[PATCH 4/5] Reduce assembly code size of exception entry points

[Frediano Ziglio <frediano.ziglio@xxxxxxxxx>]

We just pushed a 8-bytes zero and exception constants are
small so we can just write a single byte saving 3 bytes for
instruction.
With ENDBR64 this reduces the size of the entry point from 32 to 16
bytes (due to alignment).

Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
---
 xen/arch/x86/x86_64/entry.S | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index ecdd6e5b47..b6a157d96a 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -898,28 +898,28 @@ END(handle_exception)
 FUNC(entry_DE)
         ENDBR64
         pushq $0
-        movl  $X86_EXC_DE, 4(%rsp)
+        movb  $X86_EXC_DE, 4(%rsp)
         jmp   handle_exception
 END(entry_DE)
 
 FUNC(entry_MF)
         ENDBR64
         pushq $0
-        movl  $X86_EXC_MF, 4(%rsp)
+        movb  $X86_EXC_MF, 4(%rsp)
         jmp   handle_exception
 END(entry_MF)
 
 FUNC(entry_XM)
         ENDBR64
         pushq $0
-        movl  $X86_EXC_XM, 4(%rsp)
+        movb  $X86_EXC_XM, 4(%rsp)
         jmp   handle_exception
 END(entry_XM)
 
 FUNC(entry_NM)
         ENDBR64
         pushq $0
-        movl  $X86_EXC_NM, 4(%rsp)
+        movb  $X86_EXC_NM, 4(%rsp)
         jmp   handle_exception
 END(entry_NM)
 
@@ -933,28 +933,28 @@ END(entry_DB)
 FUNC(entry_BP)
         ENDBR64
         pushq $0
-        movl  $X86_EXC_BP, 4(%rsp)
+        movb  $X86_EXC_BP, 4(%rsp)
         jmp   handle_exception
 END(entry_BP)
 
 FUNC(entry_OF)
         ENDBR64
         pushq $0
-        movl  $X86_EXC_OF, 4(%rsp)
+        movb  $X86_EXC_OF, 4(%rsp)
         jmp   handle_exception
 END(entry_OF)
 
 FUNC(entry_BR)
         ENDBR64
         pushq $0
-        movl  $X86_EXC_BR, 4(%rsp)
+        movb  $X86_EXC_BR, 4(%rsp)
         jmp   handle_exception
 END(entry_BR)
 
 FUNC(entry_UD)
         ENDBR64
         pushq $0
-        movl  $X86_EXC_UD, 4(%rsp)
+        movb  $X86_EXC_UD, 4(%rsp)
         jmp   handle_exception
 END(entry_UD)
 
-- 
2.34.1