tcg/mips: Make direct jump patching thread-safe

Ensure direct jump patching in MIPS is atomic by using
atomic_read()/atomic_set() for code patching.
Signed-off-by: NSergey Fedorov <serge.fdrv@gmail.com>
Signed-off-by: NSergey Fedorov <sergey.fedorov@linaro.org>
Message-Id: <1461341333-19646-11-git-send-email-sergey.fedorov@linaro.org>
Signed-off-by: NRichard Henderson <rth@twiddle.net>
[rth: Merged the deposit32 followup.]
[rth: Merged the following followup.]
Message-Id: <1462210518-26522-1-git-send-email-sergey.fedorov@linaro.org>

tcg/mips/tcg-target.inc.c

@@ -1885,7 +1885,6 @@ static void tcg_target_init(TCGContext *s)
 
 void tb_set_jmp_target1(uintptr_t jmp_addr, uintptr_t addr)
 {
-    uint32_t *ptr = (uint32_t *)jmp_addr;
-    *ptr = deposit32(*ptr, 0, 26, addr >> 2);
+    atomic_set((uint32_t *)jmp_addr, deposit32(OPC_J, 0, 26, addr >> 2));
     flush_icache_range(jmp_addr, jmp_addr + 4);
 }