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    SubjectRe: [PATCH 1/2] x86: ioremap: fix wrong physical address handling
    On 06/18/2010 04:22 AM, Kenji Kaneshige wrote:
    > Current x86 ioremap() doesn't handle physical address higher than
    > 32-bit properly in X86_32 PAE mode. When physical address higher than
    > 32-bit is passed to ioremap(), higher 32-bits in physical address is
    > cleared wrongly. Due to this bug, ioremap() can map wrong address to
    > linear address space.
    >
    > In my case, 64-bit MMIO region was assigned to a PCI device (ioat
    > device) on my system. Because of the ioremap()'s bug, wrong physical
    > address (instead of MMIO region) was mapped to linear address space.
    > Because of this, loading ioatdma driver caused unexpected behavior
    > (kernel panic, kernel hangup, ...).
    >
    > Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
    >
    > ---
    > arch/x86/mm/ioremap.c | 12 +++++-------
    > include/linux/io.h | 4 ++--
    > include/linux/vmalloc.h | 2 +-
    > lib/ioremap.c | 10 +++++-----
    > mm/vmalloc.c | 2 +-
    > 5 files changed, 14 insertions(+), 16 deletions(-)
    >
    > Index: linux-2.6.34/arch/x86/mm/ioremap.c
    > ===================================================================
    > --- linux-2.6.34.orig/arch/x86/mm/ioremap.c
    > +++ linux-2.6.34/arch/x86/mm/ioremap.c
    > @@ -62,8 +62,8 @@ int ioremap_change_attr(unsigned long va
    > static void __iomem *__ioremap_caller(resource_size_t phys_addr,
    > unsigned long size, unsigned long prot_val, void *caller)
    > {
    > - unsigned long pfn, offset, vaddr;
    > - resource_size_t last_addr;
    > + unsigned long offset, vaddr;
    > + resource_size_t pfn, last_pfn, last_addr;
    >

    Why is pfn resource_size_t here? Is it to avoid casting, or does it
    actually need to hold more than 32 bits? I don't see any use of pfn
    aside from the page_is_ram loop, and I don't think that can go beyond 32
    bits. If you're worried about boundary conditions at the 2^44 limit,
    then you can make last_pfn inclusive, or compute num_pages and use that
    for the loop condition.

    > const resource_size_t unaligned_phys_addr = phys_addr;
    > const unsigned long unaligned_size = size;
    > struct vm_struct *area;
    > @@ -100,10 +100,8 @@ static void __iomem *__ioremap_caller(re
    > /*
    > * Don't allow anybody to remap normal RAM that we're using..
    > */
    > - for (pfn = phys_addr >> PAGE_SHIFT;
    > - (pfn << PAGE_SHIFT) < (last_addr & PAGE_MASK);
    > - pfn++) {
    > -
    > + last_pfn = last_addr >> PAGE_SHIFT;
    >

    If last_addr can be non-page aligned, should it be rounding up to the
    next pfn rather than rounding down? Ah, looks like you fix it in the
    second patch.

    J


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