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From: Kumar Gala <galak@kernel.crashing.org>
To: linuxppc-dev@ozlabs.org
Subject: [PATCH v3 2/4] powerpc: Fixes for CONFIG_PTE_64BIT for SMP support
Date: Wed,  3 Sep 2008 13:09:02 -0500	[thread overview]
Message-ID: <1220465344-16753-2-git-send-email-galak@kernel.crashing.org> (raw)
In-Reply-To: <1220465344-16753-1-git-send-email-galak@kernel.crashing.org>

There are some minor issues with support 64-bit PTEs on a 32-bit processor
when dealing with SMP.

* We need to order the stores in set_pte_at to make sure the flag word
  is set second.
* Change pte_clear to use pte_update so only the flag word is cleared

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
---

Fixed pte_clear to not break on 6xx.

- k

 arch/powerpc/include/asm/pgtable-ppc32.h |   15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/pgtable-ppc32.h b/arch/powerpc/include/asm/pgtable-ppc32.h
index 6fe39e3..dff1b7e 100644
--- a/arch/powerpc/include/asm/pgtable-ppc32.h
+++ b/arch/powerpc/include/asm/pgtable-ppc32.h
@@ -517,7 +517,8 @@ extern unsigned long bad_call_to_PMD_PAGE_SIZE(void);
 
 #define pte_none(pte)		((pte_val(pte) & ~_PTE_NONE_MASK) == 0)
 #define pte_present(pte)	(pte_val(pte) & _PAGE_PRESENT)
-#define pte_clear(mm,addr,ptep)	do { set_pte_at((mm), (addr), (ptep), __pte(0)); } while (0)
+#define pte_clear(mm, addr, ptep) \
+	do { pte_update(ptep, ~_PAGE_HASHPTE, 0); } while (0)
 
 #define pmd_none(pmd)		(!pmd_val(pmd))
 #define	pmd_bad(pmd)		(pmd_val(pmd) & _PMD_BAD)
@@ -612,9 +613,6 @@ static inline unsigned long pte_update(pte_t *p,
 	return old;
 }
 #else /* CONFIG_PTE_64BIT */
-/* TODO: Change that to only modify the low word and move set_pte_at()
- * out of line
- */
 static inline unsigned long long pte_update(pte_t *p,
 					    unsigned long clr,
 					    unsigned long set)
@@ -658,8 +656,17 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
 #if _PAGE_HASHPTE != 0
 	pte_update(ptep, ~_PAGE_HASHPTE, pte_val(pte) & ~_PAGE_HASHPTE);
 #else
+#if defined(CONFIG_PTE_64BIT) && defined(CONFIG_SMP)
+	__asm__ __volatile__("\
+		stw%U0%X0 %2,%0\n\
+		eieio\n\
+		stw%U0%X0 %L2,%1"
+	: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
+	: "r" (pte) : "memory");
+#else
 	*ptep = pte;
 #endif
+#endif
 }
 
 /*
-- 
1.5.5.1

  reply	other threads:[~2008-09-03 18:09 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-03 18:09 [PATCH v3 1/4] powerpc: Introduce local (non-broadcast) forms of tlb invalidates Kumar Gala
2008-09-03 18:09 ` Kumar Gala [this message]
2008-09-03 18:09   ` [PATCH v3 3/4] powerpc/fsl-booke: Fixup 64-bit PTE reading for SMP support Kumar Gala
2008-09-03 18:09     ` [PATCH v3 4/4] powerpc/mm: Implement _PAGE_SPECIAL & pte_special() for 32-bit Kumar Gala
2008-09-04  3:15       ` Benjamin Herrenschmidt
2008-09-04  3:14     ` [PATCH v3 3/4] powerpc/fsl-booke: Fixup 64-bit PTE reading for SMP support Benjamin Herrenschmidt
2008-09-04  3:12   ` [PATCH v3 2/4] powerpc: Fixes for CONFIG_PTE_64BIT " Benjamin Herrenschmidt
2008-09-05 19:44     ` Kumar Gala
2008-09-05 22:38       ` Benjamin Herrenschmidt
2008-09-06 15:32         ` Kumar Gala
2008-09-04 19:17 ` [PATCH v3 1/4] powerpc: Introduce local (non-broadcast) forms of tlb invalidates Rafal Jaworowski
2008-09-04 21:30   ` Benjamin Herrenschmidt

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