libxc: Support cross-bitness guest when core-dumping

This patch allows core-dumping to work on a cross-bit host/guest
configuration, whereas previously that was not supported.  It supports
both PV and FV guests. The core file format generated by the host,
needs to match that of the guest, so an alignment issue is addressed,
along with the p2m frame list handling being done according to the
guest size.

Signed-off-by: Bruce Rogers <brogers@novell.com>

1 files changed, 71 insertions, 8 deletions

diff --git a/tools/libxc/xc_core_x86.c b/tools/libxc/xc_core_x86.c
index d9eaa49b97..765c745cb6 100644
--- a/tools/libxc/xc_core_x86.c
+++ b/tools/libxc/xc_core_x86.c
@@ -20,9 +20,25 @@
 
 #include "xg_private.h"
 #include "xc_core.h"
+#include "xc_e820.h"
+
+#define GET_FIELD(_p, _f) ((guest_width==8) ? ((_p)->x64._f) : ((_p)->x32._f))
+
+#ifndef MAX
+#define MAX(_a, _b) ((_a) >= (_b) ? (_a) : (_b))
+#endif
+
+int
+xc_core_arch_gpfn_may_present(struct xc_core_arch_context *arch_ctxt,
+                              unsigned long pfn)
+{
+    if ((pfn >= 0xa0 && pfn < 0xc0) /* VGA hole */
+        || (pfn >= (HVM_BELOW_4G_MMIO_START >> PAGE_SHIFT)
+            && pfn < (1ULL<<32) >> PAGE_SHIFT)) /* MMIO */
+        return 0;
+    return 1;
+}
 
-/* Don't yet support cross-address-size core dump */
-#define guest_width (sizeof (unsigned long))
 
 static int nr_gpfns(int xc_handle, domid_t domid)
 {
@@ -37,7 +53,7 @@ xc_core_arch_auto_translated_physmap(const xc_dominfo_t *info)
 
 int
 xc_core_arch_memory_map_get(int xc_handle, struct xc_core_arch_context *unused,
-                            xc_dominfo_t *info, shared_info_t *live_shinfo,
+                            xc_dominfo_t *info, shared_info_any_t *live_shinfo,
                             xc_core_memory_map_t **mapp,
                             unsigned int *nr_entries)
 {
@@ -60,17 +76,22 @@ xc_core_arch_memory_map_get(int xc_handle, struct xc_core_arch_context *unused,
 }
 
 int
-xc_core_arch_map_p2m(int xc_handle, xc_dominfo_t *info,
-                     shared_info_t *live_shinfo, xen_pfn_t **live_p2m,
+xc_core_arch_map_p2m(int xc_handle, unsigned int guest_width, xc_dominfo_t *info,
+                     shared_info_any_t *live_shinfo, xen_pfn_t **live_p2m,
                      unsigned long *pfnp)
 {
     /* Double and single indirect references to the live P2M table */
     xen_pfn_t *live_p2m_frame_list_list = NULL;
     xen_pfn_t *live_p2m_frame_list = NULL;
+    /* Copies of the above. */
+    xen_pfn_t *p2m_frame_list_list = NULL;
+    xen_pfn_t *p2m_frame_list = NULL;
+
     uint32_t dom = info->domid;
     unsigned long p2m_size = nr_gpfns(xc_handle, info->domid);
     int ret = -1;
     int err;
+    int i;
 
     if ( p2m_size < info->nr_pages  )
     {
@@ -80,7 +101,7 @@ xc_core_arch_map_p2m(int xc_handle, xc_dominfo_t *info,
 
     live_p2m_frame_list_list =
         xc_map_foreign_range(xc_handle, dom, PAGE_SIZE, PROT_READ,
-                             live_shinfo->arch.pfn_to_mfn_frame_list_list);
+                             GET_FIELD(live_shinfo, arch.pfn_to_mfn_frame_list_list));
 
     if ( !live_p2m_frame_list_list )
     {
@@ -88,9 +109,28 @@ xc_core_arch_map_p2m(int xc_handle, xc_dominfo_t *info,
         goto out;
     }
 
+    /* Get a local copy of the live_P2M_frame_list_list */
+    if ( !(p2m_frame_list_list = malloc(PAGE_SIZE)) )
+    {
+        ERROR("Couldn't allocate p2m_frame_list_list array");
+        goto out;
+    }
+    memcpy(p2m_frame_list_list, live_p2m_frame_list_list, PAGE_SIZE);
+
+    /* Canonicalize guest's unsigned long vs ours */
+    if ( guest_width > sizeof(unsigned long) )
+        for ( i = 0; i < PAGE_SIZE/sizeof(unsigned long); i++ )
+            if ( i < PAGE_SIZE/guest_width )
+                p2m_frame_list_list[i] = ((uint64_t *)p2m_frame_list_list)[i];
+            else
+                p2m_frame_list_list[i] = 0;
+    else if ( guest_width < sizeof(unsigned long) )
+        for ( i = PAGE_SIZE/sizeof(unsigned long) - 1; i >= 0; i-- )
+            p2m_frame_list_list[i] = ((uint32_t *)p2m_frame_list_list)[i];
+
     live_p2m_frame_list =
         xc_map_foreign_pages(xc_handle, dom, PROT_READ,
-                             live_p2m_frame_list_list,
+                             p2m_frame_list_list,
                              P2M_FLL_ENTRIES);
 
     if ( !live_p2m_frame_list )
@@ -99,8 +139,25 @@ xc_core_arch_map_p2m(int xc_handle, xc_dominfo_t *info,
         goto out;
     }
 
+    /* Get a local copy of the live_P2M_frame_list */
+    if ( !(p2m_frame_list = malloc(P2M_TOOLS_FL_SIZE)) )
+    {
+        ERROR("Couldn't allocate p2m_frame_list array");
+        goto out;
+    }
+    memset(p2m_frame_list, 0, P2M_TOOLS_FL_SIZE);
+    memcpy(p2m_frame_list, live_p2m_frame_list, P2M_GUEST_FL_SIZE);
+
+    /* Canonicalize guest's unsigned long vs ours */
+    if ( guest_width > sizeof(unsigned long) )
+        for ( i = 0; i < P2M_FL_ENTRIES; i++ )
+            p2m_frame_list[i] = ((uint64_t *)p2m_frame_list)[i];
+    else if ( guest_width < sizeof(unsigned long) )
+        for ( i = P2M_FL_ENTRIES - 1; i >= 0; i-- )
+            p2m_frame_list[i] = ((uint32_t *)p2m_frame_list)[i];
+
     *live_p2m = xc_map_foreign_pages(xc_handle, dom, PROT_READ,
-                                    live_p2m_frame_list,
+                                    p2m_frame_list,
                                     P2M_FL_ENTRIES);
 
     if ( !*live_p2m )
@@ -122,6 +179,12 @@ out:
     if ( live_p2m_frame_list )
         munmap(live_p2m_frame_list, P2M_FLL_ENTRIES * PAGE_SIZE);
 
+    if ( p2m_frame_list_list )
+        free(p2m_frame_list_list);
+
+    if ( p2m_frame_list )
+        free(p2m_frame_list);
+
     errno = err;
     return ret;
 }