Add CRYPTOPP_NO_CPU_FEATURE_PROBES (GH #511)

We determine machine capabilities by performing an os/platform *query* first, like getauxv(). If the *query* fails, we move onto a cpu *probe*. The cpu *probe* tries to exeute an instruction and then catches a SIGILL on Linux or the exception EXCEPTION_ILLEGAL_INSTRUCTION on Windows. Some OSes fail to hangle a SIGILL gracefully, like Apple OSes. Apple machines corrupt memory and variables around the probe.

1 files changed, 12 insertions, 0 deletions

diff --git a/config.h b/config.h
index 092edbd6..6e0f2fb2 100644
--- a/config.h
+++ b/config.h
@@ -664,6 +664,18 @@ NAMESPACE_END
 # define CRYPTOPP_CONSTANT(x) enum {x};

 #endif

 

+// How to disable CPU feature probing. We determine machine

+//  capabilities by performing an os/platform *query* first,

+//  like getauxv(). If the *query* fails, we move onto a

+//  cpu *probe*. The cpu *probe* tries to exeute an instruction

+//  and then catches a SIGILL on Linux or the exception

+//  EXCEPTION_ILLEGAL_INSTRUCTION on Windows. Some OSes

+//  fail to hangle a SIGILL gracefully, like Apple OSes. Apple

+//  machines corrupt memory and variables around the probe.

+#if defined(__APPLE__)

+#  define CRYPTOPP_NO_CPU_FEATURE_PROBES 1

+#endif

+

 // ***************** Initialization and Constructor priorities ********************

 

 // CRYPTOPP_INIT_PRIORITY attempts to manage initialization of C++ static objects.