4.9-stable review patch. If anyone has any objections, please let me know.
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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