x86: Introduce restart_block->arch_data to remove TS_COMPAT_RESTART

Save the current_thread_info()->status of X86 in the new
restart_block->arch_data field so TS_COMPAT_RESTART can be removed again.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210201174716.GA17898@redhat.com

arch/x86/include/asm/thread_info.h

@@ -217,18 +217,10 @@ static inline int arch_within_stack_frames(const void * const stack,
 #ifndef __ASSEMBLY__
 #ifdef CONFIG_COMPAT
 #define TS_I386_REGS_POKED	0x0004	/* regs poked by 32-bit ptracer */
-#define TS_COMPAT_RESTART	0x0008
 
-#define arch_set_restart_data	arch_set_restart_data
+#define arch_set_restart_data(restart)	\
+	do { restart->arch_data = current_thread_info()->status; } while (0)
 
-static inline void arch_set_restart_data(struct restart_block *restart)
-{
-	struct thread_info *ti = current_thread_info();
-	if (ti->status & TS_COMPAT)
-		ti->status |= TS_COMPAT_RESTART;
-	else
-		ti->status &= ~TS_COMPAT_RESTART;
-}
 #endif
 
 #ifdef CONFIG_X86_32

arch/x86/kernel/signal.c

@@ -767,7 +767,7 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
 {
 #ifdef CONFIG_IA32_EMULATION
-	if (current_thread_info()->status & TS_COMPAT_RESTART)
+	if (current->restart_block.arch_data & TS_COMPAT)
 		return __NR_ia32_restart_syscall;
 #endif
 #ifdef CONFIG_X86_X32_ABI

include/linux/restart_block.h

@@ -23,6 +23,7 @@ enum timespec_type {
  * System call restart block.
  */
 struct restart_block {
+	unsigned long arch_data;
 	long (*fn)(struct restart_block *);
 	union {
 		/* For futex_wait and futex_wait_requeue_pi */