As described in PR target/91306, the alignment of entries in CRT data structures
as set in libgcc/crtstuff.c can be too large for msp430-elf.
crtstuff.c assumes the correct alignment of entries with a type of (void *) or
int32 is the "sizeof" that type.
However, for msp430-elf in the large memory model, pointer size is 4 bytes, but
they only need to be 2-byte aligned. Likewise for int32.
This is causing problems for __frame_dummy_init_array_entry, which gets
inserted into .init_array.
It is being forced into a 4 byte alignment, which can result in a gap between
__frame_dummy_init_array_entry and the previous entry (or the start of the
table). So when the startup code comes to run through the entries
in .init_array, it interprets 2-bytes of padding 0s as part of a function
address, resulting in a function call to the incorrect location.
This issue has only recently appeared because msp430-elf was just transitioned
to use init/fini_array by default, as mandated by the mspabi.
The other CRT array entries in crtstuff.c are not used for msp430-elf, so aren't
causing problems.
As suggested in the PR, I tried changing the alignment of the array entry from
sizeof(func_ptr) to __alignof__(func_ptr), and this fixed the issue. In the
attached patch I also updated the other uses of sizeof in "aligned" attributes
to use __alignof__ instead.
I understand the alignment to sizeof(func_ptr) was originally added to fix an
issue on mips64 (r182066
https://gcc.gnu.org/ml/gcc-patches/2011-12/msg00393.html), however I do
not have access to a mips64 platform for which to bootstrap on. I tried building
a cross-compiler with the "aligned" attributes removed to see if I could
reproduce the failure, but the build completed successfully.
I built the mips64 cross-compiler with my patch applied and it
also completed successfully.
I successfully regtested the patch for msp430-elf. It fixes many execution
failures for msp430-elf/-mlarge.
I also successfully bootstrapped and regtested x86_64-pc-linux-gnu (g++ gcc
gfortran libatomic libgomp libitm libstdc++ objc).
According to the mips eabi (is this the right one?
http://www.cygwin.com/ml/binutils/2003-06/msg00436.html), pointers have 64-bit
size and alignment in 64-bit mode, so I am assuming using __alignof__ instead of
sizeof isn't going to cause problems.
Ok for trunk?
>From 636ffa0c4f15047dc27c829d9a3c8fea9ad5d635 Mon Sep 17 00:00:00 2001
From: Jozef Lawrynowicz <joze...@mittosystems.com>
Date: Thu, 15 Aug 2019 14:17:25 +0100
Subject: [PATCH] libgcc/crtstuff.c: Fix incorrect alignment of entries in CRT
data structures
libgcc/ChangeLog:
2019-08-21 Jozef Lawrynowicz <joze...@mittosystems.com>
* crtstuff.c (__CTOR_LIST__): Align to the "__alignof__" the array
element type, instead of "sizeof" the element type.
(__DTOR_LIST__): Likewise.
(__TMC_LIST__): Likewise.
(__do_global_dtors_aux_fini_array_entry): Likewise.
(__frame_dummy_init_array_entry): Likewise.
(__CTOR_END__): Likewise.
(__DTOR_END__): Likweise.
(__FRAME_END__): Likewise.
(__TMC_END__): Likewise.
---
libgcc/crtstuff.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/libgcc/crtstuff.c b/libgcc/crtstuff.c
index 4927a9f8977..c8a8e2c87a5 100644
--- a/libgcc/crtstuff.c
+++ b/libgcc/crtstuff.c
@@ -233,11 +233,11 @@ CTOR_LIST_BEGIN;
static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
asm (__LIBGCC_CTORS_SECTION_ASM_OP__);
STATIC func_ptr __CTOR_LIST__[1]
- __attribute__ ((__used__, aligned(sizeof(func_ptr))))
+ __attribute__ ((__used__, aligned(__alignof__(func_ptr))))
= { (func_ptr) (-1) };
#else
STATIC func_ptr __CTOR_LIST__[1]
- __attribute__ ((__used__, section(".ctors"), aligned(sizeof(func_ptr))))
+ __attribute__ ((__used__, section(".ctors"), aligned(__alignof__(func_ptr))))
= { (func_ptr) (-1) };
#endif /* __CTOR_LIST__ alternatives */
@@ -246,11 +246,11 @@ DTOR_LIST_BEGIN;
#elif defined(__LIBGCC_DTORS_SECTION_ASM_OP__)
asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
STATIC func_ptr __DTOR_LIST__[1]
- __attribute__ ((aligned(sizeof(func_ptr))))
+ __attribute__ ((aligned(__alignof__(func_ptr))))
= { (func_ptr) (-1) };
#else
STATIC func_ptr __DTOR_LIST__[1]
- __attribute__((section(".dtors"), aligned(sizeof(func_ptr))))
+ __attribute__((section(".dtors"), aligned(__alignof__(func_ptr))))
= { (func_ptr) (-1) };
#endif /* __DTOR_LIST__ alternatives */
#endif /* USE_INITFINI_ARRAY */
@@ -265,7 +265,7 @@ STATIC EH_FRAME_SECTION_CONST char __EH_FRAME_BEGIN__[]
#if USE_TM_CLONE_REGISTRY
STATIC func_ptr __TMC_LIST__[]
- __attribute__((used, section(".tm_clone_table"), aligned(sizeof(void*))))
+ __attribute__((used, section(".tm_clone_table"), aligned(__alignof__(void*))))
= { };
# ifdef HAVE_GAS_HIDDEN
extern func_ptr __TMC_END__[] __attribute__((__visibility__ ("hidden")));
@@ -430,8 +430,8 @@ __do_global_dtors_aux (void)
CRT_CALL_STATIC_FUNCTION (FINI_SECTION_ASM_OP, __do_global_dtors_aux)
#elif defined (FINI_ARRAY_SECTION_ASM_OP)
static func_ptr __do_global_dtors_aux_fini_array_entry[]
- __attribute__ ((__used__, section(".fini_array"), aligned(sizeof(func_ptr))))
- = { __do_global_dtors_aux };
+ __attribute__ ((__used__, section(".fini_array"),
+ aligned(__alignof__(func_ptr)))) = { __do_global_dtors_aux };
#else /* !FINI_SECTION_ASM_OP && !FINI_ARRAY_SECTION_ASM_OP */
static void __attribute__((used))
__do_global_dtors_aux_1 (void)
@@ -474,8 +474,8 @@ frame_dummy (void)
CRT_CALL_STATIC_FUNCTION (__LIBGCC_INIT_SECTION_ASM_OP__, frame_dummy)
#else /* defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
static func_ptr __frame_dummy_init_array_entry[]
- __attribute__ ((__used__, section(".init_array"), aligned(sizeof(func_ptr))))
- = { frame_dummy };
+ __attribute__ ((__used__, section(".init_array"),
+ aligned(__alignof__(func_ptr)))) = { frame_dummy };
#endif /* !defined(__LIBGCC_INIT_SECTION_ASM_OP__) */
#endif /* USE_EH_FRAME_REGISTRY || USE_TM_CLONE_REGISTRY */
@@ -588,11 +588,11 @@ CTOR_LIST_END;
static func_ptr force_to_data[1] __attribute__ ((__used__)) = { };
asm (__LIBGCC_CTORS_SECTION_ASM_OP__);
STATIC func_ptr __CTOR_END__[1]
- __attribute__((aligned(sizeof(func_ptr))))
+ __attribute__((aligned(__alignof__(func_ptr))))
= { (func_ptr) 0 };
#else
STATIC func_ptr __CTOR_END__[1]
- __attribute__((section(".ctors"), aligned(sizeof(func_ptr))))
+ __attribute__((section(".ctors"), aligned(__alignof__(func_ptr))))
= { (func_ptr) 0 };
#endif
@@ -607,16 +607,16 @@ func_ptr __DTOR_END__[1]
#ifndef __LIBGCC_DTORS_SECTION_ASM_OP__
section(".dtors"),
#endif
- aligned(sizeof(func_ptr)), visibility ("hidden")))
+ aligned(__alignof__(func_ptr)), visibility ("hidden")))
= { (func_ptr) 0 };
#elif defined(__LIBGCC_DTORS_SECTION_ASM_OP__)
asm (__LIBGCC_DTORS_SECTION_ASM_OP__);
STATIC func_ptr __DTOR_END__[1]
- __attribute__ ((used, aligned(sizeof(func_ptr))))
+ __attribute__ ((used, aligned(__alignof__(func_ptr))))
= { (func_ptr) 0 };
#else
STATIC func_ptr __DTOR_END__[1]
- __attribute__((used, section(".dtors"), aligned(sizeof(func_ptr))))
+ __attribute__((used, section(".dtors"), aligned(__alignof__(func_ptr))))
= { (func_ptr) 0 };
#endif
#endif /* USE_INITFINI_ARRAY */
@@ -635,7 +635,7 @@ typedef short int32;
# endif
STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[]
__attribute__ ((used, section(__LIBGCC_EH_FRAME_SECTION_NAME__),
- aligned(sizeof(int32))))
+ aligned(__alignof__(int32))))
= { 0 };
#endif /* __LIBGCC_EH_FRAME_SECTION_NAME__ */
@@ -644,7 +644,8 @@ STATIC EH_FRAME_SECTION_CONST int32 __FRAME_END__[]
static
# endif
func_ptr __TMC_END__[]
- __attribute__((used, section(".tm_clone_table"), aligned(sizeof(void *))))
+ __attribute__((used, section(".tm_clone_table"),
+ aligned(__alignof__(void *))))
# ifdef HAVE_GAS_HIDDEN
__attribute__((__visibility__ ("hidden"))) = { };
# else
--
2.17.1
