[PATCH] firmware/psci: Add debugfs support to ease debugging

Bhupesh Sharma bhupesh.sharma at linaro.org
Wed Jul 27 13:55:20 PDT 2022



On 7/28/22 2:23 AM, Dmitry Baryshkov wrote:
> On Wed, 27 Jul 2022 at 23:15, Bhupesh Sharma <bhupesh.sharma at linaro.org> wrote:
>>
>> Hi Dmitry,
>>
>> On 7/28/22 1:39 AM, Dmitry Baryshkov wrote:
>>> To ease debugging of PSCI supported features, add debugfs file called
>>> 'psci' describing PSCI and SMC CC versions, enabled features and
>>> options.
>>>
>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>>> ---
>>>    drivers/firmware/psci/psci.c | 112 ++++++++++++++++++++++++++++++++++-
>>>    include/uapi/linux/psci.h    |   9 +++
>>>    2 files changed, 120 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
>>> index b907768eea01..6595cc964635 100644
>>> --- a/drivers/firmware/psci/psci.c
>>> +++ b/drivers/firmware/psci/psci.c
>>> @@ -9,6 +9,7 @@
>>>    #include <linux/acpi.h>
>>>    #include <linux/arm-smccc.h>
>>>    #include <linux/cpuidle.h>
>>> +#include <linux/debugfs.h>
>>>    #include <linux/errno.h>
>>>    #include <linux/linkage.h>
>>>    #include <linux/of.h>
>>> @@ -324,12 +325,121 @@ static void psci_sys_poweroff(void)
>>>        invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
>>>    }
>>>
>>> -static int __init psci_features(u32 psci_func_id)
>>> +static int psci_features(u32 psci_func_id)
>>
>> This change doesn't seem related to the patch $SUBJECT.
>> Also is it really needed? If yes, probably this should be a separate patch.
> 
> It is related and I don't think it should be moved to a separate
> patch. Removing the __init annotation from psci_features() is
> necessary to allow using psci_features() from psci_debufs_read(),
> which is definitely not an __init code. Otherwise reading from
> debugfs/psci would cause null pointer exceptions.

Ok, and what is the behavior with CONFIG_DEBUG_FS = n?
Does your patch work well in that case?

Thanks.

>>
>>>    {
>>>        return invoke_psci_fn(PSCI_1_0_FN_PSCI_FEATURES,
>>>                              psci_func_id, 0, 0);
>>>    }
>>>
>>> +#ifdef CONFIG_DEBUG_FS
>>> +
>>> +#define PSCI_ID(ver, _name) \
>>> +     { .fn = PSCI_##ver##_FN_##_name, .name = #_name, }
>>> +#define PSCI_ID_NATIVE(ver, _name) \
>>> +     { .fn = PSCI_FN_NATIVE(ver, _name), .name = #_name, }
>>> +
>>> +/* A table of all optional functions */
>>> +static const struct {
>>> +     u32 fn;
>>> +     const char *name;
>>> +} psci_fn_ids[] = {
>>> +     PSCI_ID_NATIVE(0_2, MIGRATE),
>>> +     PSCI_ID(0_2, MIGRATE_INFO_TYPE),
>>> +     PSCI_ID_NATIVE(0_2, MIGRATE_INFO_UP_CPU),
>>> +     PSCI_ID(1_0, CPU_FREEZE),
>>> +     PSCI_ID_NATIVE(1_0, CPU_DEFAULT_SUSPEND),
>>> +     PSCI_ID_NATIVE(1_0, NODE_HW_STATE),
>>> +     PSCI_ID_NATIVE(1_0, SYSTEM_SUSPEND),
>>> +     PSCI_ID(1_0, SET_SUSPEND_MODE),
>>> +     PSCI_ID_NATIVE(1_0, STAT_RESIDENCY),
>>> +     PSCI_ID_NATIVE(1_0, STAT_COUNT),
>>> +     PSCI_ID_NATIVE(1_1, SYSTEM_RESET2),
>>> +};
>>> +
>>> +static int psci_debugfs_read(struct seq_file *s, void *data)
>>> +{
>>> +     int feature, type, i;
>>> +     u32 ver;
>>> +
>>> +     ver = psci_ops.get_version();
>>> +     seq_printf(s, "PSCIv%d.%d\n",
>>> +                PSCI_VERSION_MAJOR(ver),
>>> +                PSCI_VERSION_MINOR(ver));
>>> +
>>> +     /* PSCI_FEATURES is available only starting from 1.0 */
>>> +     if (PSCI_VERSION_MAJOR(ver) < 1)
>>> +             return 0;
>>> +
>>> +     feature = psci_features(ARM_SMCCC_VERSION_FUNC_ID);
>>> +     if (feature != PSCI_RET_NOT_SUPPORTED) {
>>> +             ver = invoke_psci_fn(ARM_SMCCC_VERSION_FUNC_ID, 0, 0, 0);
>>> +             seq_printf(s, "SMC Calling Convention v%d.%d\n",
>>> +                        PSCI_VERSION_MAJOR(ver),
>>> +                        PSCI_VERSION_MINOR(ver));
>>> +     } else {
>>> +             seq_printf(s, "SMC Calling Convention v1.0 is assumed\n");
>>> +     }
>>> +
>>> +     feature = psci_features(PSCI_FN_NATIVE(0_2, CPU_SUSPEND));
>>> +     if (feature < 0) {
>>> +             seq_printf(s, "PSCI_FEATURES(CPU_SUSPEND) error (%d)\n", feature);
>>> +     } else {
>>> +             seq_printf(s, "OSI is %ssupported\n",
>>> +                        (feature & BIT(0)) ? "" : "not ");
>>> +             seq_printf(s, "%s StateID format is used\n",
>>> +                        (feature & BIT(1)) ? "Extended" : "Original");
>>> +     }
>>> +
>>> +     type = psci_ops.migrate_info_type();
>>> +     if (type == PSCI_0_2_TOS_UP_MIGRATE ||
>>> +         type == PSCI_0_2_TOS_UP_NO_MIGRATE) {
>>> +             unsigned long cpuid;
>>> +
>>> +             seq_printf(s, "Trusted OS %smigrate capable\n",
>>> +                        type == PSCI_0_2_TOS_UP_NO_MIGRATE ? "not " : "");
>>> +             cpuid = psci_migrate_info_up_cpu();
>>> +             seq_printf(s, "Trusted OS resident on physical CPU 0x%lx (#%d)\n", cpuid, resident_cpu);
>>> +     } else if (type == PSCI_0_2_TOS_MP) {
>>> +             seq_printf(s, "Trusted OS migration not required\n");
>>> +     } else {
>>> +             if (type != PSCI_RET_NOT_SUPPORTED)
>>> +                     seq_printf(s, "MIGRATE_INFO_TYPE returned unknown type (%d)\n", type);
>>> +     }
>>> +
>>> +     for (i = 0; i < ARRAY_SIZE(psci_fn_ids); i++) {
>>> +             feature = psci_features(psci_fn_ids[i].fn);
>>> +             if (feature == PSCI_RET_NOT_SUPPORTED)
>>> +                     continue;
>>> +             if (feature < 0)
>>> +                     seq_printf(s, "PSCI_FEATURES(%s) error (%d)\n", psci_fn_ids[i].name, feature);
>>> +             else
>>> +                     seq_printf(s, "%s is supported\n", psci_fn_ids[i].name);
>>> +     }
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +static int psci_debugfs_open(struct inode *inode, struct file *f)
>>> +{
>>> +     return single_open(f, psci_debugfs_read, NULL);
>>> +}
>>> +
>>> +static const struct file_operations psci_debugfs_ops = {
>>> +     .owner = THIS_MODULE,
>>> +     .open = psci_debugfs_open,
>>> +     .release = single_release,
>>> +     .read = seq_read,
>>> +     .llseek = seq_lseek
>>> +};
>>> +
>>> +static int __init psci_debugfs_init(void)
>>> +{
>>> +     return PTR_ERR_OR_ZERO(debugfs_create_file("psci", S_IRUGO, NULL, NULL,
>>> +                                                &psci_debugfs_ops));
>>> +}
>>> +late_initcall(psci_debugfs_init)
>>> +#endif
>>> +
>>>    #ifdef CONFIG_CPU_IDLE
>>>    static int psci_suspend_finisher(unsigned long state)
>>>    {
>>> diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
>>> index 2bf93c0d6354..f6f0bad5858b 100644
>>> --- a/include/uapi/linux/psci.h
>>> +++ b/include/uapi/linux/psci.h
>>> @@ -48,11 +48,20 @@
>>>    #define PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU   PSCI_0_2_FN64(7)
>>>
>>>    #define PSCI_1_0_FN_PSCI_FEATURES           PSCI_0_2_FN(10)
>>> +#define PSCI_1_0_FN_CPU_FREEZE                       PSCI_0_2_FN(11)
>>> +#define PSCI_1_0_FN_CPU_DEFAULT_SUSPEND              PSCI_0_2_FN(12)
>>> +#define PSCI_1_0_FN_NODE_HW_STATE            PSCI_0_2_FN(13)
>>>    #define PSCI_1_0_FN_SYSTEM_SUSPEND          PSCI_0_2_FN(14)
>>>    #define PSCI_1_0_FN_SET_SUSPEND_MODE                PSCI_0_2_FN(15)
>>> +#define PSCI_1_0_FN_STAT_RESIDENCY           PSCI_0_2_FN(16)
>>> +#define PSCI_1_0_FN_STAT_COUNT                       PSCI_0_2_FN(17)
>>>    #define PSCI_1_1_FN_SYSTEM_RESET2           PSCI_0_2_FN(18)
>>>
>>> +#define PSCI_1_0_FN64_CPU_DEFAULT_SUSPEND    PSCI_0_2_FN64(12)
>>> +#define PSCI_1_0_FN64_NODE_HW_STATE          PSCI_0_2_FN64(13)
>>>    #define PSCI_1_0_FN64_SYSTEM_SUSPEND                PSCI_0_2_FN64(14)
>>> +#define PSCI_1_0_FN64_STAT_RESIDENCY         PSCI_0_2_FN64(16)
>>> +#define PSCI_1_0_FN64_STAT_COUNT             PSCI_0_2_FN64(17)
>>>    #define PSCI_1_1_FN64_SYSTEM_RESET2         PSCI_0_2_FN64(18)
>>>
>>>    /* PSCI v0.2 power state encoding for CPU_SUSPEND function */
> 
> 
> 



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