[PATCH v6 04/11] powerpc/perf: Add event attribute and group to IMC pmus
Daniel Axtens
dja at axtens.net
Tue Apr 4 12:11:25 AEST 2017
Hi,
> Device tree IMC driver code parses the IMC units and their events. It
> passes the information to IMC pmu code which is placed in powerpc/perf
> as "imc-pmu.c".
>
> This patch creates only event attributes and attribute groups for the
> IMC pmus.
>
> Signed-off-by: Anju T Sudhakar <anju at linux.vnet.ibm.com>
> Signed-off-by: Hemant Kumar <hemant at linux.vnet.ibm.com>
> Signed-off-by: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
> ---
> arch/powerpc/perf/Makefile | 6 +-
> arch/powerpc/perf/imc-pmu.c | 97 +++++++++++++++++++++++++++++++
> arch/powerpc/platforms/powernv/opal-imc.c | 12 +++-
> 3 files changed, 112 insertions(+), 3 deletions(-)
> create mode 100644 arch/powerpc/perf/imc-pmu.c
>
> diff --git a/arch/powerpc/perf/Makefile b/arch/powerpc/perf/Makefile
> index 4d606b99a5cb..d0d1f04203c7 100644
> --- a/arch/powerpc/perf/Makefile
> +++ b/arch/powerpc/perf/Makefile
> @@ -2,10 +2,14 @@ subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
>
> obj-$(CONFIG_PERF_EVENTS) += callchain.o perf_regs.o
>
> +imc-$(CONFIG_PPC_POWERNV) += imc-pmu.o
> +
> obj-$(CONFIG_PPC_PERF_CTRS) += core-book3s.o bhrb.o
> obj64-$(CONFIG_PPC_PERF_CTRS) += power4-pmu.o ppc970-pmu.o power5-pmu.o \
> power5+-pmu.o power6-pmu.o power7-pmu.o \
> - isa207-common.o power8-pmu.o power9-pmu.o
> + isa207-common.o power8-pmu.o power9-pmu.o \
> + $(imc-y)
Hmm, this seems... obtuse. Will the IMC stuff fail to compile on
non-powerNV? Can we just link it in like we do with every other sort of
performance counter and let runtime detection do its thing?
> +
> obj32-$(CONFIG_PPC_PERF_CTRS) += mpc7450-pmu.o
>
> obj-$(CONFIG_FSL_EMB_PERF_EVENT) += core-fsl-emb.o
> diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
> new file mode 100644
> index 000000000000..ec464c76b749
> --- /dev/null
> +++ b/arch/powerpc/perf/imc-pmu.c
> @@ -0,0 +1,97 @@
> +/*
> + * Nest Performance Monitor counter support.
> + *
> + * Copyright (C) 2016 Madhavan Srinivasan, IBM Corporation.
> + * (C) 2016 Hemant K Shaw, IBM Corporation.
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published
> + * by the Free Software Foundation.
> + */
> +#include <linux/perf_event.h>
> +#include <linux/slab.h>
> +#include <asm/opal.h>
> +#include <asm/imc-pmu.h>
> +#include <asm/cputhreads.h>
> +#include <asm/smp.h>
> +#include <linux/string.h>
> +
> +struct perchip_nest_info nest_perchip_info[IMC_MAX_CHIPS];
> +struct imc_pmu *per_nest_pmu_arr[IMC_MAX_PMUS];
> +
> +/* dev_str_attr : Populate event "name" and string "str" in attribute */
> +static struct attribute *dev_str_attr(const char *name, const char *str)
> +{
> + struct perf_pmu_events_attr *attr;
> +
> + attr = kzalloc(sizeof(*attr), GFP_KERNEL);
> +
> + sysfs_attr_init(&attr->attr.attr);
> +
> + attr->event_str = str;
> + attr->attr.attr.name = name;
> + attr->attr.attr.mode = 0444;
> + attr->attr.show = perf_event_sysfs_show;
> +
> + return &attr->attr.attr;
> +}
> +
> +/*
> + * update_events_in_group: Update the "events" information in an attr_group
> + * and assign the attr_group to the pmu "pmu".
> + */
> +static int update_events_in_group(struct imc_events *events,
> + int idx, struct imc_pmu *pmu)
So I've probably missed a key point in the earlier patches, but for the
life of me I cannot figure out what idx is supposed to represent.
> +{
> + struct attribute_group *attr_group;
> + struct attribute **attrs;
> + int i;
> +
> + /* Allocate memory for attribute group */
> + attr_group = kzalloc(sizeof(*attr_group), GFP_KERNEL);
> + if (!attr_group)
> + return -ENOMEM;
> +
> + /* Allocate memory for attributes */
> + attrs = kzalloc((sizeof(struct attribute *) * (idx + 1)), GFP_KERNEL);
Also, idx is an int, so:
- things will go wrong if idx is -1
- things will go very wrong if idx is -2
- do you need to do some sort of validation to make sure it's within
bounds? If not in this function, what function ensures the necessary
'sanity check' preconditions for idx?
> + if (!attrs) {
> + kfree(attr_group);
> + return -ENOMEM;
> + }
> +
> + attr_group->name = "events";
> + attr_group->attrs = attrs;
> + for (i = 0; i < idx; i++, events++) {
> + attrs[i] = dev_str_attr((char *)events->ev_name,
> + (char *)events->ev_value);
> + }
> +
> + pmu->attr_groups[0] = attr_group;
Again, I may have missed something, but what's special about group 0?
Patch 1 lets you have up to 4 groups - are they used elsewhere?
> + return 0;
> +}
> +
> +/*
> + * init_imc_pmu : Setup the IMC pmu device in "pmu_ptr" and its events
> + * "events".
> + * Setup the cpu mask information for these pmus and setup the state machine
> + * hotplug notifiers as well.
I cannot figure out how this function sets cpu mask information or sets
up hotplug notifiers. Is this done in a later patch? (looking at the
subject lines - perhaps patch 6?)
> + */
> +int init_imc_pmu(struct imc_events *events, int idx,
> + struct imc_pmu *pmu_ptr)
Should this be marked __init, or can it be called in a hotplug path?
> +{
> + int ret = -ENODEV;
> +
> + ret = update_events_in_group(events, idx, pmu_ptr);
> + if (ret)
> + goto err_free;
> +
> + return 0;
> +
> +err_free:
> + /* Only free the attr_groups which are dynamically allocated */
> + if (pmu_ptr->attr_groups[0]) {
> + kfree(pmu_ptr->attr_groups[0]->attrs);
> + kfree(pmu_ptr->attr_groups[0]);
> + }
> +
> + return ret;
> +}
> diff --git a/arch/powerpc/platforms/powernv/opal-imc.c b/arch/powerpc/platforms/powernv/opal-imc.c
> index ba0203e669c0..73c46703c2af 100644
> --- a/arch/powerpc/platforms/powernv/opal-imc.c
> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
> @@ -32,8 +32,11 @@
> #include <asm/cputable.h>
> #include <asm/imc-pmu.h>
>
> -struct perchip_nest_info nest_perchip_info[IMC_MAX_CHIPS];
> -struct imc_pmu *per_nest_pmu_arr[IMC_MAX_PMUS];
> +extern struct perchip_nest_info nest_perchip_info[IMC_MAX_CHIPS];
> +extern struct imc_pmu *per_nest_pmu_arr[IMC_MAX_PMUS];
Why are these definitions being moved?
If they're still needed in this file, should the extern lines live in a
header file?
> +
> +extern int init_imc_pmu(struct imc_events *events,
> + int idx, struct imc_pmu *pmu_ptr);
>
> static int imc_event_info(char *name, struct imc_events *events)
> {
> @@ -379,6 +382,11 @@ static int imc_pmu_create(struct device_node *parent, int pmu_index)
> idx += ret;
> }
>
> + ret = init_imc_pmu(events, idx, pmu_ptr);
> + if (ret) {
> + pr_err("IMC PMU %s Register failed\n", pmu_ptr->pmu.name);
> + goto free_events;
> + }
> return 0;
>
> free_events:
> --
> 2.7.4
Regards,
Daniel
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