Messages in this thread | | | Date | Fri, 12 May 2023 17:16:38 +0530 | Subject | Re: [PATCH V6 2/3] soc: qcom: boot_stat: Add Driver Support for Boot Stats | From | Souradeep Chowdhury <> |
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On 5/11/2023 10:37 PM, Bjorn Andersson wrote: > On Tue, May 09, 2023 at 03:52:22AM -0700, Souradeep Chowdhury wrote: >> All of Qualcomm's proprietary Android boot-loaders capture boot time >> stats, like the time when the bootloader started execution and at what >> point the bootloader handed over control to the kernel etc. in the IMEM >> region. This information is captured in a specific format by this driver >> by mapping a structure to the IMEM memory region and then accessing the >> members of the structure to show the information within debugfs file. >> This information is useful in verifying if the existing boot KPIs have >> regressed or not. The information is shown in milliseconds, a sample >> log from sm8450(waipio) device is as follows:- >> >> /sys/kernel/debug/qcom_boot_stats # cat abl_time >> 17898 ms >> /sys/kernel/debug/qcom_boot_stats # cat pre_abl_time >> 2879 ms >> >> The Module Power Manager(MPM) sleep counter starts ticking at the PBL >> stage and the timestamp generated by the sleep counter is logged by >> the Qualcomm proprietary bootloader(ABL) at two points-> First when it >> starts execution which is logged here as "pre_abl_time" and the second >> when it is about to load the kernel logged as "abl_time". Documentation >> details are also added in Documentation/ABI/testing/debugfs-driver-bootstat >> > > I would have preferred some way to implement this without spending > countless kB of RAM to occasionally read out two u32 values... > > But pulling them out of /dev/mem is the only suggestion that comes to > mind... Perhaps dropping the MODULE_DEVICE_TABLE() to rely on an > explicit modprobe/insmod in the few cases where it's needed? > > @Arnd, do you have any suggestion about how to handle this kind of debug > drivers? > >> Signed-off-by: Souradeep Chowdhury <quic_schowdhu@quicinc.com> >> --- >> .../ABI/testing/debugfs-driver-bootstat | 17 +++ >> drivers/soc/qcom/Kconfig | 10 ++ >> drivers/soc/qcom/Makefile | 1 + >> drivers/soc/qcom/boot_stats.c | 100 ++++++++++++++++++ >> 4 files changed, 128 insertions(+) >> create mode 100644 Documentation/ABI/testing/debugfs-driver-bootstat >> create mode 100644 drivers/soc/qcom/boot_stats.c >> >> diff --git a/Documentation/ABI/testing/debugfs-driver-bootstat b/Documentation/ABI/testing/debugfs-driver-bootstat >> new file mode 100644 >> index 000000000000..7127d15d9f15 >> --- /dev/null >> +++ b/Documentation/ABI/testing/debugfs-driver-bootstat >> @@ -0,0 +1,17 @@ >> +What: /sys/kernel/debug/qcom_boot_stats/pre_abl_time >> +Date: May 2023 >> +Contact: Souradeep Chowdhury <quic_schowdhu@quicinc.com> >> +Description: >> + This file is used to read the KPI value pre abl time. >> + It shows the time in milliseconds from the starting >> + point of PBL to the point when the control shifted >> + to ABL(Qualcomm proprietary bootloader). >> + >> +What: /sys/kernel/debug/qcom_boot_stats/abl_time >> +Date: May 2023 >> +Contact: Souradeep Chowdhury <quic_schowdhu@quicinc.com> >> +Description: >> + This file is used to read the KPI value abl time. >> + It show the duration in milliseconds from the >> + time control switched to ABL to the point when >> + the linux kernel started getting loaded. >> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig >> index a491718f8064..04141236dcdd 100644 >> --- a/drivers/soc/qcom/Kconfig >> +++ b/drivers/soc/qcom/Kconfig >> @@ -16,6 +16,16 @@ config QCOM_AOSS_QMP >> subsystems as well as controlling the debug clocks exposed by the Always On >> Subsystem (AOSS) using Qualcomm Messaging Protocol (QMP). >> >> +config QCOM_BOOTSTAT >> + tristate "Qualcomm Technologies, Boot Stat driver" >> + depends on ARCH_QCOM || COMPILE_TEST >> + depends on DEBUG_FS >> + help >> + This option enables driver support for boot stats. Boot stat driver logs >> + the kernel bootloader information by accessing the imem region. These >> + information are exposed in the form of debugfs files. This is used to >> + determine if there is any regression in boot timings. >> + >> config QCOM_COMMAND_DB >> tristate "Qualcomm Command DB" >> depends on ARCH_QCOM || COMPILE_TEST >> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile >> index 0f43a88b4894..ae7bda96a539 100644 >> --- a/drivers/soc/qcom/Makefile >> +++ b/drivers/soc/qcom/Makefile >> @@ -1,6 +1,7 @@ >> # SPDX-License-Identifier: GPL-2.0 >> CFLAGS_rpmh-rsc.o := -I$(src) >> obj-$(CONFIG_QCOM_AOSS_QMP) += qcom_aoss.o >> +obj-$(CONFIG_QCOM_BOOTSTAT) += boot_stats.o >> obj-$(CONFIG_QCOM_GENI_SE) += qcom-geni-se.o >> obj-$(CONFIG_QCOM_COMMAND_DB) += cmd-db.o >> obj-$(CONFIG_QCOM_CPR) += cpr.o >> diff --git a/drivers/soc/qcom/boot_stats.c b/drivers/soc/qcom/boot_stats.c >> new file mode 100644 >> index 000000000000..ca67b6b5d8eb >> --- /dev/null >> +++ b/drivers/soc/qcom/boot_stats.c >> @@ -0,0 +1,100 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * Copyright (c) 2013-2019, 2021 The Linux Foundation. All rights reserved. >> + * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved. >> + */ >> + >> +#include <linux/debugfs.h> >> +#include <linux/err.h> >> +#include <linux/io.h> >> +#include <linux/init.h> >> +#include <linux/kernel.h> >> +#include <linux/module.h> >> +#include <linux/of.h> >> +#include <linux/of_address.h> >> +#include <linux/platform_device.h> >> + >> +#define TO_MS(timestamp) ((timestamp * 1000) / 32768) >> + >> +/** >> + * struct boot_stats - timestamp information related to boot stats >> + * @abl_start: Time for the starting point of the abl >> + * @abl_end: Time when the kernel starts loading from abl >> + */ >> +struct boot_stats { >> + u32 abl_start; >> + u32 abl_end; >> +} __packed; >> + >> +struct bs_data { >> + struct boot_stats __iomem *b_stats; >> + struct dentry *dbg_dir; >> +}; >> + >> +static void populate_boot_stats(char *abl_str, char *pre_abl_str, struct bs_data *drvdata) >> +{ >> + u32 abl_time, pre_abl_time; >> + >> + abl_time = TO_MS(drvdata->b_stats->abl_end) - TO_MS(drvdata->b_stats->abl_start); >> + sprintf(abl_str, "%u ms", abl_time); >> + >> + pre_abl_time = TO_MS(drvdata->b_stats->abl_start); >> + sprintf(pre_abl_str, "%u ms", pre_abl_time); >> +} >> + >> +static int boot_stats_probe(struct platform_device *pdev) >> +{ >> + char abl_str[20], pre_abl_str[20], *abl, *pre_abl; >> + struct device *bootstat_dev = &pdev->dev; >> + struct bs_data *drvdata; >> + >> + drvdata = devm_kzalloc(bootstat_dev, sizeof(*drvdata), GFP_KERNEL); >> + if (!drvdata) >> + return dev_err_probe(bootstat_dev, -ENOMEM, "failed to allocate memory"); >> + platform_set_drvdata(pdev, drvdata); >> + >> + drvdata->b_stats = devm_of_iomap(bootstat_dev, bootstat_dev->of_node, 0, NULL); > > You don't use this region past probe, so no need to keep it mapped, or > hang onto the pointer. > > This means that you don't need struct bs_data, you can just stuff the > dentry pointer directly in the drvdata.
Ack
> >> + if (IS_ERR(drvdata->b_stats)) >> + return dev_err_probe(bootstat_dev, PTR_ERR(drvdata->b_stats), >> + "failed to map imem region"); >> + >> + drvdata->dbg_dir = debugfs_create_dir("qcom_boot_stats", NULL); >> + if (IS_ERR(drvdata->dbg_dir)) > > Please omit error handling in the debugfs api.
Ack
> >> + return dev_err_probe(bootstat_dev, PTR_ERR(drvdata->dbg_dir), >> + "failed to create debugfs directory"); >> + >> + populate_boot_stats(abl_str, pre_abl_str, drvdata); >> + abl = abl_str; >> + pre_abl = pre_abl_str; >> + >> + debugfs_create_str("pre_abl_time", 0400, drvdata->dbg_dir, (char **)&pre_abl); > > abl lives on the stack, pre_abl is a pointer to the stack, &pre_abl is a > pointer to this pointer and if I read the code correctly, in > __debugfs_create_file this value is stored in inode->i_private. > > So I think this will only work if your stack isn't resused...
Ack
> > Regards, > Bjorn > >> + debugfs_create_str("abl_time", 0400, drvdata->dbg_dir, (char **)&abl); >> + >> + return 0; >> +} >> + >> +void boot_stats_remove(struct platform_device *pdev) >> +{ >> + struct bs_data *drvdata = platform_get_drvdata(pdev); >> + >> + debugfs_remove_recursive(drvdata->dbg_dir); >> +} >> + >> +static const struct of_device_id boot_stats_dt_match[] = { >> + { .compatible = "qcom,imem-bootstats" }, >> + { } >> +}; >> +MODULE_DEVICE_TABLE(of, boot_stats_dt_match); >> + >> +static struct platform_driver boot_stat_driver = { >> + .probe = boot_stats_probe, >> + .remove_new = boot_stats_remove, >> + .driver = { >> + .name = "qcom-boot-stats", >> + .of_match_table = boot_stats_dt_match, >> + }, >> +}; >> +module_platform_driver(boot_stat_driver); >> + >> +MODULE_DESCRIPTION("Qualcomm Technologies Inc. Boot Stat driver"); >> +MODULE_LICENSE("GPL"); >> -- >> 2.17.1 >>
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