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.
+
#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;
+};
+
[...]
