x86/boot: Rename "real_mode" to "boot_params"

The non-compressed boot code uses the (much more obvious) name
"boot_params" for the global pointer to the x86 boot parameters. The
compressed kernel loader code, though, was using the legacy name
"real_mode". There is no need to have a different name, and changing it
improves readability.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1460997735-24785-4-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/boot/compressed/cmdline.c

@@ -15,9 +15,9 @@ static inline char rdfs8(addr_t addr)
 #include "../cmdline.c"
 static unsigned long get_cmd_line_ptr(void)
 {
-	unsigned long cmd_line_ptr = real_mode->hdr.cmd_line_ptr;
+	unsigned long cmd_line_ptr = boot_params->hdr.cmd_line_ptr;
 
-	cmd_line_ptr |= (u64)real_mode->ext_cmd_line_ptr << 32;
+	cmd_line_ptr |= (u64)boot_params->ext_cmd_line_ptr << 32;
 
 	return cmd_line_ptr;
 }

arch/x86/boot/compressed/kaslr.c

@@ -55,7 +55,7 @@ static unsigned long get_random_boot(void)
 	unsigned long hash = 0;
 
 	hash = rotate_xor(hash, build_str, sizeof(build_str));
-	hash = rotate_xor(hash, real_mode, sizeof(*real_mode));
+	hash = rotate_xor(hash, boot_params, sizeof(*boot_params));
 
 	return hash;
 }
@@ -152,16 +152,16 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
 	mem_avoid[0].size = unsafe_len;
 
 	/* Avoid initrd. */
-	initrd_start  = (u64)real_mode->ext_ramdisk_image << 32;
-	initrd_start |= real_mode->hdr.ramdisk_image;
-	initrd_size  = (u64)real_mode->ext_ramdisk_size << 32;
-	initrd_size |= real_mode->hdr.ramdisk_size;
+	initrd_start  = (u64)boot_params->ext_ramdisk_image << 32;
+	initrd_start |= boot_params->hdr.ramdisk_image;
+	initrd_size  = (u64)boot_params->ext_ramdisk_size << 32;
+	initrd_size |= boot_params->hdr.ramdisk_size;
 	mem_avoid[1].start = initrd_start;
 	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  = (u64)boot_params->ext_cmd_line_ptr << 32;
+	cmd_line |= boot_params->hdr.cmd_line_ptr;
 	/* Calculate size of cmd_line. */
 	ptr = (char *)(unsigned long)cmd_line;
 	for (cmd_line_size = 0; ptr[cmd_line_size++]; )
@@ -190,7 +190,7 @@ static bool mem_avoid_overlap(struct mem_vector *img)
 	}
 
 	/* Avoid all entries in the setup_data linked list. */
-	ptr = (struct setup_data *)(unsigned long)real_mode->hdr.setup_data;
+	ptr = (struct setup_data *)(unsigned long)boot_params->hdr.setup_data;
 	while (ptr) {
 		struct mem_vector avoid;
 
@@ -288,8 +288,8 @@ static unsigned long find_random_addr(unsigned long minimum,
 	minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN);
 
 	/* Verify potential e820 positions, appending to slots list. */
-	for (i = 0; i < real_mode->e820_entries; i++) {
-		process_e820_entry(&real_mode->e820_map[i], minimum, size);
+	for (i = 0; i < boot_params->e820_entries; i++) {
+		process_e820_entry(&boot_params->e820_map[i], minimum, size);
 	}
 
 	return slots_fetch_random();
@@ -315,7 +315,7 @@ unsigned char *choose_kernel_location(unsigned char *input,
 	}
 #endif
 
-	real_mode->hdr.loadflags |= KASLR_FLAG;
+	boot_params->hdr.loadflags |= KASLR_FLAG;
 
 	/* Record the various known unsafe memory ranges. */
 	mem_avoid_init((unsigned long)input, input_size,

arch/x86/boot/compressed/misc.c

@@ -114,7 +114,7 @@ static void error(char *m);
 /*
  * This is set up by the setup-routine at boot-time
  */
-struct boot_params *real_mode;		/* Pointer to real-mode data */
+struct boot_params *boot_params;
 
 memptr free_mem_ptr;
 memptr free_mem_end_ptr;
@@ -184,12 +184,12 @@ void __putstr(const char *s)
 		}
 	}
 
-	if (real_mode->screen_info.orig_video_mode == 0 &&
+	if (boot_params->screen_info.orig_video_mode == 0 &&
 	    lines == 0 && cols == 0)
 		return;
 
-	x = real_mode->screen_info.orig_x;
-	y = real_mode->screen_info.orig_y;
+	x = boot_params->screen_info.orig_x;
+	y = boot_params->screen_info.orig_y;
 
 	while ((c = *s++) != '\0') {
 		if (c == '\n') {
@@ -210,8 +210,8 @@ void __putstr(const char *s)
 		}
 	}
 
-	real_mode->screen_info.orig_x = x;
-	real_mode->screen_info.orig_y = y;
+	boot_params->screen_info.orig_x = x;
+	boot_params->screen_info.orig_y = y;
 
 	pos = (x + cols * y) * 2;	/* Update cursor position */
 	outb(14, vidport);
@@ -392,14 +392,15 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
 {
 	unsigned char *output_orig = output;
 
-	real_mode = rmode;
+	/* Retain x86 boot parameters pointer passed from startup_32/64. */
+	boot_params = rmode;
 
-	/* Clear it for solely in-kernel use */
-	real_mode->hdr.loadflags &= ~KASLR_FLAG;
+	/* Clear flags intended for solely in-kernel use. */
+	boot_params->hdr.loadflags &= ~KASLR_FLAG;
 
-	sanitize_boot_params(real_mode);
+	sanitize_boot_params(boot_params);
 
-	if (real_mode->screen_info.orig_video_mode == 7) {
+	if (boot_params->screen_info.orig_video_mode == 7) {
 		vidmem = (char *) 0xb0000;
 		vidport = 0x3b4;
 	} else {
@@ -407,8 +408,8 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
 		vidport = 0x3d4;
 	}
 
-	lines = real_mode->screen_info.orig_video_lines;
-	cols = real_mode->screen_info.orig_video_cols;
+	lines = boot_params->screen_info.orig_video_lines;
+	cols = boot_params->screen_info.orig_video_cols;
 
 	console_init();
 	debug_putstr("early console in decompress_kernel\n");

arch/x86/boot/compressed/misc.h

@@ -32,7 +32,7 @@
 /* misc.c */
 extern memptr free_mem_ptr;
 extern memptr free_mem_end_ptr;
-extern struct boot_params *real_mode;		/* Pointer to real-mode data */
+extern struct boot_params *boot_params;
 void __putstr(const char *s);
 void __puthex(unsigned long value);
 #define error_putstr(__x)  __putstr(__x)