x86/KASLR: Remove unneeded boot_params argument

Since the boot_params can be found using the real_mode global variable,
there is no need to pass around a pointer to it. This slightly simplifies
the choose_kernel_location function and its callers.

[kees: rewrote changelog, tracked file rename]
Signed-off-by: Yinghai Lu <yinghai@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>
Link: http://lkml.kernel.org/r/1460997735-24785-3-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/boot/compressed/kaslr.c

@@ -295,8 +295,7 @@ static unsigned long find_random_addr(unsigned long minimum,
 	return slots_fetch_random();
 }
 
-unsigned char *choose_kernel_location(struct boot_params *boot_params,
-				      unsigned char *input,
+unsigned char *choose_kernel_location(unsigned char *input,
 				      unsigned long input_size,
 				      unsigned char *output,
 				      unsigned long output_size)
@@ -316,7 +315,7 @@ unsigned char *choose_kernel_location(struct boot_params *boot_params,
 	}
 #endif
 
-	boot_params->hdr.loadflags |= KASLR_FLAG;
+	real_mode->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

@@ -428,7 +428,7 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
 	 * the entire decompressed kernel plus relocation table, or the
 	 * entire decompressed kernel plus .bss and .brk sections.
 	 */
-	output = choose_kernel_location(real_mode, input_data, input_len, output,
+	output = choose_kernel_location(input_data, input_len, output,
 					output_len > run_size ? output_len
 							      : run_size);
 

arch/x86/boot/compressed/misc.h

@@ -67,8 +67,7 @@ int cmdline_find_option_bool(const char *option);
 
 #if CONFIG_RANDOMIZE_BASE
 /* kaslr.c */
-unsigned char *choose_kernel_location(struct boot_params *boot_params,
-				      unsigned char *input,
+unsigned char *choose_kernel_location(unsigned char *input,
 				      unsigned long input_size,
 				      unsigned char *output,
 				      unsigned long output_size);
@@ -76,8 +75,7 @@ unsigned char *choose_kernel_location(struct boot_params *boot_params,
 bool has_cpuflag(int flag);
 #else
 static inline
-unsigned char *choose_kernel_location(struct boot_params *boot_params,
-				      unsigned char *input,
+unsigned char *choose_kernel_location(unsigned char *input,
 				      unsigned long input_size,
 				      unsigned char *output,
 				      unsigned long output_size)