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authorChristoph Hellwig <hch@lst.de>2019-07-11 20:56:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-12 11:05:44 -0700
commit39656e83dab918861931ef96e5c41731b0899e56 (patch)
tree6cd4dbb48e2c11a2c934c3db06a1de0c1ed2f96c /arch
parent26f4c328079d78d6cd0462c53c14ec0b69f4748e (diff)
downloadlinux-39656e83dab918861931ef96e5c41731b0899e56.tar.bz2
mm: lift the x86_32 PAE version of gup_get_pte to common code
The split low/high access is the only non-READ_ONCE version of gup_get_pte that did show up in the various arch implemenations. Lift it to common code and drop the ifdef based arch override. Link: http://lkml.kernel.org/r/20190625143715.1689-4-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Miller <davem@davemloft.net> Cc: James Hogan <jhogan@kernel.org> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Rich Felker <dalias@libc.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/Kconfig1
-rw-r--r--arch/x86/include/asm/pgtable-3level.h47
-rw-r--r--arch/x86/kvm/mmu.c2
3 files changed, 2 insertions, 48 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index dce10b18f4bc..71c1f7864434 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -123,6 +123,7 @@ config X86
select GENERIC_STRNLEN_USER
select GENERIC_TIME_VSYSCALL
select GENERIC_GETTIMEOFDAY
+ select GUP_GET_PTE_LOW_HIGH if X86_PAE
select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
select HAVE_ACPI_APEI if ACPI
select HAVE_ACPI_APEI_NMI if ACPI
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index f8b1ad2c3828..e3633795fb22 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -285,53 +285,6 @@ static inline pud_t native_pudp_get_and_clear(pud_t *pudp)
#define __pte_to_swp_entry(pte) (__swp_entry(__pteval_swp_type(pte), \
__pteval_swp_offset(pte)))
-#define gup_get_pte gup_get_pte
-/*
- * WARNING: only to be used in the get_user_pages_fast() implementation.
- *
- * With get_user_pages_fast(), we walk down the pagetables without taking
- * any locks. For this we would like to load the pointers atomically,
- * but that is not possible (without expensive cmpxchg8b) on PAE. What
- * we do have is the guarantee that a PTE will only either go from not
- * present to present, or present to not present or both -- it will not
- * switch to a completely different present page without a TLB flush in
- * between; something that we are blocking by holding interrupts off.
- *
- * Setting ptes from not present to present goes:
- *
- * ptep->pte_high = h;
- * smp_wmb();
- * ptep->pte_low = l;
- *
- * And present to not present goes:
- *
- * ptep->pte_low = 0;
- * smp_wmb();
- * ptep->pte_high = 0;
- *
- * We must ensure here that the load of pte_low sees 'l' iff pte_high
- * sees 'h'. We load pte_high *after* loading pte_low, which ensures we
- * don't see an older value of pte_high. *Then* we recheck pte_low,
- * which ensures that we haven't picked up a changed pte high. We might
- * have gotten rubbish values from pte_low and pte_high, but we are
- * guaranteed that pte_low will not have the present bit set *unless*
- * it is 'l'. Because get_user_pages_fast() only operates on present ptes
- * we're safe.
- */
-static inline pte_t gup_get_pte(pte_t *ptep)
-{
- pte_t pte;
-
- do {
- pte.pte_low = ptep->pte_low;
- smp_rmb();
- pte.pte_high = ptep->pte_high;
- smp_rmb();
- } while (unlikely(pte.pte_low != ptep->pte_low));
-
- return pte;
-}
-
#include <asm/pgtable-invert.h>
#endif /* _ASM_X86_PGTABLE_3LEVEL_H */
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 98f6e4f88b04..4a9c63d1c20a 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -650,7 +650,7 @@ static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)
/*
* The idea using the light way get the spte on x86_32 guest is from
- * gup_get_pte(arch/x86/mm/gup.c).
+ * gup_get_pte (mm/gup.c).
*
* An spte tlb flush may be pending, because kvm_set_pte_rmapp
* coalesces them and we are running out of the MMU lock. Therefore