x86: construct static part of 1:1 mapping at build time

... rather than at boot time, removing unnecessary redundancy between
EFI and legacy boot code.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>

1 files changed, 25 insertions, 49 deletions

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 5d2ca4ebc0..23d0d48bf5 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -124,14 +124,11 @@ __start:
         bt      $29,%edx
         jnc     bad_cpu
         /* Initialise L2 identity-map and xen page table entries (16MB). */
-        mov     $sym_phys(l2_identmap),%edi
         mov     $sym_phys(l2_xenmap),%esi
         mov     $sym_phys(l2_bootmap),%edx
         mov     $0x1e3,%eax                  /* PRESENT+RW+A+D+2MB+GLOBAL */
         mov     $8,%ecx
-1:      mov     %eax,(%edi)
-        add     $8,%edi
-        mov     %eax,(%esi)
+1:      mov     %eax,(%esi)
         add     $8,%esi
         mov     %eax,(%edx)
         add     $8,%edx
@@ -163,54 +160,11 @@ __start:
         mov     %eax,sym_phys(idle_pg_table) + l4_table_offset(DIRECTMAP_VIRT_START)*8
         mov     $(sym_phys(l3_xenmap)+7),%eax
         mov     %eax,sym_phys(idle_pg_table) + l4_table_offset(XEN_VIRT_START)*8
-#else
-        /* Initialize low and high mappings of memory with 2MB pages */
-        mov     $sym_phys(idle_pg_table_l2),%edi
-        mov     $0xe3,%eax                   /* PRESENT+RW+A+D+2MB */
-1:      mov     %eax,__PAGE_OFFSET>>18(%edi) /* high mapping */
-        stosl                                /* low mapping */
-        add     $4,%edi
-        add     $(1<<L2_PAGETABLE_SHIFT),%eax
-        cmp     $DIRECTMAP_PHYS_END+0xe3,%eax
-        jne     1b
-1:      stosl   /* low mappings cover up to 16MB */
-        add     $4,%edi
-        add     $(1<<L2_PAGETABLE_SHIFT),%eax
-        cmp     $(16<<20)+0xe3,%eax
-        jne     1b
-        /* Initialise L2 fixmap page directory entry. */
-        mov     $(sym_phys(l1_fixmap)+7),%eax
-        mov     %eax,sym_phys(idle_pg_table_l2) + l2_table_offset(FIXADDR_TOP-1)*8
-#endif
-
-        /* Initialize 4kB mappings of first 2MB or 4MB of memory. */
-        mov     $sym_phys(l1_identmap),%edi
-        mov     $0x263,%eax                  /* PRESENT+RW+A+D+SMALL_PAGES */
-#if defined(__x86_64__)
-        or      $0x100,%eax                  /* GLOBAL */
-#endif
-        xor     %ecx,%ecx
-1:      stosl
-        add     $4,%edi
-        add     $PAGE_SIZE,%eax
-        inc     %ecx
-        /* VGA hole (0xa0000-0xc0000) should be mapped UC. */
-        cmp     $0xa0,%ecx
-        jne     2f
-        or      $0x10,%eax                   /* +PCD */
-2:      cmp     $0xc0,%ecx
-        jne     2f
-        and     $~0x10,%eax                  /* -PCD */
-2:      cmp     $L1_PAGETABLE_ENTRIES,%ecx
-        jne     1b
-        sub     $(PAGE_SIZE-0x63),%edi
-#if defined(__x86_64__)
+        /* Hook 4kB mappings of first 2MB of memory into L2. */
+        mov     $sym_phys(l1_identmap)+__PAGE_HYPERVISOR,%edi
         mov     %edi,sym_phys(l2_identmap)
         mov     %edi,sym_phys(l2_xenmap)
         mov     %edi,sym_phys(l2_bootmap)
-#else
-        mov     %edi,sym_phys(idle_pg_table_l2)
-        mov     %edi,sym_phys(idle_pg_table_l2) + (__PAGE_OFFSET>>18)
 #endif
 
         /* Apply relocations to bootstrap trampoline. */
@@ -269,3 +223,25 @@ __high_start:
 #else
 #include "x86_32.S"
 #endif
+
+        .section .data.page_aligned, "aw", @progbits
+        .p2align PAGE_SHIFT
+/*
+ * Mapping of first 2 megabytes of memory. This is mapped with 4kB mappings
+ * to avoid type conflicts with fixed-range MTRRs covering the lowest megabyte
+ * of physical memory. In any case the VGA hole should be mapped with type UC.
+ */
+        .globl l1_identmap
+l1_identmap:
+        pfn = 0
+        .rept L1_PAGETABLE_ENTRIES
+        /* VGA hole (0xa0000-0xc0000) should be mapped UC. */
+        .if pfn >= 0xa0 && pfn < 0xc0
+        .long (pfn << PAGE_SHIFT) | PAGE_HYPERVISOR_NOCACHE | MAP_SMALL_PAGES
+        .else
+        .long (pfn << PAGE_SHIFT) | PAGE_HYPERVISOR | MAP_SMALL_PAGES
+        .endif
+        .long 0
+        pfn = pfn + 1
+        .endr
+        .size l1_identmap, . - l1_identmap