Commit-ID: d2d3462f9f08da364c8fbd41e8e32229d610d49d Gitweb: http://git.kernel.org/tip/d2d3462f9f08da364c8fbd41e8e32229d610d49d Author: Kees Cook <[email protected]> AuthorDate: Mon, 9 May 2016 13:22:09 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 10 May 2016 10:12:08 +0200
x86/KASLR: Clarify purpose of each get_random_long() KASLR will be calling get_random_long() twice, but the debug output won't distinguishing between them. This patch adds a report on when it is fetching the physical vs virtual address. With this, once the virtual offset is separate, the report changes from: KASLR using RDTSC... KASLR using RDTSC... into: Physical KASLR using RDTSC... Virtual KASLR using RDTSC... Signed-off-by: Kees Cook <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Baoquan He <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Young <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vivek Goyal <[email protected]> Cc: Yinghai Lu <[email protected]> Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/boot/compressed/kaslr.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 016a4f4..cfeb025 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -72,7 +72,7 @@ static unsigned long get_random_boot(void) return hash; } -static unsigned long get_random_long(void) +static unsigned long get_random_long(const char *purpose) { #ifdef CONFIG_X86_64 const unsigned long mix_const = 0x5d6008cbf3848dd3UL; @@ -82,7 +82,8 @@ static unsigned long get_random_long(void) unsigned long raw, random = get_random_boot(); bool use_i8254 = true; - debug_putstr("KASLR using"); + debug_putstr(purpose); + debug_putstr(" KASLR using"); if (has_cpuflag(X86_FEATURE_RDRAND)) { debug_putstr(" RDRAND"); @@ -365,7 +366,7 @@ static unsigned long slots_fetch_random(void) if (slot_max == 0) return 0; - return slots[get_random_long() % slot_max]; + return slots[get_random_long("Physical") % slot_max]; } static void process_e820_entry(struct e820entry *entry, @@ -453,7 +454,7 @@ static unsigned long find_random_virt_addr(unsigned long minimum, slots = (KERNEL_IMAGE_SIZE - minimum - image_size) / CONFIG_PHYSICAL_ALIGN + 1; - random_addr = get_random_long() % slots; + random_addr = get_random_long("Virtual") % slots; return random_addr * CONFIG_PHYSICAL_ALIGN + minimum; }
