Messages in this thread | | | Date | Thu, 2 Feb 2023 16:36:36 +0800 | Subject | Re: [PATCH 0/8] Add ftrace direct call for arm64 | From | Xu Kuohai <> |
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On 2/2/2023 12:34 AM, Florent Revest wrote: > This series adds ftrace direct call support to arm64. > This makes BPF tracing programs (fentry/fexit/fmod_ret/lsm) work on arm64. > > It is meant to apply on top of the arm64 tree which contains Mark Rutland's > series on CALL_OPS [1] under the for-next/ftrace tag. > > The first three patches consolidate the two existing ftrace APIs for registering > direct calls. They are split to make the reviewers lives easier but if it'd be a > preferred style, I'd be happy to squash them in the next revision. > Currently, there is both a _ftrace_direct and _ftrace_direct_multi API. Apart > from samples and selftests, there are no users of the _ftrace_direct API left > in-tree so this deletes it and renames the _ftrace_direct_multi API to > _ftrace_direct for simplicity. > > The main benefit of this refactoring is that, with the API that's left, an > ftrace_ops backing a direct call will only ever point to one direct call. We can > therefore store the direct called trampoline address in the ops (patch 4) and > look it up from the ftrace trampoline on arm64 (patch 7) in the case when the > destination would be out of reach of a BL instruction at the ftrace callsite. > (in this case, ftrace_caller acts as a lightweight intermediary trampoline) > > This series has been tested on both arm64 and x86_64 with: > 1- CONFIG_FTRACE_SELFTEST (cf: patch 6) > 2- samples/ftrace/*.ko (cf: patch 8) > 3- tools/testing/selftests/bpf/test_progs (both -t lsm and -t fentry_fexit)
so it's time to update DENYLIST.aarch64 to unblock tests that failed due to lack of direct call.
> > This follows up on prior art by Xu Kuohai [2]. > The implementation here is totally different but the fix for ftrace selftests > (patch 6) is a trivial rebase of a patch originally by Xu so I kept his > authorship and trailers untouched on that patch, I hope that's ok. >
that's ok for me, thanks.
> 1: https://lore.kernel.org/all/20230123134603.1064407-1-mark.rutland@arm.com/ > 2: https://lore.kernel.org/bpf/20220913162732.163631-1-xukuohai@huaweicloud.com/ > > Florent Revest (7): > ftrace: Replace uses of _ftrace_direct APIs with _ftrace_direct_multi > ftrace: Remove the legacy _ftrace_direct API > ftrace: Rename _ftrace_direct_multi APIs to _ftrace_direct APIs > ftrace: Store direct called addresses in their ops > ftrace: Make DIRECT_CALLS work WITH_ARGS and !WITH_REGS > arm64: ftrace: Add direct call support > arm64: ftrace: Add direct called trampoline samples support > > Xu Kuohai (1): > ftrace: Fix dead loop caused by direct call in ftrace selftest > > arch/arm64/Kconfig | 4 + > arch/arm64/include/asm/ftrace.h | 24 ++ > arch/arm64/kernel/asm-offsets.c | 6 + > arch/arm64/kernel/entry-ftrace.S | 70 +++- > arch/arm64/kernel/ftrace.c | 36 +- > include/linux/ftrace.h | 51 +-- > kernel/bpf/trampoline.c | 14 +- > kernel/trace/Kconfig | 2 +- > kernel/trace/ftrace.c | 433 +------------------- > kernel/trace/trace_selftest.c | 14 +- > samples/Kconfig | 2 +- > samples/ftrace/ftrace-direct-modify.c | 41 +- > samples/ftrace/ftrace-direct-multi-modify.c | 44 +- > samples/ftrace/ftrace-direct-multi.c | 28 +- > samples/ftrace/ftrace-direct-too.c | 35 +- > samples/ftrace/ftrace-direct.c | 33 +- > 16 files changed, 333 insertions(+), 504 deletions(-) >
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