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

On Dec 15, 2020, at 12:21 PM, Yonghong Song [off-list ref] wrote:



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

quoted

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 <redacted>
---
 .../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);
 }
 

[...]

quoted

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].

Good catch! Fixing it in the next version.

Song

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