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>

1 files changed, 3 insertions, 1 deletions

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;