diff mbox series

[1/4] selftests/arm: Add mm test

Message ID 20240405084410.256788-2-dev.jain@arm.com (mailing list archive)
State New
Headers show
Series A new selftests/ directory for arm compatibility testing | expand

Commit Message

Dev Jain April 5, 2024, 8:44 a.m. UTC
This patch tests the 4GB VA restriction for 32-bit processes; it is required
to test the compat layer, whether the kernel knows that it is running a 32-bit
process or not. Chunks are allocated until the VA gets exhausted; mmap must
fail beyond 4GB. This is asserted against the VA mappings found
in /proc/self/maps.

Signed-off-by: Dev Jain <dev.jain@arm.com>
---
 tools/testing/selftests/arm/mm/compat_va.c | 94 ++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 tools/testing/selftests/arm/mm/compat_va.c

Comments

Muhammad Usama Anjum April 6, 2024, 9:23 p.m. UTC | #1
On 4/5/24 1:44 PM, Dev Jain wrote:
> This patch tests the 4GB VA restriction for 32-bit processes; it is required
> to test the compat layer, whether the kernel knows that it is running a 32-bit
> process or not. Chunks are allocated until the VA gets exhausted; mmap must
> fail beyond 4GB. This is asserted against the VA mappings found
> in /proc/self/maps.
> 
> Signed-off-by: Dev Jain <dev.jain@arm.com>
> ---
>  tools/testing/selftests/arm/mm/compat_va.c | 94 ++++++++++++++++++++++
>  1 file changed, 94 insertions(+)
>  create mode 100644 tools/testing/selftests/arm/mm/compat_va.c
> 
> diff --git a/tools/testing/selftests/arm/mm/compat_va.c b/tools/testing/selftests/arm/mm/compat_va.c
> new file mode 100644
> index 000000000000..3a78f240bc87
> --- /dev/null
> +++ b/tools/testing/selftests/arm/mm/compat_va.c
> @@ -0,0 +1,94 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2024 ARM Limited
> + *
> + * Author : Dev Jain <dev.jain@arm.com>
> + *
> + * Tests 4GB VA restriction for 32 bit process
> + */
> +
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +
> +#include <linux/sizes.h>
> +#include <kselftest.h>
> +
> +#define MAP_CHUNK_SIZE	SZ_1M
> +#define NR_CHUNKS_4G	(SZ_1G / MAP_CHUNK_SIZE) * 4	/* prevent overflow */
> +
> +static int validate_address_hint(void)
> +{
> +	char *ptr;
> +
> +	ptr = mmap((void *) (1UL << 29), MAP_CHUNK_SIZE, PROT_READ |
> +		   PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +
> +	if (ptr == MAP_FAILED)
> +		return 0;
> +
> +	return 1;
Usually we return negative value instead of positive one which indicates
error situation.

> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	char *ptr[NR_CHUNKS_4G + 3];
> +	char line[1000];
> +	const char *file_name;
> +	int chunks;
> +	FILE *file;
> +	int i;
> +
> +	ksft_print_header();
> +	ksft_set_plan(1);
There are multiple test cases. Instead of saying there is only 1 test.
There should be multiple ksft_test_result{_pass,_fail} statements for each
sub-tests.

> +
> +	/* try allocation beyond 4 GB */
> +	for (i = 0; i < NR_CHUNKS_4G + 3; ++i) {
> +		ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE,
> +			      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +
> +		if (ptr[i] == MAP_FAILED) {
> +			if (validate_address_hint())
> +				ksft_exit_fail_msg("VA exhaustion failed\n");
> +			break;
> +		}
> +	}
> +
> +	chunks = i;
> +	if (chunks >= NR_CHUNKS_4G) {
> +		ksft_test_result_fail("mmapped chunks beyond 4GB\n");
> +		ksft_finished();
> +	}
> +
> +	/* parse /proc/self/maps, confirm 32 bit VA mappings */
> +	file_name = "/proc/self/maps";
> +	file = fopen(file_name, "r");
> +	if (file == NULL)
> +		ksft_exit_fail_msg("/proc/self/maps cannot be opened\n");
> +
> +	while (fgets(line, sizeof(line), file)) {
> +		const char *whitespace_loc, *hyphen_loc;
> +
> +		hyphen_loc = strchr(line, '-');
> +		whitespace_loc = strchr(line, ' ');
> +
> +		if (!(hyphen_loc && whitespace_loc)) {
> +			ksft_test_result_skip("Unexpected format");
> +			ksft_finished();
I'm unable to follow as there are too many return statements. If you divide
the test into multiple sub-tests, you can skip/pass/fail each sub-test easily.

> +		}
> +
> +		if ((hyphen_loc - line > 8) ||
> +		    (whitespace_loc - hyphen_loc) > 9) {
> +			ksft_test_result_fail("Memory map more than 32 bits\n");
> +			ksft_finished();
> +		}
> +	}
> +
> +	for (int i = 0; i < chunks; ++i)
> +		munmap(ptr[i], MAP_CHUNK_SIZE);
> +
> +	ksft_test_result_pass("Test\n");
> +	ksft_finished();
> +}
Dev Jain April 10, 2024, 4:15 a.m. UTC | #2
On 4/7/24 02:53, Muhammad Usama Anjum wrote:
> On 4/5/24 1:44 PM, Dev Jain wrote:
>> This patch tests the 4GB VA restriction for 32-bit processes; it is required
>> to test the compat layer, whether the kernel knows that it is running a 32-bit
>> process or not. Chunks are allocated until the VA gets exhausted; mmap must
>> fail beyond 4GB. This is asserted against the VA mappings found
>> in /proc/self/maps.
>>
>> Signed-off-by: Dev Jain <dev.jain@arm.com>
>> ---
>>   tools/testing/selftests/arm/mm/compat_va.c | 94 ++++++++++++++++++++++
>>   1 file changed, 94 insertions(+)
>>   create mode 100644 tools/testing/selftests/arm/mm/compat_va.c
>>
>> diff --git a/tools/testing/selftests/arm/mm/compat_va.c b/tools/testing/selftests/arm/mm/compat_va.c
>> new file mode 100644
>> index 000000000000..3a78f240bc87
>> --- /dev/null
>> +++ b/tools/testing/selftests/arm/mm/compat_va.c
>> @@ -0,0 +1,94 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2024 ARM Limited
>> + *
>> + * Author : Dev Jain <dev.jain@arm.com>
>> + *
>> + * Tests 4GB VA restriction for 32 bit process
>> + */
>> +
>> +#define _GNU_SOURCE
>> +#include <stdio.h>
>> +#include <stdlib.h>
>> +#include <unistd.h>
>> +#include <sys/mman.h>
>> +
>> +#include <linux/sizes.h>
>> +#include <kselftest.h>
>> +
>> +#define MAP_CHUNK_SIZE	SZ_1M
>> +#define NR_CHUNKS_4G	(SZ_1G / MAP_CHUNK_SIZE) * 4	/* prevent overflow */
>> +
>> +static int validate_address_hint(void)
>> +{
>> +	char *ptr;
>> +
>> +	ptr = mmap((void *) (1UL << 29), MAP_CHUNK_SIZE, PROT_READ |
>> +		   PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
>> +
>> +	if (ptr == MAP_FAILED)
>> +		return 0;
>> +
>> +	return 1;
> Usually we return negative value instead of positive one which indicates
> error situation.
>
>> +}
>> +
>> +int main(int argc, char *argv[])
>> +{
>> +	char *ptr[NR_CHUNKS_4G + 3];
>> +	char line[1000];
>> +	const char *file_name;
>> +	int chunks;
>> +	FILE *file;
>> +	int i;
>> +
>> +	ksft_print_header();
>> +	ksft_set_plan(1);
> There are multiple test cases. Instead of saying there is only 1 test.
> There should be multiple ksft_test_result{_pass,_fail} statements for each
> sub-tests.


My initial idea was to treat this as a single logical test, as I

am asserting the restriction on the number of chunks against

the VMAs. I guess your approach is cleaner; thanks.

>
>> +
>> +	/* try allocation beyond 4 GB */
>> +	for (i = 0; i < NR_CHUNKS_4G + 3; ++i) {
>> +		ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE,
>> +			      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
>> +
>> +		if (ptr[i] == MAP_FAILED) {
>> +			if (validate_address_hint())
>> +				ksft_exit_fail_msg("VA exhaustion failed\n");
>> +			break;
>> +		}
>> +	}
>> +
>> +	chunks = i;
>> +	if (chunks >= NR_CHUNKS_4G) {
>> +		ksft_test_result_fail("mmapped chunks beyond 4GB\n");
>> +		ksft_finished();
>> +	}
>> +
>> +	/* parse /proc/self/maps, confirm 32 bit VA mappings */
>> +	file_name = "/proc/self/maps";
>> +	file = fopen(file_name, "r");
>> +	if (file == NULL)
>> +		ksft_exit_fail_msg("/proc/self/maps cannot be opened\n");
>> +
>> +	while (fgets(line, sizeof(line), file)) {
>> +		const char *whitespace_loc, *hyphen_loc;
>> +
>> +		hyphen_loc = strchr(line, '-');
>> +		whitespace_loc = strchr(line, ' ');
>> +
>> +		if (!(hyphen_loc && whitespace_loc)) {
>> +			ksft_test_result_skip("Unexpected format");
>> +			ksft_finished();
> I'm unable to follow as there are too many return statements. If you divide
> the test into multiple sub-tests, you can skip/pass/fail each sub-test easily.
>
>> +		}
>> +
>> +		if ((hyphen_loc - line > 8) ||
>> +		    (whitespace_loc - hyphen_loc) > 9) {
>> +			ksft_test_result_fail("Memory map more than 32 bits\n");
>> +			ksft_finished();
>> +		}
>> +	}
>> +
>> +	for (int i = 0; i < chunks; ++i)
>> +		munmap(ptr[i], MAP_CHUNK_SIZE);
>> +
>> +	ksft_test_result_pass("Test\n");
>> +	ksft_finished();
>> +}
Dev Jain April 17, 2024, 4:53 a.m. UTC | #3
On 4/10/24 09:45, Dev Jain wrote:
>
> On 4/7/24 02:53, Muhammad Usama Anjum wrote:
>> On 4/5/24 1:44 PM, Dev Jain wrote:
>>> This patch tests the 4GB VA restriction for 32-bit processes; it is 
>>> required
>>> to test the compat layer, whether the kernel knows that it is 
>>> running a 32-bit
>>> process or not. Chunks are allocated until the VA gets exhausted; 
>>> mmap must
>>> fail beyond 4GB. This is asserted against the VA mappings found
>>> in /proc/self/maps.
>>>
>>> Signed-off-by: Dev Jain <dev.jain@arm.com>
>>> ---
>>>   tools/testing/selftests/arm/mm/compat_va.c | 94 
>>> ++++++++++++++++++++++
>>>   1 file changed, 94 insertions(+)
>>>   create mode 100644 tools/testing/selftests/arm/mm/compat_va.c
>>>
>>> diff --git a/tools/testing/selftests/arm/mm/compat_va.c 
>>> b/tools/testing/selftests/arm/mm/compat_va.c
>>> new file mode 100644
>>> index 000000000000..3a78f240bc87
>>> --- /dev/null
>>> +++ b/tools/testing/selftests/arm/mm/compat_va.c
>>> @@ -0,0 +1,94 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Copyright (C) 2024 ARM Limited
>>> + *
>>> + * Author : Dev Jain <dev.jain@arm.com>
>>> + *
>>> + * Tests 4GB VA restriction for 32 bit process
>>> + */
>>> +
>>> +#define _GNU_SOURCE
>>> +#include <stdio.h>
>>> +#include <stdlib.h>
>>> +#include <unistd.h>
>>> +#include <sys/mman.h>
>>> +
>>> +#include <linux/sizes.h>
>>> +#include <kselftest.h>
>>> +
>>> +#define MAP_CHUNK_SIZE    SZ_1M
>>> +#define NR_CHUNKS_4G    (SZ_1G / MAP_CHUNK_SIZE) * 4    /* prevent 
>>> overflow */
>>> +
>>> +static int validate_address_hint(void)
>>> +{
>>> +    char *ptr;
>>> +
>>> +    ptr = mmap((void *) (1UL << 29), MAP_CHUNK_SIZE, PROT_READ |
>>> +           PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
>>> +
>>> +    if (ptr == MAP_FAILED)
>>> +        return 0;
>>> +
>>> +    return 1;
>> Usually we return negative value instead of positive one which indicates
>> error situation.
>>
>>> +}
>>> +
>>> +int main(int argc, char *argv[])
>>> +{
>>> +    char *ptr[NR_CHUNKS_4G + 3];
>>> +    char line[1000];
>>> +    const char *file_name;
>>> +    int chunks;
>>> +    FILE *file;
>>> +    int i;
>>> +
>>> +    ksft_print_header();
>>> +    ksft_set_plan(1);
>> There are multiple test cases. Instead of saying there is only 1 test.
>> There should be multiple ksft_test_result{_pass,_fail} statements for 
>> each
>> sub-tests.
>
>
> My initial idea was to treat this as a single logical test, as I
>
> am asserting the restriction on the number of chunks against
>
> the VMAs. I guess your approach is cleaner; thanks.


Thinking again, using a lot of return statements is in fact making the 
code easier

to follow. If I just set a variable ret = 0/1 and use it to pass or 
fail, I'll have to

unnecessarily use a lot of if/else statements. Take a look at the 
examples below.

>
>>
>>> +
>>> +    /* try allocation beyond 4 GB */
>>> +    for (i = 0; i < NR_CHUNKS_4G + 3; ++i) {
>>> +        ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE,
>>> +                  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
>>> +
>>> +        if (ptr[i] == MAP_FAILED) {
>>> +            if (validate_address_hint())
>>> +                ksft_exit_fail_msg("VA exhaustion failed\n");
>>> +            break;


I will have to set ret value here, forcing two statements inside the if 
block.

>>> +        }
>>> +    }
>>> +
>>> +    chunks = i;
>>> +    if (chunks >= NR_CHUNKS_4G) {
>>> +        ksft_test_result_fail("mmapped chunks beyond 4GB\n");
>>> +        ksft_finished();
>>> +    }
>>> +
>>> +    /* parse /proc/self/maps, confirm 32 bit VA mappings */
>>> +    file_name = "/proc/self/maps";
>>> +    file = fopen(file_name, "r");
>>> +    if (file == NULL)
>>> +        ksft_exit_fail_msg("/proc/self/maps cannot be opened\n");
>>> +


I will have to set ret here, and enclose the below while statement inside

an else block. In short, saving the value of ret will require if/else blocks

if I were to use it in the end in ksft_test_result(). When I use ksft_exit

statements, it is clear that a problem was spotted here, and there is

no need to study the remaining code.

>>> +    while (fgets(line, sizeof(line), file)) {
>>> +        const char *whitespace_loc, *hyphen_loc;
>>> +
>>> +        hyphen_loc = strchr(line, '-');
>>> +        whitespace_loc = strchr(line, ' ');
>>> +
>>> +        if (!(hyphen_loc && whitespace_loc)) {
>>> +            ksft_test_result_skip("Unexpected format");
>>> +            ksft_finished();
>> I'm unable to follow as there are too many return statements. If you 
>> divide
>> the test into multiple sub-tests, you can skip/pass/fail each 
>> sub-test easily.
>>
>>> +        }
>>> +
>>> +        if ((hyphen_loc - line > 8) ||
>>> +            (whitespace_loc - hyphen_loc) > 9) {
>>> +            ksft_test_result_fail("Memory map more than 32 bits\n");
>>> +            ksft_finished();
>>> +        }
>>> +    }
>>> +
>>> +    for (int i = 0; i < chunks; ++i)
>>> +        munmap(ptr[i], MAP_CHUNK_SIZE);
>>> +
>>> +    ksft_test_result_pass("Test\n");
>>> +    ksft_finished();
>>> +}
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
diff mbox series

Patch

diff --git a/tools/testing/selftests/arm/mm/compat_va.c b/tools/testing/selftests/arm/mm/compat_va.c
new file mode 100644
index 000000000000..3a78f240bc87
--- /dev/null
+++ b/tools/testing/selftests/arm/mm/compat_va.c
@@ -0,0 +1,94 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 ARM Limited
+ *
+ * Author : Dev Jain <dev.jain@arm.com>
+ *
+ * Tests 4GB VA restriction for 32 bit process
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+#include <linux/sizes.h>
+#include <kselftest.h>
+
+#define MAP_CHUNK_SIZE	SZ_1M
+#define NR_CHUNKS_4G	(SZ_1G / MAP_CHUNK_SIZE) * 4	/* prevent overflow */
+
+static int validate_address_hint(void)
+{
+	char *ptr;
+
+	ptr = mmap((void *) (1UL << 29), MAP_CHUNK_SIZE, PROT_READ |
+		   PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	if (ptr == MAP_FAILED)
+		return 0;
+
+	return 1;
+}
+
+int main(int argc, char *argv[])
+{
+	char *ptr[NR_CHUNKS_4G + 3];
+	char line[1000];
+	const char *file_name;
+	int chunks;
+	FILE *file;
+	int i;
+
+	ksft_print_header();
+	ksft_set_plan(1);
+
+	/* try allocation beyond 4 GB */
+	for (i = 0; i < NR_CHUNKS_4G + 3; ++i) {
+		ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE,
+			      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+		if (ptr[i] == MAP_FAILED) {
+			if (validate_address_hint())
+				ksft_exit_fail_msg("VA exhaustion failed\n");
+			break;
+		}
+	}
+
+	chunks = i;
+	if (chunks >= NR_CHUNKS_4G) {
+		ksft_test_result_fail("mmapped chunks beyond 4GB\n");
+		ksft_finished();
+	}
+
+	/* parse /proc/self/maps, confirm 32 bit VA mappings */
+	file_name = "/proc/self/maps";
+	file = fopen(file_name, "r");
+	if (file == NULL)
+		ksft_exit_fail_msg("/proc/self/maps cannot be opened\n");
+
+	while (fgets(line, sizeof(line), file)) {
+		const char *whitespace_loc, *hyphen_loc;
+
+		hyphen_loc = strchr(line, '-');
+		whitespace_loc = strchr(line, ' ');
+
+		if (!(hyphen_loc && whitespace_loc)) {
+			ksft_test_result_skip("Unexpected format");
+			ksft_finished();
+		}
+
+		if ((hyphen_loc - line > 8) ||
+		    (whitespace_loc - hyphen_loc) > 9) {
+			ksft_test_result_fail("Memory map more than 32 bits\n");
+			ksft_finished();
+		}
+	}
+
+	for (int i = 0; i < chunks; ++i)
+		munmap(ptr[i], MAP_CHUNK_SIZE);
+
+	ksft_test_result_pass("Test\n");
+	ksft_finished();
+}