From: Oliver Kurth <okurth@vmware.com>
Date: Fri, 15 Sep 2017 18:23:27 +0000 (-0700)
Subject: Stop defining Atomic_MFence() in cross platform code
X-Git-Tag: stable-10.2.0~325
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8cf4ff17a7f7f687a55075f67f8988bd45950704;p=thirdparty%2Fopen-vm-tools.git

Stop defining Atomic_MFence() in cross platform code

No functional change to open-vm-tools.
---

diff --git a/open-vm-tools/lib/include/vm_atomic.h b/open-vm-tools/lib/include/vm_atomic.h
index 1fc3b0764..e5bd1ee15 100644
--- a/open-vm-tools/lib/include/vm_atomic.h
+++ b/open-vm-tools/lib/include/vm_atomic.h
@@ -3802,6 +3802,23 @@ MAKE_ATOMIC_TYPE(Ptr, 32, void const *, void *, uintptr_t)
 MAKE_ATOMIC_TYPE(Int, 32, int, int, int)
 
 
+#if    defined VM_ARM_64 && defined VMKERNEL \
+    && !defined ATOMIC_MFENCE_SHOULD_NOT_BE_IN_CROSS_PLATFORM_CODE
+/*
+ * Atomic_MFence() is an x86-ism, so in an ideal world it should never be
+ * defined on ARM.
+ *
+ * There is ongoing work to remove all legacy Atomic_MFence() calls in
+ * cross-platform code. The vmkernel code has mostly been cleaned up, but a few
+ * calls remain in vmkernel module files which are granted an exception (by
+ * defining ATOMIC_MFENCE_SHOULD_NOT_BE_IN_CROSS_PLATFORM_CODE) for now.
+ *
+ * Do not add more Atomic_MFence() calls to cross-platform code. Do not grant
+ * any new exception. Instead, either move existing calls to an x86-specific
+ * location, or replace them with cross-platform memory barriers such as
+ * LDST_LDST_MEM_BARRIER().
+ */
+#else // Should we define Atomic_MFence?
 /* Prevent the compiler from re-ordering memory references. */
 #ifdef __GNUC__
 #define ATOMIC_COMPILER_BARRIER()   __asm__ __volatile__ ("": : :"memory")
@@ -3845,6 +3862,7 @@ Atomic_MFence(void)
 #ifdef ATOMIC_COMPILER_BARRIER
 #undef ATOMIC_COMPILER_BARRIER
 #endif /* ATOMIC_COMPILER_BARRIER */
+#endif // Should we define Atomic_MFence?
 
 #if defined(__cplusplus)
 }  // extern "C"