[Xen-changelog] [linux-2.6.18-xen] Imported patch linux-2.6.19-rc1-kexec-move_segment_code-x86_64.patch from xen-unstable.hg 15200:bd3d6b4c52ec

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxxxxx>
# Date 1180947923 -3600
# Node ID 405dae994591a785c16c59e50658bea7814b7000
# Parent  1c0aeb8749d2c27475d33143b28e53dadc154eb3
Imported patch linux-2.6.19-rc1-kexec-move_segment_code-x86_64.patch from 
xen-unstable.hg 15200:bd3d6b4c52ec
---
 arch/x86_64/kernel/machine_kexec.c   |   58 -----------------------------------
 arch/x86_64/kernel/relocate_kernel.S |   50 +++++++++++++++++++++++++++---
 2 files changed, 45 insertions(+), 63 deletions(-)

diff -r 1c0aeb8749d2 -r 405dae994591 arch/x86_64/kernel/machine_kexec.c
--- a/arch/x86_64/kernel/machine_kexec.c        Mon Jun 04 10:05:23 2007 +0100
+++ b/arch/x86_64/kernel/machine_kexec.c        Mon Jun 04 10:05:23 2007 +0100
@@ -112,47 +112,6 @@ static int init_pgtable(struct kimage *i
        return init_level4_page(image, level4p, 0, end_pfn << PAGE_SHIFT);
 }
 
-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;
@@ -209,23 +168,6 @@ NORET_TYPE void machine_kexec(struct kim
        page_list[PA_TABLE_PAGE] =
          (unsigned long)__pa(page_address(image->control_code_page));
 
-       /* 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 */
        relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
                        image->start);
 }
diff -r 1c0aeb8749d2 -r 405dae994591 arch/x86_64/kernel/relocate_kernel.S
--- a/arch/x86_64/kernel/relocate_kernel.S      Mon Jun 04 10:05:23 2007 +0100
+++ b/arch/x86_64/kernel/relocate_kernel.S      Mon Jun 04 10:05:23 2007 +0100
@@ -159,13 +159,39 @@ relocate_new_kernel:
        movq    PTR(PA_PGD)(%rsi), %r9
        movq    %r9, %cr3
 
+       /* setup idt */
+       movq    %r8, %rax
+       addq    $(idt_80 - relocate_kernel), %rax
+       lidtq   (%rax)
+
+       /* setup gdt */
+       movq    %r8, %rax
+       addq    $(gdt - relocate_kernel), %rax
+       movq    %r8, %r9
+       addq    $((gdt_80 - relocate_kernel) + 2), %r9
+       movq    %rax, (%r9)
+
+       movq    %r8, %rax
+       addq    $(gdt_80 - relocate_kernel), %rax
+       lgdtq   (%rax)
+
+       /* 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     4096(%r8), %rsp
 
-       /* jump to identity mapped page */
-       addq    $(identity_mapped - relocate_kernel), %r8
-       pushq   %r8
-       ret
+       /* load new code segment and jump to identity mapped page */
+       movq    %r8, %rax
+       addq    $(identity_mapped - relocate_kernel), %rax
+       pushq   $(gdt_cs - gdt)
+       pushq   %rax
+       lretq
 
 identity_mapped:
        /* store the start address on the stack */
@@ -272,5 +298,19 @@ 3:
        xorq    %r13, %r13
        xorq    %r14, %r14
        xorq    %r15, %r15
-
        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 */

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