Merge pull request #121 from kernigh/kernigh-openbsd

Use mmap(2) MAP_STACK to allocate stacks on OpenBSD
boostorg · Oct 4, 2019 · a4bdc60 · a4bdc60
2 parents 14b4f45 + 7e14ab9
commit a4bdc60
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Showing 5 changed files with 64 additions and 3 deletions.
diff --git a/include/boost/context/detail/config.hpp b/include/boost/context/detail/config.hpp
@@ -124,4 +124,9 @@ static constexpr std::size_t prefetch_stride{ 4 * cacheline_length };
 # include <cxxabi.h>
 #endif
 
+#if defined(__OpenBSD__)
+// stacks need mmap(2) with MAP_STACK
+# define BOOST_CONTEXT_USE_MAP_STACK
+#endif
+
 #endif // BOOST_CONTEXT_DETAIL_CONFIG_H
diff --git a/include/boost/context/fixedsize_stack.hpp b/include/boost/context/fixedsize_stack.hpp
@@ -18,6 +18,12 @@
 #include <boost/context/stack_context.hpp>
 #include <boost/context/stack_traits.hpp>
 
+#if defined(BOOST_CONTEXT_USE_MAP_STACK)
+extern "C" {
+#include <sys/mman.h>
+}
+#endif
+
 #if defined(BOOST_USE_VALGRIND)
 #include <valgrind/valgrind.h>
 #endif
@@ -42,10 +48,17 @@ class basic_fixedsize_stack {
     }
 
     stack_context allocate() {
+#if defined(BOOST_CONTEXT_USE_MAP_STACK)
+        void * vp = ::mmap( 0, size_, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_STACK, -1, 0);
+        if ( vp == MAP_FAILED) {
+            throw std::bad_alloc();
+        }
+#else
         void * vp = std::malloc( size_);
         if ( ! vp) {
             throw std::bad_alloc();
         }
+#endif
         stack_context sctx;
         sctx.size = size_;
         sctx.sp = static_cast< char * >( vp) + sctx.size;
@@ -62,7 +75,11 @@ class basic_fixedsize_stack {
         VALGRIND_STACK_DEREGISTER( sctx.valgrind_stack_id);
 #endif
         void * vp = static_cast< char * >( sctx.sp) - sctx.size;
+#if defined(BOOST_CONTEXT_USE_MAP_STACK)
+        ::munmap( vp, sctx.size);
+#else
         std::free( vp);
+#endif
     }
 };
 

diff --git a/include/boost/context/pooled_fixedsize_stack.hpp b/include/boost/context/pooled_fixedsize_stack.hpp
@@ -21,6 +21,13 @@
 #include <boost/context/stack_context.hpp>
 #include <boost/context/stack_traits.hpp>
 
+#if defined(BOOST_CONTEXT_USE_MAP_STACK)
+extern "C" {
+#include <sys/mman.h>
+#include <stdlib.h>
+}
+#endif
+
 #if defined(BOOST_USE_VALGRIND)
 #include <valgrind/valgrind.h>
 #endif
@@ -32,14 +39,43 @@
 namespace boost {
 namespace context {
 
+#if defined(BOOST_CONTEXT_USE_MAP_STACK)
+namespace detail {
+template< typename traitsT >
+struct map_stack_allocator {
+    typedef std::size_t size_type;
+    typedef std::ptrdiff_t difference_type;
+
+    static char * malloc( const size_type bytes) {
+        void * block;
+        if ( ::posix_memalign( &block, traitsT::page_size(), bytes) != 0) {
+            return 0;
+        }
+        if ( mmap( block, bytes, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_FIXED | MAP_STACK, -1, 0) == MAP_FAILED) {
+            std::free( block);
+            return 0;
+        }
+        return reinterpret_cast< char * >( block);
+    }
+    static void free( char * const block) {
+        std::free( block);
+    }
+};
+}
+#endif
+
 template< typename traitsT >
 class basic_pooled_fixedsize_stack {
 private:
     class storage {
     private:
         std::atomic< std::size_t >                                  use_count_;
         std::size_t                                                 stack_size_;
+#if defined(BOOST_CONTEXT_USE_MAP_STACK)
+        boost::pool< detail::map_stack_allocator< traitsT > >       storage_;
+#else
         boost::pool< boost::default_user_allocator_malloc_free >    storage_;
+#endif
 
     public:
         storage( std::size_t stack_size, std::size_t next_size, std::size_t max_size) :

diff --git a/include/boost/context/posix/protected_fixedsize_stack.hpp b/include/boost/context/posix/protected_fixedsize_stack.hpp
@@ -57,8 +57,9 @@ class basic_protected_fixedsize_stack {
         // add one page at bottom that will be used as guard-page
         const std::size_t size__ = ( pages + 1) * traits_type::page_size();
 
-        // conform to POSIX.4 (POSIX.1b-1993, _POSIX_C_SOURCE=199309L)
-#if defined(MAP_ANON)
+#if defined(BOOST_CONTEXT_USE_MAP_STACK)
+        void * vp = ::mmap( 0, size__, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_STACK, -1, 0);
+#elif defined(MAP_ANON)
         void * vp = ::mmap( 0, size__, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
 #else
         void * vp = ::mmap( 0, size__, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
@@ -31,7 +31,9 @@ project boost/context/test
 rule native-impl ( properties * )
 {
     local result  ;
-    if ( <target-os>darwin in $(properties) || <target-os>android in $(properties) )
+    if ( <target-os>android in $(properties) ||
+         <target-os>darwin in $(properties) ||
+         <target-os>openbsd in $(properties) )
     {
         result = <build>no ;
     }