Commit-ID: 1660e9d3d04b6c636b7171bf6c08ac7b82a7de79 Gitweb: http://git.kernel.org/tip/1660e9d3d04b6c636b7171bf6c08ac7b82a7de79 Author: Paul Mackerras <paulus@xxxxxxxxx> AuthorDate: Mon, 17 Aug 2009 14:36:32 +1000 Committer: Paul Mackerras <paulus@xxxxxxxxx> CommitDate: Tue, 18 Aug 2009 14:48:39 +1000 powerpc/32: Always order writes to halves of 64-bit PTEs On 32-bit systems with 64-bit PTEs, the PTEs have to be written in two 32-bit halves. On SMP we write the higher-order half and then the lower-order half, with a write barrier between the two halves, but on UP there was no particular ordering of the writes to the two halves. This extends the ordering that we already do on SMP to the UP case as well. The reason is that with the perf_counter subsystem potentially accessing user memory at interrupt time to get stack traces, we have to be careful not to create an incorrect but apparently valid PTE even on UP. Acked-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> --- arch/powerpc/include/asm/pgtable.h | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h index eb17da7..2a5da06 100644 --- a/arch/powerpc/include/asm/pgtable.h +++ b/arch/powerpc/include/asm/pgtable.h @@ -104,8 +104,8 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, else pte_update(ptep, ~_PAGE_HASHPTE, pte_val(pte)); -#elif defined(CONFIG_PPC32) && defined(CONFIG_PTE_64BIT) && defined(CONFIG_SMP) - /* Second case is 32-bit with 64-bit PTE in SMP mode. In this case, we +#elif defined(CONFIG_PPC32) && defined(CONFIG_PTE_64BIT) + /* Second case is 32-bit with 64-bit PTE. In this case, we * can just store as long as we do the two halves in the right order * with a barrier in between. This is possible because we take care, * in the hash code, to pre-invalidate if the PTE was already hashed, @@ -140,7 +140,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, #else /* Anything else just stores the PTE normally. That covers all 64-bit - * cases, and 32-bit non-hash with 64-bit PTEs in UP mode + * cases, and 32-bit non-hash with 32-bit PTEs. */ *ptep = pte; #endif -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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