Re: [PATCHv4 bpf-next 04/28] bpf: Add cookies support for uprobe_multi link

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On Thu, Jul 20, 2023 at 7:36 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> Adding support to specify cookies array for uprobe_multi link.
>
> The cookies array share indexes and length with other uprobe_multi
> arrays (offsets/ref_ctr_offsets).
>
> The cookies[i] value defines cookie for i-the uprobe and will be
> returned by bpf_get_attach_cookie helper when called from ebpf
> program hooked to that specific uprobe.
>
> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
>  include/uapi/linux/bpf.h       |  1 +
>  kernel/bpf/syscall.c           |  2 +-
>  kernel/trace/bpf_trace.c       | 45 +++++++++++++++++++++++++++++++---
>  tools/include/uapi/linux/bpf.h |  1 +
>  4 files changed, 44 insertions(+), 5 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index e764af513425..c6fbb0f948f4 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -1604,6 +1604,7 @@ union bpf_attr {
>                                 __aligned_u64   path;
>                                 __aligned_u64   offsets;
>                                 __aligned_u64   ref_ctr_offsets;
> +                               __aligned_u64   cookies;
>                                 __u32           cnt;
>                                 __u32           flags;
>                         } uprobe_multi;
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index f4c6a265731e..840b622b7db1 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -4832,7 +4832,7 @@ static int bpf_map_do_batch(const union bpf_attr *attr,
>         return err;
>  }
>
> -#define BPF_LINK_CREATE_LAST_FIELD link_create.kprobe_multi.cookies
> +#define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.cookies

Shouldn't it be :

#define BPF_LINK_CREATE_LAST_FIELD link_create.uprobe_multi.flags ?

other than that, this patch looks good.


>  static int link_create(union bpf_attr *attr, bpfptr_t uattr)
>  {
>         struct bpf_prog *prog;
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 10284fd46f98..d73a47bd2bbd 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -87,6 +87,8 @@ static int bpf_btf_printf_prepare(struct btf_ptr *ptr, u32 btf_ptr_size,
>  static u64 bpf_kprobe_multi_cookie(struct bpf_run_ctx *ctx);
>  static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx);
>
> +static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx);
> +
>  /**
>   * trace_call_bpf - invoke BPF program
>   * @call: tracepoint event
> @@ -1099,6 +1101,18 @@ static const struct bpf_func_proto bpf_get_attach_cookie_proto_kmulti = {
>         .arg1_type      = ARG_PTR_TO_CTX,
>  };
>
> +BPF_CALL_1(bpf_get_attach_cookie_uprobe_multi, struct pt_regs *, regs)
> +{
> +       return bpf_uprobe_multi_cookie(current->bpf_ctx);
> +}
> +
> +static const struct bpf_func_proto bpf_get_attach_cookie_proto_umulti = {
> +       .func           = bpf_get_attach_cookie_uprobe_multi,
> +       .gpl_only       = false,
> +       .ret_type       = RET_INTEGER,
> +       .arg1_type      = ARG_PTR_TO_CTX,
> +};
> +
>  BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
>  {
>         struct bpf_trace_run_ctx *run_ctx;
> @@ -1545,9 +1559,11 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>                         &bpf_get_func_ip_proto_kprobe_multi :
>                         &bpf_get_func_ip_proto_kprobe;
>         case BPF_FUNC_get_attach_cookie:
> -               return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ?
> -                       &bpf_get_attach_cookie_proto_kmulti :
> -                       &bpf_get_attach_cookie_proto_trace;
> +               if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI)
> +                       return &bpf_get_attach_cookie_proto_kmulti;
> +               if (prog->expected_attach_type == BPF_TRACE_UPROBE_MULTI)
> +                       return &bpf_get_attach_cookie_proto_umulti;
> +               return &bpf_get_attach_cookie_proto_trace;
>         default:
>                 return bpf_tracing_func_proto(func_id, prog);
>         }
> @@ -2973,6 +2989,7 @@ struct bpf_uprobe_multi_link;
>  struct bpf_uprobe {
>         struct bpf_uprobe_multi_link *link;
>         loff_t offset;
> +       u64 cookie;
>         struct uprobe_consumer consumer;
>  };
>
> @@ -2986,6 +3003,7 @@ struct bpf_uprobe_multi_link {
>  struct bpf_uprobe_multi_run_ctx {
>         struct bpf_run_ctx run_ctx;
>         unsigned long entry_ip;
> +       struct bpf_uprobe *uprobe;
>  };
>
>  static void bpf_uprobe_unregister(struct path *path, struct bpf_uprobe *uprobes,
> @@ -3029,6 +3047,7 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe,
>         struct bpf_uprobe_multi_link *link = uprobe->link;
>         struct bpf_uprobe_multi_run_ctx run_ctx = {
>                 .entry_ip = entry_ip,
> +               .uprobe = uprobe,
>         };
>         struct bpf_prog *prog = link->link.prog;
>         bool sleepable = prog->aux->sleepable;
> @@ -3075,6 +3094,14 @@ uprobe_multi_link_ret_handler(struct uprobe_consumer *con, unsigned long func, s
>         return uprobe_prog_run(uprobe, func, regs);
>  }
>
> +static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx)
> +{
> +       struct bpf_uprobe_multi_run_ctx *run_ctx;
> +
> +       run_ctx = container_of(current->bpf_ctx, struct bpf_uprobe_multi_run_ctx, run_ctx);
> +       return run_ctx->uprobe->cookie;
> +}
> +
>  int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
>  {
>         struct bpf_uprobe_multi_link *link = NULL;
> @@ -3083,6 +3110,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
>         struct bpf_link_primer link_primer;
>         struct bpf_uprobe *uprobes = NULL;
>         unsigned long __user *uoffsets;
> +       u64 __user *ucookies;
>         void __user *upath;
>         u32 flags, cnt, i;
>         struct path path;
> @@ -3102,7 +3130,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
>
>         /*
>          * path, offsets and cnt are mandatory,
> -        * ref_ctr_offsets is optional
> +        * ref_ctr_offsets and cookies are optional
>          */
>         upath = u64_to_user_ptr(attr->link_create.uprobe_multi.path);
>         uoffsets = u64_to_user_ptr(attr->link_create.uprobe_multi.offsets);
> @@ -3112,6 +3140,7 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
>                 return -EINVAL;
>
>         uref_ctr_offsets = u64_to_user_ptr(attr->link_create.uprobe_multi.ref_ctr_offsets);
> +       ucookies = u64_to_user_ptr(attr->link_create.uprobe_multi.cookies);
>
>         name = strndup_user(upath, PATH_MAX);
>         if (IS_ERR(name)) {
> @@ -3144,6 +3173,10 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
>         }
>
>         for (i = 0; i < cnt; i++) {
> +               if (ucookies && __get_user(uprobes[i].cookie, ucookies + i)) {
> +                       err = -EFAULT;
> +                       goto error_free;
> +               }
>                 if (uref_ctr_offsets && __get_user(ref_ctr_offsets[i], uref_ctr_offsets + i)) {
>                         err = -EFAULT;
>                         goto error_free;
> @@ -3201,4 +3234,8 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
>  {
>         return -EOPNOTSUPP;
>  }
> +static u64 bpf_uprobe_multi_cookie(struct bpf_run_ctx *ctx)
> +{
> +       return 0;
> +}
>  #endif /* CONFIG_UPROBES */
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 659afbf9bb8b..492072ef5029 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -1604,6 +1604,7 @@ union bpf_attr {
>                                 __aligned_u64   path;
>                                 __aligned_u64   offsets;
>                                 __aligned_u64   ref_ctr_offsets;
> +                               __aligned_u64   cookies;
>                                 __u32           cnt;
>                                 __u32           flags;
>                         } uprobe_multi;
> --
> 2.41.0
>
>


-- 
Regards
Yafang





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