linux-kernel - [PATCH] x86/aslr: use get_cmd_line_ptr() to get command line address

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Date:	Thu, 21 Jan 2016 14:45:09 +0600
From:	Alexander Kuleshov <kuleshovmail@...il.com>
To:	Ingo Molnar <mingo@...hat.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H . Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...e.de>,
	Andy Lutomirski <luto@...nel.org>,
	Jiri Kosina <jkosina@...e.cz>, x86@...nel.org,
	linux-kernel@...r.kernel.org,
	Alexander Kuleshov <kuleshovmail@...il.com>
Subject: [PATCH] x86/aslr: use get_cmd_line_ptr() to get command line address

The cmdline.c provides the get_cmd_line_ptr() accessor for the command line
address. In the same time, we get command line address in the
mem_avoid_init() in same way. Let's make the get_cmd_line_ptr() non-static
and use it in the mem_avoid_init() to get command line address to prevent
code duplication.

Signed-off-by: Alexander Kuleshov <kuleshovmail@...il.com>
---
 arch/x86/boot/compressed/aslr.c    | 3 +--
 arch/x86/boot/compressed/cmdline.c | 2 +-
 arch/x86/boot/compressed/misc.h    | 1 +
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index 6a9b96b..495a617 100644
--- a/arch/x86/boot/compressed/aslr.c
+++ b/arch/x86/boot/compressed/aslr.c
@@ -160,8 +160,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
 	mem_avoid[1].size = initrd_size;
 
 	/* Avoid kernel command line. */
-	cmd_line  = (u64)real_mode->ext_cmd_line_ptr << 32;
-	cmd_line |= real_mode->hdr.cmd_line_ptr;
+	cmd_line = get_cmd_line_ptr();
 	/* Calculate size of cmd_line. */
 	ptr = (char *)(unsigned long)cmd_line;
 	for (cmd_line_size = 0; ptr[cmd_line_size++]; )
diff --git a/arch/x86/boot/compressed/cmdline.c b/arch/x86/boot/compressed/cmdline.c
index b68e303..6b913e6 100644
--- a/arch/x86/boot/compressed/cmdline.c
+++ b/arch/x86/boot/compressed/cmdline.c
@@ -13,7 +13,7 @@ static inline char rdfs8(addr_t addr)
 	return *((char *)(fs + addr));
 }
 #include "../cmdline.c"
-static unsigned long get_cmd_line_ptr(void)
+unsigned long get_cmd_line_ptr(void)
 {
 	unsigned long cmd_line_ptr = real_mode->hdr.cmd_line_ptr;
 
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 3783dc3..7956392 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -60,6 +60,7 @@ static inline void debug_puthex(const char *s)
 
 #if CONFIG_EARLY_PRINTK || CONFIG_RANDOMIZE_BASE
 /* cmdline.c */
+unsigned long get_cmd_line_ptr(void);
 int cmdline_find_option(const char *option, char *buffer, int bufsize);
 int cmdline_find_option_bool(const char *option);
 #endif
-- 
2.7.0.25.gfc10eb5