/* * relocate_kernel.S - put the kernel image in place to boot * Copyright (C) 2002-2005 Eric Biederman * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. */ #include #include #include #include #include /* * Must be relocatable PIC code callable as a C function */ #define PTR(x) (x << 3) #define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY) /* * control_page + KEXEC_CONTROL_CODE_MAX_SIZE * ~ control_page + PAGE_SIZE are used as data storage and stack for * jumping back */ #define DATA(offset) (KEXEC_CONTROL_CODE_MAX_SIZE+(offset)) /* Minimal CPU state */ #define RSP DATA(0x0) #define CR0 DATA(0x8) #define CR3 DATA(0x10) #define CR4 DATA(0x18) /* other data */ #define CP_PA_TABLE_PAGE DATA(0x20) #define CP_PA_SWAP_PAGE DATA(0x28) #define CP_PA_BACKUP_PAGES_MAP DATA(0x30) .text .align PAGE_SIZE .code64 .globl relocate_kernel relocate_kernel: /* * %rdi indirection_page * %rsi page_list * %rdx start address * %rcx preserve_context */ /* Save the CPU context, used for jumping back */ pushq %rbx pushq %rbp pushq %r12 pushq %r13 pushq %r14 pushq %r15 pushf movq PTR(VA_CONTROL_PAGE)(%rsi), %r11 movq %rsp, RSP(%r11) movq %cr0, %rax movq %rax, CR0(%r11) movq %cr3, %rax movq %rax, CR3(%r11) movq %cr4, %rax movq %rax, CR4(%r11) /* zero out flags, and disable interrupts */ pushq $0 popfq /* * get physical address of control page now * this is impossible after page table switch */ movq PTR(PA_CONTROL_PAGE)(%rsi), %r8 /* get physical address of page table now too */ movq PTR(PA_TABLE_PAGE)(%rsi), %r9 /* get physical address of swap page now */ movq PTR(PA_SWAP_PAGE)(%rsi), %r10 /* save some information for jumping back */ movq %r9, CP_PA_TABLE_PAGE(%r11) movq %r10, CP_PA_SWAP_PAGE(%r11) movq %rdi, CP_PA_BACKUP_PAGES_MAP(%r11) /* Switch to the identity mapped page tables */ movq %r9, %cr3 /* setup a new stack at the end of the physical control page */ lea PAGE_SIZE(%r8), %rsp /* jump to identity mapped page */ addq $(identity_mapped - relocate_kernel), %r8 pushq %r8 ret identity_mapped: /* store the start address on the stack */ pushq %rdx /* * Set cr0 to a known state: * - Paging enabled * - Alignment check disabled * - Write protect disabled * - No task switch * - Don't do FP software emulation. * - Proctected mode enabled */ movq %cr0, %rax andq $~(X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %rax orl $(X86_CR0_PG | X86_CR0_PE), %eax movq %rax, %cr0 /* * Set cr4 to a known state: * - physical address extension enabled */ movq $X86_CR4_PAE, %rax movq %rax, %cr4 jmp 1f 1: /* Flush the TLB (needed?) */ movq %r9, %cr3 movq %rcx, %r11 call swap_pages /* * To be certain of avoiding problems with self-modifying code * I need to execute a serializing instruction here. * So I flush the TLB by reloading %cr3 here, it's handy, * and not processor dependent. */ movq %cr3, %rax movq %rax, %cr3 /* * set all of the registers to known values * leave %rsp alone */ testq %r11, %r11 jnz 1f xorq %rax, %rax xorq %rbx, %rbx xorq %rcx, %rcx xorq %rdx, %rdx xorq %rsi, %rsi xorq %rdi, %rdi xorq %rbp, %rbp xorq %r8, %r8 xorq %r9, %r9 xorq %r10, %r9 xorq %r11, %r11 xorq %r12, %r12 xorq %r13, %r13 xorq %r14, %r14 xorq %r15, %r15 ret 1: popq %rdx leaq PAGE_SIZE(%r10), %rsp call *%rdx /* get the re-entry point of the peer system */ movq 0(%rsp), %rbp call 1f 1: popq %r8 subq $(1b - relocate_kernel), %r8 movq CP_PA_SWAP_PAGE(%r8), %r10 movq CP_PA_BACKUP_PAGES_MAP(%r8), %rdi movq CP_PA_TABLE_PAGE(%r8), %rax movq %rax, %cr3 lea PAGE_SIZE(%r8), %rsp call swap_pages movq $virtual_mapped, %rax pushq %rax ret virtual_mapped: movq RSP(%r8), %rsp movq CR4(%r8), %rax movq %rax, %cr4 movq CR3(%r8), %rax movq CR0(%r8), %r8 movq %rax, %cr3 movq %r8, %cr0 movq %rbp, %rax popf popq %r15 popq %r14 popq %r13 popq %r12 popq %rbp popq %rbx ret /* Do the copies */ swap_pages: movq %rdi, %rcx /* Put the page_list in %rcx */ xorq %rdi, %rdi xorq %rsi, %rsi jmp 1f 0: /* top, read another word for the indirection page */ movq (%rbx), %rcx addq $8, %rbx 1: testq $0x1, %rcx /* is it a destination page? */ jz 2f movq %rcx, %rdi andq $0xfffffffffffff000, %rdi jmp 0b 2: testq $0x2, %rcx /* is it an indirection page? */ jz 2f movq %rcx, %rbx andq $0xfffffffffffff000, %rbx jmp 0b 2: testq $0x4, %rcx /* is it the done indicator? */ jz 2f jmp 3f 2: testq $0x8, %rcx /* is it the source indicator? */ jz 0b /* Ignore it otherwise */ movq %rcx, %rsi /* For ever source page do a copy */ andq $0xfffffffffffff000, %rsi movq %rdi, %rdx movq %rsi, %rax movq %r10, %rdi movq $512, %rcx rep ; movsq movq %rax, %rdi movq %rdx, %rsi movq $512, %rcx rep ; movsq movq %rdx, %rdi movq %r10, %rsi movq $512, %rcx rep ; movsq lea PAGE_SIZE(%rax), %rsi jmp 0b 3: ret .globl kexec_control_code_size .set kexec_control_code_size, . - relocate_kernel