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/*
* Compatibility kexec handler.
*/
/*
* NOTE: We rely on Xen not relocating itself above the 4G boundary. This is
* currently true but if it ever changes then compat_pg_table will
* need to be moved back below 4G at run time.
*/
#include <xen/config.h>
#include <asm/asm_defns.h>
#include <asm/msr.h>
#include <asm/page.h>
/* The unrelocated physical address of a symbol. */
#define SYM_PHYS(sym) ((sym) - __XEN_VIRT_START)
/* Load physical address of symbol into register and relocate it. */
#define RELOCATE_SYM(sym,reg) mov $SYM_PHYS(sym), reg ; \
add xen_phys_start(%rip), reg
/*
* Relocate a physical address in memory. Size of temporary register
* determines size of the value to relocate.
*/
#define RELOCATE_MEM(addr,reg) mov addr(%rip), reg ; \
add xen_phys_start(%rip), reg ; \
mov reg, addr(%rip)
.text
.code64
ENTRY(compat_machine_kexec)
/* x86/64 x86/32 */
/* %rdi - relocate_new_kernel_t CALL */
/* %rsi - indirection page 4(%esp) */
/* %rdx - page_list 8(%esp) */
/* %rcx - start address 12(%esp) */
/* cpu has pae 16(%esp) */
/* Shim the 64 bit page_list into a 32 bit page_list. */
mov $12,%r9
lea compat_page_list(%rip), %rbx
1: dec %r9
movl (%rdx,%r9,8),%eax
movl %eax,(%rbx,%r9,4)
test %r9,%r9
jnz 1b
RELOCATE_SYM(compat_page_list,%rdx)
/* Relocate compatibility mode entry point address. */
RELOCATE_MEM(compatibility_mode_far,%eax)
/* Relocate compat_pg_table. */
RELOCATE_MEM(compat_pg_table, %rax)
RELOCATE_MEM(compat_pg_table+0x8, %rax)
RELOCATE_MEM(compat_pg_table+0x10,%rax)
RELOCATE_MEM(compat_pg_table+0x18,%rax)
/*
* Setup an identity mapped region in PML4[0] of idle page
* table.
*/
RELOCATE_SYM(l3_identmap,%rax)
or $0x63,%rax
mov %rax, idle_pg_table(%rip)
/* Switch to idle page table. */
RELOCATE_SYM(idle_pg_table,%rax)
movq %rax, %cr3
/* Switch to identity mapped compatibility stack. */
RELOCATE_SYM(compat_stack,%rax)
movq %rax, %rsp
/* Save xen_phys_start for 32 bit code. */
movq xen_phys_start(%rip), %rbx
/* Jump to low identity mapping in compatibility mode. */
ljmp *compatibility_mode_far(%rip)
ud2
compatibility_mode_far:
.long SYM_PHYS(compatibility_mode)
.long __HYPERVISOR_CS32
/*
* We use 5 words of stack for the arguments passed to the kernel. The
* kernel only uses 1 word before switching to its own stack. Allocate
* 16 words to give "plenty" of room.
*/
.fill 16,4,0
compat_stack:
.code32
#undef RELOCATE_SYM
#undef RELOCATE_MEM
/*
* Load physical address of symbol into register and relocate it. %rbx
* contains xen_phys_start(%rip) saved before jump to compatibility
* mode.
*/
#define RELOCATE_SYM(sym,reg) mov $SYM_PHYS(sym), reg ; \
add %ebx, reg
compatibility_mode:
/* Setup some sane segments. */
movl $__HYPERVISOR_DS32, %eax
movl %eax, %ds
movl %eax, %es
movl %eax, %fs
movl %eax, %gs
movl %eax, %ss
/* Push arguments onto stack. */
pushl $0 /* 20(%esp) - preserve context */
pushl $1 /* 16(%esp) - cpu has pae */
pushl %ecx /* 12(%esp) - start address */
pushl %edx /* 8(%esp) - page list */
pushl %esi /* 4(%esp) - indirection page */
pushl %edi /* 0(%esp) - CALL */
/* Disable paging and therefore leave 64 bit mode. */
movl %cr0, %eax
andl $~X86_CR0_PG, %eax
movl %eax, %cr0
/* Switch to 32 bit page table. */
RELOCATE_SYM(compat_pg_table, %eax)
movl %eax, %cr3
/* Clear MSR_EFER[LME], disabling long mode */
movl $MSR_EFER,%ecx
rdmsr
btcl $_EFER_LME,%eax
wrmsr
/* Re-enable paging, but only 32 bit mode now. */
movl %cr0, %eax
orl $X86_CR0_PG, %eax
movl %eax, %cr0
jmp 1f
1:
popl %eax
call *%eax
ud2
.data
.align 4
compat_page_list:
.fill 12,4,0
.align 32,0
/*
* These compat page tables contain an identity mapping of the
* first 4G of the physical address space.
*/
compat_pg_table:
.long SYM_PHYS(compat_pg_table_l2) + 0*PAGE_SIZE + 0x01, 0
.long SYM_PHYS(compat_pg_table_l2) + 1*PAGE_SIZE + 0x01, 0
.long SYM_PHYS(compat_pg_table_l2) + 2*PAGE_SIZE + 0x01, 0
.long SYM_PHYS(compat_pg_table_l2) + 3*PAGE_SIZE + 0x01, 0
.section .data.page_aligned, "aw", @progbits
.align PAGE_SIZE,0
compat_pg_table_l2:
.macro identmap from=0, count=512
.if \count-1
identmap "(\from+0)","(\count/2)"
identmap "(\from+(0x200000*(\count/2)))","(\count/2)"
.else
.quad 0x00000000000000e3 + \from
.endif
.endm
identmap 0x00000000
identmap 0x40000000
identmap 0x80000000
identmap 0xc0000000
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