From 046dcae0e7a8131953fa5779e030be40278c2c67 Mon Sep 17 00:00:00 2001
From: Mikhail Krichanov <mikhailkrichanov@gmail.com>
Date: Mon, 2 Sep 2024 11:14:11 +0300
Subject: [PATCH] SysCall: Restored nonvolatile registers for IA32, X64.

---
 .../Dxe/SysCall/IA32/CoreBootServices.nasm    | 18 +++++++------
 .../Dxe/SysCall/X64/CoreBootServices.nasm     | 25 ++++++++++++++-----
 2 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/MdeModulePkg/Core/Dxe/SysCall/IA32/CoreBootServices.nasm b/MdeModulePkg/Core/Dxe/SysCall/IA32/CoreBootServices.nasm
index f0ae792209..32a8dad0dd 100644
--- a/MdeModulePkg/Core/Dxe/SysCall/IA32/CoreBootServices.nasm
+++ b/MdeModulePkg/Core/Dxe/SysCall/IA32/CoreBootServices.nasm
@@ -176,10 +176,14 @@ ASM_PFX(CoreBootServices):
 global ASM_PFX(CallRing3)
 ASM_PFX(CallRing3):
     cli
+    ; Save nonvolatile registers EBX, EBP, EDI, ESI, ESP.
+    push    ebx
+    push    ebp
+    push    edi
+    push    esi
 
-    ; Save Core Stack pointers.
+    ; Save Core Stack pointer.
     mov     [ASM_PFX(CoreEsp)], esp
-    mov     [ASM_PFX(CoreEbp)], ebp
 
     push dword [ASM_PFX(gRing3EntryPoint)]
     push dword [ASM_PFX(gRing3CallStackTop)]
@@ -189,7 +193,7 @@ ASM_PFX(CallRing3):
     ; Prepare SYSEXIT arguments.
     pop     ecx
     pop     edx
-    mov     eax, [esp + 4] ; Data
+    mov     eax, [esp + 4 * 5] ; Data
 
     ; Switch to User Stack.
     mov     ebp, ecx
@@ -200,7 +204,10 @@ ASM_PFX(CallRing3):
 
 coreReturnAddress:
     mov     esp, [ASM_PFX(CoreEsp)]
-    mov     ebp, [ASM_PFX(CoreEbp)]
+    pop     esi
+    pop     edi
+    pop     ebp
+    pop     ebx
 
     call ASM_PFX(DisableSMAP)
     mov     eax, [edx + 2 * 4] ; User Argument 1
@@ -214,6 +221,3 @@ coreReturnAddress:
 SECTION .data
 ASM_PFX(CoreEsp):
   resd 1
-
-ASM_PFX(CoreEbp):
-  resd 1
diff --git a/MdeModulePkg/Core/Dxe/SysCall/X64/CoreBootServices.nasm b/MdeModulePkg/Core/Dxe/SysCall/X64/CoreBootServices.nasm
index 555387bba7..a18680ed6c 100644
--- a/MdeModulePkg/Core/Dxe/SysCall/X64/CoreBootServices.nasm
+++ b/MdeModulePkg/Core/Dxe/SysCall/X64/CoreBootServices.nasm
@@ -195,10 +195,18 @@ ASM_PFX(CallRing3):
     pushfq
     pop     r11
     cli
+    ; Save nonvolatile registers RBX, RBP, RDI, RSI, RSP, R12, R13, R14, and R15.
+    push    rbx
+    push    rbp
+    push    rdi
+    push    rsi
+    push    r12
+    push    r13
+    push    r14
+    push    r15
 
-    ; Save Core Stack pointers.
+    ; Save Core Stack pointer.
     mov     [ASM_PFX(CoreRsp)], rsp
-    mov     [ASM_PFX(CoreRbp)], rbp
 
     ; Save input Arguments.
     mov     r8, [ASM_PFX(gRing3CallStackTop)]
@@ -220,7 +228,15 @@ o64 sysret
 
 coreReturnAddress:
     mov     rsp, [ASM_PFX(CoreRsp)]
-    mov     rbp, [ASM_PFX(CoreRbp)]
+    pop     r15
+    pop     r14
+    pop     r13
+    pop     r12
+    pop     rsi
+    pop     rdi
+    pop     rbp
+    pop     rbx
+
     mov     rax, rdx
     sti
     ret
@@ -228,6 +244,3 @@ coreReturnAddress:
 SECTION .data
 ASM_PFX(CoreRsp):
   resq 1
-
-ASM_PFX(CoreRbp):
-  resq 1