sw64: fix setup_rt_frame for non SA_SIGINFO

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I56YJ1

--------------------------------

Original implementation has deprecated sigframe and always use
rt_sigframe for signal handler. But glibc remain unchanged, where
handler takes $a2 as sigcontext pointer when SA_SIGINFO is not set
and compatibility is break. As on sw64, SA_SIGINFO is not only a
flag to specify sa_sigaction but also a flag to specify rt_sigframe
and rt_sigreturn. It used to setup old sigframe and specify sigreturn
for handler if SA_SIGINFO is not set.

To maintain compatibility, this patch set $a1 with exception code and
and set $a2 with sigcontext pointer in that case, which seems a mix
of modern rt_sigframe and traditional sigframe.

Actually, it is unnecessary to setup rt_sigframe for non SA_SIGINFO
handler, because a rt_sigframe is larger than sigframe. Maybe the old
sigframe will be reverted some day.
Signed-off-by: NHe Sheng <hesheng@wxiat.com>
Signed-off-by: NGu Zitao <guzitao@wxiat.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/sw_64/kernel/signal.c

@@ -240,7 +240,8 @@ setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 	if (!access_ok(frame, sizeof(*frame)))
 		return -EFAULT;
 
-	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+		err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 
 	/* Create the ucontext.  */
 	err |= __put_user(0, &frame->uc.uc_flags);
@@ -262,8 +263,15 @@ setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 	regs->r26 = r26;
 	regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 	regs->r16 = ksig->sig;                    /* a0: signal number */
-	regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
-	regs->r18 = (unsigned long) &frame->uc;   /* a2: ucontext pointer */
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+		/* a1: siginfo pointer, a2: ucontext pointer */
+		regs->r17 = (unsigned long) &frame->info;
+		regs->r18 = (unsigned long) &frame->uc;
+	} else {
+		/* a1: exception code, a2: sigcontext pointer */
+		regs->r17 = 0;
+		regs->r18 = (unsigned long) &frame->uc.uc_mcontext;
+	}
 	wrusp((unsigned long) frame);
 
 #if DEBUG_SIG