From 00963a2e75a872e5fce4d0115ac2786ec86b57a6 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Tue, 19 Jul 2022 17:21:26 -0700 Subject: bpf: Support bpf_trampoline on functions with IPMODIFY (e.g. livepatch) When tracing a function with IPMODIFY ftrace_ops (livepatch), the bpf trampoline must follow the instruction pointer saved on stack. This needs extra handling for bpf trampolines with BPF_TRAMP_F_CALL_ORIG flag. Implement bpf_tramp_ftrace_ops_func and use it for the ftrace_ops used by BPF trampoline. This enables tracing functions with livepatch. This also requires moving bpf trampoline to *_ftrace_direct_mult APIs. Signed-off-by: Song Liu Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/all/20220602193706.2607681-2-song@kernel.org/ Link: https://lore.kernel.org/bpf/20220720002126.803253-5-song@kernel.org --- include/linux/bpf.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 1d22df8bf306..20c26aed7896 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -47,6 +47,7 @@ struct kobject; struct mem_cgroup; struct module; struct bpf_func_state; +struct ftrace_ops; extern struct idr btf_idr; extern spinlock_t btf_idr_lock; @@ -756,6 +757,11 @@ struct btf_func_model { */ #define BPF_TRAMP_F_ORIG_STACK BIT(5) +/* This trampoline is on a function with another ftrace_ops with IPMODIFY, + * e.g., a live patch. This flag is set and cleared by ftrace call backs, + */ +#define BPF_TRAMP_F_SHARE_IPMODIFY BIT(6) + /* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50 * bytes on x86. */ @@ -838,9 +844,11 @@ struct bpf_tramp_image { struct bpf_trampoline { /* hlist for trampoline_table */ struct hlist_node hlist; + struct ftrace_ops *fops; /* serializes access to fields of this trampoline */ struct mutex mutex; refcount_t refcnt; + u32 flags; u64 key; struct { struct btf_func_model model; -- cgit v1.2.3