[PATCH v6 1/3] xen: introduce Kconfig function alignment option

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

And use it to replace CODE_ALIGN in assembly.  This allows to generalize the
way the code alignment gets set across all architectures.

No functional change intended.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Changes since v5:
 - New in this version.
---
 xen/Kconfig                         | 17 +++++++++++++++++
 xen/arch/arm/Kconfig                |  1 +
 xen/arch/arm/include/asm/config.h   |  3 +--
 xen/arch/ppc/Kconfig                |  1 +
 xen/arch/ppc/include/asm/config.h   |  3 ---
 xen/arch/riscv/Kconfig              |  1 +
 xen/arch/riscv/include/asm/config.h |  1 -
 xen/arch/x86/Kconfig                |  1 +
 xen/arch/x86/include/asm/config.h   |  3 +--
 xen/include/xen/linkage.h           |  5 +++--
 10 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/xen/Kconfig b/xen/Kconfig
index 134e6e68ad84..1e1b041fd52f 100644
--- a/xen/Kconfig
+++ b/xen/Kconfig
@@ -37,6 +37,23 @@ config CC_HAS_VISIBILITY_ATTRIBUTE
 config CC_SPLIT_SECTIONS
        bool
 
+# Set code alignment.
+#
+# Allow setting on a boolean basis, and then convert such selection to an
+# integer for the build system and code to consume more easily.
+config FUNCTION_ALIGNMENT_4B
+       bool
+config FUNCTION_ALIGNMENT_8B
+       bool
+config FUNCTION_ALIGNMENT_16B
+       bool
+config FUNCTION_ALIGNMENT
+       int
+       default 16 if FUNCTION_ALIGNMENT_16B
+       default  8 if  FUNCTION_ALIGNMENT_8B
+       default  4 if  FUNCTION_ALIGNMENT_4B
+       default  0
+
 source "arch/$(SRCARCH)/Kconfig"
 
 config DEFCONFIG_LIST
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index 50e9bfae1ac8..80fb5b14f04e 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -16,6 +16,7 @@ config ARM
        select HAS_PASSTHROUGH
        select HAS_UBSAN
        select IOMMU_FORCE_PT_SHARE
+       select FUNCTION_ALIGNMENT_4B
 
 config ARCH_DEFCONFIG
        string
diff --git a/xen/arch/arm/include/asm/config.h 
b/xen/arch/arm/include/asm/config.h
index 3b6d829197a4..a2e22b659d53 100644
--- a/xen/arch/arm/include/asm/config.h
+++ b/xen/arch/arm/include/asm/config.h
@@ -53,8 +53,7 @@
 
 /* Linkage for ARM */
 #ifdef __ASSEMBLY__
-#define CODE_ALIGN 4
-#define ALIGN .balign CODE_ALIGN
+#define ALIGN .balign CONFIG_FUNCTION_ALIGNMENT
 #define ENTRY(name)                             \
   .globl name;                                  \
   ALIGN;                                        \
diff --git a/xen/arch/ppc/Kconfig b/xen/arch/ppc/Kconfig
index ab116ffb2a70..6b3b2bb95f56 100644
--- a/xen/arch/ppc/Kconfig
+++ b/xen/arch/ppc/Kconfig
@@ -1,6 +1,7 @@
 config PPC
        def_bool y
        select HAS_DEVICE_TREE
+       select FUNCTION_ALIGNMENT_4B
 
 config PPC64
        def_bool y
diff --git a/xen/arch/ppc/include/asm/config.h 
b/xen/arch/ppc/include/asm/config.h
index e5d201e16c50..e0a0abfeb408 100644
--- a/xen/arch/ppc/include/asm/config.h
+++ b/xen/arch/ppc/include/asm/config.h
@@ -31,9 +31,6 @@
 #define INVALID_VCPU_ID MAX_VIRT_CPUS
 
 /* Linkage for PPC */
-#ifdef __ASSEMBLY__
-#define CODE_ALIGN 4
-#endif
 
 #define XEN_VIRT_START _AC(0xc000000000000000, UL)
 
diff --git a/xen/arch/riscv/Kconfig b/xen/arch/riscv/Kconfig
index f382b36f6c82..b4b354a7786e 100644
--- a/xen/arch/riscv/Kconfig
+++ b/xen/arch/riscv/Kconfig
@@ -1,5 +1,6 @@
 config RISCV
        def_bool y
+       select FUNCTION_ALIGNMENT_16B
 
 config RISCV_64
        def_bool y
diff --git a/xen/arch/riscv/include/asm/config.h 
b/xen/arch/riscv/include/asm/config.h
index a80cdd4f857c..99ea5635208b 100644
--- a/xen/arch/riscv/include/asm/config.h
+++ b/xen/arch/riscv/include/asm/config.h
@@ -69,7 +69,6 @@
 
 /* Linkage for RISCV */
 #ifdef __ASSEMBLY__
-#define CODE_ALIGN 16
 #define CODE_FILL /* empty */
 #endif
 
diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index 1acdffc51c22..3dd8f18b46ef 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -29,6 +29,7 @@ config X86
        select HAS_UBSAN
        select HAS_VPCI if HVM
        select NEEDS_LIBELF
+       select FUNCTION_ALIGNMENT_16B
 
 config ARCH_DEFCONFIG
        string
diff --git a/xen/arch/x86/include/asm/config.h 
b/xen/arch/x86/include/asm/config.h
index 660246d1dae5..ab7288cb3682 100644
--- a/xen/arch/x86/include/asm/config.h
+++ b/xen/arch/x86/include/asm/config.h
@@ -43,9 +43,8 @@
 
 /* Linkage for x86 */
 #ifdef __ASSEMBLY__
-#define CODE_ALIGN 16
 #define CODE_FILL 0x90
-#define ALIGN .align CODE_ALIGN, CODE_FILL
+#define ALIGN .align CONFIG_FUNCTION_ALIGNMENT, CODE_FILL
 #define ENTRY(name)                             \
   ALIGN;                                        \
   GLOBAL(name)
diff --git a/xen/include/xen/linkage.h b/xen/include/xen/linkage.h
index 0997e16810b2..770ae49963b8 100644
--- a/xen/include/xen/linkage.h
+++ b/xen/include/xen/linkage.h
@@ -41,9 +41,10 @@
  */
 #define count_args_exp(args...) count_args(args)
 #if count_args_exp(CODE_FILL)
-# define DO_CODE_ALIGN(align...) LASTARG(CODE_ALIGN, ## align), CODE_FILL
+# define DO_CODE_ALIGN(align...) LASTARG(CONFIG_FUNCTION_ALIGNMENT, ## align), 
\
+                                 CODE_FILL
 #else
-# define DO_CODE_ALIGN(align...) LASTARG(CODE_ALIGN, ## align)
+# define DO_CODE_ALIGN(align...) LASTARG(CONFIG_FUNCTION_ALIGNMENT, ## align)
 #endif
 
 #define FUNC(name, align...) \
-- 
2.43.0