This is a note to let you know that I've just added the patch titled

kaiser: KAISER depends on SMP

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: kaiser-kaiser-depends-on-smp.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Wed Jan 3 18:58:12 CET 2018

From: Hugh Dickins hughd@google.com Date: Wed, 13 Sep 2017 14:03:10 -0700 Subject: kaiser: KAISER depends on SMP

From: Hugh Dickins hughd@google.com

It is absurd that KAISER should depend on SMP, but apparently nobody has tried a UP build before: which breaks on implicit declaration of function 'per_cpu_offset' in arch/x86/mm/kaiser.c.

Now, you would expect that to be trivially fixed up; but looking at the System.map when that block is #ifdef'ed out of kaiser_init(), I see that in a UP build __per_cpu_user_mapped_end is precisely at __per_cpu_user_mapped_start, and the items carefully gathered into that section for user-mapping on SMP, dispersed elsewhere on UP.

So, some other kind of section assignment will be needed on UP, but implementing that is not a priority: just make KAISER depend on SMP for now.

Also inserted a blank line before the option, tidied up the brief Kconfig help message, and added an "If unsure, Y".

Signed-off-by: Hugh Dickins hughd@google.com Acked-by: Jiri Kosina jkosina@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- security/Kconfig | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/security/Kconfig +++ b/security/Kconfig @@ -30,14 +30,16 @@ config SECURITY model will be used.

If you are unsure how to answer this question, answer N. + config KAISER bool "Remove the kernel mapping in user mode" default y - depends on X86_64 - depends on !PARAVIRT + depends on X86_64 && SMP && !PARAVIRT help - This enforces a strict kernel and user space isolation in order to close - hardware side channels on kernel address information. + This enforces a strict kernel and user space isolation, in order + to close hardware side channels on kernel address information. + + If you are unsure how to answer this question, answer Y.

config KAISER_REAL_SWITCH bool "KAISER: actually switch page tables"

Patches currently in stable-queue which might be from hughd@google.com are

queue-4.4/kaiser-vmstat-show-nr_kaisertable-as-nr_overhead.patch queue-4.4/kaiser-add-nokaiser-boot-option-using-alternative.patch queue-4.4/kaiser-fix-unlikely-error-in-alloc_ldt_struct.patch queue-4.4/kaiser-_pgd_alloc-without-__gfp_repeat-to-avoid-stalls.patch queue-4.4/kaiser-kaiser_flush_tlb_on_return_to_user-check-pcid.patch queue-4.4/x86-paravirt-dont-patch-flush_tlb_single.patch queue-4.4/kaiser-merged-update.patch queue-4.4/kaiser-delete-kaiser_real_switch-option.patch queue-4.4/kaiser-kaiser_remove_mapping-move-along-the-pgd.patch queue-4.4/kaiser-fix-perf-crashes.patch queue-4.4/kaiser-drop-is_atomic-arg-to-kaiser_pagetable_walk.patch queue-4.4/kaiser-load_new_mm_cr3-let-switch_user_cr3-flush-user.patch queue-4.4/kaiser-enhanced-by-kernel-and-user-pcids.patch queue-4.4/kaiser-x86_cr3_pcid_noflush-and-x86_cr3_pcid_user.patch queue-4.4/kaiser-use-alternative-instead-of-x86_cr3_pcid_noflush.patch queue-4.4/kaiser-stack-map-page_size-at-thread_size-page_size.patch queue-4.4/kaiser-name-that-0x1000-kaiser_shadow_pgd_offset.patch queue-4.4/kaiser-fix-regs-to-do_nmi-ifndef-config_kaiser.patch queue-4.4/kaiser-do-not-set-_page_nx-on-pgd_none.patch queue-4.4/kaiser-tidied-up-asm-kaiser.h-somewhat.patch queue-4.4/kaiser-cleanups-while-trying-for-gold-link.patch queue-4.4/kaiser-tidied-up-kaiser_add-remove_mapping-slightly.patch queue-4.4/kaiser-fix-build-and-fixme-in-alloc_ldt_struct.patch queue-4.4/kaiser-kernel-address-isolation.patch queue-4.4/kaiser-enomem-if-kaiser_pagetable_walk-null.patch queue-4.4/kaiser-asm-tlbflush.h-handle-nopge-at-lower-level.patch queue-4.4/kaiser-paranoid_entry-pass-cr3-need-to-paranoid_exit.patch queue-4.4/kaiser-kaiser-depends-on-smp.patch queue-4.4/kaiser-pcid-0-for-kernel-and-128-for-user.patch