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Re: [ARM/FDPIC v5 00/21] FDPIC ABI for ARM
- From: Christophe Lyon <christophe dot lyon at st dot com>
- To: <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 29 Aug 2019 15:57:40 +0200
- Subject: Re: [ARM/FDPIC v5 00/21] FDPIC ABI for ARM
- References: <20190515124006.25840-1-christophe.lyon@st.com>
Hi,
On 15/05/2019 14:39, Christophe Lyon wrote:
Hello,
This patch series implements the GCC contribution of the FDPIC ABI for
ARM targets.
This ABI enables to run Linux on ARM MMU-less cores and supports
shared libraries to reduce the memory footprint.
Without MMU, text and data segments relative distances are different
from one process to another, hence the need for a dedicated FDPIC
register holding the start address of the data segment. One of the
side effects is that function pointers require two words to be
represented: the address of the code, and the data segment start
address. These two words are designated as "Function Descriptor",
hence the "FD PIC" name.
On ARM, the FDPIC register is r9 [1], and the target name is
arm-uclinuxfdpiceabi. Note that arm-uclinux exists, but uses another
ABI and the BFLAT file format; it does not support code sharing.
The -mfdpic option is enabled by default, and -mno-fdpic should be
used to build the Linux kernel.
This work was developed some time ago by STMicroelectronics, and was
presented during Linaro Connect SFO15 (September 2015). You can watch
the discussion and read the slides [2].
This presentation was related to the toolchain published on github [3],
which is based on binutils-2.22, gcc-4.7, uclibc-0.9.33.2, gdb-7.5.1
and qemu-2.3.0, and for which pre-built binaries are available [3].
The ABI itself is described in details in [1].
Our Linux kernel patches have been updated and committed by Nicolas
Pitre (Linaro) in July 2017. They are required so that the loader is
able to handle this new file type. Indeed, the ELF files are tagged
with ELFOSABI_ARM_FDPIC. This new tag has been allocated by ARM, as
well as the new relocations involved.
The binutils, QEMU and uclibc-ng patch series have been merged a few
months ago. [4][5][6]
This series provides support for architectures that support ARM and/or
Thumb-2 and has been tested on arm-linux-gnueabi without regression,
as well as arm-uclinuxfdpiceabi, using QEMU. arm-uclinuxfdpiceabi has
a few more failures than arm-linux-gnueabi, but is quite functional.
I have also booted an STM32 board (stm32f469) which uses a cortex-m4
with linux-4.20.17 and ran successfully several tools.
Are the GCC patches OK for inclusion in master?
I have addressed the comments I received on v5, and I am going to post updated versions of the patches that needed changes as follow-ups in this thread. I hope this will help reviewers as I will provide answers and updated patches next to their comments. After that, I will rebase the whole series and send it as v6 if that helps (several testsuite patches have already been approved as-is, but committing them now would change the patch numbering, thus possibly confusing reviewers).
However, note that several patches in the series haven't received feedback yet, so this is a ping for them :-)
[ARM/FDPIC v5 06/21] [ARM] FDPIC: Add support for c++ exceptions
[ARM/FDPIC v5 10/21] [ARM] FDPIC: Implement TLS support.
[ARM/FDPIC v5 11/21] [ARM] FDPIC: Add support to unwind FDPIC signal frame
[ARM/FDPIC v5 12/21] [ARM] FDPIC: Restore r9 after we call __aeabi_read_tp
[ARM/FDPIC v5 13/21] [ARM] FDPIC: Force LSB bit for PC in Cortex-M architecture
Thanks,
Christophe
Changes between v4 and v5:
- rebased on top of recent gcc-10 master (April 26th, 2019)
- fixed handling of stack-protector combined patterns in FDPIC mode
Changes between v3 and v4:
- improved documentation (patch 1)
- emit an error message (sorry) if the target architecture does not
support arm nor thumb-2 modes (patch 4)
- handle Richard's comments on patch 4 (comments, unspec)
- added .align directive (patch 5)
- fixed use of kernel helpers (__kernel_cmpxchg, __kernel_dmb) (patch 6)
- code factorization in patch 7
- typos/internal function name in patch 8
- improved patch 12
- dropped patch 16
- patch 20 introduces arm_arch*_thumb_ok effective targets to help
skip some tests
- I tested patch 2 on xtensa-buildroot-uclinux-uclibc, it adds many
new tests, but a few regressions
(https://gcc.gnu.org/ml/gcc-patches/2018-11/msg00713.html)
- I compiled and executed several LTP tests to exercise pthreads and signals
- I wrote and executed a simple testcase to change the interaction
with __kernel_cmpxchg (ie. call the kernel helper rather than use an
implementation in libgcc as requested by Richard)
Changes between v2 and v3:
- added doc entry for -mfdpic new option
- took Kyrill's comments into account (use "Armv7" instead of "7",
code factorization, use preprocessor instead of hard-coding "r9",
remove leftover code for thumb1 support, fixed comments)
- rebase over recent trunk
- patches with changes: 1, 2 (commit message), 3 (rebase), 4, 6, 7, 9,
14 (rebase), 19 (rebase)
Changes between v1 and v2:
- fix GNU coding style
- exit with an error for pre-Armv7
- use ACLE __ARM_ARCH and remove dead code for pre-Armv4
- remove unsupported attempts of pre-Armv7/thumb1 support
- add instructions in comments next to opcodes
- merge patches 11 and 13
- fixed protected visibility handling in patch 8
- merged legitimize_tls_address_fdpic and
legitimize_tls_address_not_fdpic as requested
Thanks,
Christophe.
[1] https://github.com/mickael-guene/fdpic_doc/blob/master/abi.txt
[2] http://connect.linaro.org/resource/sfo15/sfo15-406-arm-fdpic-toolset-kernel-libraries-for-cortex-m-cortex-r-mmuless-cores/
[3] https://github.com/mickael-guene/fdpic_manifest
[4] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=f1ac0afe481e83c9a33f247b81fa7de789edc4d9
[5] https://git.qemu.org/?p=qemu.git;a=commit;h=e8fa72957419c11984608062c7dcb204a6003a06
[6] https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/commit/?id=13c46fbc1e5a021f2b9ed32d83aecc93ae5e655d
Christophe Lyon (21):
[ARM] FDPIC: Add -mfdpic option support
[ARM] FDPIC: Handle arm*-*-uclinuxfdpiceabi in configure scripts
[ARM] FDPIC: Force FDPIC related options unless -mno-fdpic is provided
[ARM] FDPIC: Add support for FDPIC for arm architecture
[ARM] FDPIC: Fix __do_global_dtors_aux and frame_dummy generation
[ARM] FDPIC: Add support for c++ exceptions
[ARM] FDPIC: Avoid saving/restoring r9 on stack since it is read-only
[ARM] FDPIC: Enforce local/global binding for function descriptors
[ARM] FDPIC: Add support for taking address of nested function
[ARM] FDPIC: Implement TLS support.
[ARM] FDPIC: Add support to unwind FDPIC signal frame
[ARM] FDPIC: Restore r9 after we call __aeabi_read_tp
[ARM] FDPIC: Force LSB bit for PC in Cortex-M architecture
[ARM][testsuite] FDPIC: Skip unsupported tests
[ARM][testsuite] FDPIC: Adjust scan-assembler patterns.
[ARM][testsuite] FDPIC: Skip tests that don't work in PIC mode
[ARM][testsuite] FDPIC: Handle *-*-uclinux*
[ARM][testsuite] FDPIC: Enable tests on pie_enabled targets
[ARM][testsuite] FDPIC: Adjust pr43698.c to avoid clash with uclibc.
[ARM][testsuite] FDPIC: Skip tests using architectures unsupported by
FDPIC
[ARM] FDPIC: Handle stack-protector combined patterns
config/futex.m4 | 2 +-
config/tls.m4 | 2 +-
gcc/config.gcc | 13 +-
gcc/config/arm/arm-c.c | 2 +
gcc/config/arm/arm-protos.h | 1 +
gcc/config/arm/arm.c | 485 ++++++++++++++++++---
gcc/config/arm/arm.h | 16 +-
gcc/config/arm/arm.md | 151 ++++++-
gcc/config/arm/arm.opt | 4 +
gcc/config/arm/bpabi.h | 4 +-
gcc/config/arm/linux-eabi.h | 7 +-
gcc/config/arm/uclinuxfdpiceabi.h | 53 +++
gcc/config/arm/unspecs.md | 1 +
gcc/doc/invoke.texi | 20 +-
gcc/ginclude/unwind-arm-common.h | 2 +-
gcc/testsuite/g++.dg/abi/forced.C | 2 +-
gcc/testsuite/g++.dg/abi/guard2.C | 2 +-
gcc/testsuite/g++.dg/cpp0x/noexcept03.C | 2 +-
gcc/testsuite/g++.dg/ext/cleanup-10.C | 2 +-
gcc/testsuite/g++.dg/ext/cleanup-11.C | 2 +-
gcc/testsuite/g++.dg/ext/cleanup-8.C | 2 +-
gcc/testsuite/g++.dg/ext/cleanup-9.C | 2 +-
gcc/testsuite/g++.dg/ext/sync-4.C | 2 +-
gcc/testsuite/g++.dg/ipa/comdat.C | 2 +-
gcc/testsuite/g++.dg/ipa/devirt-c-7.C | 3 +-
gcc/testsuite/g++.dg/ipa/ivinline-1.C | 2 +-
gcc/testsuite/g++.dg/ipa/ivinline-2.C | 2 +-
gcc/testsuite/g++.dg/ipa/ivinline-3.C | 2 +-
gcc/testsuite/g++.dg/ipa/ivinline-4.C | 2 +-
gcc/testsuite/g++.dg/ipa/ivinline-5.C | 2 +-
gcc/testsuite/g++.dg/ipa/ivinline-7.C | 2 +-
gcc/testsuite/g++.dg/ipa/ivinline-8.C | 2 +-
gcc/testsuite/g++.dg/ipa/ivinline-9.C | 2 +-
gcc/testsuite/g++.dg/other/anon5.C | 1 +
gcc/testsuite/g++.dg/tls/pr79288.C | 2 +-
gcc/testsuite/gcc.c-torture/compile/pr82096.c | 2 +-
gcc/testsuite/gcc.dg/20020312-2.c | 1 +
gcc/testsuite/gcc.dg/20041106-1.c | 2 +-
gcc/testsuite/gcc.dg/addr_equal-1.c | 3 +-
gcc/testsuite/gcc.dg/cleanup-10.c | 2 +-
gcc/testsuite/gcc.dg/cleanup-11.c | 2 +-
gcc/testsuite/gcc.dg/cleanup-8.c | 2 +-
gcc/testsuite/gcc.dg/cleanup-9.c | 2 +-
gcc/testsuite/gcc.dg/const-1.c | 2 +-
gcc/testsuite/gcc.dg/fdata-sections-1.c | 2 +-
gcc/testsuite/gcc.dg/fdata-sections-2.c | 2 +-
gcc/testsuite/gcc.dg/ipa/pure-const-1.c | 2 +-
gcc/testsuite/gcc.dg/noreturn-8.c | 2 +-
gcc/testsuite/gcc.dg/pr33826.c | 3 +-
gcc/testsuite/gcc.dg/pr39323-1.c | 2 +-
gcc/testsuite/gcc.dg/pr39323-2.c | 2 +-
gcc/testsuite/gcc.dg/pr39323-3.c | 2 +-
gcc/testsuite/gcc.dg/pr65780-1.c | 2 +-
gcc/testsuite/gcc.dg/pr65780-2.c | 2 +-
gcc/testsuite/gcc.dg/pr67338.c | 2 +-
gcc/testsuite/gcc.dg/pr78185.c | 2 +-
gcc/testsuite/gcc.dg/pr83100-1.c | 2 +-
gcc/testsuite/gcc.dg/pr83100-4.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-12g.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-14g.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-14gf.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-16g.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-17g.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-18g.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-1f.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-22g.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-2f.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-31g.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-33g.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-4g.c | 2 +-
gcc/testsuite/gcc.dg/strlenopt-4gf.c | 2 +-
gcc/testsuite/gcc.dg/strncmp-2.c | 2 +-
gcc/testsuite/gcc.dg/struct-ret-3.c | 2 +-
gcc/testsuite/gcc.dg/torture/ipa-pta-1.c | 2 +-
gcc/testsuite/gcc.dg/torture/pr69760.c | 2 +-
gcc/testsuite/gcc.dg/tree-ssa/alias-2.c | 2 +-
gcc/testsuite/gcc.dg/tree-ssa/ipa-split-5.c | 2 +-
gcc/testsuite/gcc.dg/tree-ssa/loadpre6.c | 2 +-
gcc/testsuite/gcc.target/arm/20051215-1.c | 1 +
.../gcc.target/arm/armv6-unaligned-load-ice.c | 1 +
.../gcc.target/arm/attr-unaligned-load-ice.c | 1 +
gcc/testsuite/gcc.target/arm/attr_arm-err.c | 1 +
gcc/testsuite/gcc.target/arm/data-rel-2.c | 1 +
gcc/testsuite/gcc.target/arm/data-rel-3.c | 1 +
gcc/testsuite/gcc.target/arm/div64-unwinding.c | 2 +-
gcc/testsuite/gcc.target/arm/eliminate.c | 2 +-
gcc/testsuite/gcc.target/arm/ftest-armv4-arm.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv4t-arm.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv4t-thumb.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv5t-arm.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv5t-thumb.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv5te-arm.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv5te-thumb.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv6-arm.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv6-thumb.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv6k-arm.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv6k-thumb.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv6m-thumb.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv6t2-arm.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv6t2-thumb.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv6z-arm.c | 1 +
gcc/testsuite/gcc.target/arm/ftest-armv6z-thumb.c | 1 +
gcc/testsuite/gcc.target/arm/g2.c | 1 +
gcc/testsuite/gcc.target/arm/interrupt-1.c | 6 +-
gcc/testsuite/gcc.target/arm/interrupt-2.c | 6 +-
gcc/testsuite/gcc.target/arm/ivopts-2.c | 2 +-
gcc/testsuite/gcc.target/arm/ivopts-3.c | 2 +-
gcc/testsuite/gcc.target/arm/ivopts-4.c | 2 +-
gcc/testsuite/gcc.target/arm/ivopts-5.c | 2 +-
gcc/testsuite/gcc.target/arm/macro_defs1.c | 1 +
gcc/testsuite/gcc.target/arm/mmx-1.c | 1 +
gcc/testsuite/gcc.target/arm/pr19599.c | 1 +
gcc/testsuite/gcc.target/arm/pr40887.c | 1 +
gcc/testsuite/gcc.target/arm/pr43597.c | 2 +-
gcc/testsuite/gcc.target/arm/pr43698.c | 4 +-
gcc/testsuite/gcc.target/arm/pr43920-2.c | 2 +-
gcc/testsuite/gcc.target/arm/pr45701-1.c | 4 +-
gcc/testsuite/gcc.target/arm/pr45701-2.c | 4 +-
gcc/testsuite/gcc.target/arm/pr59858.c | 1 +
gcc/testsuite/gcc.target/arm/pr61948.c | 1 +
gcc/testsuite/gcc.target/arm/pr65647-2.c | 1 +
gcc/testsuite/gcc.target/arm/pr66912.c | 2 +-
gcc/testsuite/gcc.target/arm/pr70830.c | 3 +-
gcc/testsuite/gcc.target/arm/pr77933-1.c | 1 +
gcc/testsuite/gcc.target/arm/pr77933-2.c | 1 +
gcc/testsuite/gcc.target/arm/pr79058.c | 1 +
gcc/testsuite/gcc.target/arm/pr83712.c | 1 +
.../gcc.target/arm/pragma_arch_switch_2.c | 1 +
gcc/testsuite/gcc.target/arm/scd42-1.c | 1 +
gcc/testsuite/gcc.target/arm/scd42-2.c | 1 +
gcc/testsuite/gcc.target/arm/scd42-3.c | 1 +
gcc/testsuite/gcc.target/arm/sibcall-1.c | 1 +
gcc/testsuite/gcc.target/arm/stack-checking.c | 2 +-
gcc/testsuite/gcc.target/arm/stack-red-zone.c | 2 +-
gcc/testsuite/gcc.target/arm/synchronize.c | 2 +-
gcc/testsuite/gcc.target/arm/tail-long-call.c | 1 +
gcc/testsuite/gcc.target/arm/tlscall.c | 1 +
gcc/testsuite/gcc.target/arm/vfp-longcall-apcs.c | 1 +
gcc/testsuite/lib/target-supports.exp | 10 +
libatomic/configure | 8 +-
libatomic/configure.tgt | 2 +-
libgcc/config.host | 4 +-
libgcc/config/arm/linux-atomic.c | 55 ++-
libgcc/config/arm/unwind-arm.c | 5 +
libgcc/config/arm/unwind-arm.h | 31 +-
libgcc/crtstuff.c | 18 +
libgcc/unwind-arm-common.inc | 216 +++++++++
libgcc/unwind-pe.h | 17 +
libitm/configure | 20 +-
libitm/configure.tgt | 2 +-
libsanitizer/configure.tgt | 3 +
libstdc++-v3/acinclude.m4 | 12 +-
libstdc++-v3/configure | 36 +-
libstdc++-v3/configure.host | 6 +-
libstdc++-v3/libsupc++/eh_personality.cc | 10 +-
libtool.m4 | 14 +-
156 files changed, 1233 insertions(+), 219 deletions(-)
create mode 100644 gcc/config/arm/uclinuxfdpiceabi.h