[patch V2 2/6] kbuild: Disable asm goto on clang < 17

[Thomas Gleixner]

clang < 17 fails to use scope local labels with asm goto:

     {
     	__label__ local_lbl;
	...
	unsafe_get_user(uval, uaddr, local_lbl);
	...
	return 0;
	local_lbl:
		return -EFAULT;
     }

when two such scopes exist in the same function:

  error: cannot jump from this asm goto statement to one of its possible targets

That prevents using local labels for a cleanup based user access mechanism.

As there is no way to provide a simple test case for the 'depends on' test
in Kconfig, mark ASM goto broken on clang versions < 17 to get this road
block out of the way.

Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
Cc: Nathan Chancellor <nathan at kernel.org>
---
V2: New patch
---
 init/Kconfig |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/init/Kconfig
+++ b/init/Kconfig
@@ -96,9 +96,14 @@ config GCC_ASM_GOTO_OUTPUT_BROKEN
 	default y if GCC_VERSION >= 120000 && GCC_VERSION < 120400
 	default y if GCC_VERSION >= 130000 && GCC_VERSION < 130300
 
+config CLANG_ASM_GOTO_OUTPUT_BROKEN
+	bool
+	depends on CC_IS_CLANG
+	default y if CLANG_VERSION < 170000
+
 config CC_HAS_ASM_GOTO_OUTPUT
 	def_bool y
-	depends on !GCC_ASM_GOTO_OUTPUT_BROKEN
+	depends on !GCC_ASM_GOTO_OUTPUT_BROKEN && !CLANG_ASM_GOTO_OUTPUT_BROKEN
 	depends on $(success,echo 'int foo(int x) { asm goto ("": "=r"(x) ::: bar); return x; bar: return 0; }' | $(CC) -x c - -c -o /dev/null)
 
 config CC_HAS_ASM_GOTO_TIED_OUTPUT