[PATCH v4 1/3] docs: sound: add 'pcmtest' driver documentation
Add documentation for the new Virtual PCM Test Driver. It covers all possible usage cases: errors and delay injections, random and pattern-based data generation, playback and ioctl redefinition functionalities testing.
We have a lot of different virtual media drivers, which can be used for testing of the userspace applications and media subsystem middle layer. However, all of them are aimed at testing the video functionality and simulating the video devices. For audio devices we have only snd-dummy module, which is good in simulating the correct behavior of an ALSA device. I decided to write a tool, which would help to test the userspace ALSA programs (and the PCM middle layer as well) under unusual circumstances to figure out how they would behave. So I came up with this Virtual PCM Test Driver.
This new Virtual PCM Test Driver has several features which can be useful during the userspace ALSA applications testing/fuzzing, or testing/fuzzing of the PCM middle layer. Not all of them can be implemented using the existing virtual drivers (like dummy or loopback). Here is what can this driver do:
- Simulate both capture and playback processes - Check the playback stream for containing the looped pattern - Generate random or pattern-based capture data - Inject delays into the playback and capturing processes - Inject errors during the PCM callbacks
Also, this driver can check the playback stream for containing the predefined pattern, which is used in the corresponding selftest to check the PCM middle layer data transferring functionality. Additionally, this driver redefines the default RESET ioctl, and the selftest covers this PCM API functionality as well.
The driver supports both interleaved and non-interleaved access modes, and have separate pattern buffers for each channel. The driver supports up to 4 channels and up to 8 substreams.
Signed-off-by: Ivan Orlov ivan.orlov0322@gmail.com --- V1 -> V2:
- Rename the driver from from 'valsa' to 'pcmtest'. - Implement support for interleaved and non-interleaved access modes - Add support for 8 substreams and 4 channels - Extend supported formats - Extend and rewrite in C the selftest for the driver
V2 -> V3:
- Add separate pattern buffers for each channel - Speed up the capture data generation when using interleaved access mode - Extend the corresponding selftest to cover the multiple channels capturing and playback functionalities when using interleaved access mode. - Fix documentation issues
V3 -> V4:
- Fix issue in the selftest: there was a typo in the fscanf argument.
Documentation/sound/cards/index.rst | 1 + Documentation/sound/cards/pcmtest.rst | 120 ++++++++++++++++++++++++++ 2 files changed, 121 insertions(+) create mode 100644 Documentation/sound/cards/pcmtest.rst
diff --git a/Documentation/sound/cards/index.rst b/Documentation/sound/cards/index.rst index c016f8c3b88b..49c1f2f688f8 100644 --- a/Documentation/sound/cards/index.rst +++ b/Documentation/sound/cards/index.rst @@ -17,3 +17,4 @@ Card-Specific Information hdspm serial-u16550 img-spdif-in + pcmtest diff --git a/Documentation/sound/cards/pcmtest.rst b/Documentation/sound/cards/pcmtest.rst new file mode 100644 index 000000000000..e163522f3205 --- /dev/null +++ b/Documentation/sound/cards/pcmtest.rst @@ -0,0 +1,120 @@ +.. SPDX-License-Identifier: GPL-2.0 + +The Virtual PCM Test Driver +=========================== + +The Virtual PCM Test Driver emulates a generic PCM device, and can be used for +testing/fuzzing of the userspace ALSA applications, as well as for testing/fuzzing of +the PCM middle layer. Additionally, it can be used for simulating hard to reproduce +problems with PCM devices. + +What can this driver do? +~~~~~~~~~~~~~~~~~~~~~~~~ + +At this moment the driver can do the following things: + * Simulate both capture and playback processes + * Generate random or pattern-based capturing data + * Inject delays into the playback and capturing processes + * Inject errors during the PCM callbacks + +It supports up to 8 substreams and 4 channels. Also it supports both interleaved and +non-interleaved access modes. + +Also, this driver can check the playback stream for containing the predefined pattern, +which is used in the corresponding selftest (alsa/pcmtest-test.sh) to check the PCM middle +layer data transferring functionality. Additionally, this driver redefines the default +RESET ioctl, and the selftest covers this PCM API functionality as well. + +Configuration +------------- + +The driver has several parameters besides the common ALSA module parameters: + + * fill_mode (bool) - Buffer fill mode (see below) + * inject_delay (int) + * inject_hwpars_err (bool) + * inject_prepare_err (bool) + * inject_trigger_err (bool) + + +Capture Data Generation +----------------------- + +The driver has two modes of data generation: the first (0 in the fill_mode parameter) +means random data generation, the second (1 in the fill_mode) - pattern-based +data generation. Let's look at the second mode. + +First of all, you may want to specify the pattern for data generation. You can do it +by writing the pattern to the debugfs file. There are pattern buffer debugfs entries +for each channel, as well as entries which contain the pattern buffer length. + + * /sys/kernel/debug/pcmtest/fill_pattern[0-3] + * /sys/kernel/debug/pcmtest/fill_pattern[0-3]_len + +To set the pattern for the channel 0 you can execute the following command: + +.. code-block:: bash + + echo -n mycoolpattern > /sys/kernel/debug/pcmtest/fill_pattern0 + +Then, after every capture action performed on the 'pcmtest' device the buffer for the +channel 0 will contain 'mycoolpatternmycoolpatternmycoolpatternmy...'. + +The pattern itself can be up to 4096 bytes long. + +Delay injection +--------------- + +The driver has 'inject_delay' parameter, which has very self-descriptive name and +can be used for time delay/speedup simulations. The parameter has integer type, and +it means the delay added between module's internal timer ticks. + +If the 'inject_delay' value is positive, the buffer will be filled slower, if it is +negative - faster. You can try it yourself by starting a recording in any +audiorecording application (like Audacity) and selecting the 'pcmtest' device as a +source. + +This parameter can be also used for generating a huge amount of sound data in a very +short period of time (with the negative 'inject_delay' value). + +Errors injection +---------------- + +This module can be used for injecting errors into the PCM communication process. This +action can help you to figure out how the userspace ALSA program behaves under unusual +circumstances. + +For example, you can make all 'hw_params' PCM callback calls return EBUSY error by +writing '1' to the 'inject_hwpars_err' module parameter: + +.. code-block:: bash + + echo 1 > /sys/module/snd_pcmtest/parameters/inject_hwpars_err + +Errors can be injected into the following PCM callbacks: + + * hw_params (EBUSY) + * prepare (EINVAL) + * trigger (EINVAL) + +Playback test +------------- + +This driver can be also used for the playback functionality testing - every time you +write the playback data to the 'pcmtest' PCM device and close it, the driver checks the +buffer for containing the looped pattern (which is specified in the fill_pattern +debugfs file for each channel). If the playback buffer content represents the looped +pattern, 'pc_test' debugfs entry is set into '1'. Otherwise, the driver sets it to '0'. + +ioctl redefinition test +----------------------- + +The driver redefines the 'reset' ioctl, which is default for all PCM devices. To test +this functionality, we can trigger the reset ioctl and check the 'ioctl_test' debugfs +entry: + +.. code-block:: bash + + cat /sys/kernel/debug/pcmtest/ioctl_test + +If the ioctl is triggered successfully, this file will contain '1', and '0' otherwise.
This test covers the new Virtual PCM Test Driver, including the capturing, playback and ioctl redefinition functionalities for both interleaved and non-interleaved access modes. This test is also helpful as an usage example of the 'pcmtest' driver.
We have a lot of different virtual media drivers, which can be used for testing of the userspace applications and media subsystem middle layer. However, all of them are aimed at testing the video functionality and simulating the video devices. For audio devices we have only snd-dummy module, which is good in simulating the correct behavior of an ALSA device. I decided to write a tool, which would help to test the userspace ALSA programs (and the PCM middle layer as well) under unusual circumstances to figure out how they would behave. So I came up with this Virtual PCM Test Driver.
This new Virtual PCM Test Driver has several features which can be useful during the userspace ALSA applications testing/fuzzing, or testing/fuzzing of the PCM middle layer. Not all of them can be implemented using the existing virtual drivers (like dummy or loopback). Here is what can this driver do:
- Simulate both capture and playback processes - Generate random or pattern-based capture data - Check the playback stream for containing the looped pattern - Inject delays into the playback and capturing processes - Inject errors during the PCM callbacks
Also, this driver can check the playback stream for containing the predefined pattern, which is used in the corresponding selftest to check the PCM middle layer data transferring functionality. Additionally, this driver redefines the default RESET ioctl, and the selftest covers this PCM API functionality as well.
The driver supports both interleaved and non-interleaved access modes, and have separate pattern buffers for each channel. The driver supports up to 4 channels and up to 8 substreams.
Signed-off-by: Ivan Orlov ivan.orlov0322@gmail.com --- V1 -> V2:
- Rename the driver from from 'valsa' to 'pcmtest'. - Implement support for interleaved and non-interleaved access modes - Add support for 8 substreams and 4 channels - Extend supported formats - Extend and rewrite in C the selftest for the driver
V2 -> V3:
- Add separate pattern buffers for each channel - Speed up the capture data generation when using interleaved access mode - Extend the corresponding selftest to cover the multiple channels capturing and playback functionalities when using interleaved access mode. - Fix documentation issues
V3 -> V4:
- Fix issue in the selftest: there was a typo in the fscanf argument.
tools/testing/selftests/alsa/Makefile | 2 +- .../selftests/alsa/test-pcmtest-driver.c | 333 ++++++++++++++++++ 2 files changed, 334 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/alsa/test-pcmtest-driver.c
diff --git a/tools/testing/selftests/alsa/Makefile b/tools/testing/selftests/alsa/Makefile index 901949db80ad..5af9ba8a4645 100644 --- a/tools/testing/selftests/alsa/Makefile +++ b/tools/testing/selftests/alsa/Makefile @@ -12,7 +12,7 @@ LDLIBS+=-lpthread
OVERRIDE_TARGETS = 1
-TEST_GEN_PROGS := mixer-test pcm-test +TEST_GEN_PROGS := mixer-test pcm-test test-pcmtest-driver
TEST_GEN_PROGS_EXTENDED := libatest.so
diff --git a/tools/testing/selftests/alsa/test-pcmtest-driver.c b/tools/testing/selftests/alsa/test-pcmtest-driver.c new file mode 100644 index 000000000000..71931b240a83 --- /dev/null +++ b/tools/testing/selftests/alsa/test-pcmtest-driver.c @@ -0,0 +1,333 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This is the test which covers PCM middle layer data transferring using + * the virtual pcm test driver (snd-pcmtest). + * + * Copyright 2023 Ivan Orlov ivan.orlov0322@gmail.com + */ +#include <string.h> +#include <alsa/asoundlib.h> +#include "../kselftest_harness.h" + +#define CH_NUM 4 + +struct pattern_buf { + char buf[1024]; + int len; +}; + +struct pattern_buf patterns[CH_NUM]; + +struct pcmtest_test_params { + unsigned long buffer_size; + unsigned long period_size; + unsigned long channels; + unsigned int rate; + snd_pcm_access_t access; + size_t sec_buf_len; + size_t sample_size; + int time; + snd_pcm_format_t format; +}; + +static int read_patterns(void) +{ + FILE *fp, *fpl; + int i; + char pf[64]; + char plf[64]; + + for (i = 0; i < CH_NUM; i++) { + sprintf(plf, "/sys/kernel/debug/pcmtest/fill_pattern%d_len", i); + fpl = fopen(plf, "r"); + if (!fpl) + return -1; + fscanf(fpl, "%u", &patterns[i].len); + fclose(fpl); + + sprintf(pf, "/sys/kernel/debug/pcmtest/fill_pattern%d", i); + fp = fopen(pf, "r"); + if (!fp) { + fclose(fpl); + return -1; + } + fread(patterns[i].buf, 1, patterns[i].len, fp); + fclose(fp); + } + + return 0; +} + +static int get_test_results(char *debug_name) +{ + int result; + FILE *f; + char fname[128]; + + sprintf(fname, "/sys/kernel/debug/pcmtest/%s", debug_name); + + f = fopen(fname, "r"); + if (!f) { + printf("Failed to open file\n"); + return -1; + } + fscanf(f, "%d", &result); + fclose(f); + + return result; +} + +static size_t get_sec_buf_len(unsigned int rate, unsigned long channels, snd_pcm_format_t format) +{ + return rate * channels * snd_pcm_format_physical_width(format) / 8; +} + +static int setup_handle(snd_pcm_t **handle, snd_pcm_sw_params_t *swparams, + snd_pcm_hw_params_t *hwparams, struct pcmtest_test_params *params, + int card, snd_pcm_stream_t stream) +{ + char pcm_name[32]; + int err; + + sprintf(pcm_name, "hw:%d,0,0", card); + err = snd_pcm_open(handle, pcm_name, stream, 0); + if (err < 0) + return err; + snd_pcm_hw_params_any(*handle, hwparams); + snd_pcm_hw_params_set_rate_resample(*handle, hwparams, 0); + snd_pcm_hw_params_set_access(*handle, hwparams, params->access); + snd_pcm_hw_params_set_format(*handle, hwparams, params->format); + snd_pcm_hw_params_set_channels(*handle, hwparams, params->channels); + snd_pcm_hw_params_set_rate_near(*handle, hwparams, ¶ms->rate, 0); + snd_pcm_hw_params_set_period_size_near(*handle, hwparams, ¶ms->period_size, 0); + snd_pcm_hw_params_set_buffer_size_near(*handle, hwparams, ¶ms->buffer_size); + snd_pcm_hw_params(*handle, hwparams); + snd_pcm_sw_params_current(*handle, swparams); + + snd_pcm_hw_params_set_rate_resample(*handle, hwparams, 0); + snd_pcm_sw_params_set_avail_min(*handle, swparams, params->period_size); + snd_pcm_hw_params_set_buffer_size_near(*handle, hwparams, ¶ms->buffer_size); + snd_pcm_hw_params_set_period_size_near(*handle, hwparams, ¶ms->period_size, 0); + snd_pcm_sw_params(*handle, swparams); + snd_pcm_hw_params(*handle, hwparams); + + return 0; +} + +FIXTURE(pcmtest) { + int card; + snd_pcm_sw_params_t *swparams; + snd_pcm_hw_params_t *hwparams; + struct pcmtest_test_params params; +}; + +FIXTURE_TEARDOWN(pcmtest) { +} + +FIXTURE_SETUP(pcmtest) { + char *card_name; + int err; + + if (geteuid()) + SKIP(exit(-1), "This test needs root to run!"); + + err = read_patterns(); + if (err) + SKIP(exit(-1), "Can't read patterns. Probably, module isn't loaded"); + + card_name = malloc(127); + ASSERT_NE(card_name, NULL); + self->params.buffer_size = 16384; + self->params.period_size = 4096; + self->params.channels = CH_NUM; + self->params.rate = 8000; + self->params.access = SND_PCM_ACCESS_RW_INTERLEAVED; + self->params.format = SND_PCM_FORMAT_S16_LE; + self->card = -1; + self->params.sample_size = snd_pcm_format_physical_width(self->params.format) / 8; + + self->params.sec_buf_len = get_sec_buf_len(self->params.rate, self->params.channels, + self->params.format); + self->params.time = 4; + + while (snd_card_next(&self->card) >= 0) { + if (self->card == -1) + break; + snd_card_get_name(self->card, &card_name); + if (!strcmp(card_name, "PCM-Test")) + break; + } + free(card_name); + ASSERT_NE(self->card, -1); +} + +/* + * Here we are trying to send the looped monotonically increasing sequence of bytes to the driver. + * If our data isn't corrupted, the driver will set the content of 'pc_test' debugfs file to '1' + */ +TEST_F(pcmtest, playback) { + snd_pcm_t *handle; + unsigned char *it; + size_t write_res; + int test_results; + int i, cur_ch, pos_in_ch; + void *samples; + struct pcmtest_test_params *params = &self->params; + + samples = calloc(self->params.sec_buf_len * self->params.time, 1); + ASSERT_NE(samples, NULL); + + snd_pcm_sw_params_alloca(&self->swparams); + snd_pcm_hw_params_alloca(&self->hwparams); + + ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams, params, + self->card, SND_PCM_STREAM_PLAYBACK), 0); + snd_pcm_format_set_silence(params->format, samples, + params->rate * params->channels * params->time); + it = samples; + for (i = 0; i < self->params.sec_buf_len * params->time; i++) { + cur_ch = (i / params->sample_size) % CH_NUM; + pos_in_ch = i / params->sample_size / CH_NUM * params->sample_size + + (i % params->sample_size); + it[i] = patterns[cur_ch].buf[pos_in_ch % patterns[cur_ch].len]; + } + write_res = snd_pcm_writei(handle, samples, params->rate * params->time); + ASSERT_GE(write_res, 0); + + snd_pcm_close(handle); + free(samples); + test_results = get_test_results("pc_test"); + ASSERT_EQ(test_results, 1); +} + +/* + * Here we test that the virtual alsa driver returns looped and monotonically increasing sequence + * of bytes. In the interleaved mode the buffer will contain samples in the following order: + * C0, C1, C2, C3, C0, C1, ... + */ +TEST_F(pcmtest, capture) { + snd_pcm_t *handle; + unsigned char *it; + size_t read_res; + int i, cur_ch, pos_in_ch; + void *samples; + struct pcmtest_test_params *params = &self->params; + + samples = calloc(self->params.sec_buf_len * self->params.time, 1); + ASSERT_NE(samples, NULL); + + snd_pcm_sw_params_alloca(&self->swparams); + snd_pcm_hw_params_alloca(&self->hwparams); + + ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams, + params, self->card, SND_PCM_STREAM_CAPTURE), 0); + snd_pcm_format_set_silence(params->format, samples, + params->rate * params->channels * params->time); + read_res = snd_pcm_readi(handle, samples, params->rate * params->time); + ASSERT_GE(read_res, 0); + snd_pcm_close(handle); + it = (unsigned char *)samples; + for (i = 0; i < self->params.sec_buf_len * self->params.time; i++) { + cur_ch = (i / params->sample_size) % CH_NUM; + pos_in_ch = i / params->sample_size / CH_NUM * params->sample_size + + (i % params->sample_size); + ASSERT_EQ(it[i], patterns[cur_ch].buf[pos_in_ch % patterns[cur_ch].len]); + } + free(samples); +} + +// Test capture in the non-interleaved access mode. The are buffers for each recorded channel +TEST_F(pcmtest, ni_capture) { + snd_pcm_t *handle; + struct pcmtest_test_params params = self->params; + char **chan_samples; + size_t i, j, read_res; + + chan_samples = calloc(CH_NUM, sizeof(*chan_samples)); + ASSERT_NE(chan_samples, NULL); + + snd_pcm_sw_params_alloca(&self->swparams); + snd_pcm_hw_params_alloca(&self->hwparams); + + params.access = SND_PCM_ACCESS_RW_NONINTERLEAVED; + + ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams, + ¶ms, self->card, SND_PCM_STREAM_CAPTURE), 0); + + for (i = 0; i < CH_NUM; i++) + chan_samples[i] = calloc(params.sec_buf_len * params.time, 1); + + for (i = 0; i < 1; i++) { + read_res = snd_pcm_readn(handle, (void **)chan_samples, params.rate * params.time); + ASSERT_GE(read_res, 0); + } + snd_pcm_close(handle); + + for (i = 0; i < CH_NUM; i++) { + for (j = 0; j < params.rate * params.time; j++) + ASSERT_EQ(chan_samples[i][j], patterns[i].buf[j % patterns[i].len]); + free(chan_samples[i]); + } + free(chan_samples); +} + +TEST_F(pcmtest, ni_playback) { + snd_pcm_t *handle; + struct pcmtest_test_params params = self->params; + char **chan_samples; + size_t i, j, read_res; + int test_res; + + chan_samples = calloc(CH_NUM, sizeof(*chan_samples)); + ASSERT_NE(chan_samples, NULL); + + snd_pcm_sw_params_alloca(&self->swparams); + snd_pcm_hw_params_alloca(&self->hwparams); + + params.access = SND_PCM_ACCESS_RW_NONINTERLEAVED; + + ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams, + ¶ms, self->card, SND_PCM_STREAM_PLAYBACK), 0); + + for (i = 0; i < CH_NUM; i++) { + chan_samples[i] = calloc(params.sec_buf_len * params.time, 1); + for (j = 0; j < params.sec_buf_len * params.time; j++) + chan_samples[i][j] = patterns[i].buf[j % patterns[i].len]; + } + + for (i = 0; i < 1; i++) { + read_res = snd_pcm_writen(handle, (void **)chan_samples, params.rate * params.time); + ASSERT_GE(read_res, 0); + } + + snd_pcm_close(handle); + test_res = get_test_results("pc_test"); + ASSERT_EQ(test_res, 1); + + for (i = 0; i < CH_NUM; i++) + free(chan_samples[i]); + free(chan_samples); +} + +/* + * Here we are testing the custom ioctl definition inside the virtual driver. If it triggers + * successfully, the driver sets the content of 'ioctl_test' debugfs file to '1'. + */ +TEST_F(pcmtest, reset_ioctl) { + snd_pcm_t *handle; + unsigned char *it; + int test_res; + struct pcmtest_test_params *params = &self->params; + + snd_pcm_sw_params_alloca(&self->swparams); + snd_pcm_hw_params_alloca(&self->hwparams); + + ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams, params, + self->card, SND_PCM_STREAM_CAPTURE), 0); + snd_pcm_reset(handle); + test_res = get_test_results("ioctl_test"); + ASSERT_EQ(test_res, 1); + snd_pcm_close(handle); +} + +TEST_HARNESS_MAIN
On Tue, 06 Jun 2023 21:32:52 +0200, Ivan Orlov wrote:
Add documentation for the new Virtual PCM Test Driver. It covers all possible usage cases: errors and delay injections, random and pattern-based data generation, playback and ioctl redefinition functionalities testing.
We have a lot of different virtual media drivers, which can be used for testing of the userspace applications and media subsystem middle layer. However, all of them are aimed at testing the video functionality and simulating the video devices. For audio devices we have only snd-dummy module, which is good in simulating the correct behavior of an ALSA device. I decided to write a tool, which would help to test the userspace ALSA programs (and the PCM middle layer as well) under unusual circumstances to figure out how they would behave. So I came up with this Virtual PCM Test Driver.
This new Virtual PCM Test Driver has several features which can be useful during the userspace ALSA applications testing/fuzzing, or testing/fuzzing of the PCM middle layer. Not all of them can be implemented using the existing virtual drivers (like dummy or loopback). Here is what can this driver do:
- Simulate both capture and playback processes
- Check the playback stream for containing the looped pattern
- Generate random or pattern-based capture data
- Inject delays into the playback and capturing processes
- Inject errors during the PCM callbacks
Also, this driver can check the playback stream for containing the predefined pattern, which is used in the corresponding selftest to check the PCM middle layer data transferring functionality. Additionally, this driver redefines the default RESET ioctl, and the selftest covers this PCM API functionality as well.
The driver supports both interleaved and non-interleaved access modes, and have separate pattern buffers for each channel. The driver supports up to 4 channels and up to 8 substreams.
Signed-off-by: Ivan Orlov ivan.orlov0322@gmail.com
Now I merged all three patches.
thanks,
Takashi
participants (2)
-
Ivan Orlov -
Takashi Iwai