[Xen-changelog] [BUILDER] Always build initial PAE pagetables with a fourth mid-level

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID d081a485f34bc074b56828e95b7c5a5c123c5c37
# Parent  ab27023d4c5b5746b3d65154f60a9c000fa8f42b
[BUILDER] Always build initial PAE pagetables with a fourth mid-level
pgdir. This is required for Xen to be able to insert its own protected
mappings. At the same time, clean up 32b and pae pagetable-size
calculations to use the helper macro already used for x86/64.

Based on an original patch from Bruce Rogers at Novell.

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 tools/libxc/xc_linux_build.c |   42 ++++++++++++++++++++++++++----------------
 1 files changed, 26 insertions(+), 16 deletions(-)

diff -r ab27023d4c5b -r d081a485f34b tools/libxc/xc_linux_build.c
--- a/tools/libxc/xc_linux_build.c      Fri May 19 22:08:32 2006 +0100
+++ b/tools/libxc/xc_linux_build.c      Sat May 20 16:25:28 2006 +0100
@@ -327,6 +327,13 @@ static int setup_pg_tables_pae(int xc_ha
                 *vl1e &= ~_PAGE_RW;
         }
         vl1e++;
+    }
+
+    /* Xen requires a mid-level pgdir mapping 0xC0000000 region. */
+    if ( (vl3tab[3] & _PAGE_PRESENT) == 0 )
+    {
+        alloc_pt(l2tab, vl2tab, pl2tab);
+        vl3tab[3] = l2tab | L3_PROT;
     }
 
     munmap(vl1tab, PAGE_SIZE);
@@ -727,25 +734,28 @@ static int setup_guest(int xc_handle,
         v_end            = (vstack_end + (1UL<<22)-1) & ~((1UL<<22)-1);
         if ( (v_end - vstack_end) < (512UL << 10) )
             v_end += 1UL << 22; /* Add extra 4MB to get >= 512kB padding. */
-#if defined(__i386__)
-        if ( dsi.pae_kernel )
-        {
-            /* FIXME: assumes one L2 pgtable @ 0xc0000000 */
-            if ( (((v_end - dsi.v_start + ((1<<L2_PAGETABLE_SHIFT_PAE)-1)) >>
-                   L2_PAGETABLE_SHIFT_PAE) + 2) <= nr_pt_pages )
-                break;
-        }
-        else
-        {
-            if ( (((v_end - dsi.v_start + ((1<<L2_PAGETABLE_SHIFT)-1)) >>
-                   L2_PAGETABLE_SHIFT) + 1) <= nr_pt_pages )
-                break;
-        }
-#endif
-#if defined(__x86_64__)
 #define NR(_l,_h,_s) \
     (((((_h) + ((1UL<<(_s))-1)) & ~((1UL<<(_s))-1)) - \
     ((_l) & ~((1UL<<(_s))-1))) >> (_s))
+#if defined(__i386__)
+        if ( dsi.pae_kernel )
+        {
+            if ( (1 + /* # L3 */
+                  NR(dsi.v_start, v_end, L3_PAGETABLE_SHIFT_PAE) + /* # L2 */
+                  NR(dsi.v_start, v_end, L2_PAGETABLE_SHIFT_PAE) + /* # L1 */
+                  /* Include a fourth mid-level page directory for Xen. */
+                  (v_end <= (3 << L3_PAGETABLE_SHIFT_PAE)))
+                  <= nr_pt_pages )
+                break;
+        }
+        else
+        {
+            if ( (1 + /* # L2 */
+                  NR(dsi.v_start, v_end, L2_PAGETABLE_SHIFT)) /* # L1 */
+                 <= nr_pt_pages )
+                break;
+        }
+#elif defined(__x86_64__)
         if ( (1 + /* # L4 */
               NR(dsi.v_start, v_end, L4_PAGETABLE_SHIFT) + /* # L3 */
               NR(dsi.v_start, v_end, L3_PAGETABLE_SHIFT) + /* # L2 */

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