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efi/x86: Simplify 64-bit EFI firmware call wrapper 

The efi_call() wrapper used to invoke EFI runtime services serves
a number of purposes:
- realign the stack to 16 bytes
- preserve FP and CR0 register state
- translate from SysV to MS calling convention.

Preserving CR0.TS is no longer necessary in Linux, and preserving the
FP register state is also redundant in most cases, since efi_call() is
almost always used from within the scope of a pair of kernel_fpu_begin()/
kernel_fpu_end() calls, with the exception of the early call to
SetVirtualAddressMap() and the SGI UV support code.

So let's add a pair of kernel_fpu_begin()/_end() calls there as well,
and remove the unnecessary code from the assembly implementation of
efi_call(), and only keep the pieces that deal with the stack
alignment and the ABI translation.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Matthew Garrett <mjg59@google.com>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20200103113953.9571-10-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ard Biesheuvel 2020-01-03 12:39:42 +01:00 committed by Ingo Molnar
parent a46d674068
commit e5f930fe8d
4 changed files with 12 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/platform/efi/Makefile
View File

@ -1,6 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
OBJECT_FILES_NON_STANDARD_efi_thunk_$(BITS).o := y
OBJECT_FILES_NON_STANDARD_efi_stub_$(BITS).o := y
obj-$(CONFIG_EFI) += quirks.o efi.o efi_$(BITS).o efi_stub_$(BITS).o
obj-$(CONFIG_EFI_MIXED) += efi_thunk_$(BITS).o

3
arch/x86/platform/efi/efi_64.c
View File

@ -1019,6 +1019,8 @@ efi_status_t __init efi_set_virtual_address_map(unsigned long memory_map_size,
efi_switch_mm(&efi_mm);
}
kernel_fpu_begin();
/* Disable interrupts around EFI calls: */
local_irq_save(flags);
status = efi_call(efi.systab->runtime->set_virtual_address_map,
@ -1026,6 +1028,7 @@ efi_status_t __init efi_set_virtual_address_map(unsigned long memory_map_size,
descriptor_version, virtual_map);
local_irq_restore(flags);
kernel_fpu_end();
if (save_pgd)
efi_old_memmap_phys_epilog(save_pgd);

39
arch/x86/platform/efi/efi_stub_64.S
View File

@ -8,41 +8,12 @@
*/
#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/msr.h>
#include <asm/processor-flags.h>
#include <asm/page_types.h>
#define SAVE_XMM \
mov %rsp, %rax; \
subq $0x70, %rsp; \
and $~0xf, %rsp; \
mov %rax, (%rsp); \
mov %cr0, %rax; \
clts; \
mov %rax, 0x8(%rsp); \
movaps %xmm0, 0x60(%rsp); \
movaps %xmm1, 0x50(%rsp); \
movaps %xmm2, 0x40(%rsp); \
movaps %xmm3, 0x30(%rsp); \
movaps %xmm4, 0x20(%rsp); \
movaps %xmm5, 0x10(%rsp)
#define RESTORE_XMM \
movaps 0x60(%rsp), %xmm0; \
movaps 0x50(%rsp), %xmm1; \
movaps 0x40(%rsp), %xmm2; \
movaps 0x30(%rsp), %xmm3; \
movaps 0x20(%rsp), %xmm4; \
movaps 0x10(%rsp), %xmm5; \
mov 0x8(%rsp), %rsi; \
mov %rsi, %cr0; \
mov (%rsp), %rsp
#include <asm/nospec-branch.h>
SYM_FUNC_START(efi_call)
pushq %rbp
movq %rsp, %rbp
SAVE_XMM
and $~0xf, %rsp
mov 16(%rbp), %rax
subq $48, %rsp
mov %r9, 32(%rsp)
@ -50,9 +21,7 @@ SYM_FUNC_START(efi_call)
mov %r8, %r9
mov %rcx, %r8
mov %rsi, %rcx
call *%rdi
addq $48, %rsp
RESTORE_XMM
popq %rbp
CALL_NOSPEC %rdi
leave
ret
SYM_FUNC_END(efi_call)

7
arch/x86/platform/uv/bios_uv.c
View File

@ -34,10 +34,13 @@ static s64 __uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
* If EFI_OLD_MEMMAP is set, we need to fall back to using our old EFI
* callback method, which uses efi_call() directly, with the kernel page tables:
*/
if (unlikely(efi_enabled(EFI_OLD_MEMMAP)))
if (unlikely(efi_enabled(EFI_OLD_MEMMAP))) {
kernel_fpu_begin();
ret = efi_call((void *)__va(tab->function), (u64)which, a1, a2, a3, a4, a5);
else
kernel_fpu_end();
} else {
ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5);
}
return ret;
}