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[PATCH] Emit .note.GNU-stack section on linux arches which by default need executable stack

Hi!

This patch emits a .note.GNU-stack non-SHF_ALLOC section on
linux targets which have stack executable by default.
If code uses trampolines, it sets SHF_EXECINSTR bit, otherwise
leaves it clear.
This information is then collected by recent GNU ld to compute
default stack permissions for the PT_GNU_STACK segment header
which tells the kernel whether an executable or library needs
executable stack or not (it can be overridden from the command
line).
Ok to commit?

2003-06-04  Jakub Jelinek  <jakub@redhat.com>

	* function.c (trampolines_created): New variable.
	(expand_function_end): Set it when doing INITIALIZE_TRAMPOLINE.
	* function.h (trampolines_created): Add.
	* config/s390/linux.h (ASM_FILE_END): Define.
	* config/alpha/linux-elf.h (ASM_FILE_END): Define.
	* config/rs6000/linux.h (ASM_FILE_END): Define.
	* config/rs6000/linux64.h (ASM_FILE_END): Define.
	* config/sparc/linux.h (ASM_FILE_END): Define.
	* config/sparc/linux64.h (ASM_FILE_END): Define.
	* config/i386/i386.c (ix86_asm_file_end): Use SUBTARGET_FILE_END.
	* config/i386/linux.h (SUBTARGET_FILE_END): Define.
	* config/i386/linux64.h (SUBTARGET_FILE_END): Define.

--- gcc/function.c.jj	2003-05-31 15:38:26.000000000 -0400
+++ gcc/function.c	2003-06-03 19:05:24.000000000 -0400
@@ -129,6 +129,9 @@ int current_function_uses_only_leaf_regs
    post-instantiation libcalls.  */
 int virtuals_instantiated;
 
+/* Nonzero if at least one trampoline has been created.  */
+int trampolines_created;
+
 /* Assign unique numbers to labels generated for profiling, debugging, etc.  */
 static GTY(()) int funcdef_no;
 
@@ -6959,6 +6962,7 @@ expand_function_end (filename, line, end
       emit_block_move (blktramp, initial_trampoline,
 		       GEN_INT (TRAMPOLINE_SIZE), BLOCK_OP_NORMAL);
 #endif
+      trampolines_created = 1;
       INITIALIZE_TRAMPOLINE (tramp, XEXP (DECL_RTL (function), 0), context);
       seq = get_insns ();
       end_sequence ();
--- gcc/function.h.jj	2003-05-16 05:54:50.000000000 -0400
+++ gcc/function.h	2003-06-03 19:05:51.000000000 -0400
@@ -513,6 +513,9 @@ extern GTY(()) struct function *cfun;
 /* Nonzero if we've already converted virtual regs to hard regs.  */
 extern int virtuals_instantiated;
 
+/* Nonzero if at least one trampoline has been created.  */
+extern int trampolines_created;
+
 /* For backward compatibility... eventually these should all go away.  */
 #define current_function_name (cfun->name)
 #define current_function_pops_args (cfun->pops_args)
--- gcc/config/s390/linux.h.jj	2003-05-21 06:24:42.000000000 -0400
+++ gcc/config/s390/linux.h	2003-06-03 19:20:03.000000000 -0400
@@ -121,6 +121,12 @@ Boston, MA 02111-1307, USA.  */
   { "link_arch31",	LINK_ARCH31_SPEC },	\
   { "link_arch64",	LINK_ARCH64_SPEC },	\
 
+#define ASM_FILE_END(FILE) \
+  do {									\
+    named_section_flags (".note.GNU-stack",				\
+			 SECTION_DEBUG					\
+			 | (trampolines_created ? SECTION_CODE : 0));	\
+  } while (0)
 
 /* Do code reading to identify a signal frame, and set the frame
    state data appropriately.  See unwind-dw2.c for the structs.  */
--- gcc/config/alpha/linux-elf.h.jj	2003-05-16 05:55:32.000000000 -0400
+++ gcc/config/alpha/linux-elf.h	2003-06-03 19:24:21.000000000 -0400
@@ -41,3 +41,10 @@ Boston, MA 02111-1307, USA.  */
 #undef LIB_SPEC
 #define LIB_SPEC \
 "%{pthread:-lpthread} %{shared:-lc}%{!shared:%{profile:-lc_p}%{!profile:-lc}} "
+
+#define ASM_FILE_END(FILE) \
+  do {									\
+    named_section_flags (".note.GNU-stack",				\
+			 SECTION_DEBUG					\
+			 | (trampolines_created ? SECTION_CODE : 0));	\
+  } while (0)
--- gcc/config/i386/linux.h.jj	2003-06-01 09:50:37.000000000 -0400
+++ gcc/config/i386/linux.h	2003-06-03 19:13:33.000000000 -0400
@@ -219,6 +219,13 @@ Boston, MA 02111-1307, USA.  */
 	   : "=d"(BASE))
 #endif
 
+#define SUBTARGET_FILE_END(FILE) \
+  do {									\
+    named_section_flags (".note.GNU-stack",				\
+			 SECTION_DEBUG					\
+			 | (trampolines_created ? SECTION_CODE : 0));	\
+  } while (0)
+
 /* Do code reading to identify a signal frame, and set the frame
    state data appropriately.  See unwind-dw2.c for the structs.  */
 
--- gcc/config/i386/linux64.h.jj	2003-06-03 05:03:11.000000000 -0400
+++ gcc/config/i386/linux64.h	2003-06-03 19:13:56.000000000 -0400
@@ -67,6 +67,13 @@ Boston, MA 02111-1307, USA.  */
 
 #define MULTILIB_DEFAULTS { "m64" }
 
+#define SUBTARGET_FILE_END(FILE) \
+  do {									\
+    named_section_flags (".note.GNU-stack",				\
+			 SECTION_DEBUG					\
+			 | (trampolines_created ? SECTION_CODE : 0));	\
+  } while (0)
+
 /* Do code reading to identify a signal frame, and set the frame
    state data appropriately.  See unwind-dw2.c for the structs.  
    Don't use this at all if inhibit_libc is used.  */
--- gcc/config/i386/i386.c.jj	2003-05-26 17:04:25.000000000 -0400
+++ gcc/config/i386/i386.c	2003-06-03 19:14:27.000000000 -0400
@@ -4727,6 +4727,10 @@ ix86_asm_file_end (file)
       output_asm_insn ("mov{l}\t{%1, %0|%0, %1}", xops);
       output_asm_insn ("ret", xops);
     }
+
+#ifdef SUBTARGET_FILE_END
+  SUBTARGET_FILE_END (file);
+#endif
 }
 
 /* Emit code for the SET_GOT patterns.  */
--- gcc/config/rs6000/linux.h.jj	2003-06-01 09:50:37.000000000 -0400
+++ gcc/config/rs6000/linux.h	2003-06-03 19:16:46.000000000 -0400
@@ -78,6 +78,13 @@
 #undef  DRAFT_V4_STRUCT_RET
 #define DRAFT_V4_STRUCT_RET 1
 
+#define ASM_FILE_END(FILE) \
+  do {									\
+    named_section_flags (".note.GNU-stack",				\
+			 SECTION_DEBUG					\
+			 | (trampolines_created ? SECTION_CODE : 0));	\
+  } while (0)
+
 /* Do code reading to identify a signal frame, and set the frame
    state data appropriately.  See unwind-dw2.c for the structs.  */
 
--- gcc/config/rs6000/linux64.h.jj	2003-06-03 05:03:11.000000000 -0400
+++ gcc/config/rs6000/linux64.h	2003-06-03 19:19:23.000000000 -0400
@@ -411,3 +411,12 @@ while (0)
 #undef	ASM_PREFERRED_EH_DATA_FORMAT
 #define	ASM_PREFERRED_EH_DATA_FORMAT(CODE, GLOBAL) \
   (((GLOBAL) ? DW_EH_PE_indirect : 0) | DW_EH_PE_pcrel | DW_EH_PE_udata8)
+
+#define ASM_FILE_END(FILE) \
+  do {									\
+    if (! TARGET_64BIT)							\
+      named_section_flags (".note.GNU-stack",				\
+			   SECTION_DEBUG				\
+			   | (trampolines_created ? SECTION_CODE : 0));	\
+  } while (0)
+
--- gcc/config/sparc/linux.h.jj	2003-06-03 05:03:11.000000000 -0400
+++ gcc/config/sparc/linux.h	2003-06-03 19:22:02.000000000 -0400
@@ -259,6 +259,13 @@ do {									\
 #undef CTORS_SECTION_ASM_OP
 #undef DTORS_SECTION_ASM_OP
 
+#define ASM_FILE_END(FILE) \
+  do {									\
+    named_section_flags (".note.GNU-stack",				\
+			 SECTION_DEBUG					\
+			 | (trampolines_created ? SECTION_CODE : 0));	\
+  } while (0)
+
 /* Do code reading to identify a signal frame, and set the frame
    state data appropriately.  See unwind-dw2.c for the structs.  */
 
--- gcc/config/sparc/linux64.h.jj	2003-06-03 05:03:11.000000000 -0400
+++ gcc/config/sparc/linux64.h	2003-06-03 19:22:47.000000000 -0400
@@ -324,6 +324,13 @@ do {									\
 #undef CTORS_SECTION_ASM_OP
 #undef DTORS_SECTION_ASM_OP
 
+#define ASM_FILE_END(FILE) \
+  do {									\
+    named_section_flags (".note.GNU-stack",				\
+			 SECTION_DEBUG					\
+			 | (trampolines_created ? SECTION_CODE : 0));	\
+  } while (0)
+
 /* Do code reading to identify a signal frame, and set the frame
    state data appropriately.  See unwind-dw2.c for the structs.  */
 

	Jakub
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