s390/compat: correct ucontext layout for high gprs

The uc_sigmask definition in the kernel differs from the one in the
glibc, the kernel uc_sigmask has 64 bits while the glibc verison
is 1024 bits. The extension of the ucontext structure for 64-bit
register support for 31-bit compat processes added a new field
uc_gprs_high which starts 8 bytes after the uc_sigmask field.
As the glibc view of the ucontext assumes a size of 128 bytes for
uc_sigmask add a 120 byte padding to the kernel structure
ucontext_extended after the 8 byte uc_sigmask.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 9 insertions, 3 deletions

diff --git a/arch/s390/include/uapi/asm/ucontext.h b/arch/s390/include/uapi/asm/ucontext.h
index 200e06325c6a..3e077b2a4705 100644
--- a/arch/s390/include/uapi/asm/ucontext.h
+++ b/arch/s390/include/uapi/asm/ucontext.h
@@ -16,7 +16,9 @@ struct ucontext_extended {
         struct ucontext  *uc_link;
         stack_t           uc_stack;
         _sigregs          uc_mcontext;
-        unsigned long     uc_sigmask[2];
+        sigset_t          uc_sigmask;
+        /* Allow for uc_sigmask growth.  Glibc uses a 1024-bit sigset_t.  */
+        unsigned char     __unused[128 - sizeof(sigset_t)];
         unsigned long     uc_gprs_high[16];
 };
 
@@ -27,7 +29,9 @@ struct ucontext {
         struct ucontext  *uc_link;
         stack_t           uc_stack;
         _sigregs          uc_mcontext;
-        sigset_t          uc_sigmask;   /* mask last for extensibility */
+        sigset_t          uc_sigmask;
+        /* Allow for uc_sigmask growth.  Glibc uses a 1024-bit sigset_t.  */
+        unsigned char     __unused[128 - sizeof(sigset_t)];
 };
 
 #endif /* !_ASM_S390_UCONTEXT_H */
diff --git a/arch/s390/kernel/compat_linux.h b/arch/s390/kernel/compat_linux.h
index 39ddfdb40ae8..70d4b7c4beaa 100644
--- a/arch/s390/kernel/compat_linux.h
+++ b/arch/s390/kernel/compat_linux.h
@@ -69,7 +69,9 @@ struct ucontext32 {
         __u32                   uc_link;        /* pointer */   
         compat_stack_t          uc_stack;
         _sigregs32              uc_mcontext;
-        compat_sigset_t         uc_sigmask;     /* mask last for extensibility */
+        compat_sigset_t         uc_sigmask;
+        /* Allow for uc_sigmask growth.  Glibc uses a 1024-bit sigset_t.  */
+        unsigned char           __unused[128 - sizeof(compat_sigset_t)];
 };
 
 struct stat64_emu31;