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Subject[patch 20/47] Fix tlb flushing with idte.
From: Martin Schwidefsky <schwidefsky@de.ibm.com>

The clear-by-asce operation of the idte instruction gets an asce
(address-space-control-element) as argument to specify which TLBs
need to get flushed. The current code passes a plain pointer to
the start of the pgd without the additional bits which would make
the pointer an asce. The current machines don't mind the difference
but a future model might want to use the designation type control
bits in the asce as a filter for the TLBs to flush.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

arch/s390/kernel/head64.S | 2 +-
include/asm-s390/mmu_context.h | 27 ++++++++++++---------------
include/asm-s390/tlbflush.h | 12 ++++++------
3 files changed, 19 insertions(+), 22 deletions(-)

Index: quilt-2.6/arch/s390/kernel/head64.S
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/head64.S
+++ quilt-2.6/arch/s390/kernel/head64.S
@@ -157,7 +157,7 @@ startup_continue:
.long 0xb2b10000 # store facility list
tm 0xc8,0x08 # check bit for clearing-by-ASCE
bno 0f-.LPG1(%r13)
- lhi %r1,2094
+ lhi %r1,2048
lhi %r2,0
.long 0xb98e2001
oi 7(%r12),0x80 # set IDTE flag
Index: quilt-2.6/include/asm-s390/mmu_context.h
===================================================================
--- quilt-2.6.orig/include/asm-s390/mmu_context.h
+++ quilt-2.6/include/asm-s390/mmu_context.h
@@ -12,10 +12,15 @@
#include <asm/pgalloc.h>
#include <asm-generic/mm_hooks.h>

-/*
- * get a new mmu context.. S390 don't know about contexts.
- */
-#define init_new_context(tsk,mm) 0
+static inline int init_new_context(struct task_struct *tsk,
+ struct mm_struct *mm)
+{
+ mm->context = _ASCE_TABLE_LENGTH | _ASCE_USER_BITS;
+#ifdef CONFIG_64BIT
+ mm->context |= _ASCE_TYPE_REGION3;
+#endif
+ return 0;
+}

#define destroy_context(mm) do { } while (0)

@@ -27,19 +32,11 @@

static inline void update_mm(struct mm_struct *mm, struct task_struct *tsk)
{
- pgd_t *pgd = mm->pgd;
- unsigned long asce_bits;
-
- /* Calculate asce bits from the first pgd table entry. */
- asce_bits = _ASCE_TABLE_LENGTH | _ASCE_USER_BITS;
-#ifdef CONFIG_64BIT
- asce_bits |= _ASCE_TYPE_REGION3;
-#endif
- S390_lowcore.user_asce = asce_bits | __pa(pgd);
+ S390_lowcore.user_asce = mm->context | __pa(mm->pgd);
if (switch_amode) {
/* Load primary space page table origin. */
- pgd_t *shadow_pgd = get_shadow_table(pgd) ? : pgd;
- S390_lowcore.user_exec_asce = asce_bits | __pa(shadow_pgd);
+ pgd_t *shadow_pgd = get_shadow_table(mm->pgd) ? : mm->pgd;
+ S390_lowcore.user_exec_asce = mm->context | __pa(shadow_pgd);
asm volatile(LCTL_OPCODE" 1,1,%0\n"
: : "m" (S390_lowcore.user_exec_asce) );
} else
Index: quilt-2.6/include/asm-s390/tlbflush.h
===================================================================
--- quilt-2.6.orig/include/asm-s390/tlbflush.h
+++ quilt-2.6/include/asm-s390/tlbflush.h
@@ -42,11 +42,11 @@ static inline void __tlb_flush_global(vo
/*
* Flush all tlb entries of a page table on all cpus.
*/
-static inline void __tlb_flush_idte(pgd_t *pgd)
+static inline void __tlb_flush_idte(unsigned long asce)
{
asm volatile(
" .insn rrf,0xb98e0000,0,%0,%1,0"
- : : "a" (2048), "a" (__pa(pgd) & PAGE_MASK) : "cc" );
+ : : "a" (2048), "a" (asce) : "cc" );
}

static inline void __tlb_flush_mm(struct mm_struct * mm)
@@ -61,11 +61,11 @@ static inline void __tlb_flush_mm(struct
* only ran on the local cpu.
*/
if (MACHINE_HAS_IDTE) {
- pgd_t *shadow_pgd = get_shadow_table(mm->pgd);
+ pgd_t *shadow = get_shadow_table(mm->pgd);

- if (shadow_pgd)
- __tlb_flush_idte(shadow_pgd);
- __tlb_flush_idte(mm->pgd);
+ if (shadow)
+ __tlb_flush_idte((unsigned long) shadow | mm->context);
+ __tlb_flush_idte((unsigned long) mm->pgd | mm->context);
return;
}
preempt_disable();
--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.



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