On Fri, Jun 30, 2023 at 1:34 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> Adding new multi uprobe link that allows to attach bpf program
> to multiple uprobes.
>
> Uprobes to attach are specified via new link_create uprobe_multi
> union:
>
> struct {
> __u32 flags;
> __u32 cnt;
> __aligned_u64 path;
> __aligned_u64 offsets;
> __aligned_u64 ref_ctr_offsets;
> } uprobe_multi;
>
> Uprobes are defined for single binary specified in path and multiple
> calling sites specified in offsets array with optional reference
> counters specified in ref_ctr_offsets array. All specified arrays
> have length of 'cnt'.
>
> The 'flags' supports single bit for now that marks the uprobe as
> return probe.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> include/linux/trace_events.h | 6 +
> include/uapi/linux/bpf.h | 14 ++
> kernel/bpf/syscall.c | 14 +-
> kernel/trace/bpf_trace.c | 237 +++++++++++++++++++++++++++++++++
> tools/include/uapi/linux/bpf.h | 14 ++
> 5 files changed, 282 insertions(+), 3 deletions(-)
>
[...]
> + flags = attr->link_create.uprobe_multi.flags;
> + if (flags & ~BPF_F_UPROBE_MULTI_RETURN)
> + return -EINVAL;
> +
> + /*
> + * path, offsets and cnt are mandatory,
> + * ref_ctr_offsets is optional
> + */
> + upath = u64_to_user_ptr(attr->link_create.uprobe_multi.path);
> + uoffsets = u64_to_user_ptr(attr->link_create.uprobe_multi.offsets);
> + cnt = attr->link_create.uprobe_multi.cnt;
> +
> + if (!upath || !uoffsets || !cnt)
> + return -EINVAL;
see below for -EBADF, but we can also, additionally, return -EPROTO
here, for example?
> +
> + uref_ctr_offsets = u64_to_user_ptr(attr->link_create.uprobe_multi.ref_ctr_offsets);
> +
> + name = strndup_user(upath, PATH_MAX);
> + if (IS_ERR(name)) {
> + err = PTR_ERR(name);
> + return err;
> + }
> +
> + err = kern_path(name, LOOKUP_FOLLOW, &path);
> + kfree(name);
> + if (err)
> + return err;
> +
> + if (!d_is_reg(path.dentry)) {
> + err = -EINVAL;
as I mentioned in another patch, -EBADF here for feature detection
(and it makes sense by itself, probably)
> + goto error_path_put;
> + }
> +
> + err = -ENOMEM;
> +
> + link = kzalloc(sizeof(*link), GFP_KERNEL);
> + uprobes = kvcalloc(cnt, sizeof(*uprobes), GFP_KERNEL);
> +
> + if (!uprobes || !link)
> + goto error_free;
> +
> + if (uref_ctr_offsets) {
> + ref_ctr_offsets = kvcalloc(cnt, sizeof(*ref_ctr_offsets), GFP_KERNEL);
> + if (!ref_ctr_offsets)
> + goto error_free;
> + }
> +
[...]
