[Qemu-devel] [PATCH] atomic.h: Set ATOMIC_REG_SIZE=8 for MIPS n32

[Paul Burton]

ATOMIC_REG_SIZE is currently defined as the default sizeof(void *) for
all MIPS host builds, including those using the n32 ABI. n32 is the
MIPS64 ILP32 ABI and as such tcg/mips/tcg-target.h defines
TCG_TARGET_REG_BITS as 64 for n32 builds. If we attempt to build QEMU
for an n32 host with support for a 64b target architecture then
TCG_OVERSIZED_GUEST is 0 and accel/tcg/cputlb.c attempts to use atomic_*
functions. This fails because ATOMIC_REG_SIZE is 4, causing the calls to
QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE) in the various
atomic_* functions to generate errors.

Fix this by defining ATOMIC_REG_SIZE as 8 for all MIPS64 builds, which
will cover both n32 (ILP32) & n64 (LP64) ABIs in much the same was as we
already do for x86_64/x32.

Signed-off-by: Paul Burton <address@hidden>
---
 include/qemu/atomic.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
index f6993a8fb1..a6ac188188 100644
--- a/include/qemu/atomic.h
+++ b/include/qemu/atomic.h
@@ -99,9 +99,10 @@
  * those few cases by hand.
  *
  * Note that x32 is fully detected with __x86_64__ + _ILP32, and that for
- * Sparc we always force the use of sparcv9 in configure.
+ * Sparc we always force the use of sparcv9 in configure. MIPS n32 (ILP32) &
+ * n64 (LP64) ABIs are both detected using __mips64.
  */
-#if defined(__x86_64__) || defined(__sparc__)
+#if defined(__x86_64__) || defined(__sparc__) || defined(__mips64)
 # define ATOMIC_REG_SIZE  8
 #else
 # define ATOMIC_REG_SIZE  sizeof(void *)
-- 
2.19.1