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mmu_gather: move minimal range calculations into generic code 

On architectures with hardware broadcasting of TLB invalidation messages
, it makes sense to reduce the range of the mmu_gather structure when
unmapping page ranges based on the dirty address information passed to
tlb_remove_tlb_entry.

arm64 already does this by directly manipulating the start/end fields
of the gather structure, but this confuses the generic code which
does not expect these fields to change and can end up calculating
invalid, negative ranges when forcing a flush in zap_pte_range.

This patch moves the minimal range calculation out of the arm64 code
and into the generic implementation, simplifying zap_pte_range in the
process (which no longer needs to care about start/end, since they will
point to the appropriate ranges already). With the range being tracked
by core code, the need_flush flag is dropped in favour of checking that
the end of the range has actually been set.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Michal Simek <monstr@monstr.eu>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2014-10-29 10:03:09 +00:00
parent 63648dd20f
commit fb7332a9fe
7 changed files with 63 additions and 100 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

67
arch/arm64/include/asm/tlb.h
View File

@ -19,10 +19,6 @@
#ifndef __ASM_TLB_H
#define __ASM_TLB_H
#define __tlb_remove_pmd_tlb_entry __tlb_remove_pmd_tlb_entry
#include <asm-generic/tlb.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
@ -37,71 +33,22 @@ static inline void __tlb_remove_table(void *_table)
#define tlb_remove_entry(tlb, entry) tlb_remove_page(tlb, entry)
#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
/*
* There's three ways the TLB shootdown code is used:
* 1. Unmapping a range of vmas. See zap_page_range(), unmap_region().
* tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
* 2. Unmapping all vmas. See exit_mmap().
* tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
* Page tables will be freed.
* 3. Unmapping argument pages. See shift_arg_pages().
* tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
*/
#include <asm-generic/tlb.h>
static inline void tlb_flush(struct mmu_gather *tlb)
{
if (tlb->fullmm) {
flush_tlb_mm(tlb->mm);
} else if (tlb->end > 0) {
} else {
struct vm_area_struct vma = { .vm_mm = tlb->mm, };
flush_tlb_range(&vma, tlb->start, tlb->end);
tlb->start = TASK_SIZE;
tlb->end = 0;
}
}
static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
{
if (!tlb->fullmm) {
tlb->start = min(tlb->start, addr);
tlb->end = max(tlb->end, addr + PAGE_SIZE);
}
}
/*
* Memorize the range for the TLB flush.
*/
static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep,
unsigned long addr)
{
tlb_add_flush(tlb, addr);
}
/*
* In the case of tlb vma handling, we can optimise these away in the
* case where we're doing a full MM flush. When we're doing a munmap,
* the vmas are adjusted to only cover the region to be torn down.
*/
static inline void tlb_start_vma(struct mmu_gather *tlb,
struct vm_area_struct *vma)
{
if (!tlb->fullmm) {
tlb->start = TASK_SIZE;
tlb->end = 0;
}
}
static inline void tlb_end_vma(struct mmu_gather *tlb,
struct vm_area_struct *vma)
{
if (!tlb->fullmm)
tlb_flush(tlb);
}
static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
unsigned long addr)
{
pgtable_page_dtor(pte);
tlb_add_flush(tlb, addr);
tlb_remove_entry(tlb, pte);
}
@ -109,7 +56,6 @@ static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
unsigned long addr)
{
tlb_add_flush(tlb, addr);
tlb_remove_entry(tlb, virt_to_page(pmdp));
}
#endif
@ -118,15 +64,8 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pudp,
unsigned long addr)
{
tlb_add_flush(tlb, addr);
tlb_remove_entry(tlb, virt_to_page(pudp));
}
#endif
static inline void __tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp,
unsigned long address)
{
tlb_add_flush(tlb, address);
}
#endif

3
arch/microblaze/include/asm/tlb.h
View File

@ -14,7 +14,6 @@
#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm)
#include <linux/pagemap.h>
#include <asm-generic/tlb.h>
#ifdef CONFIG_MMU
#define tlb_start_vma(tlb, vma) do { } while (0)
@ -22,4 +21,6 @@
#define __tlb_remove_tlb_entry(tlb, pte, address) do { } while (0)
#endif
#include <asm-generic/tlb.h>
#endif /* _ASM_MICROBLAZE_TLB_H */

3
arch/powerpc/include/asm/pgalloc.h
View File

@ -3,7 +3,6 @@
#ifdef __KERNEL__
#include <linux/mm.h>
#include <asm-generic/tlb.h>
#ifdef CONFIG_PPC_BOOK3E
extern void tlb_flush_pgtable(struct mmu_gather *tlb, unsigned long address);
@ -14,6 +13,8 @@ static inline void tlb_flush_pgtable(struct mmu_gather *tlb,
}
#endif /* !CONFIG_PPC_BOOK3E */
extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
#ifdef CONFIG_PPC64
#include <asm/pgalloc-64.h>
#else

1
arch/powerpc/include/asm/tlb.h
View File

@ -27,6 +27,7 @@
#define tlb_start_vma(tlb, vma) do { } while (0)
#define tlb_end_vma(tlb, vma) do { } while (0)
#define __tlb_remove_tlb_entry __tlb_remove_tlb_entry
extern void tlb_flush(struct mmu_gather *tlb);

2
arch/powerpc/mm/hugetlbpage.c
View File

@ -517,8 +517,6 @@ static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshif
for (i = 0; i < num_hugepd; i++, hpdp++)
hpdp->pd = 0;
tlb->need_flush = 1;
#ifdef CONFIG_PPC_FSL_BOOK3E
hugepd_free(tlb, hugepte);
#else

57
include/asm-generic/tlb.h
View File

@ -96,10 +96,9 @@ struct mmu_gather {
#endif
unsigned long start;
unsigned long end;
unsigned int need_flush : 1, /* Did free PTEs */
/* we are in the middle of an operation to clear
* a full mm and can make some optimizations */
fullmm : 1,
unsigned int fullmm : 1,
/* we have performed an operation which
* requires a complete flush of the tlb */
need_flush_all : 1;
@ -128,16 +127,54 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
tlb_flush_mmu(tlb);
}
static inline void __tlb_adjust_range(struct mmu_gather *tlb,
unsigned long address)
{
tlb->start = min(tlb->start, address);
tlb->end = max(tlb->end, address + PAGE_SIZE);
}
static inline void __tlb_reset_range(struct mmu_gather *tlb)
{
tlb->start = TASK_SIZE;
tlb->end = 0;
}
/*
* In the case of tlb vma handling, we can optimise these away in the
* case where we're doing a full MM flush. When we're doing a munmap,
* the vmas are adjusted to only cover the region to be torn down.
*/
#ifndef tlb_start_vma
#define tlb_start_vma(tlb, vma) do { } while (0)
#endif
#define __tlb_end_vma(tlb, vma) \
do { \
if (!tlb->fullmm && tlb->end) { \
tlb_flush(tlb); \
__tlb_reset_range(tlb); \
} \
} while (0)
#ifndef tlb_end_vma
#define tlb_end_vma __tlb_end_vma
#endif
#ifndef __tlb_remove_tlb_entry
#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0)
#endif
/**
* tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
*
* Record the fact that pte's were really umapped in ->need_flush, so we can
* later optimise away the tlb invalidate. This helps when userspace is
* unmapping already-unmapped pages, which happens quite a lot.
* Record the fact that pte's were really unmapped by updating the range,
* so we can later optimise away the tlb invalidate. This helps when
* userspace is unmapping already-unmapped pages, which happens quite a lot.
*/
#define tlb_remove_tlb_entry(tlb, ptep, address) \
do { \
tlb->need_flush = 1; \
__tlb_adjust_range(tlb, address); \
__tlb_remove_tlb_entry(tlb, ptep, address); \
} while (0)
@ -151,27 +188,27 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
#define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \
do { \
tlb->need_flush = 1; \
__tlb_adjust_range(tlb, address); \
__tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \
} while (0)
#define pte_free_tlb(tlb, ptep, address) \
do { \
tlb->need_flush = 1; \
__tlb_adjust_range(tlb, address); \
__pte_free_tlb(tlb, ptep, address); \
} while (0)
#ifndef __ARCH_HAS_4LEVEL_HACK
#define pud_free_tlb(tlb, pudp, address) \
do { \
tlb->need_flush = 1; \
__tlb_adjust_range(tlb, address); \
__pud_free_tlb(tlb, pudp, address); \
} while (0)
#endif
#define pmd_free_tlb(tlb, pmdp, address) \
do { \
tlb->need_flush = 1; \
__tlb_adjust_range(tlb, address); \
__pmd_free_tlb(tlb, pmdp, address); \
} while (0)

30
mm/memory.c
View File

@ -220,9 +220,6 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long
/* Is it from 0 to ~0? */
tlb->fullmm = !(start | (end+1));
tlb->need_flush_all = 0;
tlb->start = start;
tlb->end = end;
tlb->need_flush = 0;
tlb->local.next = NULL;
tlb->local.nr = 0;
tlb->local.max = ARRAY_SIZE(tlb->__pages);
@ -232,15 +229,20 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb->batch = NULL;
#endif
__tlb_reset_range(tlb);
}
static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
{
tlb->need_flush = 0;
if (!tlb->end)
return;
tlb_flush(tlb);
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb_table_flush(tlb);
#endif
__tlb_reset_range(tlb);
}
static void tlb_flush_mmu_free(struct mmu_gather *tlb)
@ -256,8 +258,6 @@ static void tlb_flush_mmu_free(struct mmu_gather *tlb)
void tlb_flush_mmu(struct mmu_gather *tlb)
{
if (!tlb->need_flush)
return;
tlb_flush_mmu_tlbonly(tlb);
tlb_flush_mmu_free(tlb);
}
@ -292,7 +292,7 @@ int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
struct mmu_gather_batch *batch;
VM_BUG_ON(!tlb->need_flush);
VM_BUG_ON(!tlb->end);
batch = tlb->active;
batch->pages[batch->nr++] = page;
@ -359,8 +359,6 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
{
struct mmu_table_batch **batch = &tlb->batch;
tlb->need_flush = 1;
/*
* When there's less then two users of this mm there cannot be a
* concurrent page-table walk.
@ -1185,20 +1183,8 @@ again:
arch_leave_lazy_mmu_mode();
/* Do the actual TLB flush before dropping ptl */
if (force_flush) {
unsigned long old_end;
/*
* Flush the TLB just for the previous segment,
* then update the range to be the remaining
* TLB range.
*/
old_end = tlb->end;
tlb->end = addr;
if (force_flush)
tlb_flush_mmu_tlbonly(tlb);
tlb->start = addr;
tlb->end = old_end;
}
pte_unmap_unlock(start_pte, ptl);
/*