ircd::ctx: Cleanup and recondition stack-protect related.

ircd/ctx.cc

@@ -13,6 +13,16 @@
 #include <ircd/asio.h>
 #include "ctx.h"
 
+/// We make a special use of the stack-protector canary in certain places as
+/// another tool to detect corruption of a context's stack, specifically
+/// during yield and resume. This use is not really to provide security; just
+/// a kind of extra assertion, so we eliminate its emission during release.
+#ifndef NDEBUG
+	#define IRCD_CTX_STACK_PROTECT __attribute__((stack_protect))
+#else
+	#define IRCD_CTX_STACK_PROTECT
+#endif
+
 /// Instance list linkage for the list of all ctx instances.
 template<>
 decltype(ircd::util::instance_list<ircd::ctx::ctx>::list)
@@ -36,9 +46,7 @@ ircd::ctx::ctx::id_ctr
 
 /// Spawn (internal)
 void
-#ifdef IRCD_CTX_STACK_PROTECT
-__attribute__((stack_protect))
-#endif
+IRCD_CTX_STACK_PROTECT
 ircd::ctx::spawn(ctx *const c,
                  context::function func)
 {
@@ -67,10 +75,7 @@ noexcept
 /// This function is the first thing executed on the new context's stack
 /// and calls the user's function.
 void
-#ifdef IRCD_CTX_STACK_PROTECT
-__attribute__((stack_protect))
-#endif
-__attribute__((noinline))
+IRCD_CTX_STACK_PROTECT
 ircd::ctx::ctx::operator()(boost::asio::yield_context yc,
                            const std::function<void ()> func)
 noexcept try
@@ -128,9 +133,7 @@ catch(const std::exception &e)
 /// This currently doesn't work yet because the suspension state of this
 /// context has to be ready to be jumped to and that isn't implemented yet.
 void
-#ifdef IRCD_CTX_STACK_PROTECT_SWITCH
-__attribute__((stack_protect))
-#endif
+IRCD_CTX_STACK_PROTECT
 ircd::ctx::ctx::jump()
 {
 	assert(this->yc);
@@ -159,9 +162,7 @@ ircd::ctx::ctx::jump()
 /// if the context suspended and was notified. When a context wakes up the
 /// note counter is reset.
 bool
-#ifdef IRCD_CTX_STACK_PROTECT_SWITCH
-__attribute__((stack_protect))
-#endif
+IRCD_CTX_STACK_PROTECT
 ircd::ctx::ctx::wait()
 {
 	namespace errc = boost::system::errc;

ircd/ctx.h

@@ -8,11 +8,6 @@
 // copyright notice and this permission notice is present in all copies. The
 // full license for this software is available in the LICENSE file.
 
-#if RB_OPTIMIZE_LEVEL != 3
-	#define IRCD_CTX_STACK_PROTECT
-	#define IRCD_CTX_STACK_PROTECT_SWITCH
-#endif
-
 namespace ircd::ctx
 {
 	struct stack;