[Qemu-devel] [PATCH 1/4] linux-user/s390x: Mask si_addr for SIGSEGV

[Peter Maydell <peter.maydell@linaro.org>]

For s390x, the address passed to a signal handler in the
siginfo_t si_addr field is masked (in the kernel this is done in
do_sigbus() and do_sigsegv() in arch/s390/mm/fault.c). Implement
this architecture-specific oddity in linux-user.

This is one of the issues described in
https://bugs.launchpad.net/qemu/+bug/1705118

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 linux-user/main.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index aa02f25..b6dd9ef 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -3238,6 +3238,10 @@ void cpu_loop(CPUAlphaState *env)
 #endif /* TARGET_ALPHA */
 
 #ifdef TARGET_S390X
+
+/* s390x masks the fault address it reports in si_addr for SIGSEGV and SIGBUS */
+#define S390X_FAIL_ADDR_MASK -4096LL
+
 void cpu_loop(CPUS390XState *env)
 {
     CPUState *cs = CPU(s390_env_get_cpu(env));
@@ -3294,7 +3298,7 @@ void cpu_loop(CPUS390XState *env)
                 sig = TARGET_SIGSEGV;
                 /* XXX: check env->error_code */
                 n = TARGET_SEGV_MAPERR;
-                addr = env->__excp_addr;
+                addr = env->__excp_addr & S390X_FAIL_ADDR_MASK;
                 goto do_signal;
             case PGM_EXECUTE:
             case PGM_SPECIFICATION:
-- 
2.7.4