On Mon, Apr 3, 2023 at 1:21 PM Florent Revest <revest@xxxxxxxxxxxx> 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 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 v3 [3]: > - Added "BTI C" instructions at the beginning of each ftrace direct call sample Ugh, I am an idiot (let's just blame Mondays!) and didn't actually amend this change, I'm sending the series again as a v5 and this time with the change actually folded in... Please ignore this v4, sorry for the noise! :|
