From 0aa2e4ec963597794dd8f8b36f77f4d0cf4e03c8 Mon Sep 17 00:00:00 2001
From: Michael Brown <mcb30@ipxe.org>
Date: Tue, 5 Sep 2023 19:47:38 +0800
Subject: [PATCH] [librm] Use explicit operand size when pushing a label
 address

We currently use "push $1f" within inline assembly to push the address
of the real-mode code fragment, relying on the assembler to treat this
as "pushl" for 32-bit code or "pushq" for 64-bit code.

As of binutils commit 5cc0077 ("x86: further adjust extend-to-32bit-
address conditions"), first included in binutils-2.41, this implicit
operand size is no longer calculated as expected and 64-bit builds
will fail with

  Error: operand size mismatch for `push'

Fix by adding an explicit operand size to the "push" instruction.

Originally-fixed-by: Justin Cano <jstncno@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

---
 src/arch/x86/include/librm.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/arch/x86/include/librm.h b/src/arch/x86/include/librm.h
index 5196d39..40f0754 100644
--- a/src/arch/x86/include/librm.h
+++ b/src/arch/x86/include/librm.h
@@ -250,8 +250,10 @@ extern void remove_user_from_rm_stack ( userptr_t data, size_t size );
 /* CODE_DEFAULT: restore default .code32/.code64 directive */
 #ifdef __x86_64__
 #define CODE_DEFAULT ".code64"
+#define STACK_DEFAULT "q"
 #else
 #define CODE_DEFAULT ".code32"
+#define STACK_DEFAULT "l"
 #endif
 
 /* LINE_SYMBOL: declare a symbol for the current source code line */
@@ -268,7 +270,7 @@ extern void remove_user_from_rm_stack ( userptr_t data, size_t size );
 
 /* REAL_CODE: declare a fragment of code that executes in real mode */
 #define REAL_CODE( asm_code_str )			\
-	"push $1f\n\t"					\
+	"push" STACK_DEFAULT " $1f\n\t"			\
 	"call real_call\n\t"				\
 	TEXT16_CODE ( "\n1:\n\t"			\
 		      asm_code_str			\
@@ -277,7 +279,7 @@ extern void remove_user_from_rm_stack ( userptr_t data, size_t size );
 
 /* PHYS_CODE: declare a fragment of code that executes in flat physical mode */
 #define PHYS_CODE( asm_code_str )			\
-	"push $1f\n\t"					\
+	"push" STACK_DEFAULT " $1f\n\t"			\
 	"call phys_call\n\t"				\
 	".section \".text.phys\", \"ax\", @progbits\n\t"\
 	"\n" LINE_SYMBOL "\n\t"				\
-- 
2.44.0

