Commit-ID: 90397a41779645d3abba5599f6bb538fdcab9339 Gitweb: http://git.kernel.org/tip/90397a41779645d3abba5599f6bb538fdcab9339 Author: Thomas Garnier <thgar...@google.com> AuthorDate: Tue, 21 Jun 2016 17:47:06 -0700 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Fri, 8 Jul 2016 17:35:21 +0200
x86/mm: Add memory hotplug support for KASLR memory randomization Add a new option (CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING) to define the padding used for the physical memory mapping section when KASLR memory is enabled. It ensures there is enough virtual address space when CONFIG_MEMORY_HOTPLUG is used. The default value is 10 terabytes. If CONFIG_MEMORY_HOTPLUG is not used, no space is reserved increasing the entropy available. Signed-off-by: Thomas Garnier <thgar...@google.com> Signed-off-by: Kees Cook <keesc...@chromium.org> Cc: Alexander Kuleshov <kuleshovm...@gmail.com> Cc: Alexander Popov <alpo...@ptsecurity.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Andy Lutomirski <l...@kernel.org> Cc: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> Cc: Baoquan He <b...@redhat.com> Cc: Boris Ostrovsky <boris.ostrov...@oracle.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Borislav Petkov <b...@suse.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Christian Borntraeger <borntrae...@de.ibm.com> Cc: Dan Williams <dan.j.willi...@intel.com> Cc: Dave Hansen <dave.han...@linux.intel.com> Cc: Dave Young <dyo...@redhat.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: Dmitry Vyukov <dvyu...@google.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Jan Beulich <jbeul...@suse.com> Cc: Joerg Roedel <jroe...@suse.de> Cc: Jonathan Corbet <cor...@lwn.net> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Juergen Gross <jgr...@suse.com> Cc: Kirill A. Shutemov <kirill.shute...@linux.intel.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Lv Zheng <lv.zh...@intel.com> Cc: Mark Salter <msal...@redhat.com> Cc: Martin Schwidefsky <schwidef...@de.ibm.com> Cc: Matt Fleming <m...@codeblueprint.co.uk> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Stephen Smalley <s...@tycho.nsa.gov> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Toshi Kani <toshi.k...@hpe.com> Cc: Xiao Guangrong <guangrong.x...@linux.intel.com> Cc: Yinghai Lu <ying...@kernel.org> Cc: kernel-harden...@lists.openwall.com Cc: linux-...@vger.kernel.org Link: http://lkml.kernel.org/r/1466556426-32664-10-git-send-email-keesc...@chromium.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/Kconfig | 15 +++++++++++++++ arch/x86/mm/kaslr.c | 7 ++++++- 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 9719b8e..703413f 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2010,6 +2010,21 @@ config RANDOMIZE_MEMORY If unsure, say N. +config RANDOMIZE_MEMORY_PHYSICAL_PADDING + hex "Physical memory mapping padding" if EXPERT + depends on RANDOMIZE_MEMORY + default "0xa" if MEMORY_HOTPLUG + default "0x0" + range 0x1 0x40 if MEMORY_HOTPLUG + range 0x0 0x40 + ---help--- + Define the padding in terabytes added to the existing physical + memory size during kernel memory randomization. It is useful + for memory hotplug support but reduces the entropy available for + address randomization. + + If unsure, leave at the default value. + config HOTPLUG_CPU bool "Support for hot-pluggable CPUs" depends on SMP diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c index c939cfe..26dccd6 100644 --- a/arch/x86/mm/kaslr.c +++ b/arch/x86/mm/kaslr.c @@ -92,8 +92,13 @@ void __init kernel_randomize_memory(void) if (!kaslr_memory_enabled()) return; + /* + * Update Physical memory mapping to available and + * add padding if needed (especially for memory hotplug support). + */ BUG_ON(kaslr_regions[0].base != &page_offset_base); - memory_tb = ((max_pfn << PAGE_SHIFT) >> TB_SHIFT); + memory_tb = ((max_pfn << PAGE_SHIFT) >> TB_SHIFT) + + CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING; /* Adapt phyiscal memory region size based on available memory */ if (memory_tb < kaslr_regions[0].size_tb)
