X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=Documentation%2Fcachetlb.txt;h=2b5f823abd035fd180d94732c523671378c2ef9d;hb=cce913178118b0b36742eb7544c2b38a0c957ee7;hp=552cabac06082c460c55befab72b637724c86cd5;hpb=954ffcb35f5aca428661d29b96c4eee82b3c19cd;p=safe%2Fjmp%2Flinux-2.6

diff --git a/Documentation/cachetlb.txt b/Documentation/cachetlb.txt
index 552caba..2b5f823 100644
--- a/Documentation/cachetlb.txt
+++ b/Documentation/cachetlb.txt
@@ -87,43 +87,20 @@ changes occur:
 
 	This is used primarily during fault processing.
 
-5) void flush_tlb_pgtables(struct mm_struct *mm,
-			   unsigned long start, unsigned long end)
-
-   The software page tables for address space 'mm' for virtual
-   addresses in the range 'start' to 'end-1' are being torn down.
-
-   Some platforms cache the lowest level of the software page tables
-   in a linear virtually mapped array, to make TLB miss processing
-   more efficient.  On such platforms, since the TLB is caching the
-   software page table structure, it needs to be flushed when parts
-   of the software page table tree are unlinked/freed.
-
-   Sparc64 is one example of a platform which does this.
-
-   Usually, when munmap()'ing an area of user virtual address
-   space, the kernel leaves the page table parts around and just
-   marks the individual pte's as invalid.  However, if very large
-   portions of the address space are unmapped, the kernel frees up
-   those portions of the software page tables to prevent potential
-   excessive kernel memory usage caused by erratic mmap/mmunmap
-   sequences.  It is at these times that flush_tlb_pgtables will
-   be invoked.
-
-6) void update_mmu_cache(struct vm_area_struct *vma,
-			 unsigned long address, pte_t pte)
+5) void update_mmu_cache(struct vm_area_struct *vma,
+			 unsigned long address, pte_t *ptep)
 
 	At the end of every page fault, this routine is invoked to
 	tell the architecture specific code that a translation
-	described by "pte" now exists at virtual address "address"
-	for address space "vma->vm_mm", in the software page tables.
+	now exists at virtual address "address" for address space
+	"vma->vm_mm", in the software page tables.
 
 	A port may use this information in any way it so chooses.
 	For example, it could use this event to pre-load TLB
 	translations for software managed TLB configurations.
 	The sparc64 port currently does this.
 
-7) void tlb_migrate_finish(struct mm_struct *mm)
+6) void tlb_migrate_finish(struct mm_struct *mm)
 
 	This interface is called at the end of an explicit
 	process migration. This interface provides a hook
@@ -400,3 +377,27 @@ maps this page at its virtual address.
 	All the functionality of flush_icache_page can be implemented in
 	flush_dcache_page and update_mmu_cache. In 2.7 the hope is to
 	remove this interface completely.
+
+The final category of APIs is for I/O to deliberately aliased address
+ranges inside the kernel.  Such aliases are set up by use of the
+vmap/vmalloc API.  Since kernel I/O goes via physical pages, the I/O
+subsystem assumes that the user mapping and kernel offset mapping are
+the only aliases.  This isn't true for vmap aliases, so anything in
+the kernel trying to do I/O to vmap areas must manually manage
+coherency.  It must do this by flushing the vmap range before doing
+I/O and invalidating it after the I/O returns.
+
+  void flush_kernel_vmap_range(void *vaddr, int size)
+       flushes the kernel cache for a given virtual address range in
+       the vmap area.  This is to make sure that any data the kernel
+       modified in the vmap range is made visible to the physical
+       page.  The design is to make this area safe to perform I/O on.
+       Note that this API does *not* also flush the offset map alias
+       of the area.
+
+  void invalidate_kernel_vmap_range(void *vaddr, int size) invalidates
+       the cache for a given virtual address range in the vmap area
+       which prevents the processor from making the cache stale by
+       speculatively reading data while the I/O was occurring to the
+       physical pages.  This is only necessary for data reads into the
+       vmap area.