On Mon, 11 Nov 2024 00:52:31 +0900 "Masami Hiramatsu (Google)" <[email protected]> wrote:
> From: Masami Hiramatsu (Google) <[email protected]> > > Rewrite get_entry_ip() to use ftrace_get_symaddr() macro. I found a root problem of this patch. This get_entry_ip() is used not only for fprobe (kprobe_multi) but also kprobes, but that is wrong. On x86, both kprobes and ftrace (fentry) have the same restriction, it should avoid ENDBR. But on arm64, ftrace_get_symaddr() is only for fprobe, and kp->addr should point the symbol address. So what I should do is to use `ftrace_get_symaddr()` version for fprobe (kprobe_multi) and keep this original function for kprobe. Let me fix that. Thanks, > > Signed-off-by: Masami Hiramatsu (Google) <[email protected]> > --- > Changes in v19: > - Use ftrace_get_symaddr() instead of introducing new arch dependent code. > - Also, replace x86 code with ftrace_get_symaddr(), which does the same > thing. > --- > kernel/trace/bpf_trace.c | 19 ++----------------- > 1 file changed, 2 insertions(+), 17 deletions(-) > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 1532e9172bf9..e848a782bc8d 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -1024,27 +1024,12 @@ static const struct bpf_func_proto > bpf_get_func_ip_proto_tracing = { > .arg1_type = ARG_PTR_TO_CTX, > }; > > -#ifdef CONFIG_X86_KERNEL_IBT > static unsigned long get_entry_ip(unsigned long fentry_ip) > { > - u32 instr; > + unsigned long ret = ftrace_get_symaddr(fentry_ip); > > - /* We want to be extra safe in case entry ip is on the page edge, > - * but otherwise we need to avoid get_kernel_nofault()'s overhead. > - */ > - if ((fentry_ip & ~PAGE_MASK) < ENDBR_INSN_SIZE) { > - if (get_kernel_nofault(instr, (u32 *)(fentry_ip - > ENDBR_INSN_SIZE))) > - return fentry_ip; > - } else { > - instr = *(u32 *)(fentry_ip - ENDBR_INSN_SIZE); > - } > - if (is_endbr(instr)) > - fentry_ip -= ENDBR_INSN_SIZE; > - return fentry_ip; > + return ret ? : fentry_ip; > } > -#else > -#define get_entry_ip(fentry_ip) fentry_ip > -#endif > > BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs) > { > > -- Masami Hiramatsu (Google) <[email protected]>
