[PATCH] x86/fpu: use __alignof__ to avoid UB in TYPE_ALIGN

[YingChi Long]

WG14 N2350 made very clear that it is an UB having type definitions with
in "offsetof". This patch change the implementation of macro
"TYPE_ALIGN" to builtin "__alignof__" to avoid undefined behavior.

I've grepped all source files to find any type definitions within
"offsetof".

    offsetof\(struct .*\{ .*,

This implementation of macro "TYPE_ALIGN" seemes to be the only case of
type definitions within offsetof in the kernel codebase.

Signed-off-by: YingChi Long <me@xxxxxxxxx>
Link: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm
---
 arch/x86/kernel/fpu/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 621f4b6cac4a..41425ba0b6b1 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -134,7 +134,7 @@ static void __init fpu__init_system_generic(void)
 }
 
 /* Get alignment of the TYPE. */
-#define TYPE_ALIGN(TYPE) offsetof(struct { char x; TYPE test; }, test)
+#define TYPE_ALIGN(TYPE) __alignof__(TYPE)
 
 /*
  * Enforce that 'MEMBER' is the last field of 'TYPE'.
-- 
2.35.1