[PATCH v3 09/59] x86/asm: Differentiate between code and function alignment

Peter Zijlstra
2022-09-15T11:41:11Z

From: Thomas Gleixner <tglx@linutronix.de>

Create SYM_F_ALIGN to differentiate alignment requirements between
SYM_CODE and SYM_FUNC.

This distinction is useful later when adding padding in front of
functions; IOW this allows following the compiler's
patchable-function-entry option.

[peterz: Changelog]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/linkage.h | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)

--- a/arch/x86/include/asm/linkage.h
+++ b/arch/x86/include/asm/linkage.h
@@ -12,11 +12,15 @@
#define asmlinkage CPP_ASMLINKAGE __attribute__((regparm(0)))
#endif /* CONFIG_X86_32 */

-#ifdef __ASSEMBLY__
-
#define __ALIGN .balign CONFIG_FUNCTION_ALIGNMENT, 0x90;
#define __ALIGN_STR __stringify(__ALIGN)

+#define ASM_FUNC_ALIGN __ALIGN_STR
+#define __FUNC_ALIGN __ALIGN
+#define SYM_F_ALIGN __FUNC_ALIGN
+
+#ifdef __ASSEMBLY__
+
#if defined(CONFIG_RETHUNK) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
#define RET jmp __x86_return_thunk
#else /* CONFIG_RETPOLINE */
@@ -43,7 +47,7 @@

/* SYM_FUNC_START -- use for global functions */
#define SYM_FUNC_START(name) \
- SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN) \
+ SYM_START(name, SYM_L_GLOBAL, SYM_F_ALIGN) \
ENDBR

/* SYM_FUNC_START_NOALIGN -- use for global functions, w/o alignment */
@@ -53,7 +57,7 @@

/* SYM_FUNC_START_LOCAL -- use for local functions */
#define SYM_FUNC_START_LOCAL(name) \
- SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN) \
+ SYM_START(name, SYM_L_LOCAL, SYM_F_ALIGN) \
ENDBR

/* SYM_FUNC_START_LOCAL_NOALIGN -- use for local functions, w/o alignment */
@@ -63,7 +67,7 @@

/* SYM_FUNC_START_WEAK -- use for weak functions */
#define SYM_FUNC_START_WEAK(name) \
- SYM_START(name, SYM_L_WEAK, SYM_A_ALIGN) \
+ SYM_START(name, SYM_L_WEAK, SYM_F_ALIGN) \
ENDBR

/* SYM_FUNC_START_WEAK_NOALIGN -- use for weak functions, w/o alignment */