On Tue, Jan 21, 2025 at 6:32 PM Josh Poimboeuf <jpoim...@kernel.org> wrote: > > Add optional support for user space frame pointer unwinding. If > supported, the arch needs to enable CONFIG_HAVE_UNWIND_USER_FP and > define ARCH_INIT_USER_FP_FRAME. > > By encoding the frame offsets in struct unwind_user_frame, much of this > code can also be reused for future unwinder implementations like sframe. > > Signed-off-by: Josh Poimboeuf <jpoim...@kernel.org> > --- > arch/Kconfig | 4 +++ > include/asm-generic/unwind_user.h | 9 ++++++ > include/linux/unwind_user_types.h | 1 + > kernel/unwind/user.c | 49 +++++++++++++++++++++++++++++-- > 4 files changed, 60 insertions(+), 3 deletions(-) > create mode 100644 include/asm-generic/unwind_user.h >
Do you plan to reuse this logic for stack unwinding done by perf subsystem in perf_callchain_user()? See is_uprobe_at_func_entry() parts and also fixup_uretprobe_trampoline_entries() for some of the quirks that have to be taken into account when doing frame pointer-based unwinding. It would be great not to lose those in this new reimplementation. Not sure what's the best way to avoid duplicating the logic, but I thought I'd bring that up. > diff --git a/arch/Kconfig b/arch/Kconfig > index c6fa2b3ecbc6..cf996cbb8142 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -438,6 +438,10 @@ config HAVE_HARDLOCKUP_DETECTOR_ARCH > config UNWIND_USER > bool > > +config HAVE_UNWIND_USER_FP > + bool > + select UNWIND_USER > + > config AS_SFRAME > def_bool $(as-instr,.cfi_sections > .sframe\n.cfi_startproc\n.cfi_endproc) > [...]
