Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=012b7105cc816fb797eb1c161cdfc0052b5c3f53
Commit:     012b7105cc816fb797eb1c161cdfc0052b5c3f53
Parent:     9e121327b37b751ef66e6f57e2d02dd568955148
Author:     Alex Chiang <[EMAIL PROTECTED]>
AuthorDate: Wed Jul 11 11:02:15 2007 -0600
Committer:  Tony Luck <[EMAIL PROTECTED]>
CommitDate: Wed Jul 11 11:34:49 2007 -0700

    [IA64] prevent MCA when performing MMIO mmap to PCI config space
    
    Example memory map (HP rx7640 with 'default' acpiconfig setting, VGA 
disabled):
       0x00000000 - 0x3FFFBFFF  supports only WB (cacheable) access
    
    If a user attempts to perform an MMIO mmap (using the PCIIOC_MMAP_IS_MEM 
ioctl)
    to PCI config space (like mmap'ing and accessing memory at 0xA0000),
    we will MCA because the kernel will attempt to use a mapping with the UC
    attribute.
    
    So check the memory attribute in kern_mmap and the EFI memmap. If WC is
    requested, and WC or UC access is supported for the region, allow it.
    Otherwise, use the same attribute the kernel uses.
    
    Updates documentation and test cases as well.
    
    Signed-off-by: Alex Chiang <[EMAIL PROTECTED]>
    Signed-off-by: Bjorn Helgaas <[EMAIL PROTECTED]>
    Signed-off-by: Tony Luck <[EMAIL PROTECTED]>
---
 Documentation/ia64/aliasing-test.c |   26 +++++++++++++++++++-------
 Documentation/ia64/aliasing.txt    |   12 ++++++++++++
 arch/ia64/pci/pci.c                |   22 +++++++++++++++++-----
 3 files changed, 48 insertions(+), 12 deletions(-)

diff --git a/Documentation/ia64/aliasing-test.c 
b/Documentation/ia64/aliasing-test.c
index d485256..773a814 100644
--- a/Documentation/ia64/aliasing-test.c
+++ b/Documentation/ia64/aliasing-test.c
@@ -19,6 +19,7 @@
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <linux/pci.h>
 
 int sum;
 
@@ -34,13 +35,19 @@ int map_mem(char *path, off_t offset, size_t length, int 
touch)
                return -1;
        }
 
+       if (fnmatch("/proc/bus/pci/*", path, 0) == 0) {
+               rc = ioctl(fd, PCIIOC_MMAP_IS_MEM);
+               if (rc == -1)
+                       perror("PCIIOC_MMAP_IS_MEM ioctl");
+       }
+
        addr = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, offset);
        if (addr == MAP_FAILED)
                return 1;
 
        if (touch) {
                c = (int *) addr;
-               while (c < (int *) (offset + length))
+               while (c < (int *) (addr + length))
                        sum += *c++;
        }
 
@@ -54,7 +61,7 @@ int map_mem(char *path, off_t offset, size_t length, int 
touch)
        return 0;
 }
 
-int scan_sysfs(char *path, char *file, off_t offset, size_t length, int touch)
+int scan_tree(char *path, char *file, off_t offset, size_t length, int touch)
 {
        struct dirent **namelist;
        char *name, *path2;
@@ -93,7 +100,7 @@ int scan_sysfs(char *path, char *file, off_t offset, size_t 
length, int touch)
                } else {
                        r = lstat(path2, &buf);
                        if (r == 0 && S_ISDIR(buf.st_mode)) {
-                               rc = scan_sysfs(path2, file, offset, length, 
touch);
+                               rc = scan_tree(path2, file, offset, length, 
touch);
                                if (rc < 0)
                                        return rc;
                        }
@@ -238,10 +245,15 @@ int main()
        else
                fprintf(stderr, "FAIL: /dev/mem 0x0-0x100000 not accessible\n");
 
-       scan_sysfs("/sys/class/pci_bus", "legacy_mem", 0, 0xA0000, 1);
-       scan_sysfs("/sys/class/pci_bus", "legacy_mem", 0xA0000, 0x20000, 0);
-       scan_sysfs("/sys/class/pci_bus", "legacy_mem", 0xC0000, 0x40000, 1);
-       scan_sysfs("/sys/class/pci_bus", "legacy_mem", 0, 1024*1024, 0);
+       scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 0xA0000, 1);
+       scan_tree("/sys/class/pci_bus", "legacy_mem", 0xA0000, 0x20000, 0);
+       scan_tree("/sys/class/pci_bus", "legacy_mem", 0xC0000, 0x40000, 1);
+       scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 1024*1024, 0);
 
        scan_rom("/sys/devices", "rom");
+
+       scan_tree("/proc/bus/pci", "??.?", 0, 0xA0000, 1);
+       scan_tree("/proc/bus/pci", "??.?", 0xA0000, 0x20000, 0);
+       scan_tree("/proc/bus/pci", "??.?", 0xC0000, 0x40000, 1);
+       scan_tree("/proc/bus/pci", "??.?", 0, 1024*1024, 0);
 }
diff --git a/Documentation/ia64/aliasing.txt b/Documentation/ia64/aliasing.txt
index 9a431a7..aa3e953 100644
--- a/Documentation/ia64/aliasing.txt
+++ b/Documentation/ia64/aliasing.txt
@@ -112,6 +112,18 @@ POTENTIAL ATTRIBUTE ALIASING CASES
 
        The /dev/mem mmap constraints apply.
 
+    mmap of /proc/bus/pci/.../??.?
+
+       This is an MMIO mmap of PCI functions, which additionally may or
+       may not be requested as using the WC attribute.
+
+       If WC is requested, and the region in kern_memmap is either WC
+       or UC, and the EFI memory map designates the region as WC, then
+       the WC mapping is allowed.
+
+       Otherwise, the user mapping must use the same attribute as the
+       kernel mapping.
+
     read/write of /dev/mem
 
        This uses copy_from_user(), which implicitly uses a kernel
diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
index 73696b4..07d0e92 100644
--- a/arch/ia64/pci/pci.c
+++ b/arch/ia64/pci/pci.c
@@ -591,6 +591,9 @@ int
 pci_mmap_page_range (struct pci_dev *dev, struct vm_area_struct *vma,
                     enum pci_mmap_state mmap_state, int write_combine)
 {
+       unsigned long size = vma->vm_end - vma->vm_start;
+       pgprot_t prot;
+
        /*
         * I/O space cannot be accessed via normal processor loads and
         * stores on this platform.
@@ -604,15 +607,24 @@ pci_mmap_page_range (struct pci_dev *dev, struct 
vm_area_struct *vma,
                 */
                return -EINVAL;
 
+       if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
+               return -EINVAL;
+
+       prot = phys_mem_access_prot(NULL, vma->vm_pgoff, size,
+                                   vma->vm_page_prot);
+
        /*
-        * Leave vm_pgoff as-is, the PCI space address is the physical
-        * address on this platform.
+        * If the user requested WC, the kernel uses UC or WC for this region,
+        * and the chipset supports WC, we can use WC. Otherwise, we have to
+        * use the same attribute the kernel uses.
         */
-       if (write_combine && efi_range_is_wc(vma->vm_start,
-                                            vma->vm_end - vma->vm_start))
+       if (write_combine &&
+           ((pgprot_val(prot) & _PAGE_MA_MASK) == _PAGE_MA_UC ||
+            (pgprot_val(prot) & _PAGE_MA_MASK) == _PAGE_MA_WC) &&
+           efi_range_is_wc(vma->vm_start, vma->vm_end - vma->vm_start))
                vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
        else
-               vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+               vma->vm_page_prot = prot;
 
        if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
                             vma->vm_end - vma->vm_start, vma->vm_page_prot))
-
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