| Message ID | 20180926114800.770817616@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | my generic mmu_gather patches | expand |
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 <npiggin@gmail.com> > 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> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > 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 <asm-generic/tlb.h> > --- 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 <asm-generic/tlb.h> > > 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 <asm-generic/tlb.h> > --- 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
On Wed, Sep 26, 2018 at 01:53:35PM +0100, Will Deacon wrote: > On Wed, Sep 26, 2018 at 01:36:28PM +0200, Peter Zijlstra wrote: > > +#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? Probably not, that was just my fingers doing the normal #ifndef #define pattern. I'll take em out back for a 'hug' :-) > > +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? Yes. It's not much code, but if you deeply care we could frob things to get rid of it.
On Wed, Sep 26, 2018 at 03:11:41PM +0200, Peter Zijlstra wrote: > On Wed, Sep 26, 2018 at 01:53:35PM +0100, Will Deacon wrote: > > > +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? > > Yes. It's not much code, but if you deeply care we could frob things to > get rid of it. Something a little like the below... not particularly pretty but should work. --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -305,7 +305,8 @@ static inline void __tlb_reset_range(str #error Default tlb_flush() relies on default tlb_start_vma() and tlb_end_vma() #endif -#define tlb_flush tlb_flush +#define generic_tlb_flush + static inline void tlb_flush(struct mmu_gather *tlb) { if (tlb->fullmm || tlb->need_flush_all) { @@ -391,12 +392,12 @@ 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_start_vma static inline void tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) { if (tlb->fullmm) return; +#ifdef generic_tlb_flush /* * flush_tlb_range() implementations that look at VM_HUGETLB (tile, * mips-4k) flush only large pages. @@ -410,13 +411,13 @@ static inline void tlb_start_vma(struct */ tlb->vma_huge = !!(vma->vm_flags & VM_HUGETLB); tlb->vma_exec = !!(vma->vm_flags & VM_EXEC); +#endif flush_cache_range(vma, vma->vm_start, vma->vm_end); } #endif #ifndef tlb_end_vma -#define tlb_end_vma tlb_end_vma static inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) { if (tlb->fullmm)
On Wed, Sep 26, 2018 at 08:07:27PM +0200, Peter Zijlstra wrote: > --- a/include/asm-generic/tlb.h > +++ b/include/asm-generic/tlb.h > @@ -305,7 +305,8 @@ static inline void __tlb_reset_range(str > #error Default tlb_flush() relies on default tlb_start_vma() and tlb_end_vma() > #endif > > -#define tlb_flush tlb_flush > +#define generic_tlb_flush > + > static inline void tlb_flush(struct mmu_gather *tlb) > { > if (tlb->fullmm || tlb->need_flush_all) { > @@ -391,12 +392,12 @@ 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_start_vma > static inline void tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) > { > if (tlb->fullmm) > return; > > +#ifdef generic_tlb_flush > /* > * flush_tlb_range() implementations that look at VM_HUGETLB (tile, > * mips-4k) flush only large pages. > @@ -410,13 +411,13 @@ static inline void tlb_start_vma(struct > */ > tlb->vma_huge = !!(vma->vm_flags & VM_HUGETLB); > tlb->vma_exec = !!(vma->vm_flags & VM_EXEC); > +#endif Alternatively, we could wrap the two assignments above in a macro like: tlb_update_vma_flags(tlb, vma) which could be empty if the generic tlb_flush isn't in use? Anyway, as long as we resolve this one way or the other, you can add my Ack: Acked-by: Will Deacon <will.deacon@arm.com> Cheers, Will
--- 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 <asm-generic/tlb.h> --- 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 <asm-generic/tlb.h> 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 <asm-generic/tlb.h> --- 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 +static inline void tlb_flush(struct mmu_gather *tlb) +{ + if (tlb->fullmm || tlb->need_flush_all) { + flush_tlb_mm(tlb->mm); + } else { + struct vm_area_struct vma = { + .vm_mm = tlb->mm, + .vm_flags = (tlb->vma_exec ? VM_EXEC : 0) | + (tlb->vma_huge ? VM_HUGETLB : 0), + }; + + flush_tlb_range(&vma, tlb->start, tlb->end); + } } +#endif static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) { @@ -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 +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); + + 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 +static inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) +{ + if (tlb->fullmm) + return; + + /* + * Do a TLB flush and reset the range at VMA boundaries; this avoids + * the ranges growing with the unused space between consecutive VMAs, + * but also the mmu_gather::vma_* flags from tlb_start_vma() rely on + * this. + */ + tlb_flush_mmu_tlbonly(tlb); +} #endif #ifndef __tlb_remove_tlb_entry
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 <npiggin@gmail.com> 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> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- 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(-)