From b5db0e38653bfada34a92f360b4111566ede3842 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 15 Jan 2009 15:32:12 -0800 Subject: [PATCH] Revert "x86 PAT: remove CPA WARN_ON for zero pte" This reverts commit 58dab916dfb57328d50deb0aa9b3fc92efa248ff, which makes my Nehalem come to a nasty crawling almost-halt. It looks like it turns off caching of regular kernel RAM, with the understandable slowdown of a few orders of magnitude as a result. Acked-by: Ingo Molnar Cc: Yinghai Lu Cc: Peter Anvin Cc: Venkatesh Pallipadi Cc: Suresh Siddha Signed-off-by: Linus Torvalds --- arch/x86/mm/pageattr.c | 10 ++++------ arch/x86/mm/pat.c | 45 ++++++++++++------------------------------ 2 files changed, 17 insertions(+), 38 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 4cf30dee816..e89d24815f2 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -555,12 +555,10 @@ repeat: if (!pte_val(old_pte)) { if (!primary) return 0; - - /* - * Special error value returned, indicating that the mapping - * did not exist at this address. - */ - return -EFAULT; + WARN(1, KERN_WARNING "CPA: called for zero pte. " + "vaddr = %lx cpa->vaddr = %lx\n", address, + *cpa->vaddr); + return -EINVAL; } if (level == PG_LEVEL_4K) { diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 160c42d3eb8..8b08fb95527 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -505,35 +505,6 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size) } #endif /* CONFIG_STRICT_DEVMEM */ -/* - * Change the memory type for the physial address range in kernel identity - * mapping space if that range is a part of identity map. - */ -static int kernel_map_sync_memtype(u64 base, unsigned long size, - unsigned long flags) -{ - unsigned long id_sz; - int ret; - - if (!pat_enabled || base >= __pa(high_memory)) - return 0; - - id_sz = (__pa(high_memory) < base + size) ? - __pa(high_memory) - base : - size; - - ret = ioremap_change_attr((unsigned long)__va(base), id_sz, flags); - /* - * -EFAULT return means that the addr was not valid and did not have - * any identity mapping. That case is a success for - * kernel_map_sync_memtype. - */ - if (ret == -EFAULT) - ret = 0; - - return ret; -} - int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, unsigned long size, pgprot_t *vma_prot) { @@ -584,7 +555,9 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, if (retval < 0) return 0; - if (kernel_map_sync_memtype(offset, size, flags)) { + if (((pfn < max_low_pfn_mapped) || + (pfn >= (1UL<<(32 - PAGE_SHIFT)) && pfn < max_pfn_mapped)) && + ioremap_change_attr((unsigned long)__va(offset), size, flags) < 0) { free_memtype(offset, offset + size); printk(KERN_INFO "%s:%d /dev/mem ioremap_change_attr failed %s for %Lx-%Lx\n", @@ -632,7 +605,7 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot, int strict_prot) { int is_ram = 0; - int ret; + int id_sz, ret; unsigned long flags; unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK); @@ -673,7 +646,15 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot, flags); } - if (kernel_map_sync_memtype(paddr, size, flags)) { + /* Need to keep identity mapping in sync */ + if (paddr >= __pa(high_memory)) + return 0; + + id_sz = (__pa(high_memory) < paddr + size) ? + __pa(high_memory) - paddr : + size; + + if (ioremap_change_attr((unsigned long)__va(paddr), id_sz, flags) < 0) { free_memtype(paddr, paddr + size); printk(KERN_ERR "%s:%d reserve_pfn_range ioremap_change_attr failed %s " -- 2.41.0