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SubjectRe: [tip:perfcounters/core] x86: Add NMI types for kmap_atomic
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On Mon, 2009-06-15 at 14:07 +0000, tip-bot for Peter Zijlstra wrote:
> Commit-ID: 3ff0141aa3a03ca3388b40b36167d0a37919f3fd
> Gitweb: http://git.kernel.org/tip/3ff0141aa3a03ca3388b40b36167d0a37919f3fd
> Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
> AuthorDate: Mon, 15 Jun 2009 12:40:41 +0200
> Committer: Ingo Molnar <mingo@elte.hu>
> CommitDate: Mon, 15 Jun 2009 15:57:52 +0200
> x86: Add NMI types for kmap_atomic
>
> Two new kmap_atomic slots for NMI context. And teach pte_offset_map()
> about NMI context.
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> CC: Nick Piggin <npiggin@suse.de>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
>
>
> ---
> arch/x86/include/asm/kmap_types.h | 4 +++-
> arch/x86/include/asm/pgtable_32.h | 5 +++--
> 2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/include/asm/kmap_types.h b/arch/x86/include/asm/kmap_types.h
> index 5759c16..ff00a44 100644
> --- a/arch/x86/include/asm/kmap_types.h
> +++ b/arch/x86/include/asm/kmap_types.h
> @@ -21,7 +21,9 @@ D(9) KM_IRQ0,
> D(10) KM_IRQ1,
> D(11) KM_SOFTIRQ0,
> D(12) KM_SOFTIRQ1,
> -D(13) KM_TYPE_NR
> +D(13) KM_NMI,
> +D(14) KM_NMI_PTE,
> +D(15) KM_TYPE_NR
> };
>
> #undef D
> diff --git a/arch/x86/include/asm/pgtable_32.h b/arch/x86/include/asm/pgtable_32.h
> index 31bd120..8546497 100644
> --- a/arch/x86/include/asm/pgtable_32.h
> +++ b/arch/x86/include/asm/pgtable_32.h
> @@ -49,13 +49,14 @@ extern void set_pmd_pfn(unsigned long, unsigned long, pgprot_t);
> #endif
>
> #if defined(CONFIG_HIGHPTE)
> +#define __KM_PTE (in_nmi() ? KM_NMI_PTE : KM_PTE0)
> #define pte_offset_map(dir, address) \
> - ((pte_t *)kmap_atomic_pte(pmd_page(*(dir)), KM_PTE0) + \
> + ((pte_t *)kmap_atomic_pte(pmd_page(*(dir)), __KM_PTE) + \
> pte_index((address)))
> #define pte_offset_map_nested(dir, address) \
> ((pte_t *)kmap_atomic_pte(pmd_page(*(dir)), KM_PTE1) + \
> pte_index((address)))
> -#define pte_unmap(pte) kunmap_atomic((pte), KM_PTE0)
> +#define pte_unmap(pte) kunmap_atomic((pte), __KM_PTE)
> #define pte_unmap_nested(pte) kunmap_atomic((pte), KM_PTE1)
> #else
> #define pte_offset_map(dir, address) \

I just realized this has a kmap_atomic bug in...

The below would fix it, but that's getting rather ugly :-/,
alternatively I would have to introduce something like
pte_offset_map_irq() which would make the irq/nmi detection and leave
the regular code paths alone, however that would mean either duplicating
the gup_fast() pagewalk or passing down a pte function pointer, which
would only duplicate the gup_pte_range() bit, neither is really
attractive...

Index: linux-2.6/arch/x86/include/asm/kmap_types.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/kmap_types.h
+++ linux-2.6/arch/x86/include/asm/kmap_types.h
@@ -19,11 +19,12 @@ D(7) KM_PTE0,
D(8) KM_PTE1,
D(9) KM_IRQ0,
D(10) KM_IRQ1,
-D(11) KM_SOFTIRQ0,
-D(12) KM_SOFTIRQ1,
-D(13) KM_NMI,
-D(14) KM_NMI_PTE,
-D(15) KM_TYPE_NR
+D(11) KM_IRQ_PTE,
+D(12) KM_SOFTIRQ0,
+D(13) KM_SOFTIRQ1,
+D(14) KM_NMI,
+D(15) KM_NMI_PTE,
+D(16) KM_TYPE_NR
};

#undef D
Index: linux-2.6/arch/x86/include/asm/pgtable_32.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/pgtable_32.h
+++ linux-2.6/arch/x86/include/asm/pgtable_32.h
@@ -49,7 +49,10 @@ extern void set_pmd_pfn(unsigned long, u
#endif

#if defined(CONFIG_HIGHPTE)
-#define __KM_PTE (in_nmi() ? KM_NMI_PTE : KM_PTE0)
+#define __KM_PTE \
+ (in_nmi() ? KM_NMI_PTE : \
+ in_irq() ? KM_IRQ_PTE : \
+ KM_PTE0)
#define pte_offset_map(dir, address) \
((pte_t *)kmap_atomic_pte(pmd_page(*(dir)), __KM_PTE) + \
pte_index((address)))




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