patches.xen/kexec-move-segment-code-i386.patch

diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index a3fa43b..ecac7ab 100644 (file)
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -27,48 +27,6 @@
 #include <asm/cacheflush.h>
 #include <asm/debugreg.h>
 
-static void set_idt(void *newidt, __u16 limit)
-{
-       struct desc_ptr curidt;
-
-       /* ia32 supports unaliged loads & stores */
-       curidt.size    = limit;
-       curidt.address = (unsigned long)newidt;
-
-       load_idt(&curidt);
-}
-
-
-static void set_gdt(void *newgdt, __u16 limit)
-{
-       struct desc_ptr curgdt;
-
-       /* ia32 supports unaligned loads & stores */
-       curgdt.size    = limit;
-       curgdt.address = (unsigned long)newgdt;
-
-       load_gdt(&curgdt);
-}
-
-static void load_segments(void)
-{
-#define __STR(X) #X
-#define STR(X) __STR(X)
-
-       __asm__ __volatile__ (
-               "\tljmp $"STR(__KERNEL_CS)",$1f\n"
-               "\t1:\n"
-               "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
-               "\tmovl %%eax,%%ds\n"
-               "\tmovl %%eax,%%es\n"
-               "\tmovl %%eax,%%fs\n"
-               "\tmovl %%eax,%%gs\n"
-               "\tmovl %%eax,%%ss\n"
-               : : : "eax", "memory");
-#undef STR
-#undef __STR
-}
-
 static void machine_kexec_free_page_tables(struct kimage *image)
 {
        free_page((unsigned long)image->arch.pgd);
@@ -228,24 +186,6 @@ void machine_kexec(struct kimage *image)
                page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
                                                << PAGE_SHIFT);
 
-       /*
-        * The segment registers are funny things, they have both a
-        * visible and an invisible part.  Whenever the visible part is
-        * set to a specific selector, the invisible part is loaded
-        * with from a table in memory.  At no other time is the
-        * descriptor table in memory accessed.
-        *
-        * I take advantage of this here by force loading the
-        * segments, before I zap the gdt with an invalid value.
-        */
-       load_segments();
-       /*
-        * The gdt & idt are now invalid.
-        * If you want to load them you must set up your own idt & gdt.
-        */
-       set_gdt(phys_to_virt(0), 0);
-       set_idt(phys_to_virt(0), 0);
-
        /* now call it */
        image->start = relocate_kernel_ptr((unsigned long)image->head,
                                           (unsigned long)page_list,

diff --git a/arch/x86/kernel/relocate_kernel_32.S b/arch/x86/kernel/relocate_kernel_32.S
index 36818f8..06ee365 100644 (file)
--- a/arch/x86/kernel/relocate_kernel_32.S
+++ b/arch/x86/kernel/relocate_kernel_32.S
@@ -87,14 +87,32 @@ relocate_kernel:
        movl    PTR(PA_PGD)(%ebp), %eax
        movl    %eax, %cr3
 
+       /* setup idt */
+       lidtl   idt_48 - relocate_kernel(%edi)
+
+       /* setup gdt */
+       leal    gdt - relocate_kernel(%edi), %eax
+       movl    %eax, (gdt_48 - relocate_kernel) + 2(%edi)
+       lgdtl   gdt_48 - relocate_kernel(%edi)
+
+       /* setup data segment registers */
+       mov     $(gdt_ds - gdt), %eax
+       mov     %eax, %ds
+       mov     %eax, %es
+       mov     %eax, %fs
+       mov     %eax, %gs
+       mov     %eax, %ss
+
        /* setup a new stack at the end of the physical control page */
        lea     PAGE_SIZE(%edi), %esp
 
-       /* jump to identity mapped page */
+       /* load new code segment and jump to identity mapped page */
+       pushl   $0
+       pushl   $(gdt_cs - gdt)
        movl    %edi, %eax
        addl    $(identity_mapped - relocate_kernel), %eax
        pushl   %eax
-       ret
+       iretl
 
 identity_mapped:
        /* set return address to 0 if not preserving context */
@@ -273,5 +291,22 @@ swap_pages:
        popl    %ebp
        ret
 
+       .align  16
+gdt:
+       .quad   0x0000000000000000      /* NULL descriptor */
+gdt_cs:
+       .quad   0x00cf9a000000ffff      /* kernel 4GB code at 0x00000000 */
+gdt_ds:
+       .quad   0x00cf92000000ffff      /* kernel 4GB data at 0x00000000 */
+gdt_end:
+
+gdt_48:
+       .word   gdt_end - gdt - 1       /* limit */
+       .long   0                       /* base - filled in by code above */
+
+idt_48:
+       .word   0                       /* limit */
+       .long   0                       /* base */
+
        .globl kexec_control_code_size
 .set kexec_control_code_size, . - relocate_kernel