4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: James Morse <james.mo...@arm.com>
commit 811d61e384e24759372bb3f01772f3744b0a8327 upstream.
futex.h's futex_atomic_cmpxchg_inatomic() does not use the
__futex_atomic_op() macro and needs its own PAN toggling. This was missed
when the feature was implemented.
Fixes: 338d4f49d6f ("arm64: kernel: Add support for Privileged Access Never")
Signed-off-by: James Morse <james.mo...@arm.com>
Signed-off-by: Will Deacon <will.dea...@arm.com>
Cc: Mian Yousaf Kaukab <yousaf.kau...@suse.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/arm64/include/asm/futex.h | 2 ++
1 file changed, 2 insertions(+)
--- a/arch/arm64/include/asm/futex.h
+++ b/arch/arm64/include/asm/futex.h
@@ -121,6 +121,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval,
return -EFAULT;
asm volatile("// futex_atomic_cmpxchg_inatomic\n"
+ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
" prfm pstl1strm, %2\n"
"1: ldxr %w1, %2\n"
" sub %w3, %w1, %w4\n"
@@ -137,6 +138,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval,
" .align 3\n"
" .quad 1b, 4b, 2b, 4b\n"
" .popsection\n"
+ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
: "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
: "r" (oldval), "r" (newval), "Ir" (-EFAULT)
: "memory");
