Messages in this thread | | | Subject | Re: [PATCH 0/8] Add ftrace direct call for arm64 | From | Daniel Borkmann <> | Date | Thu, 2 Feb 2023 11:50:24 +0100 |
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On 2/2/23 9:36 AM, Xu Kuohai wrote: > 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)
Thanks a ton for working on this!
> so it's time to update DENYLIST.aarch64 to unblock tests that failed due to lack of direct call.
+1, with regards to logistics, if possible it might be nice to eventually gets this into a feature branch on arm64 tree, then we could pull it too from there for bpf-next and hash out the BPF CI bits for arm64 in the meantime.
>> 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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