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-rw-r--r--arch/x86/kernel/relocate_kernel_32.S291
1 files changed, 291 insertions, 0 deletions
diff --git a/arch/x86/kernel/relocate_kernel_32.S b/arch/x86/kernel/relocate_kernel_32.S
new file mode 100644
index 000000000..c7c4b1917
--- /dev/null
+++ b/arch/x86/kernel/relocate_kernel_32.S
@@ -0,0 +1,291 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * relocate_kernel.S - put the kernel image in place to boot
+ * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
+ */
+
+#include <linux/linkage.h>
+#include <asm/page_types.h>
+#include <asm/kexec.h>
+#include <asm/nospec-branch.h>
+#include <asm/processor-flags.h>
+
+/*
+ * Must be relocatable PIC code callable as a C function, in particular
+ * there must be a plain RET and not jump to return thunk.
+ */
+
+#define PTR(x) (x << 2)
+
+/*
+ * 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 ESP DATA(0x0)
+#define CR0 DATA(0x4)
+#define CR3 DATA(0x8)
+#define CR4 DATA(0xc)
+
+/* other data */
+#define CP_VA_CONTROL_PAGE DATA(0x10)
+#define CP_PA_PGD DATA(0x14)
+#define CP_PA_SWAP_PAGE DATA(0x18)
+#define CP_PA_BACKUP_PAGES_MAP DATA(0x1c)
+
+ .text
+SYM_CODE_START_NOALIGN(relocate_kernel)
+ /* Save the CPU context, used for jumping back */
+
+ pushl %ebx
+ pushl %esi
+ pushl %edi
+ pushl %ebp
+ pushf
+
+ movl 20+8(%esp), %ebp /* list of pages */
+ movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
+ movl %esp, ESP(%edi)
+ movl %cr0, %eax
+ movl %eax, CR0(%edi)
+ movl %cr3, %eax
+ movl %eax, CR3(%edi)
+ movl %cr4, %eax
+ movl %eax, CR4(%edi)
+
+ /* read the arguments and say goodbye to the stack */
+ movl 20+4(%esp), %ebx /* page_list */
+ movl 20+8(%esp), %ebp /* list of pages */
+ movl 20+12(%esp), %edx /* start address */
+ movl 20+16(%esp), %ecx /* cpu_has_pae */
+ movl 20+20(%esp), %esi /* preserve_context */
+
+ /* zero out flags, and disable interrupts */
+ pushl $0
+ popfl
+
+ /* save some information for jumping back */
+ movl PTR(VA_CONTROL_PAGE)(%ebp), %edi
+ movl %edi, CP_VA_CONTROL_PAGE(%edi)
+ movl PTR(PA_PGD)(%ebp), %eax
+ movl %eax, CP_PA_PGD(%edi)
+ movl PTR(PA_SWAP_PAGE)(%ebp), %eax
+ movl %eax, CP_PA_SWAP_PAGE(%edi)
+ movl %ebx, CP_PA_BACKUP_PAGES_MAP(%edi)
+
+ /*
+ * get physical address of control page now
+ * this is impossible after page table switch
+ */
+ movl PTR(PA_CONTROL_PAGE)(%ebp), %edi
+
+ /* switch to new set of page tables */
+ movl PTR(PA_PGD)(%ebp), %eax
+ movl %eax, %cr3
+
+ /* 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
+ ANNOTATE_UNRET_SAFE
+ ret
+ int3
+SYM_CODE_END(relocate_kernel)
+
+SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
+ /* set return address to 0 if not preserving context */
+ pushl $0
+ /* store the start address on the stack */
+ pushl %edx
+
+ /*
+ * Set cr0 to a known state:
+ * - Paging disabled
+ * - Alignment check disabled
+ * - Write protect disabled
+ * - No task switch
+ * - Don't do FP software emulation.
+ * - Protected mode enabled
+ */
+ movl %cr0, %eax
+ andl $~(X86_CR0_PG | X86_CR0_AM | X86_CR0_WP | X86_CR0_TS | X86_CR0_EM), %eax
+ orl $(X86_CR0_PE), %eax
+ movl %eax, %cr0
+
+ /* clear cr4 if applicable */
+ testl %ecx, %ecx
+ jz 1f
+ /*
+ * Set cr4 to a known state:
+ * Setting everything to zero seems safe.
+ */
+ xorl %eax, %eax
+ movl %eax, %cr4
+
+ jmp 1f
+1:
+
+ /* Flush the TLB (needed?) */
+ xorl %eax, %eax
+ movl %eax, %cr3
+
+ movl CP_PA_SWAP_PAGE(%edi), %eax
+ pushl %eax
+ pushl %ebx
+ call swap_pages
+ addl $8, %esp
+
+ /*
+ * To be certain of avoiding problems with self-modifying code
+ * I need to execute a serializing instruction here.
+ * So I flush the TLB, it's handy, and not processor dependent.
+ */
+ xorl %eax, %eax
+ movl %eax, %cr3
+
+ /*
+ * set all of the registers to known values
+ * leave %esp alone
+ */
+
+ testl %esi, %esi
+ jnz 1f
+ xorl %edi, %edi
+ xorl %eax, %eax
+ xorl %ebx, %ebx
+ xorl %ecx, %ecx
+ xorl %edx, %edx
+ xorl %esi, %esi
+ xorl %ebp, %ebp
+ ANNOTATE_UNRET_SAFE
+ ret
+ int3
+1:
+ popl %edx
+ movl CP_PA_SWAP_PAGE(%edi), %esp
+ addl $PAGE_SIZE, %esp
+2:
+ ANNOTATE_RETPOLINE_SAFE
+ call *%edx
+
+ /* get the re-entry point of the peer system */
+ movl 0(%esp), %ebp
+ call 1f
+1:
+ popl %ebx
+ subl $(1b - relocate_kernel), %ebx
+ movl CP_VA_CONTROL_PAGE(%ebx), %edi
+ lea PAGE_SIZE(%ebx), %esp
+ movl CP_PA_SWAP_PAGE(%ebx), %eax
+ movl CP_PA_BACKUP_PAGES_MAP(%ebx), %edx
+ pushl %eax
+ pushl %edx
+ call swap_pages
+ addl $8, %esp
+ movl CP_PA_PGD(%ebx), %eax
+ movl %eax, %cr3
+ movl %cr0, %eax
+ orl $X86_CR0_PG, %eax
+ movl %eax, %cr0
+ lea PAGE_SIZE(%edi), %esp
+ movl %edi, %eax
+ addl $(virtual_mapped - relocate_kernel), %eax
+ pushl %eax
+ ANNOTATE_UNRET_SAFE
+ ret
+ int3
+SYM_CODE_END(identity_mapped)
+
+SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
+ movl CR4(%edi), %eax
+ movl %eax, %cr4
+ movl CR3(%edi), %eax
+ movl %eax, %cr3
+ movl CR0(%edi), %eax
+ movl %eax, %cr0
+ movl ESP(%edi), %esp
+ movl %ebp, %eax
+
+ popf
+ popl %ebp
+ popl %edi
+ popl %esi
+ popl %ebx
+ ANNOTATE_UNRET_SAFE
+ ret
+ int3
+SYM_CODE_END(virtual_mapped)
+
+ /* Do the copies */
+SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
+ movl 8(%esp), %edx
+ movl 4(%esp), %ecx
+ pushl %ebp
+ pushl %ebx
+ pushl %edi
+ pushl %esi
+ movl %ecx, %ebx
+ jmp 1f
+
+0: /* top, read another word from the indirection page */
+ movl (%ebx), %ecx
+ addl $4, %ebx
+1:
+ testb $0x1, %cl /* is it a destination page */
+ jz 2f
+ movl %ecx, %edi
+ andl $0xfffff000, %edi
+ jmp 0b
+2:
+ testb $0x2, %cl /* is it an indirection page */
+ jz 2f
+ movl %ecx, %ebx
+ andl $0xfffff000, %ebx
+ jmp 0b
+2:
+ testb $0x4, %cl /* is it the done indicator */
+ jz 2f
+ jmp 3f
+2:
+ testb $0x8, %cl /* is it the source indicator */
+ jz 0b /* Ignore it otherwise */
+ movl %ecx, %esi /* For every source page do a copy */
+ andl $0xfffff000, %esi
+
+ movl %edi, %eax
+ movl %esi, %ebp
+
+ movl %edx, %edi
+ movl $1024, %ecx
+ rep ; movsl
+
+ movl %ebp, %edi
+ movl %eax, %esi
+ movl $1024, %ecx
+ rep ; movsl
+
+ movl %eax, %edi
+ movl %edx, %esi
+ movl $1024, %ecx
+ rep ; movsl
+
+ lea PAGE_SIZE(%ebp), %esi
+ jmp 0b
+3:
+ popl %esi
+ popl %edi
+ popl %ebx
+ popl %ebp
+ ANNOTATE_UNRET_SAFE
+ ret
+ int3
+SYM_CODE_END(swap_pages)
+
+ .globl kexec_control_code_size
+.set kexec_control_code_size, . - relocate_kernel