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

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Date:   Tue, 15 Dec 2020 20:59:21 +0000
From:   Song Liu <songliubraving@...com>
To:     Yonghong Song <yhs@...com>
CC:     bpf <bpf@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "andrii@...nel.org" <andrii@...nel.org>,
        "john.fastabend@...il.com" <john.fastabend@...il.com>,
        "kpsingh@...omium.org" <kpsingh@...omium.org>,
        Kernel Team <Kernel-team@...com>
Subject: 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 <yhs@...com> wrote:
> 
> 
> 
> 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 <songliubraving@...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].

Good catch! Fixing it in the next version.

Song

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