Commit-ID: 90397a41779645d3abba5599f6bb538fdcab9339 Gitweb: http://git.kernel.org/tip/90397a41779645d3abba5599f6bb538fdcab9339 Author: Thomas Garnier <[email protected]> AuthorDate: Tue, 21 Jun 2016 17:47:06 -0700 Committer: Ingo Molnar <[email protected]> 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 <[email protected]> Signed-off-by: Kees Cook <[email protected]> Cc: Alexander Kuleshov <[email protected]> Cc: Alexander Popov <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Aneesh Kumar K.V <[email protected]> Cc: Baoquan He <[email protected]> Cc: Boris Ostrovsky <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Christian Borntraeger <[email protected]> Cc: Dan Williams <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Dave Young <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Jan Beulich <[email protected]> Cc: Joerg Roedel <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Kirill A. Shutemov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Lv Zheng <[email protected]> Cc: Mark Salter <[email protected]> Cc: Martin Schwidefsky <[email protected]> Cc: Matt Fleming <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephen Smalley <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Toshi Kani <[email protected]> Cc: Xiao Guangrong <[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/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)
