From: Alexei Starovoitov Date: Tue, 29 Mar 2022 02:39:06 +0000 (-0700) Subject: Merge branch 'kprobes: rethook: x86: Replace kretprobe trampoline with rethook' X-Git-Tag: v6.1-rc5~1659^2~12^2~2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7df482e62282fb7839b033e332446f75b94e21c4;p=platform%2Fkernel%2Flinux-starfive.git Merge branch 'kprobes: rethook: x86: Replace kretprobe trampoline with rethook' Masami Hiramatsu says: ==================== Here are the 3rd version for generic kretprobe and kretprobe on x86 for replacing the kretprobe trampoline with rethook. The previous version is here[1] [1] https://lore.kernel.org/all/164821817332.2373735.12048266953420821089.stgit@devnote2/T/#u This version fixed typo and build issues for bpf-next and CONFIG_RETHOOK=y error. I also add temporary mitigation lines for ANNOTATE_NOENDBR macro issue for bpf-next tree [2/4]. This will be removed after merging kernel IBT series. Background: This rethook came from Jiri's request of multiple kprobe for bpf[2]. He tried to solve an issue that starting bpf with multiple kprobe will take a long time because bpf-kprobe will wait for RCU grace period for sync rcu events. Jiri wanted to attach a single bpf handler to multiple kprobes and he tried to introduce multiple-probe interface to kprobe. So I asked him to use ftrace and kretprobe-like hook if it is only for the function entry and exit, instead of adding ad-hoc interface to kprobes. For this purpose, I introduced the fprobe (kprobe like interface for ftrace) with the rethook (this is a generic return hook feature for fprobe exit handler)[3]. [2] https://lore.kernel.org/all/20220104080943.113249-1-jolsa@kernel.org/T/#u [3] https://lore.kernel.org/all/164191321766.806991.7930388561276940676.stgit@devnote2/T/#u The rethook is basically same as the kretprobe trampoline. I just made it decoupled from kprobes. Eventually, the all arch dependent kretprobe trampolines will be replaced with the rethook trampoline instead of cloning and set HAVE_RETHOOK=y. When I port the rethook for all arch which supports kretprobe, the legacy kretprobe specific code (which is for CONFIG_KRETPROBE_ON_RETHOOK=n) will be removed eventually. ==================== Acked-by: Peter Zijlstra (Intel) Signed-off-by: Alexei Starovoitov --- 7df482e62282fb7839b033e332446f75b94e21c4