4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Max Filippov <jcmvb...@gmail.com>
commit ca47480921587ae30417dd234a9f79af188e3666 upstream.
Return 0 if the operation was successful, not the userspace memory
value. Check that userspace value equals passed oldval, not itself.
Don't update *uval if the value wasn't read from userspace memory.
This fixes process hang due to infinite loop in futex_lock_pi.
It also fixes a bunch of glibc tests nptl/tst-mutexpi*.
Signed-off-by: Max Filippov <jcmvb...@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/xtensa/include/asm/futex.h | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)
--- a/arch/xtensa/include/asm/futex.h
+++ b/arch/xtensa/include/asm/futex.h
@@ -109,7 +109,6 @@ futex_atomic_cmpxchg_inatomic(u32 *uval,
u32 oldval, u32 newval)
{
int ret = 0;
- u32 prev;
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
return -EFAULT;
@@ -120,26 +119,24 @@ futex_atomic_cmpxchg_inatomic(u32 *uval,
__asm__ __volatile__ (
" # futex_atomic_cmpxchg_inatomic\n"
- "1: l32i %1, %3, 0\n"
- " mov %0, %5\n"
- " wsr %1, scompare1\n"
- "2: s32c1i %0, %3, 0\n"
- "3:\n"
+ " wsr %5, scompare1\n"
+ "1: s32c1i %1, %4, 0\n"
+ " s32i %1, %6, 0\n"
+ "2:\n"
" .section .fixup,\"ax\"\n"
" .align 4\n"
- "4: .long 3b\n"
- "5: l32r %1, 4b\n"
- " movi %0, %6\n"
+ "3: .long 2b\n"
+ "4: l32r %1, 3b\n"
+ " movi %0, %7\n"
" jx %1\n"
" .previous\n"
" .section __ex_table,\"a\"\n"
- " .long 1b,5b,2b,5b\n"
+ " .long 1b,4b\n"
" .previous\n"
- : "+r" (ret), "=&r" (prev), "+m" (*uaddr)
- : "r" (uaddr), "r" (oldval), "r" (newval), "I" (-EFAULT)
+ : "+r" (ret), "+r" (newval), "+m" (*uaddr), "+m" (*uval)
+ : "r" (uaddr), "r" (oldval), "r" (uval), "I" (-EFAULT)
: "memory");
- *uval = prev;
return ret;
}
