(2010/06/18 20:07), Jeremy Fitzhardinge wrote:
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@xxxxxxxxxxxxxx> --- 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.
The reason I changed here was phys_addr might be higher than 2^44. After the discussion, I realized there would probably be many other codes that cannot handle more than 32-bits pfn, and this would cause problems even if I changed ioremap() to be able to handle more than 32-bits pfn. So I decided to focus on making 44-bits physical address work properly this time. But, I didn't find any reason to make it go back to unsigned long. So I still make it resource_size_t even in v.3. Is there any problem on this change? And I don't understand why pfn can't go beyond 32-bits. Could you tell me why?
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.
Yes, I fixed it in the [PATCH 2/2]. Thanks, Kenji Kaneshige -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
