Commit-ID: d2d3462f9f08da364c8fbd41e8e32229d610d49d Gitweb: http://git.kernel.org/tip/d2d3462f9f08da364c8fbd41e8e32229d610d49d Author: Kees Cook <keesc...@chromium.org> AuthorDate: Mon, 9 May 2016 13:22:09 -0700 Committer: Ingo Molnar <mi...@kernel.org> 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 <keesc...@chromium.org> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Andy Lutomirski <l...@kernel.org> Cc: Baoquan He <b...@redhat.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Borislav Petkov <b...@suse.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Dave Young <dyo...@redhat.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Vivek Goyal <vgo...@redhat.com> Cc: Yinghai Lu <ying...@kernel.org> Cc: kernel-harden...@lists.openwall.com Cc: lasse.col...@tukaani.org Link: http://lkml.kernel.org/r/1462825332-10505-7-git-send-email-keesc...@chromium.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- 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; }
