linux-kernel - [PATCH v2 2/2] x86: Parse CONFIG

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Message-Id: <20220504204123.22967-3-baskov@ispras.ru>
Date:   Wed,  4 May 2022 23:41:23 +0300
From:   Baskov Evgeniy <baskov@...ras.ru>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Baskov Evgeniy <baskov@...ras.ru>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] x86: Parse CONFIG_CMDLINE in compressed kernel

CONFIG_CMDLINE, CONFIG_CMDLINE_BOOL, and CONFIG_CMDLINE_OVERRIDE were
ignored during options lookup in compressed kernel.

Parse CONFIG_CMDLINE-related options correctly in compressed kernel
code.

cmd_line_ptr is explicitly placed in .data section since it is used
and expected to be equal to zero before .bss section is cleared.

Signed-off-by: Baskov Evgeniy <baskov@...ras.ru>

diff --git a/arch/x86/boot/compressed/cmdline.c b/arch/x86/boot/compressed/cmdline.c
index f1add5d85da9..58723983933d 100644
--- a/arch/x86/boot/compressed/cmdline.c
+++ b/arch/x86/boot/compressed/cmdline.c
@@ -1,22 +1,46 @@
 // SPDX-License-Identifier: GPL-2.0
 #include "misc.h"
 
+#define COMMAND_LINE_SIZE 2048
+
 static unsigned long fs;
+
 static inline void set_fs(unsigned long seg)
 {
 	fs = seg << 4;  /* shift it back */
 }
+
 typedef unsigned long addr_t;
+
 static inline char rdfs8(addr_t addr)
 {
 	return *((char *)(fs + addr));
 }
+
 #include "../cmdline.c"
+
+static unsigned long cmd_line_ptr __section(".data");
+#ifdef CONFIG_CMDLINE_BOOL
+static char builtin_cmdline[COMMAND_LINE_SIZE] = CONFIG_CMDLINE;
+#endif
+
 unsigned long get_cmd_line_ptr(void)
 {
-	unsigned long cmd_line_ptr = boot_params->hdr.cmd_line_ptr;
+	if (!cmd_line_ptr) {
+		cmd_line_ptr = boot_params->hdr.cmd_line_ptr;
+
+		cmd_line_ptr |= (u64)boot_params->ext_cmd_line_ptr << 32;
+
+#ifdef CONFIG_CMDLINE_BOOL
+		if (!IS_ENABLED(CONFIG_CMDLINE_OVERRIDE)) {
+			strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
+			strlcat(builtin_cmdline,
+				(char *)cmd_line_ptr, COMMAND_LINE_SIZE);
+		}
 
-	cmd_line_ptr |= (u64)boot_params->ext_cmd_line_ptr << 32;
+		cmd_line_ptr = (unsigned long)builtin_cmdline;
+#endif
+	}
 
 	return cmd_line_ptr;
 }
-- 
2.36.0