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

kaiser: stack map PAGE_SIZE at THREAD_SIZE-PAGE_SIZE

to the 4.9-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-stack-map-page_size-at-thread_size-page_size.patch and it can be found in the queue-4.9 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 20:37:21 CET 2018

From: Hugh Dickins hughd@google.com Date: Sun, 3 Sep 2017 18:57:03 -0700 Subject: kaiser: stack map PAGE_SIZE at THREAD_SIZE-PAGE_SIZE

From: Hugh Dickins hughd@google.com

Kaiser only needs to map one page of the stack; and kernel/fork.c did not build on powerpc (no __PAGE_KERNEL). It's all cleaner if linux/kaiser.h provides kaiser_map_thread_stack() and kaiser_unmap_thread_stack() wrappers around asm/kaiser.h's kaiser_add_mapping() and kaiser_remove_mapping(). And use linux/kaiser.h in init/main.c to avoid the #ifdefs there.

Signed-off-by: Hugh Dickins hughd@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/kaiser.h | 40 +++++++++++++++++++++++++++++++++------- init/main.c | 6 +----- kernel/fork.c | 7 ++----- 3 files changed, 36 insertions(+), 17 deletions(-)

--- a/include/linux/kaiser.h +++ b/include/linux/kaiser.h @@ -1,26 +1,52 @@ -#ifndef _INCLUDE_KAISER_H -#define _INCLUDE_KAISER_H +#ifndef _LINUX_KAISER_H +#define _LINUX_KAISER_H

#ifdef CONFIG_KAISER #include <asm/kaiser.h> + +static inline int kaiser_map_thread_stack(void *stack) +{ + /* + * Map that page of kernel stack on which we enter from user context. + */ + return kaiser_add_mapping((unsigned long)stack + + THREAD_SIZE - PAGE_SIZE, PAGE_SIZE, __PAGE_KERNEL); +} + +static inline void kaiser_unmap_thread_stack(void *stack) +{ + /* + * Note: may be called even when kaiser_map_thread_stack() failed. + */ + kaiser_remove_mapping((unsigned long)stack + + THREAD_SIZE - PAGE_SIZE, PAGE_SIZE); +} #else

/* * These stubs are used whenever CONFIG_KAISER is off, which - * includes architectures that support KAISER, but have it - * disabled. + * includes architectures that support KAISER, but have it disabled. */

static inline void kaiser_init(void) { } -static inline void kaiser_remove_mapping(unsigned long start, unsigned long size) +static inline int kaiser_add_mapping(unsigned long addr, + unsigned long size, unsigned long flags) +{ + return 0; +} +static inline void kaiser_remove_mapping(unsigned long start, + unsigned long size) { } -static inline int kaiser_add_mapping(unsigned long addr, unsigned long size, unsigned long flags) +static inline int kaiser_map_thread_stack(void *stack) { return 0; } +static inline void kaiser_unmap_thread_stack(void *stack) +{ +}

#endif /* !CONFIG_KAISER */ -#endif /* _INCLUDE_KAISER_H */ +#endif /* _LINUX_KAISER_H */ --- a/init/main.c +++ b/init/main.c @@ -80,15 +80,13 @@ #include <linux/integrity.h> #include <linux/proc_ns.h> #include <linux/io.h> +#include <linux/kaiser.h>

#include <asm/io.h> #include <asm/bugs.h> #include <asm/setup.h> #include <asm/sections.h> #include <asm/cacheflush.h> -#ifdef CONFIG_KAISER -#include <asm/kaiser.h> -#endif

static int kernel_init(void *);

@@ -476,9 +474,7 @@ static void __init mm_init(void) pgtable_init(); vmalloc_init(); ioremap_huge_init(); -#ifdef CONFIG_KAISER kaiser_init(); -#endif }

asmlinkage __visible void __init start_kernel(void) --- a/kernel/fork.c +++ b/kernel/fork.c @@ -212,12 +212,9 @@ static unsigned long *alloc_thread_stack #endif }

-extern void kaiser_remove_mapping(unsigned long start_addr, unsigned long size); static inline void free_thread_stack(struct task_struct *tsk) { -#ifdef CONFIG_KAISER - kaiser_remove_mapping((unsigned long)tsk->stack, THREAD_SIZE); -#endif + kaiser_unmap_thread_stack(tsk->stack); #ifdef CONFIG_VMAP_STACK if (task_stack_vm_area(tsk)) { unsigned long flags; @@ -501,7 +498,7 @@ static struct task_struct *dup_task_stru */ tsk->stack = stack;

- err= kaiser_add_mapping((unsigned long)tsk->stack, THREAD_SIZE, __PAGE_KERNEL); + err= kaiser_map_thread_stack(tsk->stack); if (err) goto free_stack; #ifdef CONFIG_VMAP_STACK

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

queue-4.9/kaiser-vmstat-show-nr_kaisertable-as-nr_overhead.patch queue-4.9/kaiser-add-nokaiser-boot-option-using-alternative.patch queue-4.9/kaiser-fix-unlikely-error-in-alloc_ldt_struct.patch queue-4.9/kaiser-kaiser_flush_tlb_on_return_to_user-check-pcid.patch queue-4.9/x86-paravirt-dont-patch-flush_tlb_single.patch queue-4.9/kaiser-merged-update.patch queue-4.9/kaiser-delete-kaiser_real_switch-option.patch queue-4.9/kaiser-kaiser_remove_mapping-move-along-the-pgd.patch queue-4.9/kaiser-fix-perf-crashes.patch queue-4.9/kaiser-drop-is_atomic-arg-to-kaiser_pagetable_walk.patch queue-4.9/kaiser-load_new_mm_cr3-let-switch_user_cr3-flush-user.patch queue-4.9/kaiser-enhanced-by-kernel-and-user-pcids.patch queue-4.9/kaiser-x86_cr3_pcid_noflush-and-x86_cr3_pcid_user.patch queue-4.9/kaiser-align-addition-to-x86-mm-makefile.patch queue-4.9/kaiser-use-alternative-instead-of-x86_cr3_pcid_noflush.patch queue-4.9/kaiser-stack-map-page_size-at-thread_size-page_size.patch queue-4.9/kaiser-name-that-0x1000-kaiser_shadow_pgd_offset.patch queue-4.9/kaiser-fix-regs-to-do_nmi-ifndef-config_kaiser.patch queue-4.9/kaiser-do-not-set-_page_nx-on-pgd_none.patch queue-4.9/kaiser-tidied-up-asm-kaiser.h-somewhat.patch queue-4.9/kaiser-cleanups-while-trying-for-gold-link.patch queue-4.9/kaiser-tidied-up-kaiser_add-remove_mapping-slightly.patch queue-4.9/kaiser-fix-build-and-fixme-in-alloc_ldt_struct.patch queue-4.9/kaiser-kernel-address-isolation.patch queue-4.9/kaiser-enomem-if-kaiser_pagetable_walk-null.patch queue-4.9/kaiser-asm-tlbflush.h-handle-nopge-at-lower-level.patch queue-4.9/kaiser-paranoid_entry-pass-cr3-need-to-paranoid_exit.patch queue-4.9/kaiser-kaiser-depends-on-smp.patch queue-4.9/kaiser-pcid-0-for-kernel-and-128-for-user.patch