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linux-next/include/asm-s390/mmu_context.h
Carsten Otte 402b08622d s390: KVM preparation: provide hook to enable pgstes in user pagetable
The SIE instruction on s390 uses the 2nd half of the page table page to
virtualize the storage keys of a guest. This patch offers the s390_enable_sie
function, which reorganizes the page tables of a single-threaded process to
reserve space in the page table:
s390_enable_sie makes sure that the process is single threaded and then uses
dup_mm to create a new mm with reorganized page tables. The old mm is freed
and the process has now a page status extended field after every page table.

Code that wants to exploit pgstes should SELECT CONFIG_PGSTE.

This patch has a small common code hit, namely making dup_mm non-static.

Edit (Carsten): I've modified Martin's patch, following Jeremy Fitzhardinge's
review feedback. Now we do have the prototype for dup_mm in
include/linux/sched.h. Following Martin's suggestion, s390_enable_sie() does now
call task_lock() to prevent race against ptrace modification of mm_users.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:40 +03:00

78 lines
2.0 KiB
C

/*
* include/asm-s390/mmu_context.h
*
* S390 version
*
* Derived from "include/asm-i386/mmu_context.h"
*/
#ifndef __S390_MMU_CONTEXT_H
#define __S390_MMU_CONTEXT_H
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm-generic/mm_hooks.h>
static inline int init_new_context(struct task_struct *tsk,
struct mm_struct *mm)
{
mm->context.asce_bits = _ASCE_TABLE_LENGTH | _ASCE_USER_BITS;
#ifdef CONFIG_64BIT
mm->context.asce_bits |= _ASCE_TYPE_REGION3;
#endif
if (current->mm->context.pgstes) {
mm->context.noexec = 0;
mm->context.pgstes = 1;
} else {
mm->context.noexec = s390_noexec;
mm->context.pgstes = 0;
}
mm->context.asce_limit = STACK_TOP_MAX;
crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
return 0;
}
#define destroy_context(mm) do { } while (0)
#ifndef __s390x__
#define LCTL_OPCODE "lctl"
#else
#define LCTL_OPCODE "lctlg"
#endif
static inline void update_mm(struct mm_struct *mm, struct task_struct *tsk)
{
pgd_t *pgd = mm->pgd;
S390_lowcore.user_asce = mm->context.asce_bits | __pa(pgd);
if (switch_amode) {
/* Load primary space page table origin. */
pgd = mm->context.noexec ? get_shadow_table(pgd) : pgd;
S390_lowcore.user_exec_asce = mm->context.asce_bits | __pa(pgd);
asm volatile(LCTL_OPCODE" 1,1,%0\n"
: : "m" (S390_lowcore.user_exec_asce) );
} else
/* Load home space page table origin. */
asm volatile(LCTL_OPCODE" 13,13,%0"
: : "m" (S390_lowcore.user_asce) );
set_fs(current->thread.mm_segment);
}
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
cpu_set(smp_processor_id(), next->cpu_vm_mask);
update_mm(next, tsk);
}
#define enter_lazy_tlb(mm,tsk) do { } while (0)
#define deactivate_mm(tsk,mm) do { } while (0)
static inline void activate_mm(struct mm_struct *prev,
struct mm_struct *next)
{
switch_mm(prev, next, current);
}
#endif /* __S390_MMU_CONTEXT_H */