* config/netbsd.h (NETBSD_ENABLE_EXECUTE_STACK): Define

__enable_execute_stack function.
* config/alpha/netbsd.h (TRANSFER_FROM_TRAMPOLINE): Define
as NETBSD_ENABLE_EXECUTE_STACK.
* config/i386/netbsd-elf.h (TRANSFER_FROM_TRAMPOLINE): Ditto.
* config/i386/netbsd.h (TRANSFER_FROM_TRAMPOLINE): Ditto.
* config/i386/netbsd64.h (TRANSFER_FROM_TRAMPOLINE): Ditto.
* config/sparc/netbsd-elf.h (TRANSFER_FROM_TRAMPOLINE): Ditto.
* config/sparc/netbsd.h (TRANSFER_FROM_TRAMPOLINE): Ditto.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@58292 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 48 insertions, 0 deletions

diff --git a/gcc/config/netbsd.h b/gcc/config/netbsd.h
index 19df77ffcd8..c83ff0f545e 100644
--- a/gcc/config/netbsd.h
+++ b/gcc/config/netbsd.h
@@ -161,3 +161,51 @@ Boston, MA 02111-1307, USA.  */
 
 #undef WINT_TYPE
 #define WINT_TYPE "int"
+
+
+/* Attempt to turn on execute permission for the stack.  This may be
+   used by TRANSFER_FROM_TRAMPOLINE of the target needs it (that is,
+   if the target machine can change execute permissions on a page).
+
+   There is no way to query the execute permission of the stack, so
+   we always issue the mprotect() call.
+
+   Note that we go out of our way to use namespace-non-invasive calls
+   here.  Unfortunately, there is no libc-internal name for mprotect().
+
+   Also note that no errors should be emitted by this code; it is considered
+   dangerous for library calls to send messages to stdout/stderr.  */
+
+#define NETBSD_ENABLE_EXECUTE_STACK					\
+extern void __enable_execute_stack (void *);				\
+void									\
+__enable_execute_stack (addr)						\
+     void *addr;							\
+{									\
+  extern int mprotect (void *, size_t, int);				\
+  extern int __sysctl (int *, unsigned int, void *, size_t *,		\
+		       void *, size_t);					\
+									\
+  static int size;							\
+  static long mask;							\
+									\
+  char *page, *end;							\
+									\
+  if (size == 0)							\
+    {									\
+      int mib[2];							\
+      size_t len;							\
+									\
+      mib[0] = 6; /* CTL_HW */						\
+      mib[1] = 7; /* HW_PAGESIZE */					\
+      len = sizeof (size);						\
+      (void) __sysctl (mib, 2, &size, &len, NULL, 0);			\
+      mask = ~((long) size - 1);					\
+    }									\
+									\
+  page = (char *) (((long) addr) & mask);				\
+  end  = (char *) ((((long) (addr + TRAMPOLINE_SIZE)) & mask) + size);	\
+									\
+  /* 7 == PROT_READ | PROT_WRITE | PROT_EXEC */				\
+  (void) mprotect (page, end - page, 7);				\
+}