linux-kernel - Re: [PATCH v4 10/10] selftests/nolibc: add mmap and munmap test cases

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Date:   Wed, 21 Jun 2023 20:58:46 +0200
From:   Thomas Weißschuh <thomas@...ch.de>
To:     Zhangjin Wu <falcon@...ylab.org>
Cc:     w@....eu, david.laight@...lab.com, arnd@...db.de,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v4 10/10] selftests/nolibc: add mmap and munmap test cases

On 2023-06-19 23:55:41+0800, Zhangjin Wu wrote:
> Three mmap/munmap related test cases are added:
> 
> - mmap(NULL, 0, PROT_READ, MAP_PRIVATE, 0, 0), MAP_FAILED, EINVAL)
> 
>   The length argument must be greater than 0, otherwise, fail with -EINVAL.
> 
> - munmap((void *)-1, 4*1024), -1, EINVAL)
> 
>   Invalid (void *)-1 address fail with -EINVAL.
> 
> - test_mmap_munmap(4*1024)
> 
>   It finds a init file, mmap() it and then munmap().
> 
> Signed-off-by: Zhangjin Wu <falcon@...ylab.org>
> ---
>  tools/testing/selftests/nolibc/nolibc-test.c | 31 ++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
> index 80ab29e2887c..f7c0ca72cb28 100644
> --- a/tools/testing/selftests/nolibc/nolibc-test.c
> +++ b/tools/testing/selftests/nolibc/nolibc-test.c
> @@ -592,6 +592,34 @@ static int test_stat_timestamps(void)
>  	return 0;
>  }
>  
> +int test_mmap_munmap(int size)
> +{
> +	char init_files[5][20] = {"/init", "/sbin/init", "/etc/init", "/bin/init", "/bin/sh"};

Why not /proc/1/exe or even /proc/self/exe?

I know your other series tries to remove the procfs dependency, but
we're not there yet :-).

Also does it make sense to pass a size parameter?
Why not use either PAGE_SIZE or the real size of the binary from
fstat().

> +	int ret, fd, i;
> +	void *mem;
> +
> +	for (i = 0; i < 5; i++) {
> +		ret = fd = open(init_files[i], O_RDONLY);
> +		if (ret < 0)
> +			continue;
> +		else
> +			break;
> +	}
> +	if (ret < 0)
> +		return ret;
> +
> +	mem = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
> +	if (mem == MAP_FAILED)
> +		return -1;
> +
> +	ret = munmap(mem, size);
> +	if (ret < 0)
> +		return ret;
> +
> +	return close(fd);
> +}
> +
> +
>  /* Run syscall tests between IDs <min> and <max>.
>   * Return 0 on success, non-zero on failure.
>   */
> @@ -666,6 +694,9 @@ int run_syscall(int min, int max)
>  		CASE_TEST(lseek_m1);          EXPECT_SYSER(1, lseek(-1, 0, SEEK_SET), -1, EBADF); break;
>  		CASE_TEST(lseek_0);           EXPECT_SYSER(1, lseek(0, 0, SEEK_SET), -1, ESPIPE); break;
>  		CASE_TEST(mkdir_root);        EXPECT_SYSER(1, mkdir("/", 0755), -1, EEXIST); break;
> +		CASE_TEST(mmap_bad);          EXPECT_PTRER(1, mmap(NULL, 0, PROT_READ, MAP_PRIVATE, 0, 0), MAP_FAILED, EINVAL); break;
> +		CASE_TEST(munmap_bad);        EXPECT_SYSER(1, munmap((void *)-1, 0), -1, EINVAL); break;
> +		CASE_TEST(mmap_good);         EXPECT_SYSZR(1, test_mmap_munmap(4*1024)); break;
>  		CASE_TEST(open_tty);          EXPECT_SYSNE(1, tmp = open("/dev/null", 0), -1); if (tmp != -1) close(tmp); break;
>  		CASE_TEST(open_blah);         EXPECT_SYSER(1, tmp = open("/proc/self/blah", 0), -1, ENOENT); if (tmp != -1) close(tmp); break;
>  		CASE_TEST(poll_null);         EXPECT_SYSZR(1, poll(NULL, 0, 0)); break;
> -- 
> 2.25.1
>