sh64: fix altstack switching on sigreturn

incidentally, declaring a local variable as __user (!) to make
sparse STFU is really sick.  Especially since sparse had been
100% right - it *is* a bug.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/arch/sh/kernel/signal_64.c b/arch/sh/kernel/signal_64.c
index 23853814bd174284a3a75c62b88154ac8fb890d3..d867cd95a62261c7ae25a91b4ce5d36b179b8f0f 100644 (file)
--- a/arch/sh/kernel/signal_64.c
+++ b/arch/sh/kernel/signal_64.c
@@ -347,7 +347,6 @@ asmlinkage int sys_rt_sigreturn(unsigned long r2, unsigned long r3,
 {
        struct rt_sigframe __user *frame = (struct rt_sigframe __user *) (long) REF_REG_SP;
        sigset_t set;
-       stack_t __user st;
        long long ret;
 
        /* Always make any pending restarted system calls return -EINTR */
@@ -365,11 +364,10 @@ asmlinkage int sys_rt_sigreturn(unsigned long r2, unsigned long r3,
                goto badframe;
        regs->pc -= 4;
 
-       if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
-               goto badframe;
        /* It is more difficult to avoid calling this function than to
           call it and ignore errors.  */
-       do_sigaltstack(&st, NULL, REF_REG_SP);
+       if (do_sigaltstack(&frame->uc.uc_stack, NULL, REF_REG_SP) == -EFAULT)
+               goto badframe;
 
        return (int) ret;