1 files changed, 150 insertions, 24 deletions

diff --git a/arch/x86/kernel/relocate_kernel_32.S b/arch/x86/kernel/relocate_kernel_32.S
index c30fe25d470d..703310a99023 100644
--- a/arch/x86/kernel/relocate_kernel_32.S
+++ b/arch/x86/kernel/relocate_kernel_32.S
@@ -20,11 +20,44 @@
 #define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
 #define PAE_PGD_ATTR (_PAGE_PRESENT)
 
+/* control_page + PAGE_SIZE/2 ~ control_page + PAGE_SIZE * 3/4 are
+ * used to save some data for jumping back
+ */
+#define DATA(offset)            (PAGE_SIZE/2+(offset))
+
+/* Minimal CPU state */
+#define ESP                     DATA(0x0)
+#define CR0                     DATA(0x4)
+#define CR3                     DATA(0x8)
+#define CR4                     DATA(0xc)
+
+/* other data */
+#define CP_VA_CONTROL_PAGE      DATA(0x10)
+#define CP_PA_PGD               DATA(0x14)
+#define CP_PA_SWAP_PAGE         DATA(0x18)
+#define CP_PA_BACKUP_PAGES_MAP  DATA(0x1c)
+
         .text
         .align PAGE_SIZE
         .globl relocate_kernel
 relocate_kernel:
-        movl    8(%esp), %ebp /* list of pages */
+        /* Save the CPU context, used for jumping back */
+
+        pushl   %ebx
+        pushl   %esi
+        pushl   %edi
+        pushl   %ebp
+        pushf
+
+        movl    20+8(%esp), %ebp /* list of pages */
+        movl    PTR(VA_CONTROL_PAGE)(%ebp), %edi
+        movl    %esp, ESP(%edi)
+        movl    %cr0, %eax
+        movl    %eax, CR0(%edi)
+        movl    %cr3, %eax
+        movl    %eax, CR3(%edi)
+        movl    %cr4, %eax
+        movl    %eax, CR4(%edi)
 
 #ifdef CONFIG_X86_PAE
         /* map the control page at its virtual address */
@@ -138,15 +171,25 @@ relocate_kernel:
 
 relocate_new_kernel:
         /* read the arguments and say goodbye to the stack */
-        movl  4(%esp), %ebx /* page_list */
-        movl  8(%esp), %ebp /* list of pages */
-        movl  12(%esp), %edx /* start address */
-        movl  16(%esp), %ecx /* cpu_has_pae */
+        movl  20+4(%esp), %ebx /* page_list */
+        movl  20+8(%esp), %ebp /* list of pages */
+        movl  20+12(%esp), %edx /* start address */
+        movl  20+16(%esp), %ecx /* cpu_has_pae */
+        movl  20+20(%esp), %esi /* preserve_context */
 
         /* zero out flags, and disable interrupts */
         pushl $0
         popfl
 
+        /* save some information for jumping back */
+        movl    PTR(VA_CONTROL_PAGE)(%ebp), %edi
+        movl    %edi, CP_VA_CONTROL_PAGE(%edi)
+        movl    PTR(PA_PGD)(%ebp), %eax
+        movl    %eax, CP_PA_PGD(%edi)
+        movl    PTR(PA_SWAP_PAGE)(%ebp), %eax
+        movl    %eax, CP_PA_SWAP_PAGE(%edi)
+        movl    %ebx, CP_PA_BACKUP_PAGES_MAP(%edi)
+
         /* get physical address of control page now */
         /* this is impossible after page table switch */
         movl    PTR(PA_CONTROL_PAGE)(%ebp), %edi
@@ -197,8 +240,90 @@ identity_mapped:
         xorl    %eax, %eax
         movl    %eax, %cr3
 
+        movl    CP_PA_SWAP_PAGE(%edi), %eax
+        pushl   %eax
+        pushl   %ebx
+        call    swap_pages
+        addl    $8, %esp
+
+        /* To be certain of avoiding problems with self-modifying code
+         * I need to execute a serializing instruction here.
+         * So I flush the TLB, it's handy, and not processor dependent.
+         */
+        xorl    %eax, %eax
+        movl    %eax, %cr3
+
+        /* set all of the registers to known values */
+        /* leave %esp alone */
+
+        testl   %esi, %esi
+        jnz 1f
+        xorl    %edi, %edi
+        xorl    %eax, %eax
+        xorl    %ebx, %ebx
+        xorl    %ecx, %ecx
+        xorl    %edx, %edx
+        xorl    %esi, %esi
+        xorl    %ebp, %ebp
+        ret
+1:
+        popl    %edx
+        movl    CP_PA_SWAP_PAGE(%edi), %esp
+        addl    $PAGE_SIZE, %esp
+2:
+        call    *%edx
+
+        /* get the re-entry point of the peer system */
+        movl    0(%esp), %ebp
+        call    1f
+1:
+        popl    %ebx
+        subl    $(1b - relocate_kernel), %ebx
+        movl    CP_VA_CONTROL_PAGE(%ebx), %edi
+        lea     PAGE_SIZE(%ebx), %esp
+        movl    CP_PA_SWAP_PAGE(%ebx), %eax
+        movl    CP_PA_BACKUP_PAGES_MAP(%ebx), %edx
+        pushl   %eax
+        pushl   %edx
+        call    swap_pages
+        addl    $8, %esp
+        movl    CP_PA_PGD(%ebx), %eax
+        movl    %eax, %cr3
+        movl    %cr0, %eax
+        orl     $(1<<31), %eax
+        movl    %eax, %cr0
+        lea     PAGE_SIZE(%edi), %esp
+        movl    %edi, %eax
+        addl    $(virtual_mapped - relocate_kernel), %eax
+        pushl   %eax
+        ret
+
+virtual_mapped:
+        movl    CR4(%edi), %eax
+        movl    %eax, %cr4
+        movl    CR3(%edi), %eax
+        movl    %eax, %cr3
+        movl    CR0(%edi), %eax
+        movl    %eax, %cr0
+        movl    ESP(%edi), %esp
+        movl    %ebp, %eax
+
+        popf
+        popl    %ebp
+        popl    %edi
+        popl    %esi
+        popl    %ebx
+        ret
+
         /* Do the copies */
-        movl    %ebx, %ecx
+swap_pages:
+        movl    8(%esp), %edx
+        movl    4(%esp), %ecx
+        pushl   %ebp
+        pushl   %ebx
+        pushl   %edi
+        pushl   %esi
+        movl    %ecx, %ebx
         jmp     1f
 
 0:      /* top, read another word from the indirection page */
@@ -226,27 +351,28 @@ identity_mapped:
         movl    %ecx,   %esi /* For every source page do a copy */
         andl    $0xfffff000, %esi
 
+        movl    %edi, %eax
+        movl    %esi, %ebp
+
+        movl    %edx, %edi
         movl    $1024, %ecx
         rep ; movsl
-        jmp     0b
 
-3:
-
-        /* To be certain of avoiding problems with self-modifying code
-         * I need to execute a serializing instruction here.
-         * So I flush the TLB, it's handy, and not processor dependent.
-         */
-        xorl    %eax, %eax
-        movl    %eax, %cr3
+        movl    %ebp, %edi
+        movl    %eax, %esi
+        movl    $1024, %ecx
+        rep ; movsl
 
-        /* set all of the registers to known values */
-        /* leave %esp alone */
+        movl    %eax, %edi
+        movl    %edx, %esi
+        movl    $1024, %ecx
+        rep ; movsl
 
-        xorl    %eax, %eax
-        xorl    %ebx, %ebx
-        xorl    %ecx, %ecx
-        xorl    %edx, %edx
-        xorl    %esi, %esi
-        xorl    %edi, %edi
-        xorl    %ebp, %ebp
+        lea     PAGE_SIZE(%ebp), %esi
+        jmp     0b
+3:
+        popl    %esi
+        popl    %edi
+        popl    %ebx
+        popl    %ebp
         ret