[PATCH 12/24] alpha: add HAVE_ARCH_THREAD_STRUCT_WHITELIST support

[Matt Turner]

Alpha's thread_struct is empty (all per-thread state lives in
thread_info), so the whitelist is trivially empty. This is more
explicit than the generic fallback, which computes the full
thread_struct size as copyable.

Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Matt Turner <mattst88@xxxxxxxxx>
---
 arch/alpha/Kconfig                 | 1 +
 arch/alpha/include/asm/processor.h | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git ./arch/alpha/Kconfig ./arch/alpha/Kconfig
index 2ae514bea4cf..e6fa8da0abff 100644
--- ./arch/alpha/Kconfig
+++ ./arch/alpha/Kconfig
@@ -42,6 +42,7 @@ config ALPHA
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_SECCOMP
 	select HAVE_ARCH_SECCOMP_FILTER
+	select HAVE_ARCH_THREAD_STRUCT_WHITELIST
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_MOD_ARCH_SPECIFIC
 	select LOCK_MM_AND_FIND_VMA
diff --git ./arch/alpha/include/asm/processor.h ./arch/alpha/include/asm/processor.h
index 5dce5518a211..c461a26d47b3 100644
--- ./arch/alpha/include/asm/processor.h
+++ ./arch/alpha/include/asm/processor.h
@@ -26,6 +26,13 @@
 struct thread_struct { };
 #define INIT_THREAD  { }
 
+static inline void arch_thread_struct_whitelist(unsigned long *offset,
+						unsigned long *size)
+{
+	*offset = 0;
+	*size = 0;
+}
+
 /* Do necessary setup to start up a newly executed thread.  */
 struct pt_regs;
 extern void start_thread(struct pt_regs *, unsigned long, unsigned long);
-- 
2.54.0