When using GCC on x86-64 to compile an usdt prog with -O1 or higher
optimization, the compiler will generate SIB addressing mode for global
array and PC-relative addressing mode for global variable,
e.g. "1@-96(%rbp,%rax,8)" and "-1@4+t1(%rip)".
The current USDT implementation in libbpf cannot parse these two formats,
causing `bpf_program__attach_usdt()` to fail with -ENOENT
(unrecognized register).
This patch series adds support for SIB addressing mode in USDT probes.
The main changes include:
- add correct handling logic for SIB-addressed arguments in
`parse_usdt_arg`.
- add an usdt_o2 test case to cover SIB addressing mode.
Testing shows that the SIB probe correctly generates 8@(%rcx,%rax,8)
argument spec and passes all validation checks.
The modification history of this patch series:
Change since v1:
- refactor the code to make it more readable
- modify the commit message to explain why and how
Change since v2:
- fix the `scale` uninitialized error
Change since v3:
- force -O2 optimization for usdt.test.o to generate SIB addressing usdt
and pass all test cases.
Change since v4:
- split the patch into two parts, one for the fix and the other for the
test
Change since v5:
- Only enable optimization for x86 architecture to generate SIB addressing
usdt argument spec.
Change since v6:
- Add an usdt_o2 test case to cover SIB addressing mode.
- Reinstate the usdt.c test case.
Do we need to add support for PC-relative USDT argument spec handling in
libbpf? I have some interest in this question, but currently have no
ideas. Getting offsets based on symbols requires dependency on the symbol
table. However, once the binary file is stripped, the symtab will also be
removed, which will cause this approach to fail. Does anyone have any
thoughts on this?
Jiawei Zhao (2):
libbpf: fix USDT SIB argument handling causing unrecognized register
error
selftests/bpf: Force -O2 for USDT selftests to cover SIB handling
logic
tools/lib/bpf/usdt.bpf.h | 33 ++++++++-
tools/lib/bpf/usdt.c | 43 +++++++++--
tools/testing/selftests/bpf/Makefile | 8 +++
.../selftests/bpf/prog_tests/usdt_o2.c | 71 +++++++++++++++++++
.../selftests/bpf/progs/test_usdt_o2.c | 37 ++++++++++
5 files changed, 185 insertions(+), 7 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/usdt_o2.c
create mode 100644 tools/testing/selftests/bpf/progs/test_usdt_o2.c
--
2.43.0
When using GCC on x86-64 to compile an usdt prog with -O1 or higher
optimization, the compiler will generate SIB addressing mode for global
array and PC-relative addressing mode for global variable,
e.g. "1@-96(%rbp,%rax,8)" and "-1@4+t1(%rip)".
The current USDT implementation in libbpf cannot parse these two formats,
causing `bpf_program__attach_usdt()` to fail with -ENOENT
(unrecognized register).
This patch series adds support for SIB addressing mode in USDT probes.
The main changes include:
- add correct handling logic for SIB-addressed arguments in
`parse_usdt_arg`.
- add an usdt_o2 test case to cover SIB addressing mode.
Testing shows that the SIB probe correctly generates 8@(%rcx,%rax,8)
argument spec and passes all validation checks.
The modification history of this patch series:
Change since v1:
- refactor the code to make it more readable
- modify the commit message to explain why and how
Change since v2:
- fix the `scale` uninitialized error
Change since v3:
- force -O2 optimization for usdt.test.o to generate SIB addressing usdt
and pass all test cases.
Change since v4:
- split the patch into two parts, one for the fix and the other for the
test
Change since v5:
- Only enable optimization for x86 architecture to generate SIB addressing
usdt argument spec.
Change since v6:
- Add an usdt_o2 test case to cover SIB addressing mode.
- Reinstate the usdt.c test case.
Change since v7:
- Refactor modifications to __bpf_usdt_arg_spec to avoid increasing its size,
achieving better compatibility
- Fix some minor code style issues
- Refactor the usdt_o2 test case, removing semaphore and adding GCC attribute
to force -O2 optimization
Change since v8:
- Refactor the usdt_o2 test case, using assembly to force SIB addressing mode.
Change since v9:
- Only enable the usdt_o2 test case on x86_64 and i386 architectures since the
SIB addressing mode is only supported on x86_64 and i386.
Change since v10:
- Replace `__attribute__((optimize("O2")))` with `#pragma GCC optimize("O1")`
to fix the issue where the optimized compilation condition works improperly.
- Renamed test case usdt_o2 and relevant files name to usdt_o1 in that O1
level optimization is enough to generate SIB addressing usdt argument spec.
Change since v11:
- Replace `STAP_PROBE1` with `STAP_PROBE_ASM`
- Use bit fields instead of bit shifting operations
- Merge the usdt_o1 test case into the usdt test case
Jiawei Zhao (2):
libbpf: fix USDT SIB argument handling causing unrecognized register
error
selftests/bpf: Enrich subtest_basic_usdt case in selftests to cover
SIB handling logic
tools/lib/bpf/usdt.bpf.h | 47 ++++++++++++++-
tools/lib/bpf/usdt.c | 58 +++++++++++++++++--
tools/testing/selftests/bpf/prog_tests/usdt.c | 44 +++++++++++++-
tools/testing/selftests/bpf/progs/test_usdt.c | 30 ++++++++++
4 files changed, 170 insertions(+), 9 deletions(-)
--
2.43.0
Recently, I reviewed a patch on the mm/kselftest mailing list about a
test which had obvious type mismatch fix in it. It was strange why that
wasn't caught during development and when patch was accepted. This led
me to discover that those extra compiler options to catch these warnings
aren't being used. When I added them, I found tens of warnings in just
mm suite.
In this series, I'm adding these flags and fixing those warnings. In the
last try several months ago [1], I'd patches for individual tests. I've
made patches better by grouping the same type of fixes together. Hence
there is no changelog for individual patches.
The changes have been build tested on x86_64, arm64, powerpc64 and partially
on riscv64. The test run with and without this series has been done on
x86_64.
---
Changes since v1:
- Drop test harness patch which isn't needed anymore
- Revamp how patches are written per same kind of failure
Muhammad Usama Anjum (8):
selftests/mm: Add -Wunreachable-code and fix warnings
selftests/mm: protection_keys: Fix dead code
selftests: kselftest.h: Add __unused macro
selftests/mm: Add -Wunused family of flags
selftests/mm: Remove unused parameters
selftests/mm: Mark unused arguments with __unused
selftests/mm: Mark unused arguments with __unused
selftests/mm: Fix unused parameter warnings for different
architectures
tools/testing/selftests/kselftest.h | 4 ++
tools/testing/selftests/mm/Makefile | 3 +-
tools/testing/selftests/mm/compaction_test.c | 2 +-
tools/testing/selftests/mm/cow.c | 22 +++++------
tools/testing/selftests/mm/droppable.c | 2 +-
tools/testing/selftests/mm/gup_longterm.c | 2 +-
tools/testing/selftests/mm/hmm-tests.c | 5 +--
tools/testing/selftests/mm/hugepage-vmemmap.c | 2 +-
tools/testing/selftests/mm/hugetlb-madvise.c | 2 +-
.../selftests/mm/hugetlb-soft-offline.c | 2 +-
.../selftests/mm/hugetlb_fault_after_madv.c | 4 +-
.../selftests/mm/hugetlb_madv_vs_map.c | 6 +--
tools/testing/selftests/mm/ksm_tests.c | 17 ++++-----
tools/testing/selftests/mm/madv_populate.c | 2 +-
tools/testing/selftests/mm/map_populate.c | 2 +-
tools/testing/selftests/mm/memfd_secret.c | 6 +--
.../testing/selftests/mm/mlock-random-test.c | 2 +-
tools/testing/selftests/mm/mlock2-tests.c | 2 +-
tools/testing/selftests/mm/mseal_test.c | 8 +++-
tools/testing/selftests/mm/on-fault-limit.c | 2 +-
tools/testing/selftests/mm/pfnmap.c | 2 +-
tools/testing/selftests/mm/pkey-arm64.h | 5 ++-
tools/testing/selftests/mm/pkey-powerpc.h | 2 +-
tools/testing/selftests/mm/pkey-x86.h | 3 +-
.../selftests/mm/pkey_sighandler_tests.c | 35 ++++++++++++-----
tools/testing/selftests/mm/protection_keys.c | 22 +++++------
tools/testing/selftests/mm/soft-dirty.c | 6 +--
.../selftests/mm/split_huge_page_test.c | 8 ++--
tools/testing/selftests/mm/uffd-common.c | 15 ++++----
tools/testing/selftests/mm/uffd-common.h | 2 +-
tools/testing/selftests/mm/uffd-stress.c | 2 +-
tools/testing/selftests/mm/uffd-unit-tests.c | 38 +++++++++----------
tools/testing/selftests/mm/uffd-wp-mremap.c | 2 +-
.../selftests/mm/virtual_address_range.c | 2 +-
34 files changed, 130 insertions(+), 111 deletions(-)
--
2.39.5