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https://github.com/xen-project/xen.git
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Ian Campbell
92491dae02
This patch contains the x86_32 implementation of Kexec / Kdump for Xen. Signed-Off-By: Magnus Damm <magnus@valinux.co.jp> Signed-Off-By: Simon Horman <horms@verge.net.au>
170 lines
4.5 KiB
Diff
170 lines
4.5 KiB
Diff
kexec: Move asm segment handling code to the assembly file (i386)
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This patch moves the idt, gdt, and segment handling code from machine_kexec.c
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to relocate_kernel.S. The main reason behind this move is to avoid code
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duplication in the Xen hypervisor. With this patch all code required to kexec
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is put on the control page.
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On top of that this patch also counts as a cleanup - I think it is much
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nicer to write assembly directly in assembly files than wrap inline assembly
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in C functions for no apparent reason.
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Signed-off-by: Magnus Damm <magnus@valinux.co.jp>
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---
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Applies to 2.6.19-rc1.
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machine_kexec.c | 59 -----------------------------------------------------
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relocate_kernel.S | 58 +++++++++++++++++++++++++++++++++++++++++++++++-----
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2 files changed, 53 insertions(+), 64 deletions(-)
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--- 0002/arch/i386/kernel/machine_kexec.c
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+++ work/arch/i386/kernel/machine_kexec.c 2006-10-05 15:49:08.000000000 +0900
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@@ -29,48 +29,6 @@ static u32 kexec_pmd1[1024] PAGE_ALIGNED
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static u32 kexec_pte0[1024] PAGE_ALIGNED;
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static u32 kexec_pte1[1024] PAGE_ALIGNED;
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-static void set_idt(void *newidt, __u16 limit)
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-{
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- struct Xgt_desc_struct curidt;
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-
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- /* ia32 supports unaliged loads & stores */
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- curidt.size = limit;
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- curidt.address = (unsigned long)newidt;
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-
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- load_idt(&curidt);
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-};
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-
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-
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-static void set_gdt(void *newgdt, __u16 limit)
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-{
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- struct Xgt_desc_struct curgdt;
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-
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- /* ia32 supports unaligned loads & stores */
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- curgdt.size = limit;
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- curgdt.address = (unsigned long)newgdt;
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-
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- load_gdt(&curgdt);
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-};
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-
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-static void load_segments(void)
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-{
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-#define __STR(X) #X
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-#define STR(X) __STR(X)
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-
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- __asm__ __volatile__ (
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- "\tljmp $"STR(__KERNEL_CS)",$1f\n"
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- "\t1:\n"
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- "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
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- "\tmovl %%eax,%%ds\n"
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- "\tmovl %%eax,%%es\n"
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- "\tmovl %%eax,%%fs\n"
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- "\tmovl %%eax,%%gs\n"
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- "\tmovl %%eax,%%ss\n"
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- ::: "eax", "memory");
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-#undef STR
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-#undef __STR
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-}
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-
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/*
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* A architecture hook called to validate the
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* proposed image and prepare the control pages
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@@ -127,23 +85,6 @@ NORET_TYPE void machine_kexec(struct kim
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page_list[PA_PTE_1] = __pa(kexec_pte1);
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page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
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- /* The segment registers are funny things, they have both a
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- * visible and an invisible part. Whenever the visible part is
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- * set to a specific selector, the invisible part is loaded
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- * with from a table in memory. At no other time is the
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- * descriptor table in memory accessed.
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- *
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- * I take advantage of this here by force loading the
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- * segments, before I zap the gdt with an invalid value.
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- */
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- load_segments();
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- /* The gdt & idt are now invalid.
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- * If you want to load them you must set up your own idt & gdt.
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- */
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- set_gdt(phys_to_virt(0),0);
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- set_idt(phys_to_virt(0),0);
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-
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- /* now call it */
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relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
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image->start, cpu_has_pae);
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}
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--- 0002/arch/i386/kernel/relocate_kernel.S
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+++ work/arch/i386/kernel/relocate_kernel.S 2006-10-05 16:03:21.000000000 +0900
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@@ -154,14 +154,45 @@ relocate_new_kernel:
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movl PTR(PA_PGD)(%ebp), %eax
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movl %eax, %cr3
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+ /* setup idt */
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+ movl %edi, %eax
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+ addl $(idt_48 - relocate_kernel), %eax
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+ lidtl (%eax)
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+
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+ /* setup gdt */
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+ movl %edi, %eax
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+ addl $(gdt - relocate_kernel), %eax
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+ movl %edi, %esi
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+ addl $((gdt_48 - relocate_kernel) + 2), %esi
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+ movl %eax, (%esi)
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+
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+ movl %edi, %eax
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+ addl $(gdt_48 - relocate_kernel), %eax
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+ lgdtl (%eax)
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+
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+ /* setup data segment registers */
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+ mov $(gdt_ds - gdt), %eax
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+ mov %eax, %ds
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+ mov %eax, %es
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+ mov %eax, %fs
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+ mov %eax, %gs
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+ mov %eax, %ss
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+
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/* setup a new stack at the end of the physical control page */
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lea 4096(%edi), %esp
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- /* jump to identity mapped page */
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- movl %edi, %eax
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- addl $(identity_mapped - relocate_kernel), %eax
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- pushl %eax
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- ret
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+ /* load new code segment and jump to identity mapped page */
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+ movl %edi, %esi
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+ xorl %eax, %eax
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+ pushl %eax
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+ pushl %esi
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+ pushl %eax
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+ movl $(gdt_cs - gdt), %eax
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+ pushl %eax
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+ movl %edi, %eax
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+ addl $(identity_mapped - relocate_kernel),%eax
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+ pushl %eax
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+ iretl
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identity_mapped:
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/* store the start address on the stack */
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@@ -250,3 +281,20 @@ identity_mapped:
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xorl %edi, %edi
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xorl %ebp, %ebp
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ret
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+
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+ .align 16
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+gdt:
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+ .quad 0x0000000000000000 /* NULL descriptor */
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+gdt_cs:
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+ .quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */
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+gdt_ds:
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+ .quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */
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+gdt_end:
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+
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+gdt_48:
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+ .word gdt_end - gdt - 1 /* limit */
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+ .long 0 /* base - filled in by code above */
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+
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+idt_48:
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+ .word 0 /* limit */
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+ .long 0 /* base */
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