FROMLIST: x86: rust: Disable entry padding with Rust

rustc-1.73.0 used by Linux does not support entry padding. Mark entry
padding support as explicitly incompatible with Rust.

Bug: 316624874
Link: https://lore.kernel.org/rust-for-linux/[email protected]/
Change-Id: I177faf86a72eb424f7b707d1e21e745994901ff6
Signed-off-by: Matthew Maurer <[email protected]>

Author: maurer

arch/x86/Kconfig

@@ -2397,6 +2397,9 @@ config CC_HAS_RETURN_THUNK
 config CC_HAS_ENTRY_PADDING
 	def_bool $(cc-option,-fpatchable-function-entry=16,16)
 
+config HAVE_ENTRY_PADDING
+	def_bool CC_HAS_ENTRY_PADDING && !RUST
+
 config FUNCTION_PADDING_CFI
 	int
 	default 59 if FUNCTION_ALIGNMENT_64B
@@ -2414,17 +2417,17 @@ config FUNCTION_PADDING_BYTES
 
 config CALL_PADDING
 	def_bool n
-	depends on CC_HAS_ENTRY_PADDING && OBJTOOL
+	depends on HAVE_ENTRY_PADDING && OBJTOOL
 	select FUNCTION_ALIGNMENT_16B
 
 config FINEIBT
 	def_bool y
-	depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
+	depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE && HAVE_ENTRY_PADDING
 	select CALL_PADDING
 
 config HAVE_CALL_THUNKS
 	def_bool y
-	depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
+	depends on HAVE_ENTRY_PADDING && RETHUNK && OBJTOOL
 
 config CALL_THUNKS
 	def_bool n