From 555a578963dd5ec3731842df12c010bf6a3e9ccf Mon Sep 17 00:00:00 2001 From: Hans-Peter Nilsson Date: Fri, 17 Jul 2020 00:55:13 +0200 Subject: [PATCH] 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. --- ld/ChangeLog | 5 +++++ ld/scripttempl/mmo.sc | 12 ++++++------ ld/testsuite/ld-mmix/bpo-9m.d | 12 ++++++------ 3 files changed, 17 insertions(+), 12 deletions(-) diff --git a/ld/ChangeLog b/ld/ChangeLog index 3d8b8d663ed..32b4616dfad 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,8 @@ +2020-07-17 Hans-Peter Nilsson + + * scripttempt/mmo.sc: Move .init first in .text output section. + * testsuite/ld-mmix/bpo-9m.d: Adjust accordingly. + 2020-07-15 Jan Beulich * testsuite/ld-i386/ibt-plt-1.d, testsuite/ld-i386/ibt-plt-2a.d, diff --git a/ld/scripttempl/mmo.sc b/ld/scripttempl/mmo.sc index c3992788fbe..354a76964e7 100644 --- a/ld/scripttempl/mmo.sc +++ b/ld/scripttempl/mmo.sc @@ -24,6 +24,12 @@ 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*)} @@ -31,12 +37,6 @@ SECTIONS ${RELOCATING+*(.rodata.*)} ${RELOCATING+*(.gnu.linkonce.r*)} - /* 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 = .);} - ${RELOCATING+ PROVIDE (_fini_start = .);} ${RELOCATING+ PROVIDE (_fini = .);} ${RELOCATING+ KEEP (*(SORT_NONE(.fini)))} diff --git a/ld/testsuite/ld-mmix/bpo-9m.d b/ld/testsuite/ld-mmix/bpo-9m.d index fa3f97c2897..eb53f6b5702 100644 --- a/ld/testsuite/ld-mmix/bpo-9m.d +++ b/ld/testsuite/ld-mmix/bpo-9m.d @@ -11,12 +11,12 @@ .*: file format mmo SYMBOL TABLE: -0+ g \.text Main -0+4 g \.text x -0+ g \.text x2 +0+ g .* Main +0+14 g \.text x +0+10 g \.text x2 Contents of section \.text: - 0000 232dfe00 232dfd00 00000000 0000002d .* - 0010 00000000 0000002a .* + 0004 0000003d 00000000 0000003a 232dfe00 .* + 0014 232dfd00 .* Contents of section \.MMIX\.reg_contents: - 07e8 00000000 0000106c 00000000 0000a410 .* + 07e8 00000000 0000107c 00000000 0000a420 .* -- 2.30.2