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 be taken by the arm64 tree but it depends on the trace-direct-v6.3-rc3 tag of the linux-trace tree: git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git That tag was created by Steven Rostedt so the arm64 tree can pull the prior work this depends on. [1] Thanks to the ftrace refactoring under that tag, an ftrace_ops backing a ftrace direct call will only ever point to *one* direct call. This means we can look up the direct called trampoline address stored in the ops from the ftrace_caller trampoline in the case when the destination would be out of reach of a BL instruction at the ftrace callsite. This fixes limitations of previous attempts such as [2]. This series has been tested on arm64 with: 1- CONFIG_FTRACE_SELFTEST 2- samples/ftrace/*.ko (cf: patch 3) 3- tools/testing/selftests/bpf/test_progs (cf: patch 4) Changes since v4 [3]: - *Actually* added "BTI C" instructions at the beginning of each ftrace direct call sample (v4 was supposed to do that but I forgot to git commit --amend...) 1: https://lore.kernel.org/all/ZB2Nl7fzpHoq5V20@FVFF77S0Q05N/ 2: https://lore.kernel.org/all/20220913162732.163631-1-xukuohai@xxxxxxxxxxxxxxx/ 3: https://lore.kernel.org/bpf/20230403112059.2749695-1-revest@xxxxxxxxxxxx/ Florent Revest (4): arm64: ftrace: Add direct call support arm64: ftrace: Simplify get_ftrace_plt arm64: ftrace: Add direct call trampoline samples support selftests/bpf: Update the tests deny list on aarch64 arch/arm64/Kconfig | 6 ++ arch/arm64/include/asm/ftrace.h | 22 +++++ arch/arm64/kernel/asm-offsets.c | 6 ++ arch/arm64/kernel/entry-ftrace.S | 90 ++++++++++++++++---- arch/arm64/kernel/ftrace.c | 46 +++++++--- samples/ftrace/ftrace-direct-modify.c | 34 ++++++++ samples/ftrace/ftrace-direct-multi-modify.c | 38 +++++++++ samples/ftrace/ftrace-direct-multi.c | 23 +++++ samples/ftrace/ftrace-direct-too.c | 26 ++++++ samples/ftrace/ftrace-direct.c | 24 ++++++ tools/testing/selftests/bpf/DENYLIST.aarch64 | 82 ++---------------- 11 files changed, 295 insertions(+), 102 deletions(-) -- 2.40.0.423.gd6c402a77b-goog
