On Wed, Oct 25, 2023 at 1:24 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
[...]
> __u64 missed;
> } kprobe_multi;
> + struct {
> + __aligned_u64 path;
> + __aligned_u64 offsets;
> + __aligned_u64 ref_ctr_offsets;
> + __aligned_u64 cookies;
> + __u32 path_max; /* in/out: uprobe_multi path size */
I don't think we use path_max for output. Did I miss something?
> + __u32 count; /* in/out: uprobe_multi offsets/ref_ctr_offsets/cookies count */
> + __u32 flags;
> + __u32 pid;
> + } uprobe_multi;
> struct {
> __u32 type; /* enum bpf_perf_event_type */
> __u32 :32;
[...]
> +
> + umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);
> + info->uprobe_multi.count = umulti_link->cnt;
> + info->uprobe_multi.flags = umulti_link->flags;
> + info->uprobe_multi.pid = umulti_link->task ?
> + task_pid_nr(umulti_link->task) : (u32) -1;
I think we can just use 0 here (instead of (u32)-1)?
> +
> + if (upath) {
nit: we are only using buf and p in this {}. It is cleaner to define them here.
> + if (upath_max > PATH_MAX)
> + return -E2BIG;
I don't think we need to fail here. How about we simply do
upath_max = min_ut(u32, upath_max, PATH_MAX);
> + buf = kmalloc(upath_max, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> + p = d_path(&umulti_link->path, buf, upath_max);
> + if (IS_ERR(p)) {
> + kfree(buf);
> + return -ENOSPC;
> + }
> + left = copy_to_user(upath, p, buf + upath_max - p);
> + kfree(buf);
> + if (left)
> + return -EFAULT;
> + }
> +
> + if (!uoffsets)
> + return 0;
> +
> + if (ucount < umulti_link->cnt)
> + err = -ENOSPC;
> + else
> + ucount = umulti_link->cnt;
> +
> + for (i = 0; i < ucount; i++) {
> + if (put_user(umulti_link->uprobes[i].offset, uoffsets + i))
> + return -EFAULT;
> + if (uref_ctr_offsets &&
> + put_user(umulti_link->uprobes[i].ref_ctr_offset, uref_ctr_offsets + i))
> + return -EFAULT;
> + if (ucookies &&
> + put_user(umulti_link->uprobes[i].cookie, ucookies + i))
> + return -EFAULT;
It feels expensive to put_user() 3x in a loop. Maybe we need a new struct
with offset, ref_ctr_offset, and cookie?
Thanks,
Song
> + }
> +
> + return err;
> +}
> +
