diff options
Diffstat (limited to 'arch/x86/boot/compressed/la57toggle.S')
| -rw-r--r-- | arch/x86/boot/compressed/la57toggle.S | 112 |
1 files changed, 0 insertions, 112 deletions
diff --git a/arch/x86/boot/compressed/la57toggle.S b/arch/x86/boot/compressed/la57toggle.S deleted file mode 100644 index 9ee002387eb1..000000000000 --- a/arch/x86/boot/compressed/la57toggle.S +++ /dev/null @@ -1,112 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ - -#include <linux/linkage.h> -#include <asm/segment.h> -#include <asm/boot.h> -#include <asm/msr.h> -#include <asm/processor-flags.h> -#include "pgtable.h" - -/* - * This is the 32-bit trampoline that will be copied over to low memory. It - * will be called using the ordinary 64-bit calling convention from code - * running in 64-bit mode. - * - * Return address is at the top of the stack (might be above 4G). - * The first argument (EDI) contains the address of the temporary PGD level - * page table in 32-bit addressable memory which will be programmed into - * register CR3. - */ - - .section ".rodata", "a", @progbits -SYM_CODE_START(trampoline_32bit_src) - /* - * Preserve callee save 64-bit registers on the stack: this is - * necessary because the architecture does not guarantee that GPRs will - * retain their full 64-bit values across a 32-bit mode switch. - */ - pushq %r15 - pushq %r14 - pushq %r13 - pushq %r12 - pushq %rbp - pushq %rbx - - /* Preserve top half of RSP in a legacy mode GPR to avoid truncation */ - movq %rsp, %rbx - shrq $32, %rbx - - /* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */ - pushq $__KERNEL32_CS - leaq 0f(%rip), %rax - pushq %rax - lretq - - /* - * The 32-bit code below will do a far jump back to long mode and end - * up here after reconfiguring the number of paging levels. First, the - * stack pointer needs to be restored to its full 64-bit value before - * the callee save register contents can be popped from the stack. - */ -.Lret: - shlq $32, %rbx - orq %rbx, %rsp - - /* Restore the preserved 64-bit registers */ - popq %rbx - popq %rbp - popq %r12 - popq %r13 - popq %r14 - popq %r15 - retq - - .code32 -0: - /* Disable paging */ - movl %cr0, %eax - btrl $X86_CR0_PG_BIT, %eax - movl %eax, %cr0 - - /* Point CR3 to the trampoline's new top level page table */ - movl %edi, %cr3 - - /* Set EFER.LME=1 as a precaution in case hypervsior pulls the rug */ - movl $MSR_EFER, %ecx - rdmsr - btsl $_EFER_LME, %eax - /* Avoid writing EFER if no change was made (for TDX guest) */ - jc 1f - wrmsr -1: - /* Toggle CR4.LA57 */ - movl %cr4, %eax - btcl $X86_CR4_LA57_BIT, %eax - movl %eax, %cr4 - - /* Enable paging again. */ - movl %cr0, %eax - btsl $X86_CR0_PG_BIT, %eax - movl %eax, %cr0 - - /* - * Return to the 64-bit calling code using LJMP rather than LRET, to - * avoid the need for a 32-bit addressable stack. The destination - * address will be adjusted after the template code is copied into a - * 32-bit addressable buffer. - */ -.Ljmp: ljmpl $__KERNEL_CS, $(.Lret - trampoline_32bit_src) -SYM_CODE_END(trampoline_32bit_src) - -/* - * This symbol is placed right after trampoline_32bit_src() so its address can - * be used to infer the size of the trampoline code. - */ -SYM_DATA(trampoline_ljmp_imm_offset, .word .Ljmp + 1 - trampoline_32bit_src) - - /* - * The trampoline code has a size limit. - * Make sure we fail to compile if the trampoline code grows - * beyond TRAMPOLINE_32BIT_CODE_SIZE bytes. - */ - .org trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_SIZE |