32e62c636a
This closes a couple holes in our attribute aliasing avoidance scheme:
- The current kernel fails mmaps of some /dev/mem MMIO regions because
they don't appear in the EFI memory map. This keeps X from working
on the Intel Tiger box.
- The current kernel allows UC mmap of the 0-1MB region of
/sys/.../legacy_mem even when the chipset doesn't support UC
access. This causes an MCA when starting X on HP rx7620 and rx8620
boxes in the default configuration.
There's more detail in the Documentation/ia64/aliasing.txt file this
adds, but the general idea is that if a region might be covered by
a granule-sized kernel identity mapping, any access via /dev/mem or
mmap must use the same attribute as the identity mapping.
Otherwise, we fall back to using an attribute that is supported
according to the EFI memory map, or to using UC if the EFI memory
map doesn't mention the region.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
60 lines
1.6 KiB
C
60 lines
1.6 KiB
C
/*
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* (c) Copyright 2006 Hewlett-Packard Development Company, L.P.
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* Bjorn Helgaas <bjorn.helgaas@hp.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/compiler.h>
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#include <linux/module.h>
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#include <linux/efi.h>
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#include <asm/io.h>
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#include <asm/meminit.h>
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static inline void __iomem *
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__ioremap (unsigned long offset, unsigned long size)
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{
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return (void __iomem *) (__IA64_UNCACHED_OFFSET | offset);
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}
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void __iomem *
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ioremap (unsigned long offset, unsigned long size)
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{
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u64 attr;
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unsigned long gran_base, gran_size;
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/*
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* For things in kern_memmap, we must use the same attribute
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* as the rest of the kernel. For more details, see
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* Documentation/ia64/aliasing.txt.
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*/
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attr = kern_mem_attribute(offset, size);
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if (attr & EFI_MEMORY_WB)
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return phys_to_virt(offset);
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else if (attr & EFI_MEMORY_UC)
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return __ioremap(offset, size);
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/*
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* Some chipsets don't support UC access to memory. If
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* WB is supported for the whole granule, we prefer that.
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*/
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gran_base = GRANULEROUNDDOWN(offset);
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gran_size = GRANULEROUNDUP(offset + size) - gran_base;
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if (efi_mem_attribute(gran_base, gran_size) & EFI_MEMORY_WB)
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return phys_to_virt(offset);
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return __ioremap(offset, size);
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}
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EXPORT_SYMBOL(ioremap);
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void __iomem *
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ioremap_nocache (unsigned long offset, unsigned long size)
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{
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if (kern_mem_attribute(offset, size) & EFI_MEMORY_WB)
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return 0;
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return __ioremap(offset, size);
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}
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EXPORT_SYMBOL(ioremap_nocache);
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