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kaiser: stack map PAGE_SIZE at THREAD_SIZE-PAGE_SIZE

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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>
This commit is contained in:
Hugh Dickins 2017-09-03 18:57:03 -07:00 committed by Greg Kroah-Hartman
parent ac2f1018ac
commit 0994a2cf8f
3 changed files with 38 additions and 19 deletions
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44
include/linux/kaiser.h
View File

@ -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)
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_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 */

6
init/main.c
View File

@ -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)

7
kernel/fork.c
View File

@ -212,12 +212,9 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
#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_struct(struct task_struct *orig, int node)
*/
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