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mmu_gather: move minimal range calculations into generic code

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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
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