On Mon, Dec 18, 2023 at 10:16:23PM +0900, Masami Hiramatsu (Google) wrote:
SNIP
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 84e8a0f6e4e0..d3f8745d8ead 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2503,7 +2503,7 @@ static int __init bpf_event_init(void)
> fs_initcall(bpf_event_init);
> #endif /* CONFIG_MODULES */
>
> -#ifdef CONFIG_FPROBE
> +#if defined(CONFIG_FPROBE) && defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)
> struct bpf_kprobe_multi_link {
> struct bpf_link link;
> struct fprobe fp;
> @@ -2733,10 +2733,14 @@ kprobe_multi_link_prog_run(struct
> bpf_kprobe_multi_link *link,
>
> static int
> kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
> - unsigned long ret_ip, struct pt_regs *regs,
> + unsigned long ret_ip, struct ftrace_regs *fregs,
> void *data)
> {
> struct bpf_kprobe_multi_link *link;
> + struct pt_regs *regs = ftrace_get_regs(fregs);
> +
> + if (!regs)
> + return 0;
>
> link = container_of(fp, struct bpf_kprobe_multi_link, fp);
> kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
> @@ -3008,7 +3012,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr
> *attr, struct bpf_prog *pr
> kvfree(cookies);
> return err;
> }
> -#else /* !CONFIG_FPROBE */
> +#else /* !CONFIG_FPROBE || !CONFIG_DYNAMIC_FTRACE_WITH_REGS */
> int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog
> *prog)
> {
> return -EOPNOTSUPP;
> diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> index 6cd2a4e3afb8..f12569494d8a 100644
> --- a/kernel/trace/fprobe.c
> +++ b/kernel/trace/fprobe.c
> @@ -46,7 +46,7 @@ static inline void __fprobe_handler(unsigned long ip,
> unsigned long parent_ip,
> }
>
> if (fp->entry_handler)
> - ret = fp->entry_handler(fp, ip, parent_ip,
> ftrace_get_regs(fregs), entry_data);
> + ret = fp->entry_handler(fp, ip, parent_ip, fregs, entry_data);
>
> /* If entry_handler returns !0, nmissed is not counted. */
> if (rh) {
> @@ -182,7 +182,7 @@ static void fprobe_init(struct fprobe *fp)
> fp->ops.func = fprobe_kprobe_handler;
> else
> fp->ops.func = fprobe_handler;
> - fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
> + fp->ops.flags |= FTRACE_OPS_FL_SAVE_ARGS;
so with this change you move to ftrace_caller trampoline,
but we need ftrace_regs_caller right?
otherwise the (!regs) check in kprobe_multi_link_handler
will be allways true IIUC
jirka
> }
>
> static int fprobe_init_rethook(struct fprobe *fp, int num)
> diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
> index 7d2ddbcfa377..ef6b36fd05ae 100644
> --- a/kernel/trace/trace_fprobe.c
> +++ b/kernel/trace/trace_fprobe.c
> @@ -320,12 +320,16 @@ NOKPROBE_SYMBOL(fexit_perf_func);
> #endif /* CONFIG_PERF_EVENTS */
>
> static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,
> - unsigned long ret_ip, struct pt_regs *regs,
> + unsigned long ret_ip, struct ftrace_regs *fregs,
> void *entry_data)
> {
> struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
> + struct pt_regs *regs = ftrace_get_regs(fregs);
> int ret = 0;
>
> + if (!regs)
> + return 0;
> +
> if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
> fentry_trace_func(tf, entry_ip, regs);
> #ifdef CONFIG_PERF_EVENTS
> diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
> index 24de0e5ff859..ff607babba18 100644
> --- a/lib/test_fprobe.c
> +++ b/lib/test_fprobe.c
> @@ -40,7 +40,7 @@ static noinline u32 fprobe_selftest_nest_target(u32 value,
> u32 (*nest)(u32))
>
> static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
> unsigned long ret_ip,
> - struct pt_regs *regs, void *data)
> + struct ftrace_regs *fregs, void *data)
> {
> KUNIT_EXPECT_FALSE(current_test, preemptible());
> /* This can be called on the fprobe_selftest_target and the
> fprobe_selftest_target2 */
> @@ -81,7 +81,7 @@ static notrace void fp_exit_handler(struct fprobe *fp,
> unsigned long ip,
>
> static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,
> unsigned long ret_ip,
> - struct pt_regs *regs, void *data)
> + struct ftrace_regs *fregs, void *data)
> {
> KUNIT_EXPECT_FALSE(current_test, preemptible());
> return 0;
> diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
> index 64e715e7ed11..1545a1aac616 100644
> --- a/samples/fprobe/fprobe_example.c
> +++ b/samples/fprobe/fprobe_example.c
> @@ -50,7 +50,7 @@ static void show_backtrace(void)
>
> static int sample_entry_handler(struct fprobe *fp, unsigned long ip,
> unsigned long ret_ip,
> - struct pt_regs *regs, void *data)
> + struct ftrace_regs *fregs, void *data)
> {
> if (use_trace)
> /*
>
