--- /dev/null
+Subject: kexec: Move asm segment handling code to the assembly file (i386)
+From: http://xenbits.xensource.com/xen-unstable.hg (tip 13816)
+Patch-mainline: obsolete
+
+This patch moves the idt, gdt, and segment handling code from machine_kexec.c
+to relocate_kernel.S. The main reason behind this move is to avoid code
+duplication in the Xen hypervisor. With this patch all code required to kexec
+is put on the control page.
+
+On top of that this patch also counts as a cleanup - I think it is much
+nicer to write assembly directly in assembly files than wrap inline assembly
+in C functions for no apparent reason.
+
+Signed-off-by: Magnus Damm <magnus@valinux.co.jp>
+Acked-by: jbeulich@novell.com
+---
+
+ Applies to 2.6.19-rc1.
+
+ machine_kexec.c | 59 -----------------------------------------------------
+ relocate_kernel.S | 58 +++++++++++++++++++++++++++++++++++++++++++++++-----
+ 2 files changed, 53 insertions(+), 64 deletions(-)
+
+Index: head-2008-11-17/arch/x86/kernel/machine_kexec_32.c
+===================================================================
+--- head-2008-11-17.orig/arch/x86/kernel/machine_kexec_32.c 2008-11-17 13:15:56.000000000 +0100
++++ head-2008-11-17/arch/x86/kernel/machine_kexec_32.c 2008-11-17 13:38:03.000000000 +0100
+@@ -34,48 +34,6 @@ static u32 kexec_pmd1[1024] PAGE_ALIGNED
+ static u32 kexec_pte0[1024] PAGE_ALIGNED;
+ static u32 kexec_pte1[1024] PAGE_ALIGNED;
+
+-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
+-}
+-
+ /*
+ * A architecture hook called to validate the
+ * proposed image and prepare the control pages
+@@ -167,23 +125,6 @@ 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,
+ image->start, cpu_has_pae,
+Index: head-2008-11-17/arch/x86/kernel/relocate_kernel_32.S
+===================================================================
+--- head-2008-11-17.orig/arch/x86/kernel/relocate_kernel_32.S 2008-11-17 13:15:56.000000000 +0100
++++ head-2008-11-17/arch/x86/kernel/relocate_kernel_32.S 2008-11-17 13:38:03.000000000 +0100
+@@ -199,14 +199,45 @@ 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 PAGE_SIZE(%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 */
+@@ -378,5 +409,22 @@ 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
projects / people / pmueller / ipfire-2.x.git / blobdiff