Define `static_assert()` when not defined by kernel

[lttng-modules.git] / include / wrapper / compiler.h

diff --git a/include/wrapper/compiler.h b/include/wrapper/compiler.h
index 38974c062e0cc9428ee9541c7b8ac2fca736210c..ade06fe702de4e4133868fb7ece4509b4c0369de 100644 (file)
--- a/include/wrapper/compiler.h
+++ b/include/wrapper/compiler.h
@@ -9,6 +9,7 @@
 #define _LTTNG_WRAPPER_COMPILER_H
 
 #include <linux/compiler.h>
+#include <lttng/kernel-version.h>
 
 /*
  * Don't allow compiling with buggy compiler.
@@ -24,6 +25,16 @@
 #   error Your gcc version produces clobbered frame accesses
 #  endif
 # endif
+
+/*
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
+ */
+# ifdef __aarch64__
+#  if GCC_VERSION < 50100
+#   error Your gcc version performs unsafe access to deallocated stack
+#  endif
+# endif
+
 #endif
 
 /*
@@ -39,6 +50,35 @@
 # define WRITE_ONCE(x, val)    ({ ACCESS_ONCE(x) = val; })
 #endif
 
+/*
+ * In v4.15 a smp read barrier was added to READ_ONCE to replace
+ * lockless_dereference(), replicate this behavior on prior kernels
+ * and remove calls to smp_read_barrier_depends which was dropped
+ * in v5.9.
+ */
+#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,15,0))
+#define LTTNG_READ_ONCE(x)     READ_ONCE(x)
+#else
+#define LTTNG_READ_ONCE(x)                     \
+({                                             \
+       typeof(x) __val = READ_ONCE(x);         \
+       smp_read_barrier_depends();             \
+       __val;                                  \
+})
+#endif
+
 #define __LTTNG_COMPOUND_LITERAL(type, ...)    (type[]) { __VA_ARGS__ }
 
+/*
+ * The static_assert macro was defined by the kernel in v5.1.
+ * If the macro is not defined, we define it.
+ * (kernel source: include/linux/build_bug.h)
+ */
+#ifndef static_assert
+
+# define static_assert(expr, ...)  __static_assert(expr, ##__VA_ARGS__, #expr)
+# define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
+
+#endif
+
 #endif /* _LTTNG_WRAPPER_COMPILER_H */