patches.xen/kexec-move-segment-code-x86_64.patch

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index b3ea9db..9d17e4f 100644 (file)
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -203,47 +203,6 @@ static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
        return init_transition_pgtable(image, level4p);
 }
 
-static void set_idt(void *newidt, u16 limit)
-{
-       struct desc_ptr curidt;
-
-       /* x86-64 supports unaliged loads & stores */
-       curidt.size    = limit;
-       curidt.address = (unsigned long)newidt;
-
-       __asm__ __volatile__ (
-               "lidtq %0\n"
-               : : "m" (curidt)
-               );
-};
-
-
-static void set_gdt(void *newgdt, u16 limit)
-{
-       struct desc_ptr curgdt;
-
-       /* x86-64 supports unaligned loads & stores */
-       curgdt.size    = limit;
-       curgdt.address = (unsigned long)newgdt;
-
-       __asm__ __volatile__ (
-               "lgdtq %0\n"
-               : : "m" (curgdt)
-               );
-};
-
-static void load_segments(void)
-{
-       __asm__ __volatile__ (
-               "\tmovl %0,%%ds\n"
-               "\tmovl %0,%%es\n"
-               "\tmovl %0,%%ss\n"
-               "\tmovl %0,%%fs\n"
-               "\tmovl %0,%%gs\n"
-               : : "a" (__KERNEL_DS) : "memory"
-               );
-}
-
 int machine_kexec_prepare(struct kimage *image)
 {
        unsigned long start_pgtable;
@@ -311,24 +270,6 @@ 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((unsigned long)image->head,
                                       (unsigned long)page_list,

diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 7a6f3b3..b591fca 100644 (file)
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -91,13 +91,30 @@ relocate_kernel:
        /* Switch to the identity mapped page tables */
        movq    %r9, %cr3
 
+       /* setup idt */
+       lidtq   idt_80 - relocate_kernel(%r8)
+
+       /* setup gdt */
+       leaq    gdt - relocate_kernel(%r8), %rax
+       movq    %rax, (gdt_80 - relocate_kernel) + 2(%r8)
+       lgdtq   gdt_80 - relocate_kernel(%r8)
+
+       /* setup data segment registers */
+       xorl    %eax, %eax
+       movl    %eax, %ds
+       movl    %eax, %es
+       movl    %eax, %fs
+       movl    %eax, %gs
+       movl    %eax, %ss
+
        /* setup a new stack at the end of the physical control page */
        lea     PAGE_SIZE(%r8), %rsp
 
-       /* jump to identity mapped page */
+       /* load new code segment and jump to identity mapped page */
        addq    $(identity_mapped - relocate_kernel), %r8
+       pushq   $(gdt_cs - gdt)
        pushq   %r8
-       ret
+       lretq
 
 identity_mapped:
        /* set return address to 0 if not preserving context */
@@ -264,5 +281,20 @@ swap_pages:
 3:
        ret
 
+       .align  16
+gdt:
+       .quad   0x0000000000000000      /* NULL descriptor */
+gdt_cs:
+       .quad   0x00af9a000000ffff
+gdt_end:
+
+gdt_80:
+       .word   gdt_end - gdt - 1       /* limit */
+       .quad   0                       /* base - filled in by code above */
+
+idt_80:
+       .word   0                       /* limit */
+       .quad   0                       /* base */
+
        .globl kexec_control_code_size
 .set kexec_control_code_size, . - relocate_kernel