[Xen-changelog] [linux-2.6.18-xen] Imported patch linux-2.6.19-rc1-kexec-move_segment_code-i386.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 948d16bbacc2d9362626015f536ea928d2415edf
# Parent  07baeb6664de2fe650f32a2c77ed30217a84c701
Imported patch linux-2.6.19-rc1-kexec-move_segment_code-i386.patch from 
xen-unstable.hg 15200:bd3d6b4c52ec
---
 arch/i386/kernel/machine_kexec.c   |   59 -------------------------------------
 arch/i386/kernel/relocate_kernel.S |   58 +++++++++++++++++++++++++++++++++---
 2 files changed, 53 insertions(+), 64 deletions(-)

diff -r 07baeb6664de -r 948d16bbacc2 arch/i386/kernel/machine_kexec.c
--- a/arch/i386/kernel/machine_kexec.c  Mon Jun 04 10:05:23 2007 +0100
+++ b/arch/i386/kernel/machine_kexec.c  Mon Jun 04 10:05:23 2007 +0100
@@ -27,48 +27,6 @@ static u32 kexec_pmd1[1024] PAGE_ALIGNED
 #endif
 static u32 kexec_pte0[1024] PAGE_ALIGNED;
 static u32 kexec_pte1[1024] PAGE_ALIGNED;
-
-static void set_idt(void *newidt, __u16 limit)
-{
-       struct Xgt_desc_struct 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 Xgt_desc_struct 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
-}
 
 /*
  * A architecture hook called to validate the
@@ -126,23 +84,6 @@ NORET_TYPE void machine_kexec(struct kim
        page_list[PA_PTE_1] = __pa(kexec_pte1);
        page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
 
-       /* 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, cpu_has_pae);
 }
diff -r 07baeb6664de -r 948d16bbacc2 arch/i386/kernel/relocate_kernel.S
--- a/arch/i386/kernel/relocate_kernel.S        Mon Jun 04 10:05:23 2007 +0100
+++ b/arch/i386/kernel/relocate_kernel.S        Mon Jun 04 10:05:23 2007 +0100
@@ -154,14 +154,45 @@ relocate_new_kernel:
        movl    PTR(PA_PGD)(%ebp), %eax
        movl    %eax, %cr3
 
+       /* setup idt */
+       movl    %edi, %eax
+       addl    $(idt_48 - relocate_kernel), %eax
+       lidtl   (%eax)
+
+       /* setup gdt */
+       movl    %edi, %eax
+       addl    $(gdt - relocate_kernel), %eax
+       movl    %edi, %esi
+       addl    $((gdt_48 - relocate_kernel) + 2), %esi
+       movl    %eax, (%esi)
+       
+       movl    %edi, %eax
+       addl    $(gdt_48 - relocate_kernel), %eax
+       lgdtl   (%eax)
+
+       /* 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     4096(%edi), %esp
 
-       /* jump to identity mapped page */
-       movl    %edi, %eax
-       addl    $(identity_mapped - relocate_kernel), %eax
-       pushl   %eax
-       ret
+       /* load new code segment and jump to identity mapped page */
+       movl    %edi, %esi
+       xorl    %eax, %eax
+       pushl   %eax
+       pushl   %esi
+       pushl   %eax
+       movl    $(gdt_cs - gdt), %eax
+       pushl   %eax    
+       movl    %edi, %eax
+       addl    $(identity_mapped - relocate_kernel),%eax
+       pushl   %eax
+       iretl
 
 identity_mapped:
        /* store the start address on the stack */
@@ -250,3 +281,20 @@ 3:
        xorl    %edi, %edi
        xorl    %ebp, %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 */

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