--- zzzz-none-000/linux-3.10.107/arch/x86/platform/efi/efi_stub_64.S	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/arch/x86/platform/efi/efi_stub_64.S	2021-02-04 17:41:59.000000000 +0000
@@ -7,6 +7,10 @@
  */
 
 #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;			\
@@ -34,72 +38,42 @@
 	mov %rsi, %cr0;			\
 	mov (%rsp), %rsp
 
-ENTRY(efi_call0)
-	SAVE_XMM
-	subq $32, %rsp
-	call *%rdi
-	addq $32, %rsp
-	RESTORE_XMM
-	ret
-ENDPROC(efi_call0)
-
-ENTRY(efi_call1)
-	SAVE_XMM
-	subq $32, %rsp
-	mov  %rsi, %rcx
-	call *%rdi
-	addq $32, %rsp
-	RESTORE_XMM
-	ret
-ENDPROC(efi_call1)
-
-ENTRY(efi_call2)
-	SAVE_XMM
-	subq $32, %rsp
-	mov  %rsi, %rcx
-	call *%rdi
-	addq $32, %rsp
-	RESTORE_XMM
-	ret
-ENDPROC(efi_call2)
-
-ENTRY(efi_call3)
-	SAVE_XMM
-	subq $32, %rsp
-	mov  %rcx, %r8
-	mov  %rsi, %rcx
-	call *%rdi
-	addq $32, %rsp
-	RESTORE_XMM
-	ret
-ENDPROC(efi_call3)
+	/* stolen from gcc */
+	.macro FLUSH_TLB_ALL
+	movq %r15, efi_scratch(%rip)
+	movq %r14, efi_scratch+8(%rip)
+	movq %cr4, %r15
+	movq %r15, %r14
+	andb $0x7f, %r14b
+	movq %r14, %cr4
+	movq %r15, %cr4
+	movq efi_scratch+8(%rip), %r14
+	movq efi_scratch(%rip), %r15
+	.endm
+
+	.macro SWITCH_PGT
+	cmpb $0, efi_scratch+24(%rip)
+	je 1f
+	movq %r15, efi_scratch(%rip)		# r15
+	# save previous CR3
+	movq %cr3, %r15
+	movq %r15, efi_scratch+8(%rip)		# prev_cr3
+	movq efi_scratch+16(%rip), %r15		# EFI pgt
+	movq %r15, %cr3
+	1:
+	.endm
+
+	.macro RESTORE_PGT
+	cmpb $0, efi_scratch+24(%rip)
+	je 2f
+	movq efi_scratch+8(%rip), %r15
+	movq %r15, %cr3
+	movq efi_scratch(%rip), %r15
+	FLUSH_TLB_ALL
+	2:
+	.endm
 
-ENTRY(efi_call4)
-	SAVE_XMM
-	subq $32, %rsp
-	mov %r8, %r9
-	mov %rcx, %r8
-	mov %rsi, %rcx
-	call *%rdi
-	addq $32, %rsp
-	RESTORE_XMM
-	ret
-ENDPROC(efi_call4)
-
-ENTRY(efi_call5)
-	SAVE_XMM
-	subq $48, %rsp
-	mov %r9, 32(%rsp)
-	mov %r8, %r9
-	mov %rcx, %r8
-	mov %rsi, %rcx
-	call *%rdi
-	addq $48, %rsp
-	RESTORE_XMM
-	ret
-ENDPROC(efi_call5)
-
-ENTRY(efi_call6)
+ENTRY(efi_call)
 	SAVE_XMM
 	mov (%rsp), %rax
 	mov 8(%rax), %rax
@@ -109,8 +83,16 @@
 	mov %r8, %r9
 	mov %rcx, %r8
 	mov %rsi, %rcx
+	SWITCH_PGT
 	call *%rdi
+	RESTORE_PGT
 	addq $48, %rsp
 	RESTORE_XMM
 	ret
-ENDPROC(efi_call6)
+ENDPROC(efi_call)
+
+	.data
+ENTRY(efi_scratch)
+	.fill 3,8,0
+	.byte 0
+	.quad 0