[edk2-devel] [PATCH] UefiCpuPkg/CpuDxe: Fix boot error

[Guo Dong]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3084

When DXE drivers are dispatched above 4GB memory in 64bit
mode, the address setCodeSelectorLongJump in stack will
be override by parameter. Jump to Qword is not supported
by some processors. So use retfq instead.

Signed-off-by: Guo Dong <guo.dong at intel.com>
---
 UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm b/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
index c3489bcc3e..e33ddb2784 100644
--- a/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
+++ b/UefiCpuPkg/CpuDxe/X64/CpuAsm.nasm
@@ -20,13 +20,11 @@
 ;------------------------------------------------------------------------------
 global ASM_PFX(SetCodeSelector)
 ASM_PFX(SetCodeSelector):
-    sub     rsp, 0x10
+    push    rcx,
     lea     rax, [setCodeSelectorLongJump]
-    mov     [rsp], rax
-    mov     [rsp+4], cx
-    jmp     dword far [rsp]
+    push    rax
+    DB 0x48, 0xcb                      ; retfq
 setCodeSelectorLongJump:
-    add     rsp, 0x10
     ret
 
 ;------------------------------------------------------------------------------
-- 
2.16.2.windows.1



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