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    Subject[RFC PATCH 04/12] PAT 64b: reserve_mattr and free_mattr for PAT
    Straight forward port of pat-conflict.patch to x86 tree.

    Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
    Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
    ---
    Index: linux-2.6.24-rc4/arch/x86/mm/ioremap_64.c
    ===================================================================
    --- linux-2.6.24-rc4.orig/arch/x86/mm/ioremap_64.c 2007-12-11 14:24:56.000000000 -0800
    +++ linux-2.6.24-rc4/arch/x86/mm/ioremap_64.c 2007-12-12 15:03:26.000000000 -0800
    @@ -19,6 +19,7 @@
    #include <asm/tlbflush.h>
    #include <asm/cacheflush.h>
    #include <asm/proto.h>
    +#include <asm/pat.h>

    unsigned long __phys_addr(unsigned long x)
    {
    @@ -125,12 +126,23 @@
    remove_vm_area((void *)(PAGE_MASK & (unsigned long) addr));
    return NULL;
    }
    +
    + /* For plain ioremap() get the existing attributes. Otherwise
    + check against the existing ones */
    + if (reserve_mattr(phys_addr, phys_addr + size, flags,
    + flags ? NULL : &flags) < 0)
    + goto out;
    +
    if (flags && ioremap_change_attr(phys_addr, size, flags) < 0) {
    - area->flags &= 0xffffff;
    - vunmap(addr);
    - return NULL;
    + free_mattr(phys_addr, phys_addr + size, flags);
    + goto out;
    }
    return (__force void __iomem *) (offset + (char *)addr);
    +
    +out:
    + area->flags &= 0xffffff;
    + vunmap(addr);
    + return NULL;
    }
    EXPORT_SYMBOL(__ioremap);

    @@ -198,8 +210,10 @@
    }

    /* Reset the direct mapping. Can block */
    - if (p->flags >> 20)
    + if (p->flags >> 20) {
    + free_mattr(p->phys_addr, p->phys_addr + p->size, p->flags>>20);
    ioremap_change_attr(p->phys_addr, p->size, 0);
    + }

    /* Finally remove it */
    o = remove_vm_area((void *)addr);
    Index: linux-2.6.24-rc4/arch/x86/mm/pat.c
    ===================================================================
    --- linux-2.6.24-rc4.orig/arch/x86/mm/pat.c 2007-12-11 15:08:12.000000000 -0800
    +++ linux-2.6.24-rc4/arch/x86/mm/pat.c 2007-12-12 15:06:52.000000000 -0800
    @@ -6,6 +6,8 @@
    #include <asm/msr.h>
    #include <asm/tlbflush.h>
    #include <asm/processor.h>
    +#include <asm/pgtable.h>
    +#include <asm/pat.h>

    static u64 boot_pat_state;

    @@ -55,3 +57,96 @@
    }
    }

    +/* The global memattr list keeps track of caching attributes for specific
    + physical memory areas. Conflicting caching attributes in different
    + mappings can cause CPU cache corruption. To avoid this we keep track.
    +
    + The list is sorted and can contain multiple entries for each address
    + (this allows reference counting for overlapping areas). All the aliases
    + have the same cache attributes of course. Zero attributes are represente
    + as holes.
    +
    + Currently the data structure is a list because the number of mappings
    + are right now expected to be relatively small. If this should be a problem
    + it could be changed to a rbtree or similar.
    +
    + mattr_lock protects the whole list. */
    +
    +struct memattr {
    + struct list_head nd;
    + u64 start;
    + u64 end;
    + unsigned long attr;
    +};
    +
    +static LIST_HEAD(mattr_list);
    +static DEFINE_SPINLOCK(mattr_lock); /* protects memattr list */
    +
    +int reserve_mattr(u64 start, u64 end, unsigned long attr, unsigned long *fattr)
    +{
    + struct memattr *ma = NULL, *ml;
    + int err = 0;
    + if (attr) {
    + ma = kmalloc(sizeof(struct memattr), GFP_KERNEL);
    + if (!ma)
    + return -ENOMEM;
    + ma->start = start;
    + ma->end = end;
    + ma->attr = attr;
    + }
    + if (fattr)
    + *fattr = attr;
    + spin_lock(&mattr_lock);
    + list_for_each_entry(ml, &mattr_list, nd) {
    + if (ml->start <= start && ml->end >= end) {
    + if (fattr) {
    + attr = ml->attr;
    + *fattr = attr;
    + }
    + if (attr != ml->attr) {
    + printk(
    + KERN_ERR "%s:%d conflicting cache attribute %Lx-%Lx %lx<->%lx\n",
    + current->comm, current->pid,
    + start, end, attr, ml->attr);
    + err = -EBUSY;
    + break;
    + }
    + } else if (ml->start >= end) {
    + if (ma) {
    + list_add(&ma->nd, ml->nd.prev);
    + ma = NULL;
    + }
    + break;
    + }
    + }
    + if (ma)
    + list_add_tail(&ma->nd, &mattr_list);
    + spin_unlock(&mattr_lock);
    + return 0;
    +}
    +
    +int free_mattr(u64 start, u64 end, unsigned long attr)
    +{
    + struct memattr *ml;
    + int err = attr ? -EBUSY : 0;
    + spin_lock(&mattr_lock);
    + list_for_each_entry(ml, &mattr_list, nd) {
    + if (ml->start == start && ml->end == end) {
    + if (ml->attr != attr)
    + printk(KERN_ERR
    + "%s:%d conflicting cache attributes on free %Lx-%Lx %lx<->%lx\n",
    + current->comm, current->pid, start, end, attr,ml->attr);
    + list_del(&ml->nd);
    + kfree(ml);
    + err = 0;
    + break;
    + }
    + }
    + spin_unlock(&mattr_lock);
    + if (err)
    + printk(KERN_ERR "%s:%d freeing invalid mattr %Lx-%Lx %lx\n",
    + current->comm, current->pid,
    + start, end, attr);
    + return err;
    +}
    +
    Index: linux-2.6.24-rc4/include/asm-x86/pat.h
    ===================================================================
    --- /dev/null 1970-01-01 00:00:00.000000000 +0000
    +++ linux-2.6.24-rc4/include/asm-x86/pat.h 2007-12-11 15:39:28.000000000 -0800
    @@ -0,0 +1,12 @@
    +#ifndef _ASM_PAT_H
    +#define _ASM_PAT_H 1
    +
    +#include <linux/types.h>
    +
    +/* Handle the page attribute table (PAT) of the CPU */
    +
    +int reserve_mattr(u64 start, u64 end, unsigned long attr, unsigned long *fattr);
    +int free_mattr(u64 start, u64 end, unsigned long attr);
    +
    +#endif
    +
    --


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