Author: John David Anglin <dave.anglin@xxxxxxxx>
CONFIG_PARISC_TMPALIAS enables clear_user_highpage and copy_user_highpage.
These are essentially alternative implementations of clear_user_page and
copy_user_page. They don't have anything to do with x86 high pages, but they
build on the infrastructure to save a few instructions. Read the comment in
clear_user_highpage as it is very important to the implementation. For this
reason, there isn't any gain in using the TMPALIAS/highpage approach.
Signed-off-by: John David Anglin <dave.anglin@xxxxxxxx>
Signed-off-by: Helge Deller <deller@xxxxxx>
diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index b89a85a..703ed48 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -529,3 +595,67 @@ flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long
__flush_cache_page(vma, vmaddr, page_to_phys(pfn_to_page(pfn)));
}
+
+#ifdef CONFIG_PARISC_TMPALIAS
+
+void clear_user_highpage(struct page *page, unsigned long vaddr)
+{
+ void *vto;
+ unsigned long flags;
+
+ /* Clear using TMPALIAS region. The page doesn't need to
+ be flushed but the kernel mapping needs to be purged. */
+
+ vto = kmap_atomic(page, KM_USER0);
+
+ /* The PA-RISC 2.0 Architecture book states on page F-6:
+ "Before a write-capable translation is enabled, *all*
+ non-equivalently-aliased translations must be removed
+ from the page table and purged from the TLB. (Note
+ that the caches are not required to be flushed at this
+ time.) Before any non-equivalent aliased translation
+ is re-enabled, the virtual address range for the writeable
+ page (the entire page) must be flushed from the cache,
+ and the write-capable translation removed from the page
+ table and purged from the TLB." */
+
+ purge_kernel_dcache_page_asm((unsigned long)vto);
+ purge_tlb_start(flags);
+ pdtlb_kernel(vto);
+ purge_tlb_end(flags);
+ preempt_disable();
+ clear_user_page_asm(vto, vaddr);
+ preempt_enable();
+
+ pagefault_enable(); /* kunmap_atomic(addr, KM_USER0); */
+}
+
+void copy_user_highpage(struct page *to, struct page *from,
+ unsigned long vaddr, struct vm_area_struct *vma)
+{
+ void *vfrom, *vto;
+ unsigned long flags;
+
+ /* Copy using TMPALIAS region. This has the advantage
+ that the `from' page doesn't need to be flushed. However,
+ the `to' page must be flushed in copy_user_page_asm since
+ it can be used to bring in executable code. */
+
+ vfrom = kmap_atomic(from, KM_USER0);
+ vto = kmap_atomic(to, KM_USER1);
+
+ purge_kernel_dcache_page_asm((unsigned long)vto);
+ purge_tlb_start(flags);
+ pdtlb_kernel(vto);
+ pdtlb_kernel(vfrom);
+ purge_tlb_end(flags);
+ preempt_disable();
+ copy_user_page_asm(vto, vfrom, vaddr);
+ flush_dcache_page_asm(__pa(vto), vaddr);
+ preempt_enable();
+
+ pagefault_enable(); /* kunmap_atomic(addr, KM_USER1); */
+ pagefault_enable(); /* kunmap_atomic(addr, KM_USER0); */
+}
+
+#endif /* CONFIG_PARISC_TMPALIAS */
--
To unsubscribe from this list: send the line "unsubscribe linux-parisc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
