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[Xen-devel] [PATCH v2 22/23] x86: make Xen early boot code relocatable



Every multiboot protocol (regardless of version) compatible image must
specify its load address (in ELF or multiboot header). Multiboot protocol
compatible loader have to load image at specified address. However, there
is no guarantee that the requested memory region (in case of Xen it starts
at 1 MiB and ends at 17 MiB) where image should be loaded initially is a RAM
and it is free (legacy BIOS platforms are merciful for Xen but I found at
least one EFI platform on which Xen load address conflicts with EFI boot
services; it is Dell PowerEdge R820 with latest firmware). To cope with
that problem we must make Xen early boot code relocatable. This patch does
that. However, it does not add multiboot2 protocol interface which is done
in next patch.

This patch changes following things:
  - default load address is changed from 1 MiB to 2 MiB; I did that because
    initial page tables are using 2 MiB huge pages and this way required
    updates for them are quite easy; it means that e.g. we avoid spacial
    cases for beginning and end of required memory region if it live at
    address not aligned to 2 MiB,
  - %ebp register is used as a storage for Xen image base address; this way
    we can get this value very quickly if it is needed; however, %ebp register
    is not used directly to access a given memory region,
  - %fs register is filled with segment descriptor which describes memory region
    with Xen image (it could be relocated or not); it is used to access some of
    Xen data in early boot code; potentially we can use above mentioned segment
    descriptor to access data using %ds:%esi and/or %es:%esi (e.g. movs*); 
however,
    I think that it could unnecessarily obfuscate code (e.g. we need at least
    to operations to reload a given segment descriptor) and current solution
    looks quite optimal.

Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
---
 xen/arch/x86/Makefile          |    6 +-
 xen/arch/x86/Rules.mk          |    4 +
 xen/arch/x86/boot/head.S       |  165 ++++++++++++++++++++++++++++++----------
 xen/arch/x86/boot/trampoline.S |   11 ++-
 xen/arch/x86/boot/wakeup.S     |    6 +-
 xen/arch/x86/boot/x86_64.S     |   34 ++++-----
 xen/arch/x86/setup.c           |   33 ++++----
 xen/arch/x86/x86_64/mm.c       |    2 +-
 xen/arch/x86/xen.lds.S         |    2 +-
 xen/include/asm-x86/config.h   |    3 +
 xen/include/asm-x86/page.h     |    2 +-
 11 files changed, 182 insertions(+), 86 deletions(-)

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 82c5a93..93069a8 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -72,8 +72,10 @@ efi-$(x86_64) := $(shell if [ ! -r 
$(BASEDIR)/include/xen/compile.h -o \
                          echo '$(TARGET).efi'; fi)
 
 $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32
-       ./boot/mkelf32 $(TARGET)-syms $(TARGET) 0x100000 \
-       `$(NM) -nr $(TARGET)-syms | head -n 1 | sed -e 's/^\([^ ]*\).*/0x\1/'`
+#      THIS IS UGLY HACK! PLEASE DO NOT COMPLAIN. I WILL FIX IT IN NEXT 
RELEASE.
+       ./boot/mkelf32 $(TARGET)-syms $(TARGET) $(XEN_IMG_PHYS_START) 
0xffff82d081000000
+#      ./boot/mkelf32 $(TARGET)-syms $(TARGET) 0x100000 \
+#      `$(NM) -nr $(TARGET)-syms | head -n 1 | sed -e 's/^\([^ ]*\).*/0x\1/'`
 
 
 ALL_OBJS := $(BASEDIR)/arch/x86/boot/built_in.o 
$(BASEDIR)/arch/x86/efi/built_in.o $(ALL_OBJS)
diff --git a/xen/arch/x86/Rules.mk b/xen/arch/x86/Rules.mk
index 4a04a8a..7ccb8a0 100644
--- a/xen/arch/x86/Rules.mk
+++ b/xen/arch/x86/Rules.mk
@@ -15,6 +15,10 @@ HAS_GDBSX := y
 HAS_PDX := y
 xenoprof := y
 
+XEN_IMG_PHYS_START = 0x200000
+
+CFLAGS += -DXEN_IMG_PHYS_START=$(XEN_IMG_PHYS_START)
+
 CFLAGS += -I$(BASEDIR)/include 
 CFLAGS += -I$(BASEDIR)/include/asm-x86/mach-generic
 CFLAGS += -I$(BASEDIR)/include/asm-x86/mach-default
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 3f1054d..d484f68 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -12,13 +12,15 @@
         .text
         .code32
 
-#define sym_phys(sym)     ((sym) - __XEN_VIRT_START)
+#define sym_phys(sym)     ((sym) - __XEN_VIRT_START + XEN_IMG_PHYS_START - 
XEN_IMG_OFFSET)
+#define sym_offset(sym)   ((sym) - __XEN_VIRT_START)
 
 #define BOOT_CS32        0x0008
 #define BOOT_CS64        0x0010
 #define BOOT_DS          0x0018
 #define BOOT_PSEUDORM_CS 0x0020
 #define BOOT_PSEUDORM_DS 0x0028
+#define BOOT_FS          0x0030
 
 #define MB2_HT(name)      (MULTIBOOT2_HEADER_TAG_##name)
 #define MB2_TT(name)      (MULTIBOOT2_TAG_TYPE_##name)
@@ -105,12 +107,13 @@ multiboot1_header_end:
 
         .word   0
 gdt_boot_descr:
-        .word   6*8-1
-        .long   sym_phys(trampoline_gdt)
+        .word   7*8-1
+gdt_boot_descr_addr:
+        .long   sym_offset(trampoline_gdt)
         .long   0 /* Needed for 64-bit lgdt */
 
 cs32_switch_addr:
-        .long   sym_phys(cs32_switch)
+        .long   sym_offset(cs32_switch)
         .word   BOOT_CS32
 
 .Lbad_cpu_msg: .asciz "ERR: Not a 64-bit CPU!"
@@ -120,13 +123,13 @@ cs32_switch_addr:
         .section .init.text, "ax", @progbits
 
 bad_cpu:
-        mov     $(sym_phys(.Lbad_cpu_msg)),%esi # Error message
+        lea     sym_offset(.Lbad_cpu_msg)(%ebp),%esi # Error message
         jmp     print_err
 not_multiboot:
-        mov     $(sym_phys(.Lbad_ldr_msg)),%esi # Error message
+        lea     sym_offset(.Lbad_ldr_msg)(%ebp),%esi # Error message
         jmp     print_err
 mb2_too_old:
-        mov     $(sym_phys(.Lbad_mb2_ldr)),%esi # Error message
+        lea     sym_offset(.Lbad_mb2_ldr)(%ebp),%esi # Error message
 print_err:
         mov     $0xB8000,%edi  # VGA framebuffer
 1:      mov     (%esi),%bl
@@ -151,6 +154,9 @@ print_err:
 __efi64_start:
         cld
 
+        /* Load default Xen image base address. */
+        mov     $sym_phys(__image_base__),%ebp
+
         /* Check for Multiboot2 bootloader. */
         cmp     $MULTIBOOT2_BOOTLOADER_MAGIC,%eax
         je      efi_multiboot2_proto
@@ -235,9 +241,11 @@ x86_32_switch:
         cli
 
         /* Initialise GDT. */
+        add     %ebp,gdt_boot_descr_addr(%rip)
         lgdt    gdt_boot_descr(%rip)
 
         /* Reload code selector. */
+        add     %ebp,cs32_switch_addr(%rip)
         ljmpl   *cs32_switch_addr(%rip)
 
         .code32
@@ -263,12 +271,8 @@ __start:
         cld
         cli
 
-        /* Initialise GDT and basic data segments. */
-        lgdt    %cs:sym_phys(gdt_boot_descr)
-        mov     $BOOT_DS,%ecx
-        mov     %ecx,%ds
-        mov     %ecx,%es
-        mov     %ecx,%ss
+        /* Load default Xen image base address. */
+        mov     $sym_phys(__image_base__),%ebp
 
         /* Bootloaders may set multiboot{1,2}.mem_lower to a nonzero value. */
         xor     %edx,%edx
@@ -319,6 +323,19 @@ multiboot2_proto:
         jmp     0b
 
 trampoline_bios_setup:
+        mov     %ebp,%esi
+
+        /* Initialise GDT and basic data segments. */
+        add     %ebp,sym_offset(gdt_boot_descr_addr)(%esi)
+        lgdt    sym_offset(gdt_boot_descr)(%esi)
+
+        mov     $BOOT_DS,%ecx
+        mov     %ecx,%ds
+        mov     %ecx,%es
+        mov     %ecx,%fs
+        mov     %ecx,%gs
+        mov     %ecx,%ss
+
         /* Set up trampoline segment 64k below EBDA */
         movzwl  0x40e,%ecx          /* EBDA segment */
         cmp     $0xa000,%ecx        /* sanity check (high) */
@@ -340,33 +357,58 @@ trampoline_bios_setup:
         cmovb   %edx,%ecx           /* and use the smaller */
 
 trampoline_setup:
+        mov     %ebp,%esi
+
+        /* Initialize 0-15 bits of BOOT_FS segment descriptor base address. */
+        mov     %ebp,%edx
+        shl     $16,%edx
+        or      %edx,(sym_offset(trampoline_gdt)+BOOT_FS)(%esi)
+
+        /* Initialize 16-23 bits of BOOT_FS segment descriptor base address. */
+        mov     %ebp,%edx
+        shr     $16,%edx
+        and     $0x000000ff,%edx
+        or      %edx,(sym_offset(trampoline_gdt)+BOOT_FS+4)(%esi)
+
+        /* Initialize 24-31 bits of BOOT_FS segment descriptor base address. */
+        mov     %ebp,%edx
+        and     $0xff000000,%edx
+        or      %edx,(sym_offset(trampoline_gdt)+BOOT_FS+4)(%esi)
+
+        /* Initialize %fs and later use it to access Xen data if possible. */
+        mov     $BOOT_FS,%edx
+        mov     %edx,%fs
+
         /* Reserve 64kb for the trampoline. */
         sub     $0x1000,%ecx
 
         /* From arch/x86/smpboot.c: start_eip had better be page-aligned! */
         xor     %cl, %cl
         shl     $4, %ecx
-        mov     %ecx,sym_phys(trampoline_phys)
+        mov     %ecx,%fs:sym_offset(trampoline_phys)
+
+        /* Save Xen image base address for later use. */
+        mov     %ebp,%fs:sym_offset(xen_img_base_phys_addr)
 
         /* Save the Multiboot info struct (after relocation) for later use. */
-        mov     $sym_phys(cpu0_stack)+1024,%esp
+        lea     (sym_offset(cpu0_stack)+1024)(%ebp),%esp
         push    %eax                /* Multiboot magic. */
         push    %ebx                /* Multiboot information address. */
         push    %ecx                /* Boot trampoline address. */
         call    reloc
         add     $12,%esp            /* Remove reloc() args from stack. */
-        mov     %eax,sym_phys(multiboot_ptr)
+        mov     %eax,%fs:sym_offset(multiboot_ptr)
 
         /*
          * Do not zero BSS on EFI platform here.
          * It was initialized earlier.
          */
-        cmpb    $1,sym_phys(skip_realmode)
+        cmpb    $1,%fs:sym_offset(skip_realmode)
         je      1f
 
         /* Initialize BSS (no nasty surprises!). */
-        mov     $sym_phys(__bss_start),%edi
-        mov     $sym_phys(__bss_end),%ecx
+        lea     sym_offset(__bss_start)(%ebp),%edi
+        lea     sym_offset(__bss_end)(%ebp),%ecx
         sub     %edi,%ecx
         shr     $2,%ecx
         xor     %eax,%eax
@@ -381,8 +423,8 @@ trampoline_setup:
         jbe     1f
         mov     $0x80000001,%eax
         cpuid
-1:      mov     %edx,sym_phys(cpuid_ext_features)
-        mov     
%edx,sym_phys(boot_cpu_data)+CPUINFO_FEATURE_OFFSET(X86_FEATURE_LM)
+1:      mov     %edx,%fs:sym_offset(cpuid_ext_features)
+        mov     
%edx,%fs:(sym_offset(boot_cpu_data)+CPUINFO_FEATURE_OFFSET(X86_FEATURE_LM))
 
         /* Check for availability of long mode. */
         bt      $X86_FEATURE_LM & 0x1f,%edx
@@ -390,72 +432,111 @@ trampoline_setup:
 
         /* Stash TSC to calculate a good approximation of time-since-boot */
         rdtsc
-        mov     %eax,sym_phys(boot_tsc_stamp)
-        mov     %edx,sym_phys(boot_tsc_stamp+4)
+        mov     %eax,%fs:sym_offset(boot_tsc_stamp)
+        mov     %edx,%fs:sym_offset(boot_tsc_stamp+4)
 
-        /* Initialise L2 boot-map page table entries (16MB). */
-        mov     $sym_phys(l2_bootmap),%edx
-        mov     $PAGE_HYPERVISOR|_PAGE_PSE,%eax
-        mov     $8,%ecx
+        /* Update frame addreses in page tables. */
+        lea     sym_offset(__page_tables_start)(%ebp),%edx
+        mov     $((__page_tables_end-__page_tables_start)/8),%ecx
+1:      testl   $_PAGE_PRESENT,(%edx)
+        jz      2f
+        add     %ebp,(%edx)
+2:      add     $8,%edx
+        loop    1b
+
+        /* Initialise L2 boot-map page table entries (14MB). */
+        lea     sym_offset(l2_bootmap)(%ebp),%edx
+        lea     sym_offset(start)(%ebp),%eax
+        and     $~((1<<L2_PAGETABLE_SHIFT)-1),%eax
+        mov     %eax,%ebx
+        shr     $(L2_PAGETABLE_SHIFT-3),%ebx
+        and     $(L2_PAGETABLE_ENTRIES*4*8-1),%ebx
+        add     %ebx,%edx
+        add     $(PAGE_HYPERVISOR|_PAGE_PSE),%eax
+        mov     $7,%ecx
 1:      mov     %eax,(%edx)
         add     $8,%edx
         add     $(1<<L2_PAGETABLE_SHIFT),%eax
         loop    1b
+
         /* Initialise L3 boot-map page directory entry. */
-        mov     $sym_phys(l2_bootmap)+__PAGE_HYPERVISOR,%eax
-        mov     %eax,sym_phys(l3_bootmap) + 0*8
+        lea     (sym_offset(l2_bootmap)+__PAGE_HYPERVISOR)(%ebp),%eax
+        lea     sym_offset(l3_bootmap)(%ebp),%ebx
+        mov     $4,%ecx
+1:      mov     %eax,(%ebx)
+        add     $8,%ebx
+        add     $(L2_PAGETABLE_ENTRIES*8),%eax
+        loop    1b
+
+        /* Initialise L2 direct map page table entries (14MB). */
+        lea     sym_offset(l2_identmap)(%ebp),%edx
+        lea     sym_offset(start)(%ebp),%eax
+        and     $~((1<<L2_PAGETABLE_SHIFT)-1),%eax
+        mov     %eax,%ebx
+        shr     $(L2_PAGETABLE_SHIFT-3),%ebx
+        and     $(L2_PAGETABLE_ENTRIES*4*8-1),%ebx
+        add     %ebx,%edx
+        add     $(PAGE_HYPERVISOR|_PAGE_PSE),%eax
+        mov     $7,%ecx
+1:      mov     %eax,(%edx)
+        add     $8,%edx
+        add     $(1<<L2_PAGETABLE_SHIFT),%eax
+        loop    1b
+
         /* Hook 4kB mappings of first 2MB of memory into L2. */
-        mov     $sym_phys(l1_identmap)+__PAGE_HYPERVISOR,%edi
-        mov     %edi,sym_phys(l2_xenmap)
-        mov     %edi,sym_phys(l2_bootmap)
+        lea     (sym_offset(l1_identmap)+__PAGE_HYPERVISOR)(%ebp),%edi
+        mov     %edi,%fs:sym_offset(l2_bootmap)
 
         /* Apply relocations to bootstrap trampoline. */
-        mov     sym_phys(trampoline_phys),%edx
-        mov     $sym_phys(__trampoline_rel_start),%edi
+        mov     %fs:sym_offset(trampoline_phys),%edx
+        lea     sym_offset(__trampoline_rel_start)(%ebp),%edi
+        lea     sym_offset(__trampoline_rel_stop)(%ebp),%esi
 1:
         mov     (%edi),%eax
         add     %edx,(%edi,%eax)
         add     $4,%edi
-        cmp     $sym_phys(__trampoline_rel_stop),%edi
+        cmp     %esi,%edi
         jb      1b
 
         /* Patch in the trampoline segment. */
         shr     $4,%edx
-        mov     $sym_phys(__trampoline_seg_start),%edi
+        lea     sym_offset(__trampoline_seg_start)(%ebp),%edi
+        lea     sym_offset(__trampoline_seg_stop)(%ebp),%esi
 1:
         mov     (%edi),%eax
         mov     %dx,(%edi,%eax)
         add     $4,%edi
-        cmp     $sym_phys(__trampoline_seg_stop),%edi
+        cmp     %esi,%edi
         jb      1b
 
         /* Do not parse command line on EFI platform here. */
-        cmpb    $1,sym_phys(skip_realmode)
+        cmpb    $1,%fs:sym_offset(skip_realmode)
         je      1f
 
         /* Bail if there is no command line to parse. */
-        mov     sym_phys(multiboot_ptr),%ebx
+        mov     %fs:sym_offset(multiboot_ptr),%ebx
         testl   $MBI_CMDLINE,MB_flags(%ebx)
         jz      1f
 
         cmpl    $0,MB_cmdline(%ebx)
         jz      1f
 
-        pushl   $sym_phys(early_boot_opts)
+        lea     sym_offset(early_boot_opts)(%ebp),%eax
+        push    %eax
         pushl   MB_cmdline(%ebx)
         call    cmdline_parse_early
         add     $8,%esp             /* Remove cmdline_parse_early() args from 
stack. */
 
 1:
         /* Switch to low-memory stack.  */
-        mov     sym_phys(trampoline_phys),%edi
+        mov     %fs:sym_offset(trampoline_phys),%edi
         lea     0x10000(%edi),%esp
         lea     trampoline_boot_cpu_entry-trampoline_start(%edi),%eax
         pushl   $BOOT_CS32
         push    %eax
 
         /* Copy bootstrap trampoline to low memory, below 1MB. */
-        mov     $sym_phys(trampoline_start),%esi
+        lea     sym_offset(trampoline_start)(%ebp),%esi
         mov     $trampoline_end - trampoline_start,%ecx
         rep     movsb
 
diff --git a/xen/arch/x86/boot/trampoline.S b/xen/arch/x86/boot/trampoline.S
index 3c2714d..a8909ce 100644
--- a/xen/arch/x86/boot/trampoline.S
+++ b/xen/arch/x86/boot/trampoline.S
@@ -52,12 +52,20 @@ trampoline_gdt:
         /* 0x0028: real-mode data @ BOOT_TRAMPOLINE */
         .long   0x0000ffff
         .long   0x00009200
+        /*
+         * 0x0030: ring 0 Xen data, 16 MiB size, base
+         * address is initialized during runtime.
+         */
+        .quad   0x00c0920000001000
 
         .pushsection .trampoline_rel, "a"
         .long   trampoline_gdt + BOOT_PSEUDORM_CS + 2 - .
         .long   trampoline_gdt + BOOT_PSEUDORM_DS + 2 - .
         .popsection
 
+GLOBAL(xen_img_base_phys_addr)
+        .long   0
+
 GLOBAL(cpuid_ext_features)
         .long   0
 
@@ -82,7 +90,8 @@ trampoline_protmode_entry:
         mov     %ecx,%cr4
 
         /* Load pagetable base register. */
-        mov     $sym_phys(idle_pg_table),%eax
+        mov     bootsym_rel(xen_img_base_phys_addr,4,%eax)
+        lea     sym_offset(idle_pg_table)(%eax),%eax
         add     bootsym_rel(trampoline_xen_phys_start,4,%eax)
         mov     %eax,%cr3
 
diff --git a/xen/arch/x86/boot/wakeup.S b/xen/arch/x86/boot/wakeup.S
index 08ea9b2..ff80f7f 100644
--- a/xen/arch/x86/boot/wakeup.S
+++ b/xen/arch/x86/boot/wakeup.S
@@ -119,8 +119,10 @@ wakeup_32:
         mov     %eax, %ss
         mov     $bootsym_rel(wakeup_stack, 4, %esp)
 
+        mov     bootsym_rel(xen_img_base_phys_addr, 4, %ebx)
+
         # check saved magic again
-        mov     $sym_phys(saved_magic), %eax
+        lea     sym_offset(saved_magic)(%ebx), %eax
         add     bootsym_rel(trampoline_xen_phys_start, 4, %eax)
         mov     (%eax), %eax
         cmp     $0x9abcdef0, %eax
@@ -133,7 +135,7 @@ wakeup_32:
         mov     %ecx, %cr4
 
         /* Load pagetable base register */
-        mov     $sym_phys(idle_pg_table),%eax
+        lea     sym_offset(idle_pg_table)(%ebx),%eax
         add     bootsym_rel(trampoline_xen_phys_start,4,%eax)
         mov     %eax,%cr3
 
diff --git a/xen/arch/x86/boot/x86_64.S b/xen/arch/x86/boot/x86_64.S
index c8bf9d0..ae4bebd 100644
--- a/xen/arch/x86/boot/x86_64.S
+++ b/xen/arch/x86/boot/x86_64.S
@@ -81,7 +81,6 @@ GLOBAL(boot_cpu_compat_gdt_table)
         .quad 0x0000910000000000     /* per-CPU entry (limit == cpu)      */
         .align PAGE_SIZE, 0
 
-GLOBAL(__page_tables_start)
 /*
  * 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
@@ -101,21 +100,18 @@ GLOBAL(l1_identmap)
         .endr
         .size l1_identmap, . - l1_identmap
 
-/* Mapping of first 16 megabytes of memory. */
+GLOBAL(__page_tables_start)
+
 GLOBAL(l2_identmap)
-        .quad sym_phys(l1_identmap) + __PAGE_HYPERVISOR
-        pfn = 0
-        .rept 7
-        pfn = pfn + (1 << PAGETABLE_ORDER)
-        .quad (pfn << PAGE_SHIFT) | PAGE_HYPERVISOR | _PAGE_PSE
-        .endr
-        .fill 4 * L2_PAGETABLE_ENTRIES - 8, 8, 0
+        .quad sym_offset(l1_identmap) + __PAGE_HYPERVISOR
+        .fill 4 * L2_PAGETABLE_ENTRIES - 1, 8, 0
         .size l2_identmap, . - l2_identmap
 
 GLOBAL(l2_xenmap)
-        idx = 0
-        .rept 8
-        .quad sym_phys(__image_base__) + (idx << L2_PAGETABLE_SHIFT) + 
(PAGE_HYPERVISOR | _PAGE_PSE)
+        .quad 0
+        idx = 1
+        .rept 7
+        .quad sym_offset(__image_base__) + (idx << L2_PAGETABLE_SHIFT) + 
(PAGE_HYPERVISOR | _PAGE_PSE)
         idx = idx + 1
         .endr
         .fill L2_PAGETABLE_ENTRIES - 8, 8, 0
@@ -125,7 +121,7 @@ l2_fixmap:
         idx = 0
         .rept L2_PAGETABLE_ENTRIES
         .if idx == l2_table_offset(FIXADDR_TOP - 1)
-        .quad sym_phys(l1_fixmap) + __PAGE_HYPERVISOR
+        .quad sym_offset(l1_fixmap) + __PAGE_HYPERVISOR
         .else
         .quad 0
         .endif
@@ -136,7 +132,7 @@ l2_fixmap:
 GLOBAL(l3_identmap)
         idx = 0
         .rept 4
-        .quad sym_phys(l2_identmap) + (idx << PAGE_SHIFT) + __PAGE_HYPERVISOR
+        .quad sym_offset(l2_identmap) + (idx << PAGE_SHIFT) + __PAGE_HYPERVISOR
         idx = idx + 1
         .endr
         .fill L3_PAGETABLE_ENTRIES - 4, 8, 0
@@ -146,9 +142,9 @@ l3_xenmap:
         idx = 0
         .rept L3_PAGETABLE_ENTRIES
         .if idx == l3_table_offset(XEN_VIRT_START)
-        .quad sym_phys(l2_xenmap) + __PAGE_HYPERVISOR
+        .quad sym_offset(l2_xenmap) + __PAGE_HYPERVISOR
         .elseif idx == l3_table_offset(FIXADDR_TOP - 1)
-        .quad sym_phys(l2_fixmap) + __PAGE_HYPERVISOR
+        .quad sym_offset(l2_fixmap) + __PAGE_HYPERVISOR
         .else
         .quad 0
         .endif
@@ -158,13 +154,13 @@ l3_xenmap:
 
 /* Top-level master (and idle-domain) page directory. */
 GLOBAL(idle_pg_table)
-        .quad sym_phys(l3_bootmap) + __PAGE_HYPERVISOR
+        .quad sym_offset(l3_bootmap) + __PAGE_HYPERVISOR
         idx = 1
         .rept L4_PAGETABLE_ENTRIES - 1
         .if idx == l4_table_offset(DIRECTMAP_VIRT_START)
-        .quad sym_phys(l3_identmap) + __PAGE_HYPERVISOR
+        .quad sym_offset(l3_identmap) + __PAGE_HYPERVISOR
         .elseif idx == l4_table_offset(XEN_VIRT_START)
-        .quad sym_phys(l3_xenmap) + __PAGE_HYPERVISOR
+        .quad sym_offset(l3_xenmap) + __PAGE_HYPERVISOR
         .else
         .quad 0
         .endif
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 8bec67f..8172520 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -291,9 +291,6 @@ static void *__init bootstrap_map(const module_t *mod)
     if ( start >= end )
         return NULL;
 
-    if ( end <= BOOTSTRAP_MAP_BASE )
-        return (void *)(unsigned long)start;
-
     ret = (void *)(map_cur + (unsigned long)(start & mask));
     start &= ~mask;
     end = (end + mask) & ~mask;
@@ -641,6 +638,9 @@ void __init noreturn __start_xen(unsigned long mbi_p)
 
     printk("Command line: %s\n", cmdline);
 
+    printk("Xen image base address: 0x%08lx\n",
+           xen_phys_start ? xen_phys_start : (unsigned 
long)xen_img_base_phys_addr);
+
     printk("Video information:\n");
 
     /* Print VGA display mode information. */
@@ -835,10 +835,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
         uint64_t s, e, mask = (1UL << L2_PAGETABLE_SHIFT) - 1;
         uint64_t end, limit = ARRAY_SIZE(l2_identmap) << L2_PAGETABLE_SHIFT;
 
-        /* Superpage-aligned chunks from BOOTSTRAP_MAP_BASE. */
         s = (boot_e820.map[i].addr + mask) & ~mask;
         e = (boot_e820.map[i].addr + boot_e820.map[i].size) & ~mask;
-        s = max_t(uint64_t, s, BOOTSTRAP_MAP_BASE);
         if ( (boot_e820.map[i].type != E820_RAM) || (s >= e) )
             continue;
 
@@ -876,7 +874,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
             /* Select relocation address. */
             e = end - reloc_size;
             xen_phys_start = e;
-            bootsym(trampoline_xen_phys_start) = e;
+            bootsym(trampoline_xen_phys_start) = e - xen_img_base_phys_addr;
 
             /*
              * Perform relocation to new physical address.
@@ -886,7 +884,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
              */
             load_start = (unsigned long)_start - XEN_VIRT_START;
             barrier();
-            move_memory(e + load_start, load_start, _end - _start, 1);
+            move_memory(e + load_start, load_start + xen_img_base_phys_addr, 
_end - _start, 1);
 
             /* Walk initial pagetables, relocating page directory entries. */
             pl4e = __va(__pa(idle_pg_table));
@@ -895,27 +893,27 @@ void __init noreturn __start_xen(unsigned long mbi_p)
                 if ( !(l4e_get_flags(*pl4e) & _PAGE_PRESENT) )
                     continue;
                 *pl4e = l4e_from_intpte(l4e_get_intpte(*pl4e) +
-                                        xen_phys_start);
+                                        xen_phys_start - 
xen_img_base_phys_addr);
                 pl3e = l4e_to_l3e(*pl4e);
                 for ( j = 0; j < L3_PAGETABLE_ENTRIES; j++, pl3e++ )
                 {
                     /* Not present, 1GB mapping, or already relocated? */
                     if ( !(l3e_get_flags(*pl3e) & _PAGE_PRESENT) ||
                          (l3e_get_flags(*pl3e) & _PAGE_PSE) ||
-                         (l3e_get_pfn(*pl3e) > 0x1000) )
+                         (l3e_get_pfn(*pl3e) > PFN_DOWN(xen_phys_start)) )
                         continue;
                     *pl3e = l3e_from_intpte(l3e_get_intpte(*pl3e) +
-                                            xen_phys_start);
+                                            xen_phys_start - 
xen_img_base_phys_addr);
                     pl2e = l3e_to_l2e(*pl3e);
                     for ( k = 0; k < L2_PAGETABLE_ENTRIES; k++, pl2e++ )
                     {
                         /* Not present, PSE, or already relocated? */
                         if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) ||
                              (l2e_get_flags(*pl2e) & _PAGE_PSE) ||
-                             (l2e_get_pfn(*pl2e) > 0x1000) )
+                             (l2e_get_pfn(*pl2e) > PFN_DOWN(xen_phys_start)) )
                             continue;
                         *pl2e = l2e_from_intpte(l2e_get_intpte(*pl2e) +
-                                                xen_phys_start);
+                                                xen_phys_start - 
xen_img_base_phys_addr);
                     }
                 }
             }
@@ -926,10 +924,10 @@ void __init noreturn __start_xen(unsigned long mbi_p)
                                    PAGE_HYPERVISOR_RWX | _PAGE_PSE);
             for ( i = 1; i < L2_PAGETABLE_ENTRIES; i++, pl2e++ )
             {
-                if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) )
+                if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) || 
(l2e_get_pfn(*pl2e) > PFN_DOWN(xen_phys_start)))
                     continue;
                 *pl2e = l2e_from_intpte(l2e_get_intpte(*pl2e) +
-                                        xen_phys_start);
+                                        xen_phys_start - 
xen_img_base_phys_addr);
             }
 
             /* Re-sync the stack and then switch to relocated pagetables. */
@@ -998,6 +996,9 @@ void __init noreturn __start_xen(unsigned long mbi_p)
 
     if ( !xen_phys_start )
         panic("Not enough memory to relocate Xen.");
+
+    printk("New Xen image base address: 0x%08lx\n", xen_phys_start);
+
     reserve_e820_ram(&boot_e820, __pa(&_start), __pa(&_end));
 
     /* Late kexec reservation (dynamic start address). */
@@ -1070,14 +1071,12 @@ void __init noreturn __start_xen(unsigned long mbi_p)
 
         set_pdx_range(s >> PAGE_SHIFT, e >> PAGE_SHIFT);
 
-        /* Need to create mappings above BOOTSTRAP_MAP_BASE. */
-        map_s = max_t(uint64_t, s, BOOTSTRAP_MAP_BASE);
+        map_s = s;
         map_e = min_t(uint64_t, e,
                       ARRAY_SIZE(l2_identmap) << L2_PAGETABLE_SHIFT);
 
         /* Pass mapped memory to allocator /before/ creating new mappings. */
         init_boot_pages(s, min(map_s, e));
-        s = map_s;
         if ( s < map_e )
         {
             uint64_t mask = (1UL << L2_PAGETABLE_SHIFT) - 1;
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 98310f3..baa6461 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -44,7 +44,7 @@ unsigned int __read_mostly m2p_compat_vstart = 
__HYPERVISOR_COMPAT_VIRT_START;
 
 /* Enough page directories to map into the bottom 1GB. */
 l3_pgentry_t __section(".bss.page_aligned") l3_bootmap[L3_PAGETABLE_ENTRIES];
-l2_pgentry_t __section(".bss.page_aligned") l2_bootmap[L2_PAGETABLE_ENTRIES];
+l2_pgentry_t __section(".bss.page_aligned") l2_bootmap[4 * 
L2_PAGETABLE_ENTRIES];
 
 l2_pgentry_t *compat_idle_pg_table_l2;
 
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index a399615..b666a3f 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -38,7 +38,7 @@ SECTIONS
   . = __XEN_VIRT_START;
   __image_base__ = .;
 #endif
-  . = __XEN_VIRT_START + MB(1);
+  . = __XEN_VIRT_START + XEN_IMG_OFFSET;
   _start = .;
   .text : {
         _stext = .;            /* Text and read-only data */
diff --git a/xen/include/asm-x86/config.h b/xen/include/asm-x86/config.h
index 3e9be83..6d21cb7 100644
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -114,6 +114,7 @@ extern unsigned long trampoline_phys;
                  trampoline_phys-__pa(trampoline_start)))
 extern char trampoline_start[], trampoline_end[];
 extern char trampoline_realmode_entry[];
+extern unsigned int xen_img_base_phys_addr;
 extern unsigned int trampoline_xen_phys_start;
 extern unsigned char trampoline_cpu_started;
 extern char wakeup_start[];
@@ -280,6 +281,8 @@ extern unsigned char boot_edid_info[128];
 #endif
 #define DIRECTMAP_VIRT_END      (DIRECTMAP_VIRT_START + DIRECTMAP_SIZE)
 
+#define XEN_IMG_OFFSET          0x200000
+
 #ifndef __ASSEMBLY__
 
 /* This is not a fixed value, just a lower limit. */
diff --git a/xen/include/asm-x86/page.h b/xen/include/asm-x86/page.h
index 87b3341..27481ac 100644
--- a/xen/include/asm-x86/page.h
+++ b/xen/include/asm-x86/page.h
@@ -283,7 +283,7 @@ extern root_pgentry_t idle_pg_table[ROOT_PAGETABLE_ENTRIES];
 extern l2_pgentry_t  *compat_idle_pg_table_l2;
 extern unsigned int   m2p_compat_vstart;
 extern l2_pgentry_t l2_xenmap[L2_PAGETABLE_ENTRIES],
-    l2_bootmap[L2_PAGETABLE_ENTRIES];
+    l2_bootmap[4*L2_PAGETABLE_ENTRIES];
 extern l3_pgentry_t l3_bootmap[L3_PAGETABLE_ENTRIES];
 extern l2_pgentry_t l2_identmap[4*L2_PAGETABLE_ENTRIES];
 extern l1_pgentry_t l1_identmap[L1_PAGETABLE_ENTRIES],
-- 
1.7.10.4


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