From acca4f4d9bd657e8bc7e1665ba5077465138f133 Mon Sep 17 00:00:00 2001 From: Paul Mundt Date: Mon, 10 Nov 2008 20:00:45 +0900 Subject: sh: Handle fixmap TLB eviction more coherently. There was a race in the kmap_coherent() implementation. While we guarded against preemption, there was nothing preventing eviction of the pre-faulted fixmap entry from the UTLB. Under certain workloads this would result in the fixmap entries used for cache colouring being evicted from the UTLB in the midst of a copy_page(). In addition to pre-faulting, we also make sure to preserve the PTEs in the kernel page table and introduce a cached PTE for kmap_coherent() usage. This follows a similar change on MIPS ("[MIPS] Fix aliasing bug in copy_to_user_page / copy_from_user_page"). Reported-by: Hideo Saito Reported-by: CHIKAMA Masaki Tested-by: Yoshihiro Shimoda Signed-off-by: Paul Mundt --- arch/sh/mm/pg-sh4.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'arch/sh/mm/pg-sh4.c') diff --git a/arch/sh/mm/pg-sh4.c b/arch/sh/mm/pg-sh4.c index 38870e0fc18..2fe14da1f83 100644 --- a/arch/sh/mm/pg-sh4.c +++ b/arch/sh/mm/pg-sh4.c @@ -7,6 +7,7 @@ * Released under the terms of the GNU GPL v2.0. */ #include +#include #include #include #include @@ -16,6 +17,20 @@ #define CACHE_ALIAS (current_cpu_data.dcache.alias_mask) +#define kmap_get_fixmap_pte(vaddr) \ + pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), (vaddr)) + +static pte_t *kmap_coherent_pte; + +void __init kmap_coherent_init(void) +{ + unsigned long vaddr; + + /* cache the first coherent kmap pte */ + vaddr = __fix_to_virt(FIX_CMAP_BEGIN); + kmap_coherent_pte = kmap_get_fixmap_pte(vaddr); +} + static inline void *kmap_coherent(struct page *page, unsigned long addr) { enum fixed_addresses idx; @@ -34,6 +49,8 @@ static inline void *kmap_coherent(struct page *page, unsigned long addr) update_mmu_cache(NULL, vaddr, pte); + set_pte(kmap_coherent_pte - (FIX_CMAP_END - idx), pte); + return (void *)vaddr; } -- cgit v1.2.3