lguest: assume Switcher text is a single page.

ie. SHARED_SWITCHER_PAGES == 1.  It is well under a page, and it's a
minor simplification: it's nice to have *one* simplification in a
patch series!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/arch/x86/include/asm/lguest.h b/arch/x86/include/asm/lguest.h
index 85ecdb80d1218c6adf70d8742af3c9c12c7b0868..74edebd010aba1420052120c3c9de01fa8b51e46 100644 (file)
--- a/arch/x86/include/asm/lguest.h
+++ b/arch/x86/include/asm/lguest.h
@@ -11,11 +11,8 @@
 
 #define GUEST_PL 1
 
-/* Every guest maps the core switcher code. */
-#define SHARED_SWITCHER_PAGES \
-       DIV_ROUND_UP(end_switcher_text - start_switcher_text, PAGE_SIZE)
-/* Pages for switcher itself, then two pages per cpu */
-#define TOTAL_SWITCHER_PAGES (SHARED_SWITCHER_PAGES + 2 * nr_cpu_ids)
+/* Page for Switcher text itself, then two pages per cpu */
+#define TOTAL_SWITCHER_PAGES (1 + 2 * nr_cpu_ids)
 
 /* We map at -4M (-2M for PAE) for ease of mapping (one PTE page). */
 #ifdef CONFIG_X86_PAE

diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 211d8267992b42acc8d7303da3bec8f98fbff317..4209065b9b1e0903ea6ac6ccf0dc36ad01a48d92 100644 (file)
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -52,6 +52,13 @@ static __init int map_switcher(void)
         * easy.
         */
 
+       /* We assume Switcher text fits into a single page. */
+       if (end_switcher_text - start_switcher_text > PAGE_SIZE) {
+               printk(KERN_ERR "lguest: switcher text too large (%zu)\n",
+                      end_switcher_text - start_switcher_text);
+               return -EINVAL;
+       }
+
        /*
         * We allocate an array of struct page pointers.  map_vm_area() wants
         * this, rather than just an array of pages.
@@ -326,7 +333,7 @@ static int __init init(void)
                goto out;
 
        /* Now we set up the pagetable implementation for the Guests. */
-       err = init_pagetables(switcher_pages, SHARED_SWITCHER_PAGES);
+       err = init_pagetables(switcher_pages);
        if (err)
                goto unmap;
 

diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 8bf68c54ff7f0f25f0bd4b7cae8024f119f2afeb..4c3e532d50d64f9a3222c0bc8c5fa1f0440b2f35 100644 (file)
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -15,7 +15,7 @@
 #include <asm/lguest.h>
 
 void free_pagetables(void);
-int init_pagetables(struct page **switcher_pages, unsigned int pages);
+int init_pagetables(struct page **switcher_pages);
 
 struct pgdir {
        unsigned long gpgdir;

diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
index 21685580eb9f2184ba133d764d516d14b6da255c..758466299b0d46895d6f61f22cd8df9489f17941 100644 (file)
--- a/drivers/lguest/page_tables.c
+++ b/drivers/lguest/page_tables.c
@@ -1079,25 +1079,20 @@ static void free_switcher_pte_pages(void)
 
 /*H:520
  * Setting up the Switcher PTE page for given CPU is fairly easy, given
- * the CPU number and the "struct page"s for the Switcher code itself.
- *
- * Currently the Switcher is less than a page long, so "pages" is always 1.
+ * the CPU number and the "struct page"s for the Switcher and per-cpu pages.
  */
 static __init void populate_switcher_pte_page(unsigned int cpu,
-                                             struct page *switcher_pages[],
-                                             unsigned int pages)
+                                             struct page *switcher_pages[])
 {
-       unsigned int i;
        pte_t *pte = switcher_pte_page(cpu);
+       int i;
 
-       /* The first entries are easy: they map the Switcher code. */
-       for (i = 0; i < pages; i++) {
-               set_pte(&pte[i], mk_pte(switcher_pages[i],
+       /* The first entries maps the Switcher code. */
+       set_pte(&pte[0], mk_pte(switcher_pages[0],
                                __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED)));
-       }
 
        /* The only other thing we map is this CPU's pair of pages. */
-       i = pages + cpu*2;
+       i = 1 + cpu*2;
 
        /* First page (Guest registers) is writable from the Guest */
        set_pte(&pte[i], pfn_pte(page_to_pfn(switcher_pages[i]),
@@ -1128,7 +1123,7 @@ static __init void populate_switcher_pte_page(unsigned int cpu,
  * At boot or module load time, init_pagetables() allocates and populates
  * the Switcher PTE page for each CPU.
  */
-__init int init_pagetables(struct page **switcher_pages, unsigned int pages)
+__init int init_pagetables(struct page **switcher_pages)
 {
        unsigned int i;
 
@@ -1138,7 +1133,7 @@ __init int init_pagetables(struct page **switcher_pages, unsigned int pages)
                        free_switcher_pte_pages();
                        return -ENOMEM;
                }
-               populate_switcher_pte_page(i, switcher_pages, pages);
+               populate_switcher_pte_page(i, switcher_pages);
        }
        return 0;
 }

diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index 20fae765d600936d898b4b6d090ce4bbb6762cf4..f0a3347b644190b4ca76b199daf9903f32c2578a 100644 (file)
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -62,11 +62,10 @@ static unsigned long switcher_offset(void)
        return switcher_addr - (unsigned long)start_switcher_text;
 }
 
-/* This cpu's struct lguest_pages. */
+/* This cpu's struct lguest_pages (after the Switcher text page) */
 static struct lguest_pages *lguest_pages(unsigned int cpu)
 {
-       return &(((struct lguest_pages *)
-                 (switcher_addr + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
+       return &(((struct lguest_pages *)(switcher_addr + PAGE_SIZE))[cpu]);
 }
 
 static DEFINE_PER_CPU(struct lg_cpu *, lg_last_cpu);