binutils-gdb/ld/scripttempl/mmo.sc
Hans-Peter Nilsson 555a578963 mmix ld: move .init (and _init) first.
This both makes the section layout more similar to that of the general
default for ELF and fixes (makes true) an assumption that code and
rodata is located between _init and __etext, in
libgcc/config/mmix/crti.S.  Sadly, that's not actually true for ELF
(generally and for elf64mmix), where exception-tables and .rodata is
after _etext; I'm pondering what to do about that.

The original mmix simulator behavior is that memory magically appears
on access, initialized with 0, which is not preferable when chasing
bugs by throwing code the size of the gcc test-suite to the simulator.
The code in crti.S compatibly enables simulator machinery to identify
undefined memory and instead stopping the simulator with an error
(going to interactive mode for interactive runs).  See
http://gcc.gnu.org/legacy-ml/gcc-patches/2012-10/msg01871.html for
more, including the mmix-sim.ch "patch file".

This fixes only one error in the gcc testsuite,
gcc.c-torture/execute/pr20621-1.c with LTO, where for some reason
gcc/lto chooses to move (writable) data that is only used to read 0 to
.rodata.  An access (sufficiently far inside a block) in an
unregistered place is flagged as an invalid access.

The bpo-9m test that I had to adjust, actually exposes a wart: mmo
does not have the notion of symbol types (or sections) and the
test-case now has leading zeros at "Main" eventually leading to it
being misdiagnosed as being outside .text and .data, thus here mapped
to BFD as an absolute symbol.  The test is not intended to check the
mmo symbol-type machinery, so I'm just tweaking it to be
symbol-type-neutral for "Main".

Since you have to jump through hoops to see the problem, I don't think
this commit is worth putting on the 2.35-branch.

ld:
	* scripttempt/mmo.sc: Move .init first in .text output section.
	* testsuite/ld-mmix/bpo-9m.d: Adjust accordingly.
2020-07-17 00:56:17 +02:00

154 lines
5.0 KiB
Scala

# Copyright (C) 2014-2020 Free Software Foundation, Inc.
#
# Copying and distribution of this file, with or without modification,
# are permitted in any medium without royalty provided the copyright
# notice and this notice are preserved.
# MMO is not a relocateable format, and we don't want to require an
# explicit (e.g.) "-m elf64mmix" when -r is used.
test -z $RELOCATEABLE_OUTPUT_FORMAT && RELOCATEABLE_OUTPUT_FORMAT=$OUTPUT_FORMAT
test -z ${RELOCATING+0} && OUTPUT_FORMAT=$RELOCATEABLE_OUTPUT_FORMAT
cat <<EOF
/* Copyright (C) 2014-2020 Free Software Foundation, Inc.
Copying and distribution of this script, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved. */
OUTPUT_FORMAT("$OUTPUT_FORMAT")
OUTPUT_ARCH(mmix)
${RELOCATING+ENTRY(Main)}
SECTIONS
{
.text ${RELOCATING+ ${TEXT_START_ADDR}}:
{
/* FIXME: Move .init, .fini, .ctors and .dtors to their own sections. */
${RELOCATING+ PROVIDE (_init_start = .);}
${RELOCATING+ PROVIDE (_init = .);}
${RELOCATING+ KEEP (*(SORT_NONE(.init)))}
${RELOCATING+ PROVIDE (_init_end = .);}
*(.text)
${RELOCATING+*(.text.*)}
${RELOCATING+*(.gnu.linkonce.t*)}
${RELOCATING+*(.rodata)}
${RELOCATING+*(.rodata.*)}
${RELOCATING+*(.gnu.linkonce.r*)}
${RELOCATING+ PROVIDE (_fini_start = .);}
${RELOCATING+ PROVIDE (_fini = .);}
${RELOCATING+ KEEP (*(SORT_NONE(.fini)))}
${RELOCATING+ PROVIDE (_fini_end = .);}
/* FIXME: Align ctors, dtors, ehframe. */
${RELOCATING+ PROVIDE (_ctors_start = .);}
${RELOCATING+ PROVIDE (__ctors_start = .);}
${RELOCATING+ PROVIDE (_ctors = .);}
${RELOCATING+ PROVIDE (__ctors = .);}
${RELOCATING+ KEEP (*crtbegin.o(.ctors))}
${RELOCATING+ KEEP (*crtbegin?.o(.ctors))}
${RELOCATING+ KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o) .ctors))}
${RELOCATING+ KEEP (*(SORT(.ctors.*)))}
${RELOCATING+ KEEP (*(.ctors))}
${RELOCATING+ PROVIDE (_ctors_end = .);}
${RELOCATING+ PROVIDE (__ctors_end = .);}
${RELOCATING+ PROVIDE (_dtors_start = .);}
${RELOCATING+ PROVIDE (__dtors_start = .);}
${RELOCATING+ PROVIDE (_dtors = .);}
${RELOCATING+ PROVIDE (__dtors = .);}
${RELOCATING+ KEEP (*crtbegin.o(.dtors))}
${RELOCATING+ KEEP (*crtbegin?.o(.dtors))}
${RELOCATING+ KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o) .dtors))}
${RELOCATING+ KEEP (*(SORT(.dtors.*)))}
${RELOCATING+ KEEP (*(.dtors))}
${RELOCATING+ PROVIDE (_dtors_end = .);}
${RELOCATING+ PROVIDE (__dtors_end = .);}
${RELOCATING+KEEP (*(.jcr))}
${RELOCATING+KEEP (*(.eh_frame))}
${RELOCATING+*(.gcc_except_table)}
${RELOCATING+Main = DEFINED (Main) ? Main : (DEFINED (_start) ? _start : ADDR (.text));}
}
/* The following NOP assignment and those after .data and .bss, are
necessary to get orphan sections adopted by the .text inserted before
the following end-section symbols. An output section would also serve
this purpose, but we can't do that. */
. = .;
${RELOCATING+ PROVIDE(etext = .);}
${RELOCATING+ PROVIDE(_etext = .);}
${RELOCATING+ PROVIDE(__etext = .);}
.data ${RELOCATING+ ${DATA_ADDR}}:
{
${RELOCATING+ PROVIDE(__Sdata = .);}
*(.data);
${RELOCATING+*(.data.*)}
${RELOCATING+*(.gnu.linkonce.d*)}
}
. = .;
${RELOCATING+ PROVIDE(__Edata = .);}
/* Deprecated, use __Edata. */
${RELOCATING+ PROVIDE(edata = .);}
${RELOCATING+ PROVIDE(_edata = .);}
${RELOCATING+ PROVIDE(__edata = .);}
/* At the moment, although perhaps we should, we can't map sections
without contents to sections *with* contents due to FIXME: a BFD bug.
Anyway, the mmo back-end ignores sections without contents when
writing out sections, so this works fine. */
.bss :
{
${RELOCATING+ PROVIDE(__Sbss = .);}
${RELOCATING+ PROVIDE(__bss_start = .);}
${RELOCATING+ *(.sbss);}
${RELOCATING+ *(.bss);}
${RELOCATING+*(.bss.*)}
${RELOCATING+ *(COMMON);}
}
. = .;
${RELOCATING+ PROVIDE(__Ebss = .);}
/* Deprecated, use __Ebss or __Eall as appropriate. */
${RELOCATING+ PROVIDE(end = .);}
${RELOCATING+ PROVIDE(_end = .);}
${RELOCATING+ PROVIDE(__end = .);}
${RELOCATING+ PROVIDE(__Eall = .);}
.stab 0 : { *(.stab) }
.stabstr 0 : { *(.stabstr) }
.stab.excl 0 : { *(.stab.excl) }
.stab.exclstr 0 : { *(.stab.exclstr) }
.stab.index 0 : { *(.stab.index) }
.stab.indexstr 0 : { *(.stab.indexstr) }
EOF
. $srcdir/scripttempl/DWARF.sc
cat <<EOF
.MMIX.reg_contents :
{
/* Note that this section always has a fixed VMA - that of its
first register * 8. */
*(.MMIX.reg_contents.linker_allocated);
*(.MMIX.reg_contents);
}
${RELOCATING+/* By default, put the high end of the stack where the register stack
begins. They grow in opposite directions. */
PROVIDE (__Stack_start = 0x6000000000000000);}
/* Unfortunately, stabs are not mappable from ELF to MMO.
It can probably be fixed with some amount of work. */
/DISCARD/ :
{ ${RELOCATING+ *(.gnu.warning.*);} }
.gnu.attributes 0 : { KEEP (*(.gnu.attributes)) }
}
EOF