diff mbox series

[v3,1/3] x86/retpoline: split retpoline compiler support into separate option

Message ID 20220218143416.34475-2-roger.pau@citrix.com (mailing list archive)
State New, archived
Headers show
Series retpoline: add clang support + Kconfig selectable | expand

Commit Message

Roger Pau Monné Feb. 18, 2022, 2:34 p.m. UTC 
Keep the previous option as a way to signal generic retpoline support
regardless of the underlying compiler, while introducing a new
CC_INDIRECT_THUNK that signals whether the underlying compiler
supports retpoline.

No functional change intended.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Changes since v2:
 - Make the compiler option check generic instead of GCC only.

Changes since v1:
 - Put def_bool before depend on.
---
 xen/arch/x86/Kconfig |  6 +++++-
 xen/arch/x86/arch.mk | 10 ++++++----
 2 files changed, 11 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index b4abfca46f..a1a90da4fc 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -32,9 +32,13 @@  config ARCH_DEFCONFIG
 	string
 	default "arch/x86/configs/x86_64_defconfig"
 
-config INDIRECT_THUNK
+config CC_INDIRECT_THUNK
 	def_bool $(cc-option,-mindirect-branch-register)
 
+config INDIRECT_THUNK
+	def_bool y
+	depends on CC_INDIRECT_THUNK
+
 config HAS_AS_CET_SS
 	# binutils >= 2.29 or LLVM >= 6
 	def_bool $(as-instr,wrssq %rax$(comma)0;setssbsy)
diff --git a/xen/arch/x86/arch.mk b/xen/arch/x86/arch.mk
index fa7cf38443..6388b1d93f 100644
--- a/xen/arch/x86/arch.mk
+++ b/xen/arch/x86/arch.mk
@@ -42,10 +42,12 @@  CFLAGS += -mno-red-zone -fpic
 # SSE setup for variadic function calls.
 CFLAGS += -mno-sse $(call cc-option,$(CC),-mskip-rax-setup)
 
-# Compile with thunk-extern, indirect-branch-register if avaiable.
-CFLAGS-$(CONFIG_INDIRECT_THUNK) += -mindirect-branch=thunk-extern
-CFLAGS-$(CONFIG_INDIRECT_THUNK) += -mindirect-branch-register
-CFLAGS-$(CONFIG_INDIRECT_THUNK) += -fno-jump-tables
+ifeq ($(CONFIG_INDIRECT_THUNK),y)
+# Compile with gcc thunk-extern, indirect-branch-register if available.
+CFLAGS-$(CONFIG_CC_IS_GCC) += -mindirect-branch=thunk-extern
+CFLAGS-$(CONFIG_CC_IS_GCC) += -mindirect-branch-register
+CFLAGS-$(CONFIG_CC_IS_GCC) += -fno-jump-tables
+endif
 
 # If supported by the compiler, reduce stack alignment to 8 bytes. But allow
 # this to be overridden elsewhere.