[Xen-changelog] [xen-unstable] x86: Better bzimage_headroom() crash fix.

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

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1233313464 0
# Node ID deab3a069185a215fd2a497be21c7abb5a730603
# Parent  5848b49b74fc93c09e87197c006feb6447f4e6f0
x86: Better bzimage_headroom() crash fix.
Signed-off-by:  Joseph Cihula <joseph.cihula@xxxxxxxxx>
---
 xen/arch/x86/setup.c |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diff -r 5848b49b74fc -r deab3a069185 xen/arch/x86/setup.c
--- a/xen/arch/x86/setup.c      Fri Jan 30 11:03:28 2009 +0000
+++ b/xen/arch/x86/setup.c      Fri Jan 30 11:04:24 2009 +0000
@@ -417,7 +417,7 @@ void __init __start_xen(unsigned long mb
     unsigned int initrdidx = 1;
     multiboot_info_t *mbi = __va(mbi_p);
     module_t *mod = (module_t *)__va(mbi->mods_addr);
-    unsigned long nr_pages, modules_length, modules_headroom = -1;
+    unsigned long nr_pages, modules_length, modules_headroom;
     unsigned long allocator_bitmap_end;
     int i, e820_warn = 0, bytes = 0;
     struct ns16550_defaults ns16550 = {
@@ -617,6 +617,12 @@ void __init __start_xen(unsigned long mb
      * x86/64, we relocate Xen to higher memory.
      */
     modules_length = mod[mbi->mods_count-1].mod_end - mod[0].mod_start;
+
+    /* ensure mod[0] is mapped before parsing */
+    bootstrap_map(mod[0].mod_start, mod[0].mod_end);
+    modules_headroom = bzimage_headroom(
+                      (char *)(unsigned long)mod[0].mod_start,
+                      (unsigned long)(mod[0].mod_end - mod[0].mod_start));
 
     for ( i = boot_e820.nr_map-1; i >= 0; i-- )
     {
@@ -721,11 +727,6 @@ void __init __start_xen(unsigned long mb
         }
 #endif
 
-        if ( modules_headroom == -1 )
-            modules_headroom = bzimage_headroom(
-                      (char *)(unsigned long)mod[0].mod_start,
-                      (unsigned long)(mod[0].mod_end - mod[0].mod_start));
-
         /* Is the region suitable for relocating the multiboot modules? */
         if ( !initial_images_start && (s < e) &&
              ((e-s) >= (modules_length+modules_headroom)) )

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