Re: [PATCH bpf-next 4/4] selftests/bpf: add test for bpf_iter_task_vma

[Yonghong Song]

On 12/11/20 6:48 PM, Song Liu wrote:

The test dumps information similar to /proc/pid/maps. The first line of
the output is compared against the /proc file to make sure they match.

Signed-off-by: Song Liu <songliubrav...@fb.com>
---
  .../selftests/bpf/prog_tests/bpf_iter.c       | 106 ++++++++++++++++--
  tools/testing/selftests/bpf/progs/bpf_iter.h  |   9 ++
  .../selftests/bpf/progs/bpf_iter_task_vma.c   |  55 +++++++++
  3 files changed, 160 insertions(+), 10 deletions(-)
  create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_vma.c

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c 
b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index 0e586368948dd..7afd3abae1899 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -7,6 +7,7 @@
  #include "bpf_iter_task.skel.h"
  #include "bpf_iter_task_stack.skel.h"
  #include "bpf_iter_task_file.skel.h"
+#include "bpf_iter_task_vma.skel.h"
  #include "bpf_iter_task_btf.skel.h"
  #include "bpf_iter_tcp4.skel.h"
  #include "bpf_iter_tcp6.skel.h"
@@ -64,6 +65,22 @@ static void do_dummy_read(struct bpf_program *prog)
        bpf_link__destroy(link);
  }

[...]

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_vma.c 
b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma.c
new file mode 100644
index 0000000000000..d60b5b38cb396
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "bpf_iter.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+/* Copied from mm.h */
+#define VM_READ                0x00000001
+#define VM_WRITE       0x00000002
+#define VM_EXEC                0x00000004
+#define VM_MAYSHARE    0x00000080
+
+/* Copied from kdev_t.h */
+#define MINORBITS      20
+#define MINORMASK      ((1U << MINORBITS) - 1)
+#define MAJOR(dev)     ((unsigned int) ((dev) >> MINORBITS))
+#define MINOR(dev)     ((unsigned int) ((dev) & MINORMASK))
+
+#define D_PATH_BUF_SIZE 1024
+char d_path_buf[D_PATH_BUF_SIZE];
+__u32 pid;
+
+SEC("iter.s/task_vma") int proc_maps(struct bpf_iter__task_vma *ctx)
+{
+       struct __vm_area_struct *vma = ctx->vma;
+       struct seq_file *seq = ctx->meta->seq;
+       struct task_struct *task = ctx->task;
+       struct file *file = ctx->file;
+       char perm_str[] = "----";
+
+       if (task == (void *)0 || vma == (void *)0 || task->pid != pid)
+               return 0;
+
+       perm_str[0] = (vma->flags & VM_READ) ? 'r' : '-';
+       perm_str[1] = (vma->flags & VM_WRITE) ? 'w' : '-';
+       perm_str[1] = (vma->flags & VM_EXEC) ? 'x' : '-';

typo here? The above should be perm_str[2].

+       perm_str[3] = (vma->flags & VM_MAYSHARE) ? 's' : 'p';
+       BPF_SEQ_PRINTF(seq, "%08llx-%08llx %s ", vma->start, vma->end, 
perm_str);
+
+       if (file) {
+               __u32 dev = file->f_inode->i_sb->s_dev;
+
+               bpf_d_path(&file->f_path, d_path_buf, D_PATH_BUF_SIZE);
+
+               BPF_SEQ_PRINTF(seq, "%08llx ", vma->pgoff << 12);
+               BPF_SEQ_PRINTF(seq, "%02x:%02x %u", MAJOR(dev), MINOR(dev),
+                              file->f_inode->i_ino);
+               BPF_SEQ_PRINTF(seq, "\t%s\n", d_path_buf);
+       } else {
+               BPF_SEQ_PRINTF(seq, "%08llx 00:00 0\n", 0ULL);
+       }
+       return 0;
+}