Add endbr32/64 instruction at the start of asm functions

Only do so when compiling with -fcf-protection (=> __CET__ is defined).

Inspired by:
004ff08738

Comment:
  Fixes SIGILL in tests on 11th gen intel (IBT)

#23

src/lib/amd64_blend.S

@@ -1,8 +1,6 @@
 #include <config.h>
 #include "asm.h"
 
-#ifdef DO_AMD64_ASM
-
 /*\
 |*| AMD64 SSE2 assembly blending routines for Imlib2
 |*| Written by John Slaten <zartheenumerator@comcast.net>
@@ -98,10 +96,8 @@ FN_(imlib_amd64_reshade_copy_rgb_to_rgba)
 \*/
 
 
-
-
-
 #define ENTER		\
+	ENDBR_		; \
 	pushq %rbp	; \
 	movq %rsp, %rbp	; \
 	pushq %rbx	; \
@@ -5521,8 +5517,6 @@ PR_(imlib_amd64_reshade_copy_rgb_to_rgba):
 	LEAVE
 SIZE(imlib_amd64_reshade_copy_rgb_to_rgba)
 
-#endif
-
 #ifdef __ELF__
 .section .note.GNU-stack,"",@progbits
 #endif

src/lib/amd64_blend_cmod.S

@@ -1,8 +1,6 @@
 #include <config.h>
 #include "asm.h"
 
-#ifdef DO_AMD64_ASM
-
 /*\
 |*| AMD64 SSE2 assembly blending routines for Imlib2
 |*| Written by John Slaten <zartheenumerator@comcast.net>
@@ -106,14 +104,8 @@ FN_(imlib_amd64_reshade_copy_rgb_to_rgba_cmod)
 \*/
 
 
-
-
-
-
-
-
-
 #define ENTER		\
+	ENDBR_		; \
 	pushq %rbp	; \
 	movq %rsp, %rbp	; \
 	pushq %rbx	; \
@@ -16778,8 +16770,6 @@ PR_(imlib_amd64_reshade_copy_rgb_to_rgba_cmod):
 	LEAVE
 SIZE(imlib_amd64_reshade_copy_rgb_to_rgba_cmod)
 
-#endif
-
 #ifdef __ELF__
 .section .note.GNU-stack,"",@progbits
 #endif

src/lib/asm.h

@@ -17,4 +17,14 @@
     .size PR_(sym),.-PR_(sym); \
     .align 8;
 
+#ifdef __CET__
+#if defined(DO_MMX_ASM)
+#define ENDBR_ endbr32
+#elif defined(DO_AMD64_ASM)
+#define ENDBR_ endbr64
+#endif
+#else
+#define ENDBR_
+#endif
+
 #endif                          /* __ASM_H */

src/lib/asm_blend.S

@@ -1,8 +1,6 @@
 #include <config.h>
 #include "asm.h"
 
-#ifdef DO_MMX_ASM
-
 /*\
 |*| MMX assembly blending routines for Imlib2
 |*| Written by Willem Monsuwe <willem@stack.nl>
@@ -63,6 +61,7 @@ FN_(imlib_mmx_reshade_copy_rgb_to_rgba)
 /*\ Common code \*/
 /*\ Set MMX mode, save registers, load common parameters \*/
 #define ENTER				\
+	ENDBR_				;\
 	pushl %ebp			;\
 	movl  %esp, %ebp		;\
 	pushl %ebx			;\
@@ -95,7 +94,6 @@ FN_(imlib_mmx_reshade_copy_rgb_to_rgba)
 	decl %edx			;\
 	jns 8b
 
-
 /*\ Unset MMX mode, reset registers, return \*/
 #define LEAVE			\
 9:				;\
@@ -1024,8 +1022,6 @@ PR_(imlib_mmx_reshade_copy_rgb_to_rgba):
 
 SIZE(imlib_mmx_reshade_copy_rgb_to_rgba)
 
-#endif
-
 #ifdef __ELF__
 .section .note.GNU-stack,"",@progbits
 #endif

src/lib/asm_blend_cmod.S

@@ -1,8 +1,6 @@
 #include <config.h>
 #include "asm.h"
 
-#ifdef DO_MMX_ASM
-
 /*\
 |*| MMX assembly blending routines, with colour modding, for Imlib2
 |*| Written by Willem Monsuwe <willem@stack.nl>
@@ -81,6 +79,7 @@ FN_(imlib_mmx_reshade_copy_rgb_to_rgba_cmod)
 /*\ Common code \*/
 /*\ Set MMX mode, save registers, load common parameters \*/
 #define ENTER				\
+	ENDBR_				;\
 	pushl %ebp			;\
 	movl  %esp, %ebp		;\
 	pushl %ebx			;\
@@ -113,7 +112,6 @@ FN_(imlib_mmx_reshade_copy_rgb_to_rgba_cmod)
 	decl %edx			;\
 	jns 8b
 
-
 /*\ Unset MMX mode, reset registers, return \*/
 #define LEAVE			\
 9:				;\
@@ -1563,8 +1561,6 @@ PR_(imlib_mmx_reshade_copy_rgb_to_rgba_cmod):
 
 SIZE(imlib_mmx_reshade_copy_rgb_to_rgba_cmod)
 
-#endif
-
 #ifdef __ELF__
 .section .note.GNU-stack,"",@progbits
 #endif

src/lib/asm_rgba.S

@@ -1,8 +1,6 @@
 #include <config.h>
 #include "asm.h"
 
-#ifdef DO_MMX_ASM
-
 /*\
 |*| MMX assembly rgba rendering routines for Imlib2
 |*| Written by Willem Monsuwe <willem@stack.nl>
@@ -38,6 +36,7 @@ FN_(imlib_get_cpuid)
 /*\ Common code \*/
 /*\ Save registers, load common parameters \*/
 #define ENTER			\
+	ENDBR_;			\
 	pushl %ebp;		\
 	movl  %esp, %ebp;	\
 	pushl %ebx;		\
@@ -81,7 +80,6 @@ FN_(imlib_get_cpuid)
 	ret
 
 
-
 PR_(imlib_mmx_bgr565_fast):
 	LOAD_IMMQ(mul_bgr565, %mm7)	/*\ This constant is the only difference \*/
 	CLEANUP_IMMQ_LOADS(1)
@@ -273,8 +271,6 @@ PR_(imlib_get_cpuid):
 
 SIZE(imlib_get_cpuid)
 
-#endif
-
 #ifdef __ELF__
 .section .note.GNU-stack,"",@progbits
 #endif

src/lib/asm_rotate.S

@@ -1,8 +1,6 @@
 #include <config.h>
 #include "asm.h"
 
-#ifdef DO_MMX_ASM
-
 /*\
 |*| MMX assembly rotation routine for Imlib2
 |*| Written by Willem Monsuwe <willem@stack.nl>
@@ -447,8 +445,6 @@ PR_(imlib_mmx_RotateAA):
 
 SIZE(imlib_mmx_RotateAA)
 
-#endif
-
 #ifdef __ELF__
 .section .note.GNU-stack,"",@progbits
 #endif

src/lib/asm_scale.S

@@ -1,8 +1,6 @@
 #include <config.h>
 #include "asm.h"
 
-#ifdef DO_MMX_ASM
-
 /*\
 |*| MMX assembly scaling routine for Imlib2
 |*| Written by Willem Monsuwe <willem@stack.nl>
@@ -788,8 +786,6 @@ PR_(imlib_Scale_mmx_AARGBA):
 
 SIZE(imlib_Scale_mmx_AARGBA)
 
-#endif
-
 #ifdef __ELF__
 .section .note.GNU-stack,"",@progbits
 #endif