[PATCH] mips/o32: fix internal_syscall5/6/7

[Aurelien Jarno <aurelien@aurel32.net>]

The internal_syscall5/6/7 functions use the stack pointer to store
the 5th and following arguments on the stack. In some cases GCC optimize
out the stack pointer, and thus storing the data to the stack causes a
segmentation fault.

Fix that by declaring the sp register as clobbered. Not sure it is the
best way to do that, but it seems to be enough to force GCC to not
optimize it out.

This fixes the nptl/tst-rwlock15 test on mips/o32.

ChangeLog:
	* sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
	(internal_syscall5): Add "$29" to the clobber list.
	(internal_syscall6): Likewise.
	(internal_syscall7): Likewise.
---
 ChangeLog                                    | 7 +++++++
 sysdeps/unix/sysv/linux/mips/mips32/sysdep.h | 6 +++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 56540f55a1..5d1a088431 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2017-08-15  Aurelien Jarno <aurelien@aurel32.net>
+
+	* sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
+	(internal_syscall5): Add "$29" to the clobber list.
+	(internal_syscall6): Likewise.
+	(internal_syscall7): Likewise.
+
 2017-08-14  Joseph Myers  <joseph@codesourcery.com>
 
 	* conform/data/sys/wait.h-data (si_value): Do not expect for
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h b/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
index e9e3ee7e82..0df32c186f 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
+++ b/sysdeps/unix/sysv/linux/mips/mips32/sysdep.h
@@ -294,7 +294,7 @@
 	: "=r" (__v0), "+r" (__a3)					\
 	: input, "r" (__a0), "r" (__a1), "r" (__a2),			\
 	  "r" ((long) (arg5))						\
-	: __SYSCALL_CLOBBERS);						\
+	: __SYSCALL_CLOBBERS, "$29");					\
 	err = __a3;							\
 	_sys_result = __v0;						\
 	}								\
@@ -327,7 +327,7 @@
 	: "=r" (__v0), "+r" (__a3)					\
 	: input, "r" (__a0), "r" (__a1), "r" (__a2),			\
 	  "r" ((long) (arg5)), "r" ((long) (arg6))			\
-	: __SYSCALL_CLOBBERS);						\
+	: __SYSCALL_CLOBBERS, "$29");					\
 	err = __a3;							\
 	_sys_result = __v0;						\
 	}								\
@@ -361,7 +361,7 @@
 	: "=r" (__v0), "+r" (__a3)					\
 	: input, "r" (__a0), "r" (__a1), "r" (__a2),			\
 	  "r" ((long) (arg5)), "r" ((long) (arg6)), "r" ((long) (arg7))	\
-	: __SYSCALL_CLOBBERS);						\
+	: __SYSCALL_CLOBBERS, "$29");					\
 	err = __a3;							\
 	_sys_result = __v0;						\
 	}								\
-- 
2.13.2