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xtensa: fix futex_atomic_cmpxchg_inatomic 

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*.

Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov 2018-01-05 14:27:58 -08:00
parent 32bb954dbf
commit ca47480921
1 changed files with 10 additions and 13 deletions
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23
arch/xtensa/include/asm/futex.h
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@ -92,7 +92,6 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
int ret = 0;
u32 prev;
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
return -EFAULT;
@ -103,26 +102,24 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
__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;
}