Make colored memory optionally un-cachable.

3 files changed, 39 insertions, 10 deletions

diff --git a/litmus/Kconfig b/litmus/Kconfig
index 69150b954dba..272b64c30ba3 100644
--- a/litmus/Kconfig
+++ b/litmus/Kconfig
@@ -19,6 +19,13 @@ config PLUGIN_COLOR
         help
           Include the scheduling with colors scheduler.
 
+config PLUGIN_COLOR_UNCACHABLE
+        bool "Colored memory is not cachable"
+        depends on PLUGIN_COLOR && X86_PAT
+        default n
+        help
+          Any memory allocated to the color plugin is not CPU cached.
+
 config PLUGIN_PFAIR
         bool "PFAIR"
         depends on HIGH_RES_TIMERS && !NO_HZ
diff --git a/litmus/color.c b/litmus/color.c
index 0b99523bcf66..8a9f68544e8f 100644
--- a/litmus/color.c
+++ b/litmus/color.c
@@ -8,6 +8,10 @@
 #include <linux/sched.h> /* required by litmus.h */
 #include <asm/io.h> /* page_to_phys on SPARC */
 
+#ifdef CONFIG_PLUGIN_COLOR_UNCACHABLE
+#include <asm/cacheflush.h> /* set_memory_uc */
+#endif
+
 #include <litmus/color.h>
 #include <litmus/litmus.h> /* for in_list(...) */
 
@@ -106,6 +110,10 @@ static int do_add_pages(void)
         int ret = 0;
 
         while (smallest_nr_pages() < PAGES_PER_COLOR) {
+#ifdef CONFIG_PLUGIN_COLOR_UNCACHABLE
+                unsigned long vaddr;
+#endif
+
 #if defined(CONFIG_X86)
                 page = alloc_page(GFP_HIGHUSER | __GFP_ZERO |
                                 __GFP_MOVABLE);
@@ -122,6 +130,13 @@ static int do_add_pages(void)
                 color = page_color(page);
                 if (atomic_read(&color_groups[color].nr_pages) < PAGES_PER_COLOR) {
                         SetPageReserved(page);
+#ifdef CONFIG_PLUGIN_COLOR_UNCACHABLE
+                        vaddr = (unsigned long) pfn_to_kaddr(page_to_pfn(page));
+                        if (set_memory_uc(vaddr, 1)) {
+                                printk(KERN_ALERT "Could not set_memory_uc\n");
+                                BUG();
+                        }
+#endif
                         add_page_to_color_list(page);
                 } else
                         list_add_tail(&page->lru, &free_later);
diff --git a/litmus/color_dev.c b/litmus/color_dev.c
index d8480d7fd543..51760328418e 100644
--- a/litmus/color_dev.c
+++ b/litmus/color_dev.c
@@ -159,6 +159,10 @@ static int do_map_colored_pages(struct vm_area_struct *vma)
         TRACE_CUR(ALLOC_NAME ": allocating %lu pages (flags:%lx prot:%lx)\n",
                         nr_pages, vma->vm_flags, pgprot_val(vma->vm_page_prot));
 
+#ifdef CONFIG_PLUGIN_COLOR_UNCACHABLE
+        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+#endif
+
         for (i = 0, nr_mapped = 0; nr_mapped < nr_pages; ++i) {
                 const unsigned long color_no = color_ctrl->colors[i];
                 unsigned int page_no = 0;
@@ -167,6 +171,11 @@ static int do_map_colored_pages(struct vm_area_struct *vma)
                         const unsigned long addr = vma->vm_start +
                                 (nr_mapped << PAGE_SHIFT);
                         struct page *page = get_colored_page(color_no);
+#ifdef CONFIG_PLUGIN_COLOR_UNCACHABLE
+                        const pgprot_t ins_prot = pgprot_noncached(PAGE_SHARED);
+#else
+                        const pgprot_t ins_prot = PAGE_SHARED;
+#endif
 
                         if (!page) {
                                 TRACE_CUR(ALLOC_NAME ": Could not get page with"
@@ -181,21 +190,19 @@ static int do_map_colored_pages(struct vm_area_struct *vma)
 #endif
 
                         TRACE_CUR(ALLOC_NAME ": insert page (pa:0x%10llx, "
-                                  "pfn:%8lu, color:%3lu) at 0x%lx (flags:%16lx "
-                                  "prot:%16lx) PAGE_SHARED:0x%16lx\n",
+                                  "pfn:%8lu, color:%3lu, prot:%lx) at 0x%lx "
+                                  "vma:(flags:%16lx prot:%16lx)\n",
                                   page_to_phys(page),
-                                  page_to_pfn(page), color_no, addr,
-                                  vma->vm_flags, pgprot_val(vma->vm_page_prot),
-                                  PAGE_SHARED);
+                                  page_to_pfn(page), color_no,
+                                  pgprot_val(ins_prot), addr,
+                                  vma->vm_flags,
+                                  pgprot_val(vma->vm_page_prot));
 
                         err = remap_pfn_range(vma, addr, page_to_pfn(page),
-                                              PAGE_SIZE, PAGE_SHARED);
-
+                                        PAGE_SIZE, ins_prot);
                         if (err) {
                                 TRACE_CUR(ALLOC_NAME ": remap_pfn_range() fail "
-                                          "(%d) (flags:%lx prot:%lx)\n", err,
-                                          vma->vm_flags,
-                                          pgprot_val(vma->vm_page_prot));
+                                          "(%d)\n", err);
                                 /* TODO unmap mapped pages */
                                 err = -EINVAL;
                                 goto out;