[PULL 1/2] linux-user/s390x: Use the guest pointer for the sigreturn stub

[Laurent Vivier <laurent@vivier.eu>]

From: Andreas Krebbel <krebbel@linux.ibm.com>

When setting up the pointer for the sigreturn stub in the return
address register (r14) we currently use the host frame address instead
of the guest frame address.

Note: This only caused problems if Qemu has been built with
--disable-pie (as it is in distros nowadays). Otherwise guest_base
defaults to 0 hiding the actual problem.

Signed-off-by: Andreas Krebbel <krebbel@linux.ibm.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210324185128.63971-1-krebbel@linux.ibm.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/s390x/signal.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/linux-user/s390x/signal.c b/linux-user/s390x/signal.c
index ecfa2a14a982..7107c5fb5335 100644
--- a/linux-user/s390x/signal.c
+++ b/linux-user/s390x/signal.c
@@ -211,9 +211,10 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
     /* Set up to return from userspace.  If provided, use a stub
        already in userspace.  */
     if (ka->sa_flags & TARGET_SA_RESTORER) {
-        env->regs[14] = (unsigned long) ka->sa_restorer | PSW_ADDR_AMODE;
+        env->regs[14] = ka->sa_restorer | PSW_ADDR_AMODE;
     } else {
-        env->regs[14] = (unsigned long) frame->retcode | PSW_ADDR_AMODE;
+        env->regs[14] = (frame_addr + offsetof(typeof(*frame), retcode))
+                        | PSW_ADDR_AMODE;
         __put_user(S390_SYSCALL_OPCODE | TARGET_NR_rt_sigreturn,
                    (uint16_t *)(frame->retcode));
     }
-- 
2.30.2