mm: x86 pgtable: require X86_64 for soft-dirty tracker

Tracking dirty status on 2 level pages requires very ugly macros and
taking into account how old the machines who can operate without PAE mode
only are, lets drop soft dirty tracker from them for code simplicity (note
I can't drop all the macros from 2 level pages by now since
_PAGE_BIT_PROTNONE and _PAGE_BIT_FILE are still used even without
tracker).

Linus proposed to completely rip off softdirty support on x86-32 (even
with PAE) and since for CRIU we're not planning to support native x86-32
mode, lets do that.

(Softdirty tracker is relatively new feature which is mostly used by CRIU
so I don't expect if such API change would cause problems for userspace).

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Noonan <steven@uplinklabs.net>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b7f4a2e7604d604c75dd41961f221141f6b556fb..c1fd51b87caa7f9d6f71fdd13681aa835335cf69 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -105,7 +105,7 @@ config X86
        select HAVE_ARCH_SECCOMP_FILTER
        select BUILDTIME_EXTABLE_SORT
        select GENERIC_CMOS_UPDATE
-       select HAVE_ARCH_SOFT_DIRTY
+       select HAVE_ARCH_SOFT_DIRTY if X86_64
        select CLOCKSOURCE_WATCHDOG
        select GENERIC_CLOCKEVENTS
        select ARCH_CLOCKSOURCE_DATA

diff --git a/arch/x86/include/asm/pgtable-2level.h b/arch/x86/include/asm/pgtable-2level.h
index eec82d4c4473920ce155f2c68839fd53024c6777..206a87fdd22dacf37ea5549c802aac75fcfca72c 100644 (file)
--- a/arch/x86/include/asm/pgtable-2level.h
+++ b/arch/x86/include/asm/pgtable-2level.h
@@ -62,53 +62,6 @@ static inline unsigned long pte_bitop(unsigned long value, unsigned int rightshi
        return ((value >> rightshift) & mask) << leftshift;
 }
 
-#ifdef CONFIG_MEM_SOFT_DIRTY
-
-/*
- * Bits _PAGE_BIT_PRESENT, _PAGE_BIT_FILE, _PAGE_BIT_SOFT_DIRTY and
- * _PAGE_BIT_PROTNONE are taken, split up the 28 bits of offset
- * into this range.
- */
-#define PTE_FILE_MAX_BITS      28
-#define PTE_FILE_SHIFT1                (_PAGE_BIT_PRESENT + 1)
-#define PTE_FILE_SHIFT2                (_PAGE_BIT_FILE + 1)
-#define PTE_FILE_SHIFT3                (_PAGE_BIT_PROTNONE + 1)
-#define PTE_FILE_SHIFT4                (_PAGE_BIT_SOFT_DIRTY + 1)
-#define PTE_FILE_BITS1         (PTE_FILE_SHIFT2 - PTE_FILE_SHIFT1 - 1)
-#define PTE_FILE_BITS2         (PTE_FILE_SHIFT3 - PTE_FILE_SHIFT2 - 1)
-#define PTE_FILE_BITS3         (PTE_FILE_SHIFT4 - PTE_FILE_SHIFT3 - 1)
-
-#define PTE_FILE_MASK1         ((1U << PTE_FILE_BITS1) - 1)
-#define PTE_FILE_MASK2         ((1U << PTE_FILE_BITS2) - 1)
-#define PTE_FILE_MASK3         ((1U << PTE_FILE_BITS3) - 1)
-
-#define PTE_FILE_LSHIFT2       (PTE_FILE_BITS1)
-#define PTE_FILE_LSHIFT3       (PTE_FILE_BITS1 + PTE_FILE_BITS2)
-#define PTE_FILE_LSHIFT4       (PTE_FILE_BITS1 + PTE_FILE_BITS2 + PTE_FILE_BITS3)
-
-static __always_inline pgoff_t pte_to_pgoff(pte_t pte)
-{
-       return (pgoff_t)
-               (pte_bitop(pte.pte_low, PTE_FILE_SHIFT1, PTE_FILE_MASK1,  0)                +
-                pte_bitop(pte.pte_low, PTE_FILE_SHIFT2, PTE_FILE_MASK2,  PTE_FILE_LSHIFT2) +
-                pte_bitop(pte.pte_low, PTE_FILE_SHIFT3, PTE_FILE_MASK3,  PTE_FILE_LSHIFT3) +
-                pte_bitop(pte.pte_low, PTE_FILE_SHIFT4,           -1UL,  PTE_FILE_LSHIFT4));
-}
-
-static __always_inline pte_t pgoff_to_pte(pgoff_t off)
-{
-       return (pte_t){
-               .pte_low =
-                       pte_bitop(off,                0, PTE_FILE_MASK1,  PTE_FILE_SHIFT1) +
-                       pte_bitop(off, PTE_FILE_LSHIFT2, PTE_FILE_MASK2,  PTE_FILE_SHIFT2) +
-                       pte_bitop(off, PTE_FILE_LSHIFT3, PTE_FILE_MASK3,  PTE_FILE_SHIFT3) +
-                       pte_bitop(off, PTE_FILE_LSHIFT4,           -1UL,  PTE_FILE_SHIFT4) +
-                       _PAGE_FILE,
-       };
-}
-
-#else /* CONFIG_MEM_SOFT_DIRTY */
-
 /*
  * Bits _PAGE_BIT_PRESENT, _PAGE_BIT_FILE and _PAGE_BIT_PROTNONE are taken,
  * split up the 29 bits of offset into this range.
@@ -145,8 +98,6 @@ static __always_inline pte_t pgoff_to_pte(pgoff_t off)
        };
 }
 
-#endif /* CONFIG_MEM_SOFT_DIRTY */
-
 /* Encode and de-code a swap entry */
 #define SWP_TYPE_BITS (_PAGE_BIT_FILE - _PAGE_BIT_PRESENT - 1)
 #define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 1)