This is the mail archive of the libffi-discuss@sourceware.org mailing list for the libffi project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[PATCH] Fix up libffi linux64*.S for ppc32-linux


Hi!

I've noticed that on 4.8 branch libgo recently (in the last few months)
started being linked with
  GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RWE 0x10
i.e. requiring executable stack on powerpc-linux (32-bit).

The problem is that we link into libffi linux64.o and linux64_closure.o
unconditionally, both for 32-bit and 64-bit compilations, just for 32-bit
ones all the assembly is ifdefed out, so they have just empty sections.
The .note.GNU-stack section isn't emitted in that case either, which means
that the linker conservatively treats those as possibly needing executable
stack.

The following patch should fix that, ok for trunk/4.9/4.8?

BTW, I wonder if e.g. libffi/src/arm/trampoline.S or
libffi/src/aarch64/sysv.S shouldn't have those notes too (note, both of
those were added after 2008 when most of the *.S files were marked that
way).

2014-09-10  Jakub Jelinek  <jakub@redhat.com>

	* src/powerpc/linux64.S: Emit .note.GNU-stack even when
	POWERPC64 is not defined.
	* src/powerpc/linux64_closure.S: Likewise.  Also test _CALL_ELF == 2.

--- libffi/src/powerpc/linux64.S.jj	2013-12-10 08:52:16.000000000 +0100
+++ libffi/src/powerpc/linux64.S	2014-09-10 16:36:23.881137722 +0200
@@ -254,7 +254,8 @@ ffi_call_LINUX64:
 	.align 3
 .LEFDE1:
 
-# if (defined __ELF__ && defined __linux__) || _CALL_ELF == 2
+#endif
+
+#if (defined __ELF__ && defined __linux__) || _CALL_ELF == 2
 	.section	.note.GNU-stack,"",@progbits
-# endif
 #endif
--- libffi/src/powerpc/linux64_closure.S.jj	2013-12-10 08:52:16.000000000 +0100
+++ libffi/src/powerpc/linux64_closure.S	2014-09-10 16:37:38.104747027 +0200
@@ -381,7 +381,8 @@ ffi_closure_LINUX64:
 	.align 3
 .LEFDE1:
 
-# if defined __ELF__ && defined __linux__
+#endif
+
+#if (defined __ELF__ && defined __linux__) || _CALL_ELF == 2
 	.section	.note.GNU-stack,"",@progbits
-# endif
 #endif

	Jakub


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]