On Wed, May 13, 2026 at 4:32 PM Ian Rogers <irogers@google.com> wrote:
>
> Fix the libunwind build for when libdw and libunwind are feature
> detected, currently failing with a duplicate symbol.
>
> Refactor the libunwind support so that whenever a remote target is
> available, perf functions using the ELF machine can use that remote
> target regardless of what the host/local machine is. Migrate existing
> libunwind supported architectures like powerpc, arm64 and loongarch so
> that they can work in a cross-architecture way. Add support for
> RISC-V. Make the code more regular in function names, etc. and avoid
> including a C-file. This increases the lines of code. It is similar in
> style to the unwind-libdw implementation. It is hoped that the more
> uniform nature of the code will help with refactoring the perf
> registers for SIMD/APX support.
>
> Aside from local host testing these patches are under tested, in part
> as I'm failing to see how to build libunwind with support for multiple
> remote targets. Please could I get help in testing.
So the patches failed to apply in Sashiko:
https://sashiko.dev/#/patchset/20260513233151.572332-1-irogers%40google.com
The baseline logs show perf-tools-next was at commit 8c8f20936143
("perf build: Remove NO_GTK2 build test") which is 6 patches
out-of-date compared to the current tip these patches are against. I
ran Sashiko locally, so I don't expect a huge amount from the reviews.
Currently Sashiko is catching up with a backlog because its tokens
have a lower priority and there was high load earlier in the week.
Anyway, I could repost the patches for Sashiko review but given the
backlog I think that would just create noise at the moment. Hopefully
I can get human review so we can move forward with merging these
improvements.
Thanks,
Ian
> v5: Rebase dropping merged loong arch fix patch. Fixes to Sashiko
> review feedback:
> - Patch 1: Hooked unwind__configure() into perf_default_config().
> Standardized unwinder return contracts (>0 success, 0 fallback,
> <0 fatal). Fixed UNWIND_STYLE_UNKNOWN fallback and added
> memset() to clear config array on override.
> - Patch 2: Dynamically populated FILES list in
> tools/build/feature/Makefile using LIBUNWIND_ARCHS. Added
> libunwind cases to FEATURE_TESTS_EXTRA in
> tools/build/Makefile.feature for proper FEATURE-DUMP caching.
> - Patch 3: Restored core -lunwind linkage to
> FEATURE_CHECK_LDFLAGS. Restored NO_LIBUNWIND fallback
> validation, corrected EXTLIBS evaluation ordering for
> BIONIC/Android compatibility, and restored static linking
> multiple definition flags.
> - Patch 4: Fixed out-of-bounds array read bugs (>= ARRAY_SIZE) in
> libunwind-i386.c and libunwind-x86_64.c. Fixed constant typos
> across LoongArch, PowerPC, and s390x.
> - Patch 5: Added early EM_NONE and ops validation checks to
> prevent warnings and NULL dereferences. Checked return value of
> unwind__prepare_access() in maps__copy_from(). Corrected
> architecture binding in thread__insert_map() by calculating
> e_machine after map insertion.
> - Patch 6: Aligned all remote architecture accessors to match
> 5-argument generic declarations (removing trailing
> sizeof(unw_word_t)). Prevented frame discard on stack depth
> limit by returning 0 instead of -1 in unwind_step(). Fixed
> 32-bit big-endian register corruption by replacing memcpy() with
> conditional type-casted assignment. Fixed max_stack == 1
> fallback trigger. Fixed .debug_frame layout union corruption by
> changing di.u.rti to di.u.ti across all DWARF find wrappers.
> - Patch 7: Applied the same corrections (5-argument accessors,
> u.ti union accessors, 0 return on max_ips) to the newly
> introduced libunwind-riscv.c.
>
> v4: Rebase, in particular the zalloc->calloc change conflicted.
> https://lore.kernel.org/linux-perf-users/20260413024805.1316480-1-irogers@google.com/
>
> v3: Minor whitespace clean up and warn when a dynamic choice of libdw
> or libunwind is selected for unwinding and support is missing (Arnaldo).
> https://lore.kernel.org/lkml/20260404054032.1538095-1-irogers@google.com/
>
> v2: Move two fixes patches to position 1 and 2 in the series. Fix
> struct naming inconsistency, Andrew Jones
> <andrew.jones@oss.qualcomm.com>. Fix other inconsistencies and
> potential non-x86 build issues.
> https://lore.kernel.org/lkml/20260305221927.3237145-1-irogers@google.com/
>
> v1: https://lore.kernel.org/lkml/20260224142938.26088-1-irogers@google.com/
>
> Ian Rogers (7):
> perf unwind: Refactor get_entries to allow dynamic libdw/libunwind
> selection
> tools build: Deduplicate test-libunwind for different architectures
> perf build: Be more programmatic when setting up libunwind variables
> perf unwind-libunwind: Make libunwind register reading cross platform
> perf unwind-libunwind: Move flush/finish access out of local
> perf unwind-libunwind: Remove libunwind-local
> perf unwind-libunwind: Add RISC-V libunwind support
>
> tools/build/Makefile.feature | 12 +-
> tools/build/feature/Makefile | 46 +-
> tools/build/feature/test-libunwind-aarch64.c | 27 -
> tools/build/feature/test-libunwind-arm.c | 28 -
> .../test-libunwind-debug-frame-aarch64.c | 17 -
> .../feature/test-libunwind-debug-frame-arm.c | 17 -
> .../feature/test-libunwind-debug-frame.c | 1 -
> tools/build/feature/test-libunwind-x86.c | 28 -
> tools/build/feature/test-libunwind-x86_64.c | 28 -
> tools/build/feature/test-libunwind.c | 1 -
> tools/perf/Makefile.config | 226 +++--
> tools/perf/arch/arm/util/Build | 2 -
> tools/perf/arch/arm/util/unwind-libunwind.c | 50 --
> tools/perf/arch/arm64/util/Build | 1 -
> tools/perf/arch/arm64/util/unwind-libunwind.c | 17 -
> tools/perf/arch/loongarch/util/Build | 2 -
> .../arch/loongarch/util/unwind-libunwind.c | 82 --
> tools/perf/arch/mips/Build | 1 -
> tools/perf/arch/mips/util/Build | 1 -
> tools/perf/arch/mips/util/unwind-libunwind.c | 22 -
> tools/perf/arch/powerpc/util/Build | 1 -
> .../perf/arch/powerpc/util/unwind-libunwind.c | 92 --
> tools/perf/arch/x86/util/Build | 3 -
> tools/perf/arch/x86/util/unwind-libunwind.c | 115 ---
> tools/perf/builtin-inject.c | 4 +
> tools/perf/builtin-report.c | 4 +
> tools/perf/builtin-script.c | 4 +
> tools/perf/util/Build | 5 +-
> tools/perf/util/config.c | 4 +
> tools/perf/util/libunwind-arch/Build | 11 +
> .../perf/util/libunwind-arch/libunwind-arch.c | 319 +++++++
> .../perf/util/libunwind-arch/libunwind-arch.h | 296 +++++++
> .../perf/util/libunwind-arch/libunwind-arm.c | 290 ++++++
> .../util/libunwind-arch/libunwind-arm64.c | 289 ++++++
> .../perf/util/libunwind-arch/libunwind-i386.c | 312 +++++++
> .../util/libunwind-arch/libunwind-loongarch.c | 297 +++++++
> .../perf/util/libunwind-arch/libunwind-mips.c | 299 +++++++
> .../util/libunwind-arch/libunwind-ppc32.c | 301 +++++++
> .../util/libunwind-arch/libunwind-ppc64.c | 303 +++++++
> .../util/libunwind-arch/libunwind-riscv.c | 297 +++++++
> .../perf/util/libunwind-arch/libunwind-s390.c | 299 +++++++
> .../util/libunwind-arch/libunwind-x86_64.c | 320 +++++++
> tools/perf/util/libunwind/arm64.c | 40 -
> tools/perf/util/libunwind/x86_32.c | 41 -
> tools/perf/util/maps.c | 34 +-
> tools/perf/util/maps.h | 4 +-
> tools/perf/util/symbol_conf.h | 10 +
> tools/perf/util/thread.c | 32 +-
> tools/perf/util/unwind-libdw.c | 20 +-
> tools/perf/util/unwind-libunwind-local.c | 831 ------------------
> tools/perf/util/unwind-libunwind.c | 699 +++++++++++++--
> tools/perf/util/unwind.c | 104 +++
> tools/perf/util/unwind.h | 73 +-
> 53 files changed, 4623 insertions(+), 1739 deletions(-)
> delete mode 100644 tools/build/feature/test-libunwind-aarch64.c
> delete mode 100644 tools/build/feature/test-libunwind-arm.c
> delete mode 100644 tools/build/feature/test-libunwind-debug-frame-aarch64.c
> delete mode 100644 tools/build/feature/test-libunwind-debug-frame-arm.c
> delete mode 100644 tools/build/feature/test-libunwind-x86.c
> delete mode 100644 tools/build/feature/test-libunwind-x86_64.c
> delete mode 100644 tools/perf/arch/arm/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/arm64/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/loongarch/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/mips/Build
> delete mode 100644 tools/perf/arch/mips/util/Build
> delete mode 100644 tools/perf/arch/mips/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/powerpc/util/unwind-libunwind.c
> delete mode 100644 tools/perf/arch/x86/util/unwind-libunwind.c
> create mode 100644 tools/perf/util/libunwind-arch/Build
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-arch.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-arch.h
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-arm.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-arm64.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-i386.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-loongarch.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-mips.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-ppc32.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-ppc64.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-riscv.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-s390.c
> create mode 100644 tools/perf/util/libunwind-arch/libunwind-x86_64.c
> delete mode 100644 tools/perf/util/libunwind/arm64.c
> delete mode 100644 tools/perf/util/libunwind/x86_32.c
> delete mode 100644 tools/perf/util/unwind-libunwind-local.c
> create mode 100644 tools/perf/util/unwind.c
>
> --
> 2.54.0.563.g4f69b47b94-goog
>