[PATCH 3/3] signal.c: fix gcc warning on 32 bits kernel

[Franck Bui-Huu <vagabon.xyz@gmail.com>]

From: Franck Bui-Huu <fbuihuu@gmail.com>

This hack prevents gcc to produce the following warning:

  CC      arch/mips/kernel/signal.o
arch/mips/kernel/signal.c: In function `sys_sigaction':
arch/mips/kernel/signal.c:266: warning: cast to pointer from integer of 
different size

This warning is due to the following line:

        __get_user(new_ka.sa.sa_handler, &act->sa_handler);

Indeed when __get_user() is expanded it produces the following
code:

        switch (sizeof(*(&act->sa_handler))) {
        ... [snip] ...
        case 8: {
                unsigned long long __gu_tmp;
                __asm__ __volatile__(
                        "1: lw      %1, (%3)                  \n"
                        "2: lw      %D1, 4(%3)                \n"
                        "   move    %0, $0                    \n"
                        "3: .section        .fixup,\"ax\"     \n"
                        "4: li      %0, %4                    \n"
                        "   move    %1, $0                    \n"
                        "   move    %D1, $0                   \n"
                        "   j       3b                        \n"
                        "   .previous                         \n"
                        "   .section        __ex_table,\"a\"  \n"
                        "   " ".word" "     1b, 4b            \n"
                        "   " ".word" "     2b, 4b            \n"
                        "   .previous                         \n"
                        : "=r" (__gu_err), "=&r" (__gu_tmp)
                        : "0" (0), "r" ((&act->sa_handler)), "i" (-14));

                (((new_ka.sa.sa_handler))) = 
(__typeof__(*((&act->sa_handler)))) __gu_tmp;
                };
                break;
        default:
                __get_user_unknown();
                break;
        }

which actually try to do:

        new_ka.sa.sa_handler = (__sighandler_t) __gu_tmp;

Here we try to cast an 'unsigned long long' into a 32 bits pointer and
that's the reason of the warning.

Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
---
 arch/mips/kernel/signal.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index a3c04d0..ac8a05a 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -260,15 +260,17 @@ asmlinkage int sys_sigaction(int sig, const struct 
sigaction __user *act,
 
        if (act) {
                old_sigset_t mask;
+               unsigned long tmp; /* fix a gcc warning */
 
                if (!access_ok(VERIFY_READ, act, sizeof(*act)))
                        return -EFAULT;
-               err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
+               err |= __get_user(tmp, (unsigned long *)&act->sa_handler);
                err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
                err |= __get_user(mask, &act->sa_mask.sig[0]);
                if (err)
                        return -EFAULT;
 
+               new_ka.sa.sa_handler = (__sighandler_t)tmp;
                siginitset(&new_ka.sa.sa_mask, mask);
        }
 
-- 
1.4.4.3.ge6d4