[PATCH v2] firmware/psci: Add debugfs support to ease debugging
Dmitry Baryshkov
dmitry.baryshkov at linaro.org
Thu Aug 4 08:26:29 PDT 2022
On Thu, 4 Aug 2022 at 17:49, Mark Rutland <mark.rutland at arm.com> wrote:
>
> On Thu, Aug 04, 2022 at 04:15:07PM +0300, 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>
> > ---
> > Changes since v1:
> > - Extended the table to include MEM_PROTECT functions (noted by Mark
> > Brown)
> > - Switched to seq_puts where possible
> > - Changed S_IRUGO to 0444
> > ---
> > drivers/firmware/psci/psci.c | 116 ++++++++++++++++++++++++++++++++++-
> > include/uapi/linux/psci.h | 14 +++++
> > 2 files changed, 129 insertions(+), 1 deletion(-)
>
> TBH I am really not keen on exposing this to userspace. AFAICT this is his is
> incredibly niche, and is going to be very painful to maintain.
>
> Without a strong rationale, I do not thing we should do this.
>
> Who is going to use this, and when?
I sketched this while trying to narrow down the particular issue on
the Qualcomm platform (which started as an attempt to implement PSCI
domains, but then led to understanding that while the platform claims
supports OSI, it doesn't support SET_SUSPEND). We were going to use
this to help to narrow down issues with the PSCI support on other
platforms as well.
Moreover during v1 review I saw at least a subtle request to include
other information as well (e.g. the output from STAT_*),
>
> I'd be much happier logging stuff as it's probed into dmesg; I'm happy to add
> more information there (and/or a command line parameter to be more verbose).
Collecting logs is a nice thing, but asking the user to send the
debugfs file is much easier compared to rebooting the kernel with
different cmdline args (which in the Qualcomm case involves rebuilding
the boot image).
>
> Thanks,
> Mark.
>
> >
> > diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> > index 1628f1edef4a..42cae0ba10e2 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>
> > @@ -326,12 +327,125 @@ 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)
> > {
> > 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),
> > + PSCI_ID(1_1, MEM_PROTECT),
> > + PSCI_ID_NATIVE(1_1, MEM_PROTECT_CHECK_RANGE),
> > +};
> > +
> > +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_puts(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_puts(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", 0444, 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..3511095c2702 100644
> > --- a/include/uapi/linux/psci.h
> > +++ b/include/uapi/linux/psci.h
> > @@ -48,12 +48,26 @@
> > #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_1_FN_MEM_PROTECT PSCI_0_2_FN(19)
> > +#define PSCI_1_1_FN_MEM_PROTECT_CHECK_RANGE PSCI_0_2_FN(19)
> >
> > +#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)
> > +#define PSCI_1_1_FN64_MEM_PROTECT_CHECK_RANGE PSCI_0_2_FN64(19)
> >
> > /* PSCI v0.2 power state encoding for CPU_SUSPEND function */
> > #define PSCI_0_2_POWER_STATE_ID_MASK 0xffff
> > --
> > 2.35.1
> >
--
With best wishes
Dmitry
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