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Date: Thu, 21 Feb 2019 08:22:57 +0530
From: Souptick Joarder <jrdr.linux@...il.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: will.deacon@....com,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
Andrew Morton <akpm@...ux-foundation.org>, npiggin@...il.com,
linux-arch@...r.kernel.org, Linux-MM <linux-mm@...ck.org>,
linux-kernel@...r.kernel.org,
Russell King - ARM Linux <linux@...linux.org.uk>,
heiko.carstens@...ibm.com, Rik van Riel <riel@...riel.com>,
Tony Luck <tony.luck@...el.com>
Subject: Re: [PATCH v6 09/18] ia64/tlb: Conver to generic mmu_gather
On Tue, Feb 19, 2019 at 4:03 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> Generic mmu_gather provides everything ia64 needs (range tracking).
>
> Cc: Will Deacon <will.deacon@....com>
> Cc: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Nick Piggin <npiggin@...il.com>
> Cc: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
> arch/ia64/include/asm/tlb.h | 256 ---------------------------------------
> arch/ia64/include/asm/tlbflush.h | 25 +++
> arch/ia64/mm/tlb.c | 23 +++
> 3 files changed, 47 insertions(+), 257 deletions(-)
>
> --- a/arch/ia64/include/asm/tlb.h
> +++ b/arch/ia64/include/asm/tlb.h
> @@ -47,262 +47,8 @@
> #include <asm/tlbflush.h>
> #include <asm/machvec.h>
>
> -/*
> - * If we can't allocate a page to make a big batch of page pointers
> - * to work on, then just handle a few from the on-stack structure.
> - */
> -#define IA64_GATHER_BUNDLE 8
> -
> -struct mmu_gather {
> - struct mm_struct *mm;
> - unsigned int nr;
> - unsigned int max;
> - unsigned char fullmm; /* non-zero means full mm flush */
> - unsigned char need_flush; /* really unmapped some PTEs? */
> - unsigned long start, end;
> - unsigned long start_addr;
> - unsigned long end_addr;
> - struct page **pages;
> - struct page *local[IA64_GATHER_BUNDLE];
> -};
> -
> -struct ia64_tr_entry {
> - u64 ifa;
> - u64 itir;
> - u64 pte;
> - u64 rr;
> -}; /*Record for tr entry!*/
> -
> -extern int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size);
> -extern void ia64_ptr_entry(u64 target_mask, int slot);
> -
> -extern struct ia64_tr_entry *ia64_idtrs[NR_CPUS];
> -
> -/*
> - region register macros
> -*/
> -#define RR_TO_VE(val) (((val) >> 0) & 0x0000000000000001)
> -#define RR_VE(val) (((val) & 0x0000000000000001) << 0)
> -#define RR_VE_MASK 0x0000000000000001L
> -#define RR_VE_SHIFT 0
> -#define RR_TO_PS(val) (((val) >> 2) & 0x000000000000003f)
> -#define RR_PS(val) (((val) & 0x000000000000003f) << 2)
> -#define RR_PS_MASK 0x00000000000000fcL
> -#define RR_PS_SHIFT 2
> -#define RR_RID_MASK 0x00000000ffffff00L
> -#define RR_TO_RID(val) ((val >> 8) & 0xffffff)
> -
> -static inline void
> -ia64_tlb_flush_mmu_tlbonly(struct mmu_gather *tlb, unsigned long start, unsigned long end)
> -{
> - tlb->need_flush = 0;
> -
> - if (tlb->fullmm) {
> - /*
> - * Tearing down the entire address space. This happens both as a result
> - * of exit() and execve(). The latter case necessitates the call to
> - * flush_tlb_mm() here.
> - */
> - flush_tlb_mm(tlb->mm);
> - } else if (unlikely (end - start >= 1024*1024*1024*1024UL
> - || REGION_NUMBER(start) != REGION_NUMBER(end - 1)))
> - {
> - /*
> - * If we flush more than a tera-byte or across regions, we're probably
> - * better off just flushing the entire TLB(s). This should be very rare
> - * and is not worth optimizing for.
> - */
> - flush_tlb_all();
> - } else {
> - /*
> - * flush_tlb_range() takes a vma instead of a mm pointer because
> - * some architectures want the vm_flags for ITLB/DTLB flush.
> - */
> - struct vm_area_struct vma = TLB_FLUSH_VMA(tlb->mm, 0);
> -
> - /* flush the address range from the tlb: */
> - flush_tlb_range(&vma, start, end);
> - /* now flush the virt. page-table area mapping the address range: */
> - flush_tlb_range(&vma, ia64_thash(start), ia64_thash(end));
> - }
> -
> -}
> -
> -static inline void
> -ia64_tlb_flush_mmu_free(struct mmu_gather *tlb)
> -{
> - unsigned long i;
> - unsigned int nr;
> -
> - /* lastly, release the freed pages */
> - nr = tlb->nr;
> -
> - tlb->nr = 0;
> - tlb->start_addr = ~0UL;
> - for (i = 0; i < nr; ++i)
> - free_page_and_swap_cache(tlb->pages[i]);
> -}
> -
> -/*
> - * Flush the TLB for address range START to END and, if not in fast mode, release the
> - * freed pages that where gathered up to this point.
> - */
> -static inline void
> -ia64_tlb_flush_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
> -{
> - if (!tlb->need_flush)
> - return;
> - ia64_tlb_flush_mmu_tlbonly(tlb, start, end);
> - ia64_tlb_flush_mmu_free(tlb);
> -}
> -
> -static inline void __tlb_alloc_page(struct mmu_gather *tlb)
> -{
> - unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
> -
> - if (addr) {
> - tlb->pages = (void *)addr;
> - tlb->max = PAGE_SIZE / sizeof(void *);
> - }
> -}
> -
> -
> -static inline void
> -arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
> - unsigned long start, unsigned long end)
> -{
> - tlb->mm = mm;
> - tlb->max = ARRAY_SIZE(tlb->local);
> - tlb->pages = tlb->local;
> - tlb->nr = 0;
> - tlb->fullmm = !(start | (end+1));
> - tlb->start = start;
> - tlb->end = end;
> - tlb->start_addr = ~0UL;
> -}
> -
> -/*
> - * Called at the end of the shootdown operation to free up any resources that were
> - * collected.
> - */
> -static inline void
> -arch_tlb_finish_mmu(struct mmu_gather *tlb,
> - unsigned long start, unsigned long end, bool force)
> -{
> - if (force)
> - tlb->need_flush = 1;
> - /*
> - * Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and
> - * tlb->end_addr.
> - */
> - ia64_tlb_flush_mmu(tlb, start, end);
> -
> - /* keep the page table cache within bounds */
> - check_pgt_cache();
> -
> - if (tlb->pages != tlb->local)
> - free_pages((unsigned long)tlb->pages, 0);
> -}
> -
> -/*
> - * Logically, this routine frees PAGE. On MP machines, the actual freeing of the page
> - * must be delayed until after the TLB has been flushed (see comments at the beginning of
> - * this file).
> - */
> -static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
> -{
> - tlb->need_flush = 1;
> -
> - if (!tlb->nr && tlb->pages == tlb->local)
> - __tlb_alloc_page(tlb);
> -
> - tlb->pages[tlb->nr++] = page;
> - VM_WARN_ON(tlb->nr > tlb->max);
> - if (tlb->nr == tlb->max)
> - return true;
> - return false;
> -}
> -
> -static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
> -{
> - ia64_tlb_flush_mmu_tlbonly(tlb, tlb->start_addr, tlb->end_addr);
> -}
> -
> -static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
> -{
> - ia64_tlb_flush_mmu_free(tlb);
> -}
> -
> -static inline void tlb_flush_mmu(struct mmu_gather *tlb)
> -{
> - ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr);
> -}
> -
> -static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
> -{
> - if (__tlb_remove_page(tlb, page))
> - tlb_flush_mmu(tlb);
> -}
> -
> -static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
> - struct page *page, int page_size)
> -{
> - return __tlb_remove_page(tlb, page);
> -}
> -
> -static inline void tlb_remove_page_size(struct mmu_gather *tlb,
> - struct page *page, int page_size)
> -{
> - return tlb_remove_page(tlb, page);
> -}
> -
> -/*
> - * Remove TLB entry for PTE mapped at virtual address ADDRESS. This is called for any
> - * PTE, not just those pointing to (normal) physical memory.
> - */
> -static inline void
> -__tlb_remove_tlb_entry (struct mmu_gather *tlb, pte_t *ptep, unsigned long address)
> -{
> - if (tlb->start_addr == ~0UL)
> - tlb->start_addr = address;
> - tlb->end_addr = address + PAGE_SIZE;
> -}
> -
> #define tlb_migrate_finish(mm) platform_tlb_migrate_finish(mm)
>
> -#define tlb_start_vma(tlb, vma) do { } while (0)
> -#define tlb_end_vma(tlb, vma) do { } while (0)
> -
> -#define tlb_remove_tlb_entry(tlb, ptep, addr) \
> -do { \
> - tlb->need_flush = 1; \
> - __tlb_remove_tlb_entry(tlb, ptep, addr); \
> -} while (0)
> -
> -#define tlb_remove_huge_tlb_entry(h, tlb, ptep, address) \
> - tlb_remove_tlb_entry(tlb, ptep, address)
> -
> -static inline void tlb_change_page_size(struct mmu_gather *tlb,
> - unsigned int page_size)
> -{
> -}
> -
> -#define pte_free_tlb(tlb, ptep, address) \
> -do { \
> - tlb->need_flush = 1; \
> - __pte_free_tlb(tlb, ptep, address); \
> -} while (0)
> -
> -#define pmd_free_tlb(tlb, ptep, address) \
> -do { \
> - tlb->need_flush = 1; \
> - __pmd_free_tlb(tlb, ptep, address); \
> -} while (0)
> -
> -#define pud_free_tlb(tlb, pudp, address) \
> -do { \
> - tlb->need_flush = 1; \
> - __pud_free_tlb(tlb, pudp, address); \
> -} while (0)
> +#include <asm-generic/tlb.h>
>
> #endif /* _ASM_IA64_TLB_H */
> --- a/arch/ia64/include/asm/tlbflush.h
> +++ b/arch/ia64/include/asm/tlbflush.h
> @@ -14,6 +14,31 @@
> #include <asm/mmu_context.h>
> #include <asm/page.h>
>
> +struct ia64_tr_entry {
> + u64 ifa;
> + u64 itir;
> + u64 pte;
> + u64 rr;
> +}; /*Record for tr entry!*/
> +
> +extern int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size);
> +extern void ia64_ptr_entry(u64 target_mask, int slot);
> +extern struct ia64_tr_entry *ia64_idtrs[NR_CPUS];
> +
> +/*
> + region register macros
> +*/
> +#define RR_TO_VE(val) (((val) >> 0) & 0x0000000000000001)
> +#define RR_VE(val) (((val) & 0x0000000000000001) << 0)
> +#define RR_VE_MASK 0x0000000000000001L
> +#define RR_VE_SHIFT 0
> +#define RR_TO_PS(val) (((val) >> 2) & 0x000000000000003f)
> +#define RR_PS(val) (((val) & 0x000000000000003f) << 2)
> +#define RR_PS_MASK 0x00000000000000fcL
> +#define RR_PS_SHIFT 2
> +#define RR_RID_MASK 0x00000000ffffff00L
> +#define RR_TO_RID(val) ((val >> 8) & 0xffffff)
> +
> /*
> * Now for some TLB flushing routines. This is the kind of stuff that
> * can be very expensive, so try to avoid them whenever possible.
> --- a/arch/ia64/mm/tlb.c
> +++ b/arch/ia64/mm/tlb.c
> @@ -297,8 +297,8 @@ local_flush_tlb_all (void)
> ia64_srlz_i(); /* srlz.i implies srlz.d */
> }
>
> -void
> -flush_tlb_range (struct vm_area_struct *vma, unsigned long start,
> +static void
> +__flush_tlb_range (struct vm_area_struct *vma, unsigned long start,
> unsigned long end)
> {
> struct mm_struct *mm = vma->vm_mm;
> @@ -335,6 +335,25 @@ flush_tlb_range (struct vm_area_struct *
> preempt_enable();
> ia64_srlz_i(); /* srlz.i implies srlz.d */
> }
> +
> +void flush_tlb_range(struct vm_area_struct *vma,
> + unsigned long start, unsigned long end)
> +{
> + if (unlikely(end - start >= 1024*1024*1024*1024UL
> + || REGION_NUMBER(start) != REGION_NUMBER(end - 1))) {
> + /*
> + * If we flush more than a tera-byte or across regions, we're
> + * probably better off just flushing the entire TLB(s). This
> + * should be very rare and is not worth optimizing for.
> + */
> + flush_tlb_all();
> + } else {
> + /* flush the address range from the tlb */
> + __flush_tlb_range(vma, start, end);
> + /* flush the virt. page-table area mapping the addr range */
> + __flush_tlb_range(vma, ia64_thash(start), ia64_thash(end));
> + }
> +}
> EXPORT_SYMBOL(flush_tlb_range);
Just a minor one,
As this is a public API, I think adding docs might be helpful.
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