[PATCH,V1 00/14] Definition and support for SFrame unwind format
Indu Bhagat
indu.bhagat@oracle.com
Fri Sep 30 00:04:26 GMT 2022
Hello,
This patch series was previously being reviewed in the set "[PATCH,V6 00/10]
Definition and Implementation of CTF Frame format" here
https://sourceware.org/pipermail/binutils/2022-August/122147.html
(Posting links here of previous posting with old name "CTF Frame" for easy
lookup:
Initial (V1) posting contains necessary introductions:
https://sourceware.org/pipermail/binutils/2022-May/120731.html
V2 posting with some improvements:
https://sourceware.org/pipermail/binutils/2022-May/120899.html
V3 posting with further improvements:
https://sourceware.org/pipermail/binutils/2022-June/121245.html
V4 posting with further improvements and bugfixes:
https://sourceware.org/pipermail/binutils/2022-June/121478.html
V5 posting:
https://sourceware.org/pipermail/binutils/2022-July/121839.html
)
After the discussions at LPC and GNU Tools Cauldron this year, it seemed like
the format needed a more suitable name. The previous name was justifiably
bringing up some questions around: 1. How tied is the proposed frame format
with CTF (Compact C-Type Format), and 2. Is the format applicable for only
applications written in C. The answers to these questions are: 1. It is
independent of the CTF debug format, and 2. No. So, we think the format needed
a more appropriate name. The new chosen name is "Simple Frame format", or
"SFrame" format for plain vanilla backtracing.
This patch series has addressed the review comments sent earlier in August 2022
(and apologies for the long delay in sending this series):
- include/sframe.h uses ansidecl.h and ATTRIBUTE_PACKED
- gas patches have been split up. The gas testsuite is now a separate patch,
hopefully it eases some pain around testing each patch as the gas
testsuite needs the readelf/objdump support. The bfd/linker patch still
has the testsuite combined in it though ...
- bfd/elf-sframe.c now uses less BFD_ASSERTs. Some of them remain and I will
deal with them over time.
- fixes made for the compile-time warnings around incompatible pointer type
[-Werror=incompatible-pointer-types] noted on i686 build.
- other fixes around return type of some APIs, goofy labels and like.
- added binutils/NEWS, gas/NEWS and updated the src-release.sh
The format specification document still mains a TODO at this time. I plan to
resume working on this after I have tackled the task of SFrame generation for
PLT/veneers in aarch64.
Another comment/feedback received at Cauldron was around the representation of
the SFrame Frame Row Entries: Can SFrame FREs be made fixed length and hence,
possibly compacted further such that all SFrame FREs across functions can then
possibly share the SP/FP/RA offset records. This still remains to be
experimented with.
PS: libsframe/configure has been REMOVED from the patch series, as it causes
the size of some patches to go beyond the allowed limit. Please regenerate
libsframe/configure after applying the series.
Testing notes:
- Tested natively on x86_64-linux, aarch64-linux and i686-linux with
'--enable-shared'.
- Cross builds for various targets on x86_64 host with no explicit
'--enable-shared'. Ran a regression script that checks for failures in gas,
ld, binutils, libctf with no reported regressions. libsframe tests ran as
expected. libsframebt (the backtracer) tests (which are present in
libsframe/testsuite/libsframe.unwind) have been disabled with host != target.
What is SFrame format and why do we need it
-------------------------------------------
SFrame format is the Simple Frame format. It can be used to represent the
minimal necessary information for backtracing. As such, it only encodes how to
recover the CFA (based on SP/FP) and the return address (RA) for all
instructions of a program.
The format is supported on AMD64 and AARCH64 ABIs only. The information stored
in the .sframe section is a subset of what .eh_frame can convey: .eh_frame can
convey how to resurrect all callee-saved registers, if need be; but .sframe
does not.
SFrame format is intended for usecases where fast virtual stack unwind is
needed, along with a need for a small simple unwinder. So, those applications
which struggle with the following two complaints will want to consider SFrame
format:
- EH Frame based unwinders are complex and slow to manage with
- EH Frame based unwinders are large as they need to deal with DWARF
opcodes via a stack machine implementation
More details about the format are available in include/sframe.h, please see
commit "sframe.h: Add SFrame format definition".
Our not-so-exhaustive experiments (basically binutils programs built with
-Wa,--gsframe) show that SFrame/EH Frame section ratio to be an average of 0.8x
for x86_64 and 0.7x for aarch64.
Support in binutils
-------------------
This patch series adds support for SFrame format in GNU as, ld, readelf and
objdump. Two new libraries are being added:
- libsframe - provides means to decode, encode/write, and probe SFrame
sections. This is used by GNU ld and libsframebt.
- libsframebt - small backtracer based on SFrame format.
More details on each of these components are provided in the respective commit
message.
Thanks,
Indu Bhagat (11):
sframe.h: Add SFrame format definition
gas: add new command line option --gsframe
gas: generate .sframe from CFI directives
gas: testsuite: add new tests for SFrame unwind info
bfd: linker: merge .sframe sections
readelf/objdump: support for SFrame section
gdb: sim: buildsystem changes to accommodate libsframe
libctf: add libsframe to LDFLAGS and LIBS
src-release.sh: Add libsframe
binutils/NEWS: add text for SFrame support
gas/NEWS: add text about new command line option and SFrame support
Weimin Pan (3):
libsframe: add the SFrame library
unwinder: generate backtrace using SFrame format
unwinder: Add SFrame unwinder tests
Makefile.def | 6 +
Makefile.in | 1299 +++++++++++++-
bfd/Makefile.am | 6 +-
bfd/Makefile.in | 7 +-
bfd/bfd-in2.h | 1 +
bfd/configure | 2 +-
bfd/configure.ac | 2 +-
bfd/elf-bfd.h | 54 +
bfd/elf-sframe.c | 533 ++++++
bfd/elf.c | 32 +
bfd/elf64-x86-64.c | 97 +-
bfd/elflink.c | 52 +
bfd/elfxx-x86.c | 377 +++-
bfd/elfxx-x86.h | 46 +
bfd/section.c | 1 +
binutils/Makefile.am | 10 +-
binutils/Makefile.in | 9 +-
binutils/NEWS | 2 +
binutils/doc/binutils.texi | 4 +
binutils/doc/sframe.options.texi | 10 +
binutils/objdump.c | 76 +
binutils/readelf.c | 47 +
config/sframe.m4 | 16 +
configure | 2 +-
configure.ac | 2 +-
gas/Makefile.am | 3 +
gas/Makefile.in | 22 +-
gas/NEWS | 3 +
gas/as.c | 10 +-
gas/as.h | 13 +-
gas/config/tc-aarch64.c | 41 +
gas/config/tc-aarch64.h | 29 +
gas/config/tc-i386.c | 44 +
gas/config/tc-i386.h | 26 +
gas/config/tc-xtensa.c | 1 +
gas/doc/as.texi | 19 +-
gas/dw2gencfi.c | 30 +
gas/dw2gencfi.h | 1 +
gas/gen-sframe.c | 1300 ++++++++++++++
gas/gen-sframe.h | 141 ++
gas/sframe-opt.c | 158 ++
.../gas/cfi-sframe/cfi-sframe-aarch64-1.d | 20 +
.../gas/cfi-sframe/cfi-sframe-aarch64-1.s | 61 +
.../gas/cfi-sframe/cfi-sframe-common-1.d | 17 +
.../gas/cfi-sframe/cfi-sframe-common-1.s | 3 +
.../gas/cfi-sframe/cfi-sframe-common-2.d | 17 +
.../gas/cfi-sframe/cfi-sframe-common-2.s | 2 +
.../gas/cfi-sframe/cfi-sframe-common-3.d | 17 +
.../gas/cfi-sframe/cfi-sframe-common-3.s | 4 +
.../gas/cfi-sframe/cfi-sframe-common-4.d | 21 +
.../gas/cfi-sframe/cfi-sframe-common-4.s | 8 +
.../gas/cfi-sframe/cfi-sframe-common-5.d | 21 +
.../gas/cfi-sframe/cfi-sframe-common-5.s | 7 +
.../gas/cfi-sframe/cfi-sframe-common-6.d | 21 +
.../gas/cfi-sframe/cfi-sframe-common-6.s | 7 +
.../gas/cfi-sframe/cfi-sframe-common-7.d | 21 +
.../gas/cfi-sframe/cfi-sframe-common-7.s | 7 +
.../gas/cfi-sframe/cfi-sframe-common-8.d | 20 +
.../gas/cfi-sframe/cfi-sframe-common-8.s | 12 +
.../gas/cfi-sframe/cfi-sframe-x86_64-1.d | 22 +
.../gas/cfi-sframe/cfi-sframe-x86_64-1.s | 30 +
gas/testsuite/gas/cfi-sframe/cfi-sframe.exp | 58 +
gas/testsuite/gas/cfi-sframe/common-empty-1.d | 14 +
gas/testsuite/gas/cfi-sframe/common-empty-1.s | 5 +
gas/testsuite/gas/cfi-sframe/common-empty-2.d | 14 +
gas/testsuite/gas/cfi-sframe/common-empty-2.s | 8 +
gas/testsuite/gas/cfi-sframe/common-empty-3.d | 14 +
gas/testsuite/gas/cfi-sframe/common-empty-3.s | 9 +
gas/testsuite/gas/cfi-sframe/common-empty-4.d | 14 +
gas/testsuite/gas/cfi-sframe/common-empty-4.s | 17 +
gas/write.c | 13 +
gdb/Makefile.in | 8 +-
gdb/acinclude.m4 | 4 +-
gdb/configure | 35 +-
gdb/configure.ac | 11 +
include/elf/common.h | 1 +
include/elf/internal.h | 1 +
include/sframe-api.h | 214 +++
include/sframe-backtrace-api.h | 57 +
include/sframe.h | 281 +++
ld/Makefile.am | 2 +
ld/Makefile.in | 2 +
ld/configure | 8 +-
ld/configure.ac | 3 +
ld/ld.texi | 4 +-
ld/scripttempl/elf.sc | 2 +
ld/testsuite/ld-aarch64/aarch64-elf.exp | 2 +
ld/testsuite/ld-aarch64/sframe-bar.s | 7 +
ld/testsuite/ld-aarch64/sframe-foo.s | 10 +
ld/testsuite/ld-aarch64/sframe-simple-1.d | 26 +
ld/testsuite/ld-bootstrap/bootstrap.exp | 8 +-
ld/testsuite/ld-sframe/discard.d | 10 +
ld/testsuite/ld-sframe/discard.ld | 9 +
ld/testsuite/ld-sframe/discard.s | 13 +
ld/testsuite/ld-sframe/sframe-empty.d | 10 +
ld/testsuite/ld-sframe/sframe-empty.s | 2 +
ld/testsuite/ld-sframe/sframe.exp | 47 +
ld/testsuite/ld-x86-64/sframe-bar.s | 31 +
ld/testsuite/ld-x86-64/sframe-foo.s | 37 +
ld/testsuite/ld-x86-64/sframe-plt-1.d | 29 +
ld/testsuite/ld-x86-64/sframe-simple-1.d | 35 +
ld/testsuite/ld-x86-64/x86-64.exp | 2 +
ld/testsuite/lib/ld-lib.exp | 45 +
libctf/configure | 4 +-
libctf/configure.ac | 4 +-
libsframe/Makefile.am | 54 +
libsframe/Makefile.in | 1100 ++++++++++++
libsframe/aclocal.m4 | 1242 +++++++++++++
libsframe/config.h.in | 144 ++
libsframe/configure.ac | 97 +
libsframe/sframe-backtrace-err.c | 46 +
libsframe/sframe-backtrace.c | 619 +++++++
libsframe/sframe-dump.c | 181 ++
libsframe/sframe-error.c | 49 +
libsframe/sframe-impl.h | 55 +
libsframe/sframe.c | 1584 +++++++++++++++++
libsframe/testsuite/Makefile.am | 23 +
libsframe/testsuite/Makefile.in | 684 +++++++
libsframe/testsuite/config/default.exp | 57 +
libsframe/testsuite/lib/sframe-lib.exp | 180 ++
libsframe/testsuite/libsframe.decode/DATA1 | Bin 0 -> 59 bytes
libsframe/testsuite/libsframe.decode/DATA2 | Bin 0 -> 91 bytes
.../testsuite/libsframe.decode/DATA_BIGE | Bin 0 -> 59 bytes
.../testsuite/libsframe.decode/Makefile.am | 14 +
.../testsuite/libsframe.decode/Makefile.in | 663 +++++++
.../libsframe.decode/bigendian_data.c | 107 ++
.../testsuite/libsframe.decode/decode.exp | 41 +
.../testsuite/libsframe.decode/frecnt_1.c | 99 ++
.../testsuite/libsframe.decode/frecnt_2.c | 103 ++
.../testsuite/libsframe.encode/Makefile.am | 6 +
.../testsuite/libsframe.encode/Makefile.in | 610 +++++++
.../testsuite/libsframe.encode/encode.exp | 25 +
.../testsuite/libsframe.encode/encode_1.c | 182 ++
.../testsuite/libsframe.unwind/backtrace.c | 145 ++
.../testsuite/libsframe.unwind/backtrace.lk | 3 +
.../testsuite/libsframe.unwind/inline-cmds.c | 136 ++
.../testsuite/libsframe.unwind/inline-cmds.lk | 3 +
libsframe/testsuite/libsframe.unwind/inline.c | 97 +
.../testsuite/libsframe.unwind/inline.lk | 3 +
.../testsuite/libsframe.unwind/solib-lib1.c | 8 +
.../testsuite/libsframe.unwind/solib-lib2.c | 51 +
.../testsuite/libsframe.unwind/solib-main.c | 47 +
.../testsuite/libsframe.unwind/solib-main.d | 3 +
.../testsuite/libsframe.unwind/solib.exp | 75 +
.../testsuite/libsframe.unwind/solib_lib1.h | 3 +
.../testsuite/libsframe.unwind/solib_lib2.h | 3 +
.../testsuite/libsframe.unwind/tailcall.c | 103 ++
.../testsuite/libsframe.unwind/tailcall.lk | 3 +
libsframe/testsuite/libsframe.unwind/ttest.c | 127 ++
libsframe/testsuite/libsframe.unwind/ttest.lk | 3 +
.../testsuite/libsframe.unwind/unwind.exp | 200 +++
sim/common/Make-common.in | 7 +-
src-release.sh | 4 +-
153 files changed, 14927 insertions(+), 64 deletions(-)
create mode 100644 bfd/elf-sframe.c
create mode 100644 binutils/doc/sframe.options.texi
create mode 100644 config/sframe.m4
create mode 100644 gas/gen-sframe.c
create mode 100644 gas/gen-sframe.h
create mode 100644 gas/sframe-opt.c
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-aarch64-1.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-aarch64-1.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-1.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-1.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-2.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-2.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-3.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-3.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-4.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-4.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-5.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-5.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-6.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-6.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-7.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-7.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-8.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-8.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-x86_64-1.d
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-x86_64-1.s
create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe.exp
create mode 100644 gas/testsuite/gas/cfi-sframe/common-empty-1.d
create mode 100644 gas/testsuite/gas/cfi-sframe/common-empty-1.s
create mode 100644 gas/testsuite/gas/cfi-sframe/common-empty-2.d
create mode 100644 gas/testsuite/gas/cfi-sframe/common-empty-2.s
create mode 100644 gas/testsuite/gas/cfi-sframe/common-empty-3.d
create mode 100644 gas/testsuite/gas/cfi-sframe/common-empty-3.s
create mode 100644 gas/testsuite/gas/cfi-sframe/common-empty-4.d
create mode 100644 gas/testsuite/gas/cfi-sframe/common-empty-4.s
create mode 100644 include/sframe-api.h
create mode 100644 include/sframe-backtrace-api.h
create mode 100644 include/sframe.h
create mode 100644 ld/testsuite/ld-aarch64/sframe-bar.s
create mode 100644 ld/testsuite/ld-aarch64/sframe-foo.s
create mode 100644 ld/testsuite/ld-aarch64/sframe-simple-1.d
create mode 100644 ld/testsuite/ld-sframe/discard.d
create mode 100644 ld/testsuite/ld-sframe/discard.ld
create mode 100644 ld/testsuite/ld-sframe/discard.s
create mode 100644 ld/testsuite/ld-sframe/sframe-empty.d
create mode 100644 ld/testsuite/ld-sframe/sframe-empty.s
create mode 100644 ld/testsuite/ld-sframe/sframe.exp
create mode 100644 ld/testsuite/ld-x86-64/sframe-bar.s
create mode 100644 ld/testsuite/ld-x86-64/sframe-foo.s
create mode 100644 ld/testsuite/ld-x86-64/sframe-plt-1.d
create mode 100644 ld/testsuite/ld-x86-64/sframe-simple-1.d
create mode 100644 libsframe/Makefile.am
create mode 100644 libsframe/Makefile.in
create mode 100644 libsframe/aclocal.m4
create mode 100644 libsframe/config.h.in
create mode 100644 libsframe/configure.ac
create mode 100644 libsframe/sframe-backtrace-err.c
create mode 100644 libsframe/sframe-backtrace.c
create mode 100644 libsframe/sframe-dump.c
create mode 100644 libsframe/sframe-error.c
create mode 100644 libsframe/sframe-impl.h
create mode 100644 libsframe/sframe.c
create mode 100644 libsframe/testsuite/Makefile.am
create mode 100644 libsframe/testsuite/Makefile.in
create mode 100644 libsframe/testsuite/config/default.exp
create mode 100644 libsframe/testsuite/lib/sframe-lib.exp
create mode 100644 libsframe/testsuite/libsframe.decode/DATA1
create mode 100644 libsframe/testsuite/libsframe.decode/DATA2
create mode 100644 libsframe/testsuite/libsframe.decode/DATA_BIGE
create mode 100644 libsframe/testsuite/libsframe.decode/Makefile.am
create mode 100644 libsframe/testsuite/libsframe.decode/Makefile.in
create mode 100644 libsframe/testsuite/libsframe.decode/bigendian_data.c
create mode 100644 libsframe/testsuite/libsframe.decode/decode.exp
create mode 100644 libsframe/testsuite/libsframe.decode/frecnt_1.c
create mode 100644 libsframe/testsuite/libsframe.decode/frecnt_2.c
create mode 100644 libsframe/testsuite/libsframe.encode/Makefile.am
create mode 100644 libsframe/testsuite/libsframe.encode/Makefile.in
create mode 100644 libsframe/testsuite/libsframe.encode/encode.exp
create mode 100644 libsframe/testsuite/libsframe.encode/encode_1.c
create mode 100644 libsframe/testsuite/libsframe.unwind/backtrace.c
create mode 100644 libsframe/testsuite/libsframe.unwind/backtrace.lk
create mode 100644 libsframe/testsuite/libsframe.unwind/inline-cmds.c
create mode 100644 libsframe/testsuite/libsframe.unwind/inline-cmds.lk
create mode 100644 libsframe/testsuite/libsframe.unwind/inline.c
create mode 100644 libsframe/testsuite/libsframe.unwind/inline.lk
create mode 100644 libsframe/testsuite/libsframe.unwind/solib-lib1.c
create mode 100644 libsframe/testsuite/libsframe.unwind/solib-lib2.c
create mode 100644 libsframe/testsuite/libsframe.unwind/solib-main.c
create mode 100644 libsframe/testsuite/libsframe.unwind/solib-main.d
create mode 100644 libsframe/testsuite/libsframe.unwind/solib.exp
create mode 100644 libsframe/testsuite/libsframe.unwind/solib_lib1.h
create mode 100644 libsframe/testsuite/libsframe.unwind/solib_lib2.h
create mode 100644 libsframe/testsuite/libsframe.unwind/tailcall.c
create mode 100644 libsframe/testsuite/libsframe.unwind/tailcall.lk
create mode 100644 libsframe/testsuite/libsframe.unwind/ttest.c
create mode 100644 libsframe/testsuite/libsframe.unwind/ttest.lk
create mode 100644 libsframe/testsuite/libsframe.unwind/unwind.exp
--
2.37.2
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