From: Peter Zijlstra <peterz@infradead.org> To: Vineet Gupta <vineet.gupta1@synopsys.com> Cc: "will.deacon@arm.com" <will.deacon@arm.com>, "aneesh.kumar@linux.vnet.ibm.com" <aneesh.kumar@linux.vnet.ibm.com>, "akpm@linux-foundation.org" <akpm@linux-foundation.org>, "npiggin@gmail.com" <npiggin@gmail.com>, "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux@armlinux.org.uk" <linux@armlinux.org.uk>, "heiko.carstens@de.ibm.com" <heiko.carstens@de.ibm.com>, "riel@surriel.com" <riel@surriel.com>, Richard Henderson <rth@twiddle.net>, Mark Salter <msalter@redhat.com>, Richard Kuo <rkuo@codeaurora.org>, Michal Simek <monstr@monstr.eu>, Paul Burton <paul.burton@mips.com>, Greentime Hu <green.hu@gmail.com>, Ley Foon Tan <lftan@altera.com> Subject: Re: [PATCH 12/18] arch/tlb: Clean up simple architectures Date: Thu, 11 Oct 2018 17:04:06 +0200 [thread overview] Message-ID: <20181011150406.GL9848@hirez.programming.kicks-ass.net> (raw) In-Reply-To: <C2D7FE5348E1B147BCA15975FBA23075012B09A59E@us01wembx1.internal.synopsys.com> On Wed, Oct 03, 2018 at 05:03:50PM +0000, Vineet Gupta wrote: > On 09/26/2018 04:56 AM, Peter Zijlstra wrote: > > There are generally two cases: > > > > 1) either the platform has an efficient flush_tlb_range() and > > asm-generic/tlb.h doesn't need any overrides at all. > > > > 2) or an architecture lacks an efficient flush_tlb_range() and > > we override tlb_end_vma() and tlb_flush(). > > > > Convert all 'simple' architectures to one of these two forms. > > > > --- a/arch/arc/include/asm/tlb.h > > +++ b/arch/arc/include/asm/tlb.h > > @@ -9,29 +9,6 @@ > > #ifndef _ASM_ARC_TLB_H > > #define _ASM_ARC_TLB_H > > > > -#define tlb_flush(tlb) \ > > -do { \ > > - if (tlb->fullmm) \ > > - flush_tlb_mm((tlb)->mm); \ > > -} while (0) > > - > > -/* > > - * This pair is called at time of munmap/exit to flush cache and TLB entries > > - * for mappings being torn down. > > - * 1) cache-flush part -implemented via tlb_start_vma( ) for VIPT aliasing D$ > > - * 2) tlb-flush part - implemted via tlb_end_vma( ) flushes the TLB range > > - * > > - * Note, read https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.org_lkml_2004_1_15_6&d=DwIBaQ&c=DPL6_X_6JkXFx7AXWqB0tg&r=c14YS-cH-kdhTOW89KozFhBtBJgs1zXscZojEZQ0THs&m=5jiyvgRek4SKK5DUWDBGufVcuLez5G-jJCh3K-ndHsg&s=7uAzzw_jdAXMfb07B-vGPh3V1vggbTAsB7xL6Kie47A&e= > > - */ > > - > > -#define tlb_end_vma(tlb, vma) \ > > -do { \ > > - if (!tlb->fullmm) \ > > - flush_tlb_range(vma, vma->vm_start, vma->vm_end); \ > > -} while (0) > > - > > -#define __tlb_remove_tlb_entry(tlb, ptep, address) > > - > > #include <linux/pagemap.h> > > #include <asm-generic/tlb.h> > > LGTM per discussion in an earlier thread. However given that for "simpler" arches > the whole series doesn't apply can you please beef up the changelog so I don't go > scratching my head 2 years down the line. It currently describes the hows of > things but not exactly whys: shift_arg_pages missing tlb_start_vma, > move_page_tables look dodgy, yady yadda ? Right you are. Thanks for pointing out the somewhat sparse Changelog; typically I end up kicking myself a few years down the line. I think I will in fact change the implementation a little and provide a symbol/Kconfig to switch the default implementation between flush_tlb_vma() and flush_tlb_mm(). That avoids some of the repetition. But see here a preview of the new Changelog, does that clarify things enough? --- Subject: arch/tlb: Clean up simple architectures From: Peter Zijlstra <peterz@infradead.org> Date: Tue Sep 4 17:04:07 CEST 2018 The generic mmu_gather implementation is geared towards range tracking and provided the architecture provides a fairly efficient flush_tlb_range() implementation (or provides a custom tlb_flush() implementation) things will work well. The one case this doesn't cover well is where there is no (efficient) range invalidate at all. In this case we can select MMU_GATHER_NO_RANGE. So this reduces to two cases: 1) either the platform has an efficient flush_tlb_range() and asm-generic/tlb.h doesn't need any overrides at all. 2) or an architecture lacks an efficient flush_tlb_range() and we need to select MMU_GATHER_NO_RANGE. Convert all 'simple' architectures to one of these two forms. alpha: has no range invalidate -> 2 arc: already used flush_tlb_range() -> 1 c6x: has no range invalidate -> 2 hexagon: has an efficient flush_tlb_range() -> 1 (flush_tlb_mm() is in fact a full range invalidate, so no need to shoot down everything) m68k: has inefficient flush_tlb_range() -> 2 microblaze: has no flush_tlb_range() -> 2 mips: has efficient flush_tlb_range() -> 1 (even though it currently seems to use flush_tlb_mm()) nds32: already uses flush_tlb_range() -> 1 nios2: has inefficient flush_tlb_range() -> 2 (no limit on range iteration) openrisc: has inefficient flush_tlb_range() -> 2 (no limit on range iteration) parisc: already uses flush_tlb_range() -> 1 sparc32: already uses flush_tlb_range() -> 1 unicore32: has inefficient flush_tlb_range() -> 2 (no limit on range iteration) xtensa: has efficient flush_tlb_range() -> 1 Note this also fixes a bug in the existing code for a number platforms. Those platforms that did: tlb_end_vma() -> if (!fullmm) flush_tlb_*() tlb_flush -> if (full_mm) flush_tlb_mm() missed the case of shift_arg_pages(), which doesn't have @fullmm set, nor calls into tlb_*vma(), but still frees page-tables and thus needs an invalidate. The new code handles this by detecting a non-empty range, and either issuing the matching range invalidate or a full invalidate, depending on the capabilities. Cc: Nick Piggin <npiggin@gmail.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michal Simek <monstr@monstr.eu> Cc: Helge Deller <deller@gmx.de> Cc: Greentime Hu <green.hu@gmail.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Ley Foon Tan <lftan@altera.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Mark Salter <msalter@redhat.com> Cc: Richard Kuo <rkuo@codeaurora.org Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Guan Xuetao <gxt@pku.edu.cn> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org> To: Vineet Gupta <vineet.gupta1@synopsys.com> Cc: "will.deacon@arm.com" <will.deacon@arm.com>, "aneesh.kumar@linux.vnet.ibm.com" <aneesh.kumar@linux.vnet.ibm.com>, "akpm@linux-foundation.org" <akpm@linux-foundation.org>, "npiggin@gmail.com" <npiggin@gmail.com>, "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux@armlinux.org.uk" <linux@armlinux.org.uk>, "heiko.carstens@de.ibm.com" <heiko.carstens@de.ibm.com>, "riel@surriel.com" <riel@surriel.com>, Richard Henderson <rth@twiddle.net>, Mark Salter <msalter@redhat.com>, Richard Kuo <rkuo@codeaurora.org>, Michal Simek <monstr@monstr.eu>, Paul Burton <paul.burton@mips.com>, Greentime Hu <green.hu@gmail.com>, Ley Foon Tan <lftan@altera.com>, Jonas Bonn <jonas@southpole.se>, Helge Deller <deller@gmx.de>, "David S. Miller" <davem@davemloft.net>, Guan Xuetao <gxt@pku.edu.cn>, Max Filippov <jcmvbkbc@gmail.com> Subject: Re: [PATCH 12/18] arch/tlb: Clean up simple architectures Date: Thu, 11 Oct 2018 17:04:06 +0200 [thread overview] Message-ID: <20181011150406.GL9848@hirez.programming.kicks-ass.net> (raw) Message-ID: <20181011150406._C2RPFVGa4QlqA5A9VemFagASBZXqd5WPyb52ZlZ_EU@z> (raw) In-Reply-To: <C2D7FE5348E1B147BCA15975FBA23075012B09A59E@us01wembx1.internal.synopsys.com> On Wed, Oct 03, 2018 at 05:03:50PM +0000, Vineet Gupta wrote: > On 09/26/2018 04:56 AM, Peter Zijlstra wrote: > > There are generally two cases: > > > > 1) either the platform has an efficient flush_tlb_range() and > > asm-generic/tlb.h doesn't need any overrides at all. > > > > 2) or an architecture lacks an efficient flush_tlb_range() and > > we override tlb_end_vma() and tlb_flush(). > > > > Convert all 'simple' architectures to one of these two forms. > > > > --- a/arch/arc/include/asm/tlb.h > > +++ b/arch/arc/include/asm/tlb.h > > @@ -9,29 +9,6 @@ > > #ifndef _ASM_ARC_TLB_H > > #define _ASM_ARC_TLB_H > > > > -#define tlb_flush(tlb) \ > > -do { \ > > - if (tlb->fullmm) \ > > - flush_tlb_mm((tlb)->mm); \ > > -} while (0) > > - > > -/* > > - * This pair is called at time of munmap/exit to flush cache and TLB entries > > - * for mappings being torn down. > > - * 1) cache-flush part -implemented via tlb_start_vma( ) for VIPT aliasing D$ > > - * 2) tlb-flush part - implemted via tlb_end_vma( ) flushes the TLB range > > - * > > - * Note, read https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.org_lkml_2004_1_15_6&d=DwIBaQ&c=DPL6_X_6JkXFx7AXWqB0tg&r=c14YS-cH-kdhTOW89KozFhBtBJgs1zXscZojEZQ0THs&m=5jiyvgRek4SKK5DUWDBGufVcuLez5G-jJCh3K-ndHsg&s=7uAzzw_jdAXMfb07B-vGPh3V1vggbTAsB7xL6Kie47A&e= > > - */ > > - > > -#define tlb_end_vma(tlb, vma) \ > > -do { \ > > - if (!tlb->fullmm) \ > > - flush_tlb_range(vma, vma->vm_start, vma->vm_end); \ > > -} while (0) > > - > > -#define __tlb_remove_tlb_entry(tlb, ptep, address) > > - > > #include <linux/pagemap.h> > > #include <asm-generic/tlb.h> > > LGTM per discussion in an earlier thread. However given that for "simpler" arches > the whole series doesn't apply can you please beef up the changelog so I don't go > scratching my head 2 years down the line. It currently describes the hows of > things but not exactly whys: shift_arg_pages missing tlb_start_vma, > move_page_tables look dodgy, yady yadda ? Right you are. Thanks for pointing out the somewhat sparse Changelog; typically I end up kicking myself a few years down the line. I think I will in fact change the implementation a little and provide a symbol/Kconfig to switch the default implementation between flush_tlb_vma() and flush_tlb_mm(). That avoids some of the repetition. But see here a preview of the new Changelog, does that clarify things enough? --- Subject: arch/tlb: Clean up simple architectures From: Peter Zijlstra <peterz@infradead.org> Date: Tue Sep 4 17:04:07 CEST 2018 The generic mmu_gather implementation is geared towards range tracking and provided the architecture provides a fairly efficient flush_tlb_range() implementation (or provides a custom tlb_flush() implementation) things will work well. The one case this doesn't cover well is where there is no (efficient) range invalidate at all. In this case we can select MMU_GATHER_NO_RANGE. So this reduces to two cases: 1) either the platform has an efficient flush_tlb_range() and asm-generic/tlb.h doesn't need any overrides at all. 2) or an architecture lacks an efficient flush_tlb_range() and we need to select MMU_GATHER_NO_RANGE. Convert all 'simple' architectures to one of these two forms. alpha: has no range invalidate -> 2 arc: already used flush_tlb_range() -> 1 c6x: has no range invalidate -> 2 hexagon: has an efficient flush_tlb_range() -> 1 (flush_tlb_mm() is in fact a full range invalidate, so no need to shoot down everything) m68k: has inefficient flush_tlb_range() -> 2 microblaze: has no flush_tlb_range() -> 2 mips: has efficient flush_tlb_range() -> 1 (even though it currently seems to use flush_tlb_mm()) nds32: already uses flush_tlb_range() -> 1 nios2: has inefficient flush_tlb_range() -> 2 (no limit on range iteration) openrisc: has inefficient flush_tlb_range() -> 2 (no limit on range iteration) parisc: already uses flush_tlb_range() -> 1 sparc32: already uses flush_tlb_range() -> 1 unicore32: has inefficient flush_tlb_range() -> 2 (no limit on range iteration) xtensa: has efficient flush_tlb_range() -> 1 Note this also fixes a bug in the existing code for a number platforms. Those platforms that did: tlb_end_vma() -> if (!fullmm) flush_tlb_*() tlb_flush -> if (full_mm) flush_tlb_mm() missed the case of shift_arg_pages(), which doesn't have @fullmm set, nor calls into tlb_*vma(), but still frees page-tables and thus needs an invalidate. The new code handles this by detecting a non-empty range, and either issuing the matching range invalidate or a full invalidate, depending on the capabilities. Cc: Nick Piggin <npiggin@gmail.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michal Simek <monstr@monstr.eu> Cc: Helge Deller <deller@gmx.de> Cc: Greentime Hu <green.hu@gmail.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Ley Foon Tan <lftan@altera.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Mark Salter <msalter@redhat.com> Cc: Richard Kuo <rkuo@codeaurora.org Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Guan Xuetao <gxt@pku.edu.cn> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
next prev parent reply other threads:[~2018-10-11 15:04 UTC|newest] Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-09-26 11:36 [PATCH 00/18] my generic mmu_gather patches Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 01/18] asm-generic/tlb: Provide a comment Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 02/18] asm-generic/tlb: Provide HAVE_MMU_GATHER_PAGE_SIZE Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 03/18] x86/mm: Page size aware flush_tlb_mm_range() Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 04/18] asm-generic/tlb: Provide generic VIPT cache flush Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 05/18] asm-generic/tlb: Provide generic tlb_flush Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 12:53 ` Will Deacon 2018-09-26 12:53 ` Will Deacon 2018-09-26 13:11 ` Peter Zijlstra 2018-09-26 13:11 ` Peter Zijlstra 2018-09-26 18:07 ` Peter Zijlstra 2018-09-26 18:07 ` Peter Zijlstra 2018-09-27 12:14 ` Will Deacon 2018-09-27 12:14 ` Will Deacon 2018-09-26 11:36 ` [PATCH 06/18] asm-generic/tlb: Conditionally provide tlb_migrate_finish() Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 12:53 ` Will Deacon 2018-09-26 12:53 ` Will Deacon 2018-09-26 11:36 ` [PATCH 07/18] asm-generic/tlb: Invert HAVE_RCU_TABLE_INVALIDATE Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 08/18] arm/tlb: Convert to generic mmu_gather Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 12:54 ` Will Deacon 2018-09-26 12:54 ` Will Deacon 2018-09-26 11:36 ` [PATCH 09/18] ia64/tlb: Conver " Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 10/18] sh/tlb: Convert SH " Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 11/18] um/tlb: Convert " Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 12/18] arch/tlb: Clean up simple architectures Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-10-03 17:03 ` Vineet Gupta 2018-10-03 17:03 ` Vineet Gupta 2018-10-11 15:04 ` Peter Zijlstra [this message] 2018-10-11 15:04 ` Peter Zijlstra 2018-10-12 19:40 ` Vineet Gupta 2018-10-12 19:40 ` Vineet Gupta 2018-10-15 14:14 ` Peter Zijlstra 2018-10-15 14:14 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 13/18] asm-generic/tlb: Introduce HAVE_MMU_GATHER_NO_GATHER Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-12-11 5:43 ` Aneesh Kumar K.V 2018-12-11 5:43 ` Aneesh Kumar K.V 2018-09-26 11:36 ` [PATCH 14/18] s390/tlb: convert to generic mmu_gather Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 15/18] asm-generic/tlb: Remove arch_tlb*_mmu() Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 16/18] asm-generic/tlb: Remove HAVE_GENERIC_MMU_GATHER Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 17/18] asm-generic/tlb: Remove tlb_flush_mmu_free() Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 11:36 ` [PATCH 18/18] asm-generic/tlb: Remove tlb_table_flush() Peter Zijlstra 2018-09-26 11:36 ` Peter Zijlstra 2018-09-26 12:47 ` [PATCH 00/18] my generic mmu_gather patches Will Deacon 2018-09-26 12:47 ` Will Deacon 2018-12-11 5:50 ` Aneesh Kumar K.V 2018-12-11 5:50 ` Aneesh Kumar K.V
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