From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH 05/18] asm-generic/tlb: Provide generic tlb_flush Date: Wed, 26 Sep 2018 13:53:35 +0100 Message-ID: <20180926125335.GG2979@brain-police> References: <20180926113623.863696043@infradead.org> <20180926114800.770817616@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20180926114800.770817616@infradead.org> Sender: linux-kernel-owner@vger.kernel.org To: Peter Zijlstra Cc: aneesh.kumar@linux.vnet.ibm.com, akpm@linux-foundation.org, npiggin@gmail.com, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux@armlinux.org.uk, heiko.carstens@de.ibm.com, riel@surriel.com List-Id: linux-arch.vger.kernel.org On Wed, Sep 26, 2018 at 01:36:28PM +0200, Peter Zijlstra wrote: > Provide a generic tlb_flush() implementation that relies on > flush_tlb_range(). This is a little awkward because flush_tlb_range() > assumes a VMA for range invalidation, but we no longer have one. > > Audit of all flush_tlb_range() implementations shows only vma->vm_mm > and vma->vm_flags are used, and of the latter only VM_EXEC (I-TLB > invalidates) and VM_HUGETLB (large TLB invalidate) are used. > > Therefore, track VM_EXEC and VM_HUGETLB in two more bits, and create a > 'fake' VMA. > > This allows architectures that have a reasonably efficient > flush_tlb_range() to not require any additional effort. > > Cc: Nick Piggin > Cc: Andrew Morton > Cc: "Aneesh Kumar K.V" > Cc: Will Deacon > Signed-off-by: Peter Zijlstra (Intel) > --- > arch/arm64/include/asm/tlb.h | 1 > arch/powerpc/include/asm/tlb.h | 1 > arch/riscv/include/asm/tlb.h | 1 > arch/x86/include/asm/tlb.h | 1 > include/asm-generic/tlb.h | 80 +++++++++++++++++++++++++++++++++++------ > 5 files changed, 74 insertions(+), 10 deletions(-) > > --- a/arch/arm64/include/asm/tlb.h > +++ b/arch/arm64/include/asm/tlb.h > @@ -27,6 +27,7 @@ static inline void __tlb_remove_table(vo > free_page_and_swap_cache((struct page *)_table); > } > > +#define tlb_flush tlb_flush > static void tlb_flush(struct mmu_gather *tlb); > > #include > --- a/arch/powerpc/include/asm/tlb.h > +++ b/arch/powerpc/include/asm/tlb.h > @@ -28,6 +28,7 @@ > #define tlb_end_vma(tlb, vma) do { } while (0) > #define __tlb_remove_tlb_entry __tlb_remove_tlb_entry > > +#define tlb_flush tlb_flush > extern void tlb_flush(struct mmu_gather *tlb); > > /* Get the generic bits... */ > --- a/arch/riscv/include/asm/tlb.h > +++ b/arch/riscv/include/asm/tlb.h > @@ -18,6 +18,7 @@ struct mmu_gather; > > static void tlb_flush(struct mmu_gather *tlb); > > +#define tlb_flush tlb_flush > #include > > static inline void tlb_flush(struct mmu_gather *tlb) > --- a/arch/x86/include/asm/tlb.h > +++ b/arch/x86/include/asm/tlb.h > @@ -6,6 +6,7 @@ > #define tlb_end_vma(tlb, vma) do { } while (0) > #define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0) > > +#define tlb_flush tlb_flush > static inline void tlb_flush(struct mmu_gather *tlb); > > #include > --- a/include/asm-generic/tlb.h > +++ b/include/asm-generic/tlb.h > @@ -241,6 +241,12 @@ struct mmu_gather { > unsigned int cleared_puds : 1; > unsigned int cleared_p4ds : 1; > > + /* > + * tracks VM_EXEC | VM_HUGETLB in tlb_start_vma > + */ > + unsigned int vma_exec : 1; > + unsigned int vma_huge : 1; > + > unsigned int batch_count; > > struct mmu_gather_batch *active; > @@ -282,7 +288,35 @@ static inline void __tlb_reset_range(str > tlb->cleared_pmds = 0; > tlb->cleared_puds = 0; > tlb->cleared_p4ds = 0; > + /* > + * Do not reset mmu_gather::vma_* fields here, we do not > + * call into tlb_start_vma() again to set them if there is an > + * intermediate flush. > + */ > +} > + > +#ifndef tlb_flush > + > +#if defined(tlb_start_vma) || defined(tlb_end_vma) > +#error Default tlb_flush() relies on default tlb_start_vma() and tlb_end_vma() > +#endif > + > +#define tlb_flush tlb_flush Do we need this #define? > @@ -353,19 +387,45 @@ static inline unsigned long tlb_get_unma > * the vmas are adjusted to only cover the region to be torn down. > */ > #ifndef tlb_start_vma > -#define tlb_start_vma(tlb, vma) \ > -do { \ > - if (!tlb->fullmm) \ > - flush_cache_range(vma, vma->vm_start, vma->vm_end); \ > -} while (0) > +#define tlb_start_vma tlb_start_vma Or this one? > +static inline void tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) > +{ > + if (tlb->fullmm) > + return; > + > + /* > + * flush_tlb_range() implementations that look at VM_HUGETLB (tile, > + * mips-4k) flush only large pages. > + * > + * flush_tlb_range() implementations that flush I-TLB also flush D-TLB > + * (tile, xtensa, arm), so it's ok to just add VM_EXEC to an existing > + * range. > + * > + * We rely on tlb_end_vma() to issue a flush, such that when we reset > + * these values the batch is empty. > + */ > + tlb->vma_huge = !!(vma->vm_flags & VM_HUGETLB); > + tlb->vma_exec = !!(vma->vm_flags & VM_EXEC); Hmm, does this result in code generation for archs that don't care about the vm_flags? > + flush_cache_range(vma, vma->vm_start, vma->vm_end); > +} > #endif > > #ifndef tlb_end_vma > -#define tlb_end_vma(tlb, vma) \ > -do { \ > - if (!tlb->fullmm) \ > - tlb_flush_mmu_tlbonly(tlb); \ > -} while (0) > +#define tlb_end_vma tlb_end_vma Another #define we can drop? Will From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:45444 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726768AbeIZTGc (ORCPT ); Wed, 26 Sep 2018 15:06:32 -0400 Date: Wed, 26 Sep 2018 13:53:35 +0100 From: Will Deacon Subject: Re: [PATCH 05/18] asm-generic/tlb: Provide generic tlb_flush Message-ID: <20180926125335.GG2979@brain-police> References: <20180926113623.863696043@infradead.org> <20180926114800.770817616@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180926114800.770817616@infradead.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: aneesh.kumar@linux.vnet.ibm.com, akpm@linux-foundation.org, npiggin@gmail.com, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux@armlinux.org.uk, heiko.carstens@de.ibm.com, riel@surriel.com Message-ID: <20180926125335.lGnCKCANjO_9POOmtT2b58_Wp65w6NOAzSpy9-Ojcls@z> On Wed, Sep 26, 2018 at 01:36:28PM +0200, Peter Zijlstra wrote: > Provide a generic tlb_flush() implementation that relies on > flush_tlb_range(). This is a little awkward because flush_tlb_range() > assumes a VMA for range invalidation, but we no longer have one. > > Audit of all flush_tlb_range() implementations shows only vma->vm_mm > and vma->vm_flags are used, and of the latter only VM_EXEC (I-TLB > invalidates) and VM_HUGETLB (large TLB invalidate) are used. > > Therefore, track VM_EXEC and VM_HUGETLB in two more bits, and create a > 'fake' VMA. > > This allows architectures that have a reasonably efficient > flush_tlb_range() to not require any additional effort. > > Cc: Nick Piggin > Cc: Andrew Morton > Cc: "Aneesh Kumar K.V" > Cc: Will Deacon > Signed-off-by: Peter Zijlstra (Intel) > --- > arch/arm64/include/asm/tlb.h | 1 > arch/powerpc/include/asm/tlb.h | 1 > arch/riscv/include/asm/tlb.h | 1 > arch/x86/include/asm/tlb.h | 1 > include/asm-generic/tlb.h | 80 +++++++++++++++++++++++++++++++++++------ > 5 files changed, 74 insertions(+), 10 deletions(-) > > --- a/arch/arm64/include/asm/tlb.h > +++ b/arch/arm64/include/asm/tlb.h > @@ -27,6 +27,7 @@ static inline void __tlb_remove_table(vo > free_page_and_swap_cache((struct page *)_table); > } > > +#define tlb_flush tlb_flush > static void tlb_flush(struct mmu_gather *tlb); > > #include > --- a/arch/powerpc/include/asm/tlb.h > +++ b/arch/powerpc/include/asm/tlb.h > @@ -28,6 +28,7 @@ > #define tlb_end_vma(tlb, vma) do { } while (0) > #define __tlb_remove_tlb_entry __tlb_remove_tlb_entry > > +#define tlb_flush tlb_flush > extern void tlb_flush(struct mmu_gather *tlb); > > /* Get the generic bits... */ > --- a/arch/riscv/include/asm/tlb.h > +++ b/arch/riscv/include/asm/tlb.h > @@ -18,6 +18,7 @@ struct mmu_gather; > > static void tlb_flush(struct mmu_gather *tlb); > > +#define tlb_flush tlb_flush > #include > > static inline void tlb_flush(struct mmu_gather *tlb) > --- a/arch/x86/include/asm/tlb.h > +++ b/arch/x86/include/asm/tlb.h > @@ -6,6 +6,7 @@ > #define tlb_end_vma(tlb, vma) do { } while (0) > #define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0) > > +#define tlb_flush tlb_flush > static inline void tlb_flush(struct mmu_gather *tlb); > > #include > --- a/include/asm-generic/tlb.h > +++ b/include/asm-generic/tlb.h > @@ -241,6 +241,12 @@ struct mmu_gather { > unsigned int cleared_puds : 1; > unsigned int cleared_p4ds : 1; > > + /* > + * tracks VM_EXEC | VM_HUGETLB in tlb_start_vma > + */ > + unsigned int vma_exec : 1; > + unsigned int vma_huge : 1; > + > unsigned int batch_count; > > struct mmu_gather_batch *active; > @@ -282,7 +288,35 @@ static inline void __tlb_reset_range(str > tlb->cleared_pmds = 0; > tlb->cleared_puds = 0; > tlb->cleared_p4ds = 0; > + /* > + * Do not reset mmu_gather::vma_* fields here, we do not > + * call into tlb_start_vma() again to set them if there is an > + * intermediate flush. > + */ > +} > + > +#ifndef tlb_flush > + > +#if defined(tlb_start_vma) || defined(tlb_end_vma) > +#error Default tlb_flush() relies on default tlb_start_vma() and tlb_end_vma() > +#endif > + > +#define tlb_flush tlb_flush Do we need this #define? > @@ -353,19 +387,45 @@ static inline unsigned long tlb_get_unma > * the vmas are adjusted to only cover the region to be torn down. > */ > #ifndef tlb_start_vma > -#define tlb_start_vma(tlb, vma) \ > -do { \ > - if (!tlb->fullmm) \ > - flush_cache_range(vma, vma->vm_start, vma->vm_end); \ > -} while (0) > +#define tlb_start_vma tlb_start_vma Or this one? > +static inline void tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) > +{ > + if (tlb->fullmm) > + return; > + > + /* > + * flush_tlb_range() implementations that look at VM_HUGETLB (tile, > + * mips-4k) flush only large pages. > + * > + * flush_tlb_range() implementations that flush I-TLB also flush D-TLB > + * (tile, xtensa, arm), so it's ok to just add VM_EXEC to an existing > + * range. > + * > + * We rely on tlb_end_vma() to issue a flush, such that when we reset > + * these values the batch is empty. > + */ > + tlb->vma_huge = !!(vma->vm_flags & VM_HUGETLB); > + tlb->vma_exec = !!(vma->vm_flags & VM_EXEC); Hmm, does this result in code generation for archs that don't care about the vm_flags? > + flush_cache_range(vma, vma->vm_start, vma->vm_end); > +} > #endif > > #ifndef tlb_end_vma > -#define tlb_end_vma(tlb, vma) \ > -do { \ > - if (!tlb->fullmm) \ > - tlb_flush_mmu_tlbonly(tlb); \ > -} while (0) > +#define tlb_end_vma tlb_end_vma Another #define we can drop? Will