mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-08-05 16:54:27 +00:00
4f2d1bbc2c
Linus expressed a strong preference for arch-specific asm code (i.e., virtually all of it) to reside under arch/ rather than anywhere else. So move the EFI mixed mode startup code back, and put it under arch/x86/boot/startup/ where all shared x86 startup code is going to live. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20250401133416.1436741-11-ardb+git@google.com
253 lines
6 KiB
ArmAsm
253 lines
6 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* Copyright (C) 2014, 2015 Intel Corporation; author Matt Fleming
|
|
*
|
|
* Early support for invoking 32-bit EFI services from a 64-bit kernel.
|
|
*
|
|
* Because this thunking occurs before ExitBootServices() we have to
|
|
* restore the firmware's 32-bit GDT and IDT before we make EFI service
|
|
* calls.
|
|
*
|
|
* On the plus side, we don't have to worry about mangling 64-bit
|
|
* addresses into 32-bits because we're executing with an identity
|
|
* mapped pagetable and haven't transitioned to 64-bit virtual addresses
|
|
* yet.
|
|
*/
|
|
|
|
#include <linux/linkage.h>
|
|
#include <asm/desc_defs.h>
|
|
#include <asm/msr.h>
|
|
#include <asm/page_types.h>
|
|
#include <asm/pgtable_types.h>
|
|
#include <asm/processor-flags.h>
|
|
#include <asm/segment.h>
|
|
|
|
.text
|
|
.code32
|
|
#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
|
|
SYM_FUNC_START(efi32_stub_entry)
|
|
call 1f
|
|
1: popl %ecx
|
|
|
|
/* Clear BSS */
|
|
xorl %eax, %eax
|
|
leal (_bss - 1b)(%ecx), %edi
|
|
leal (_ebss - 1b)(%ecx), %ecx
|
|
subl %edi, %ecx
|
|
shrl $2, %ecx
|
|
cld
|
|
rep stosl
|
|
|
|
add $0x4, %esp /* Discard return address */
|
|
movl 8(%esp), %ebx /* struct boot_params pointer */
|
|
jmp efi32_startup
|
|
SYM_FUNC_END(efi32_stub_entry)
|
|
#endif
|
|
|
|
/*
|
|
* Called using a far call from __efi64_thunk() below, using the x86_64 SysV
|
|
* ABI (except for R8/R9 which are inaccessible to 32-bit code - EAX/EBX are
|
|
* used instead). EBP+16 points to the arguments passed via the stack.
|
|
*
|
|
* The first argument (EDI) is a pointer to the boot service or protocol, to
|
|
* which the remaining arguments are passed, each truncated to 32 bits.
|
|
*/
|
|
SYM_FUNC_START_LOCAL(efi_enter32)
|
|
/*
|
|
* Convert x86-64 SysV ABI params to i386 ABI
|
|
*/
|
|
pushl 32(%ebp) /* Up to 3 args passed via the stack */
|
|
pushl 24(%ebp)
|
|
pushl 16(%ebp)
|
|
pushl %ebx /* R9 */
|
|
pushl %eax /* R8 */
|
|
pushl %ecx
|
|
pushl %edx
|
|
pushl %esi
|
|
|
|
/* Disable paging */
|
|
movl %cr0, %eax
|
|
btrl $X86_CR0_PG_BIT, %eax
|
|
movl %eax, %cr0
|
|
|
|
/* Disable long mode via EFER */
|
|
movl $MSR_EFER, %ecx
|
|
rdmsr
|
|
btrl $_EFER_LME, %eax
|
|
wrmsr
|
|
|
|
call *%edi
|
|
|
|
/* We must preserve return value */
|
|
movl %eax, %edi
|
|
|
|
call efi32_enable_long_mode
|
|
|
|
addl $32, %esp
|
|
movl %edi, %eax
|
|
lret
|
|
SYM_FUNC_END(efi_enter32)
|
|
|
|
.code64
|
|
SYM_FUNC_START(__efi64_thunk)
|
|
push %rbp
|
|
movl %esp, %ebp
|
|
push %rbx
|
|
|
|
/* Move args #5 and #6 into 32-bit accessible registers */
|
|
movl %r8d, %eax
|
|
movl %r9d, %ebx
|
|
|
|
lcalll *efi32_call(%rip)
|
|
|
|
pop %rbx
|
|
pop %rbp
|
|
RET
|
|
SYM_FUNC_END(__efi64_thunk)
|
|
|
|
.code32
|
|
SYM_FUNC_START_LOCAL(efi32_enable_long_mode)
|
|
movl %cr4, %eax
|
|
btsl $(X86_CR4_PAE_BIT), %eax
|
|
movl %eax, %cr4
|
|
|
|
movl $MSR_EFER, %ecx
|
|
rdmsr
|
|
btsl $_EFER_LME, %eax
|
|
wrmsr
|
|
|
|
/* Disable interrupts - the firmware's IDT does not work in long mode */
|
|
cli
|
|
|
|
/* Enable paging */
|
|
movl %cr0, %eax
|
|
btsl $X86_CR0_PG_BIT, %eax
|
|
movl %eax, %cr0
|
|
ret
|
|
SYM_FUNC_END(efi32_enable_long_mode)
|
|
|
|
/*
|
|
* This is the common EFI stub entry point for mixed mode. It sets up the GDT
|
|
* and page tables needed for 64-bit execution, after which it calls the
|
|
* common 64-bit EFI entrypoint efi_stub_entry().
|
|
*
|
|
* Arguments: 0(%esp) image handle
|
|
* 4(%esp) EFI system table pointer
|
|
* %ebx struct boot_params pointer (or NULL)
|
|
*
|
|
* Since this is the point of no return for ordinary execution, no registers
|
|
* are considered live except for the function parameters. [Note that the EFI
|
|
* stub may still exit and return to the firmware using the Exit() EFI boot
|
|
* service.]
|
|
*/
|
|
SYM_FUNC_START_LOCAL(efi32_startup)
|
|
movl %esp, %ebp
|
|
|
|
subl $8, %esp
|
|
sgdtl (%esp) /* Save GDT descriptor to the stack */
|
|
movl 2(%esp), %esi /* Existing GDT pointer */
|
|
movzwl (%esp), %ecx /* Existing GDT limit */
|
|
inc %ecx /* Existing GDT size */
|
|
andl $~7, %ecx /* Ensure size is multiple of 8 */
|
|
|
|
subl %ecx, %esp /* Allocate new GDT */
|
|
andl $~15, %esp /* Realign the stack */
|
|
movl %esp, %edi /* New GDT address */
|
|
leal 7(%ecx), %eax /* New GDT limit */
|
|
pushw %cx /* Push 64-bit CS (for LJMP below) */
|
|
pushl %edi /* Push new GDT address */
|
|
pushw %ax /* Push new GDT limit */
|
|
|
|
/* Copy GDT to the stack and add a 64-bit code segment at the end */
|
|
movl $GDT_ENTRY(DESC_CODE64, 0, 0xfffff) & 0xffffffff, (%edi,%ecx)
|
|
movl $GDT_ENTRY(DESC_CODE64, 0, 0xfffff) >> 32, 4(%edi,%ecx)
|
|
shrl $2, %ecx
|
|
cld
|
|
rep movsl /* Copy the firmware GDT */
|
|
lgdtl (%esp) /* Switch to the new GDT */
|
|
|
|
call 1f
|
|
1: pop %edi
|
|
|
|
/* Record mixed mode entry */
|
|
movb $0x0, (efi_is64 - 1b)(%edi)
|
|
|
|
/* Set up indirect far call to re-enter 32-bit mode */
|
|
leal (efi32_call - 1b)(%edi), %eax
|
|
addl %eax, (%eax)
|
|
movw %cs, 4(%eax)
|
|
|
|
/* Disable paging */
|
|
movl %cr0, %eax
|
|
btrl $X86_CR0_PG_BIT, %eax
|
|
movl %eax, %cr0
|
|
|
|
/* Set up 1:1 mapping */
|
|
leal (pte - 1b)(%edi), %eax
|
|
movl $_PAGE_PRESENT | _PAGE_RW | _PAGE_PSE, %ecx
|
|
leal (_PAGE_PRESENT | _PAGE_RW)(%eax), %edx
|
|
2: movl %ecx, (%eax)
|
|
addl $8, %eax
|
|
addl $PMD_SIZE, %ecx
|
|
jnc 2b
|
|
|
|
movl $PAGE_SIZE, %ecx
|
|
.irpc l, 0123
|
|
movl %edx, \l * 8(%eax)
|
|
addl %ecx, %edx
|
|
.endr
|
|
addl %ecx, %eax
|
|
movl %edx, (%eax)
|
|
movl %eax, %cr3
|
|
|
|
call efi32_enable_long_mode
|
|
|
|
/* Set up far jump to 64-bit mode (CS is already on the stack) */
|
|
leal (efi_stub_entry - 1b)(%edi), %eax
|
|
movl %eax, 2(%esp)
|
|
|
|
movl 0(%ebp), %edi
|
|
movl 4(%ebp), %esi
|
|
movl %ebx, %edx
|
|
ljmpl *2(%esp)
|
|
SYM_FUNC_END(efi32_startup)
|
|
|
|
/*
|
|
* efi_status_t efi32_pe_entry(efi_handle_t image_handle,
|
|
* efi_system_table_32_t *sys_table)
|
|
*/
|
|
SYM_FUNC_START(efi32_pe_entry)
|
|
pushl %ebx // save callee-save registers
|
|
|
|
/* Check whether the CPU supports long mode */
|
|
movl $0x80000001, %eax // assume extended info support
|
|
cpuid
|
|
btl $29, %edx // check long mode bit
|
|
jnc 1f
|
|
leal 8(%esp), %esp // preserve stack alignment
|
|
xor %ebx, %ebx // no struct boot_params pointer
|
|
jmp efi32_startup // only ESP and EBX remain live
|
|
1: movl $0x80000003, %eax // EFI_UNSUPPORTED
|
|
popl %ebx
|
|
RET
|
|
SYM_FUNC_END(efi32_pe_entry)
|
|
|
|
#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
|
|
.org efi32_stub_entry + 0x200
|
|
.code64
|
|
SYM_FUNC_START_NOALIGN(efi64_stub_entry)
|
|
jmp efi_handover_entry
|
|
SYM_FUNC_END(efi64_stub_entry)
|
|
#endif
|
|
|
|
.data
|
|
.balign 8
|
|
SYM_DATA_START_LOCAL(efi32_call)
|
|
.long efi_enter32 - .
|
|
.word 0x0
|
|
SYM_DATA_END(efi32_call)
|
|
SYM_DATA(efi_is64, .byte 1)
|
|
|
|
.bss
|
|
.balign PAGE_SIZE
|
|
SYM_DATA_LOCAL(pte, .fill 6 * PAGE_SIZE, 1, 0)
|