[Xen-devel] [PATCH 05/12] arm: avoid placing Xen over any modules.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

This will still fail if the modules are such that Xen is pushed out of
the top 32M of RAM since it will then overlap with the domheap (or
possibly xenheap). This will be dealt with later.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Acked-by: Tim Deegan <tim@xxxxxxx>
---
v2: Xen is module 0, modules start at 1.
---
 xen/arch/arm/setup.c |   68 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 61 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index b0b30d6..587b1e7 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -68,17 +68,55 @@ static void __init processor_id(void)
            READ_CP32(ID_ISAR3), READ_CP32(ID_ISAR4), READ_CP32(ID_ISAR5));
 }
 
+/*
+ * Returns the end address of the highest region in the range s..e
+ * with required size and alignment that does not conflict with the
+ * modules from first_mod to nr_modules.
+ *
+ * For non-recursive callers first_mod should normally be 1.
+ */
+static paddr_t __init consider_modules(paddr_t s, paddr_t e,
+                                       uint32_t size, paddr_t align,
+                                       int first_mod)
+{
+    const struct dt_module_info *mi = &early_info.modules;
+    int i;
+
+    s = (s+align-1) & ~(align-1);
+    e = e & ~(align-1);
+
+    if ( s > e ||  e - s < size )
+        return 0;
+
+    for ( i = first_mod; i <= mi->nr_mods; i++ )
+    {
+        paddr_t mod_s = mi->module[i].start;
+        paddr_t mod_e = mod_s + mi->module[i].size;
+
+        if ( s < mod_e && mod_s < e )
+        {
+            mod_e = consider_modules(mod_e, e, size, align, i+1);
+            if ( mod_e )
+                return mod_e;
+
+            return consider_modules(s, mod_s, size, align, i+1);
+        }
+    }
+
+    return e;
+}
+
 /**
  * get_xen_paddr - get physical address to relocate Xen to
  *
- * Xen is relocated to the top of RAM and aligned to a XEN_PADDR_ALIGN
- * boundary.
+ * Xen is relocated to as near to the top of RAM as possible and
+ * aligned to a XEN_PADDR_ALIGN boundary.
  */
 static paddr_t __init get_xen_paddr(void)
 {
     struct dt_mem_info *mi = &early_info.mem;
     paddr_t min_size;
-    paddr_t paddr = 0, t;
+    paddr_t paddr = 0;
     int i;
 
     min_size = (_end - _start + (XEN_PADDR_ALIGN-1)) & ~(XEN_PADDR_ALIGN-1);
@@ -86,17 +124,33 @@ static paddr_t __init get_xen_paddr(void)
     /* Find the highest bank with enough space. */
     for ( i = 0; i < mi->nr_banks; i++ )
     {
-        if ( mi->bank[i].size >= min_size )
+        const struct membank *bank = &mi->bank[i];
+        paddr_t s, e;
+
+        if ( bank->size >= min_size )
         {
-            t = mi->bank[i].start + mi->bank[i].size - min_size;
-            if ( t > paddr )
-                paddr = t;
+            e = consider_modules(bank->start, bank->start + bank->size,
+                                 min_size, XEN_PADDR_ALIGN, 1);
+            if ( !e )
+                continue;
+
+            s = e - min_size;
+
+            if ( s > paddr )
+                paddr = s;
         }
     }
 
     if ( !paddr )
         early_panic("Not enough memory to relocate Xen\n");
 
+    early_printk("Placing Xen at 0x%"PRIpaddr"-0x%"PRIpaddr"\n",
+                 paddr, paddr + min_size);
+
+    /* Xen is module 0 */
+    early_info.modules.module[0].start = paddr;
+    early_info.modules.module[0].size = min_size;
+
     return paddr;
 }
 
-- 
1.7.9.1


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