arm64: signal32: Drop pointless call to sigdelsetmask()

Commit 77097ae5 ("most of set_current_blocked() callers want
SIGKILL/SIGSTOP removed from set") extended set_current_blocked() to
remove SIGKILL and SIGSTOP from the new signal set and updated all
callers accordingly.

Unfortunately, this collided with the merge of the arm64 architecture,
which duly removes these signals when restoring the compat sigframe, as
this was what was previously done by arch/arm/.

Remove the redundant call to sigdelsetmask() from
compat_restore_sigframe().
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210825093911.24493-1-will@kernel.orgSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/signal32.c

@@ -46,8 +46,6 @@ struct compat_aux_sigframe {
 	unsigned long			end_magic;
 } __attribute__((__aligned__(8)));
 
-#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
-
 static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
 {
 	compat_sigset_t	cset;
@@ -190,10 +188,8 @@ static int compat_restore_sigframe(struct pt_regs *regs,
 	unsigned long psr;
 
 	err = get_sigset_t(&set, &sf->uc.uc_sigmask);
-	if (err == 0) {
-		sigdelsetmask(&set, ~_BLOCKABLE);
+	if (err == 0)
 		set_current_blocked(&set);
-	}
 
 	__get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
 	__get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);