> On Dec 13, 2020, at 11:13 PM, Yonghong Song <yhs@xxxxxx> wrote:
>
>
>
> On 12/11/20 6:48 PM, Song Liu wrote:
>> Introduce task_vma bpf_iter to print memory information of a process. It
>> can be used to print customized information similar to /proc/<pid>/maps.
>> task_vma iterator releases mmap_lock before calling the BPF program.
>> Therefore, we cannot pass vm_area_struct directly to the BPF program. A
>> new __vm_area_struct is introduced to keep key information of a vma. On
>> each iteration, task_vma gathers information in __vm_area_struct and
>> passes it to the BPF program.
>> If the vma maps to a file, task_vma also holds a reference to the file
>> while calling the BPF program.
>> Signed-off-by: Song Liu <songliubraving@xxxxxx>
>> ---
>> include/linux/bpf.h | 2 +-
>> include/uapi/linux/bpf.h | 7 ++
>> kernel/bpf/task_iter.c | 193 ++++++++++++++++++++++++++++++++++++++-
>> 3 files changed, 200 insertions(+), 2 deletions(-)
>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>> index 07cb5d15e7439..49dd1e29c8118 100644
>> --- a/include/linux/bpf.h
>> +++ b/include/linux/bpf.h
>> @@ -1325,7 +1325,7 @@ enum bpf_iter_feature {
>> BPF_ITER_RESCHED = BIT(0),
>> };
>> -#define BPF_ITER_CTX_ARG_MAX 2
>> +#define BPF_ITER_CTX_ARG_MAX 3
>> struct bpf_iter_reg {
>> const char *target;
>> bpf_iter_attach_target_t attach_target;
>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
>> index 30b477a264827..c2db8a1d0cbd2 100644
>> --- a/include/uapi/linux/bpf.h
>> +++ b/include/uapi/linux/bpf.h
>> @@ -5151,4 +5151,11 @@ enum {
>> BTF_F_ZERO = (1ULL << 3),
>> };
>> +struct __vm_area_struct {
>> + __u64 start;
>> + __u64 end;
>> + __u64 flags;
>> + __u64 pgoff;
>> +};
>
> Probably we should not expose the above structure as uapi.
> All other bpf_iter ctx argument layouts are btf based
> and consider unstable. btf_iter itself is considered
> as an unstable interface to dump kernel internal
> data structures.
Yes, we can keep it in task_iter.c. I moved it to uapi to follow __sk_buff
pattern. It works fine in task_iter.c
Thanks,
Song
>
>> +
>> #endif /* _UAPI__LINUX_BPF_H__ */
>> diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
>> index 0458a40edf10a..30e5475d0831e 100644
>> --- a/kernel/bpf/task_iter.c
>> +++ b/kernel/bpf/task_iter.c
>> @@ -304,9 +304,171 @@ static const struct seq_operations task_file_seq_ops = {
>> .show = task_file_seq_show,
>> };
>> +struct bpf_iter_seq_task_vma_info {
>> + /* The first field must be struct bpf_iter_seq_task_common.
>> + * this is assumed by {init, fini}_seq_pidns() callback functions.
>> + */
>> + struct bpf_iter_seq_task_common common;
>> + struct task_struct *task;
>> + struct __vm_area_struct vma;
>> + struct file *file;
>> + u32 tid;
>> +};
>> +
> [...]
