static char __initdata command_line[COMMAND_LINE_SIZE];
 #ifdef CONFIG_CMDLINE_BOOL
-static char __initdata builtin_cmdline[COMMAND_LINE_SIZE] = CONFIG_CMDLINE;
+char builtin_cmdline[COMMAND_LINE_SIZE] = CONFIG_CMDLINE;
 bool builtin_cmdline_added __ro_after_init;
 #endif
 
diff --git a/arch/x86/lib/cmdline.c b/arch/x86/lib/cmdline.c
index 384da1fdd5c6..c51726c251a0 100644
--- a/arch/x86/lib/cmdline.c
+++ b/arch/x86/lib/cmdline.c
@@ -207,18 +207,33 @@ __cmdline_find_option(const char *cmdline, int max_cmdline_size,
 
 int cmdline_find_option_bool(const char *cmdline, const char *option)
 {
-	if (IS_ENABLED(CONFIG_CMDLINE_BOOL))
-		WARN_ON_ONCE(!builtin_cmdline_added);
+	int ret;
 
-	return __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option);
+	ret = __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option);
+	if (ret > 0)
+		return ret;
+
+	if (IS_ENABLED(CONFIG_CMDLINE_BOOL)) {
+		if (!builtin_cmdline_added)
+			return __cmdline_find_option_bool(builtin_cmdline, COMMAND_LINE_SIZE, option);
+	}
+
+	return ret;
 }
 
 int cmdline_find_option(const char *cmdline, const char *option, char *buffer,
 			int bufsize)
 {
-	if (IS_ENABLED(CONFIG_CMDLINE_BOOL))
-		WARN_ON_ONCE(!builtin_cmdline_added);
+	int ret;
+
+	ret = __cmdline_find_option(cmdline, COMMAND_LINE_SIZE, option, buffer, bufsize);
+	if (ret > 0)
+		return ret;
+
+	if (IS_ENABLED(CONFIG_CMDLINE_BOOL)) {
+		if (!builtin_cmdline_added)
+			return __cmdline_find_option(builtin_cmdline, COMMAND_LINE_SIZE, option, buffer, bufsize);
+	}
 
-	return __cmdline_find_option(cmdline, COMMAND_LINE_SIZE, option,
-				     buffer, bufsize);
+	return ret;
 }
-- 
2.43.0

-- 
Regards/Gruss,
    Boris.

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