Hi Dylan, On Tue, Apr 28, 2026 at 06:36:35PM +0000, Dylan Hatch wrote: > Implement a generic kernel sframe-based [1] unwinder. The main goal is > to improve reliable stacktrace on arm64 by unwinding across exception > boundaries.
Thanks for this! Just as a holding reply: I'm going over the series now, and I have some partially-written comments that I'll try to finish up and get out tomorrow. Mark. > On x86, the ORC unwinder provides reliable stacktrace through similar > methodology, but arm64 lacks the necessary support from objtool to > create ORC unwind tables. > > Currently, there's already a sframe unwinder proposed for userspace: [2]. > To maintain common definitions and algorithms for sframe lookup, a > substantial portion of this patch series aims to refactor the sframe > lookup code to support both kernel and userspace sframe sections. > > Currently, only GNU Binutils support sframe. This series relies on the > Sframe V3 format, which is supported in binutils 2.46. > > These patches are based on Steven Rostedt's sframe/core branch [3], > which is and aggregation of existing work done for x86 sframe userspace > unwind, and contains [2]. This branch is, in turn, based on Linux > v7.0-rc3. This full series (applied to the sframe/core branch) is > available on github: [4]. > > Ref: > [1]: https://sourceware.org/binutils/docs/sframe-spec.html > [2]: > https://lore.kernel.org/lkml/[email protected]/ > [3]: > https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git/log/?h=sframe/core > [4]: https://github.com/dylanbhatch/linux/tree/sframe-v5 > > Changes since v4: > - (Jens) Fix some minor nits. > - Handle .init.text and .exit.text in function address validation. > > Changes since v3: > > - (Jens) Clean up patch summaries. > - (Jens) Rename SFRAME_LOOKUP -> UNWIND_SFRAME_LOOKUP to fit existing > naming convention. > - (Randy) Correct typo errors in new config options. > - (Jens) Move unwind types to a new unwind_types.h to match their > usage. > - (Jens) Update KERNEL_[COPY|GET] to use label-based error handling > like their userspace counterparts. > - (Jens) Rename SFRAME_UNWINDER -> HAVE_UNWIND_KERNEL_SFRAME and > ARCH_SUPPORTS_SFRAME_UNWINDER -> ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME > to match existing naming convention. > - (Jens) Move HAVE_UNWIND_KERNEL_SFRAME config option to arch/Kconfig. > - (Jens) Rename/move extern definitions of __[start|end]_sframe into > include/asm-generic/sections.h. > - (Jens) Fix up CFI annotations at kernel entry. > - (Jens) Fix error path for unsorted FDE lookup. > - (Jens) Zero-out module sframe_section before init. > - (Jens) For SFRAME_VALIDATION, use an arch-specific function-address > validation helper so that .rodata.text can be correctly handled on > arm64 vmlinux. > - (Jens) Fixup and better comment kernel stacktrace code. > > Changes since v2: > > The biggest change from v2 is the switch from adding a dedicated, > in-kernel sframe-lookup library, to refactoring/using the existing > library developed by Josh, Jens, and Steve. Consequently, this series > now depends on Sframe V3, though this upgrade would likely have been > necessary anyway. Below is a full accounting of the changes since v2. > > - (Josh) Add stricter reliability checks during unwind. > - (Puranjay, Indu, Jens) Update to use a common sframe library with > userpace unwind, thus resolving the need to support > SFRAME_F_FDE_FUNC_START_PCREL, added in binutils 2.45. > - (Jens) Add check for sframe V3, thus resolving the prior need for V2 > and SFRAME_F_FDE_FUNC_START_PCREL support. > - (Will) Add ARCH_SUPPORTS_SFRAME_UNWINDER, remove SFRAME_UNWIND_TABLE > - (Indu) add support for unsorted FDE tables, allowing for module > sframe lookups. > - (Mark) Prefer frame-pointer unwind when possible, for better > performance. > - Simplify compile-time logic, adding stubbs when necessary. > - Add support for in-kernel SFRAME_VALIDATION. > - Rebase onto core/sframe (with v7.0-rc3 base) > > Dylan Hatch (7): > sframe: Allow kernelspace sframe sections > arm64, unwind: build kernel with sframe V3 info > sframe: Provide PC lookup for vmlinux .sframe section > sframe: Allow unsorted FDEs > arm64/module, sframe: Add sframe support for modules > sframe: Introduce in-kernel SFRAME_VALIDATION > unwind: arm64: Use sframe to unwind interrupt frames > > Weinan Liu (1): > arm64: entry: add unwind info for various kernel entries > > MAINTAINERS | 3 +- > Makefile | 8 + > arch/Kconfig | 27 +- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/module.h | 6 + > arch/arm64/include/asm/sections.h | 1 + > arch/arm64/include/asm/stacktrace/common.h | 6 + > arch/arm64/include/asm/unwind_sframe.h | 55 +++ > arch/arm64/kernel/entry.S | 23 + > arch/arm64/kernel/module.c | 8 + > arch/arm64/kernel/setup.c | 2 + > arch/arm64/kernel/stacktrace.c | 246 ++++++++++- > arch/arm64/kernel/vdso/Makefile | 2 +- > arch/arm64/kernel/vmlinux.lds.S | 2 + > .../{unwind_user_sframe.h => unwind_sframe.h} | 6 +- > arch/x86/include/asm/unwind_user.h | 12 +- > include/asm-generic/sections.h | 4 + > include/asm-generic/vmlinux.lds.h | 15 + > include/linux/sframe.h | 67 ++- > include/linux/unwind_types.h | 46 ++ > include/linux/unwind_user_types.h | 41 -- > kernel/unwind/Makefile | 2 +- > kernel/unwind/sframe.c | 410 ++++++++++++++---- > kernel/unwind/user.c | 41 +- > 24 files changed, 827 insertions(+), 207 deletions(-) > create mode 100644 arch/arm64/include/asm/unwind_sframe.h > rename arch/x86/include/asm/{unwind_user_sframe.h => unwind_sframe.h} (50%) > create mode 100644 include/linux/unwind_types.h > > -- > 2.54.0.545.g6539524ca2-goog >
