commit fff42f183ea4c3967405d4c1dce6d97dae4d64c8
author Emilio G. Cota <cota@braap.org> Wed Oct 10 10:48:50 2018 -0400
committer Richard Henderson <richard.henderson@linaro.org> Thu Oct 18 18:58:10 2018 -0700
tree 5d68af55ddf42c9025133a17c0a21e318a47aaae
parent d7f425fdea991f052241c6479acd9feae834063b

tcg: access cpu->icount_decr.u16.high with atomics

Consistently access u16.high with atomics to avoid
undefined behaviour in MTTCG.

Note that icount_decr.u16.low is only used in icount mode,
so regular accesses to it are OK.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181010144853.13005-2-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

accel/tcg/tcg-all.c

diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c
index 56dbb56..3d25bdc 100644
--- a/accel/tcg/tcg-all.c
+++ b/accel/tcg/tcg-all.c
@@ -51,7 +51,7 @@
     if (!qemu_cpu_is_self(cpu)) {
         qemu_cpu_kick(cpu);
     } else {
-        cpu->icount_decr.u16.high = -1;
+        atomic_set(&cpu->icount_decr.u16.high, -1);
         if (use_icount &&
             !cpu->can_do_io
             && (mask & ~old_mask) != 0) {

accel/tcg/translate-all.c

diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index ad5c758..356dcd0 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -2341,7 +2341,7 @@
 {
     g_assert(qemu_mutex_iothread_locked());
     cpu->interrupt_request |= mask;
-    cpu->icount_decr.u16.high = -1;
+    atomic_set(&cpu->icount_decr.u16.high, -1);
 }
 
 /*

qom/cpu.c

diff --git a/qom/cpu.c b/qom/cpu.c
index f774654..9ad1372 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -265,7 +265,7 @@
     cpu->mem_io_pc = 0;
     cpu->mem_io_vaddr = 0;
     cpu->icount_extra = 0;
-    cpu->icount_decr.u32 = 0;
+    atomic_set(&cpu->icount_decr.u32, 0);
     cpu->can_do_io = 1;
     cpu->exception_index = -1;
     cpu->crash_occurred = false;