Commit 9878268b authored by Ze Zuo's avatar Ze Zuo
Browse files

mm/mem_sampling.c: Add controlling interface for mem_sampling 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I9GZAQ


CVE: NA

--------------------------------

Add sysctl to enable or disable mem_sampling actions.

A static key controlled by sysctl is added. When this is
set to false, mem_sampling disable new sampling requests and
stop hardware pmu in interrupts, otherwise permit the
sampling requests, and automatically continue sampling in
interrupts.

Signed-off-by: default avatarZe Zuo <zuoze1@huawei.com>
Signed-off-by: default avatarTong Tiangen <tongtiangen@huawei.com>
Signed-off-by: default avatarShuang Yan <yanshuang7@huawei.com>
parent 0695e18b

mm/mem_sampling.c

+98 −2
Original line number Diff line number Diff line
@@ -21,6 +21,10 @@ 


struct mem_sampling_ops_struct mem_sampling_ops;



#define MEM_SAMPLING_DISABLED		0x0

#define MEM_SAMPLING_NORMAL		0x1



static int mem_sampling_override __initdata;

struct mem_sampling_record_cb_list_entry {

	struct list_head list;

	mem_sampling_record_cb_type cb;
@@ -61,8 +65,12 @@ void mem_sampling_record_cb_unregister(mem_sampling_record_cb_type cb) 
	}

}



DEFINE_STATIC_KEY_FALSE(mem_sampling_access_hints);



void mem_sampling_sched_in(struct task_struct *prev, struct task_struct *curr)

{

	if (!static_branch_unlikely(&mem_sampling_access_hints))

		return;

	if (!mem_sampling_ops.sampling_start)

		return;
@@ -88,7 +96,11 @@ static void mem_sampling_process(struct mem_sampling_record *record_base, int nr 
		}

	}

out:

	/* if mem_sampling_access_hints is set to false, stop sampling */

	if (static_branch_unlikely(&mem_sampling_access_hints))

		mem_sampling_ops.sampling_continue();

	else

		mem_sampling_ops.sampling_stop();

}



static inline enum mem_sampling_type_enum mem_sampling_get_type(void)
@@ -100,14 +112,93 @@ static inline enum mem_sampling_type_enum mem_sampling_get_type(void) 
#endif

}



static int sysctl_mem_sampling_mode;



static void __set_mem_sampling_state(bool enabled)

{

	if (enabled)

		static_branch_enable(&mem_sampling_access_hints);

	else

		static_branch_disable(&mem_sampling_access_hints);

}



static void set_mem_sampling_state(bool enabled)

{

	if (!mem_sampling_ops.sampling_start)

		return;

	if (enabled)

		sysctl_mem_sampling_mode = MEM_SAMPLING_NORMAL;

	else

		sysctl_mem_sampling_mode = MEM_SAMPLING_DISABLED;

	__set_mem_sampling_state(enabled);

}



#ifdef CONFIG_PROC_SYSCTL

static int sysctl_mem_sampling_enable(struct ctl_table *table, int write,

			  void *buffer, size_t *lenp, loff_t *ppos)

{

	struct ctl_table t;

	int err;

	int state = sysctl_mem_sampling_mode;



	if (write && !capable(CAP_SYS_ADMIN))

		return -EPERM;



	t = *table;

	t.data = &state;

	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);

	if (err < 0)

		return err;

	if (write)

		set_mem_sampling_state(state);

	return err;

}

#endif



static struct ctl_table ctl_table[] = {

	{

		.procname       = "mem_sampling_enable",

		.data           = NULL, /* filled in by handler */

		.maxlen		= sizeof(unsigned int),

		.mode		= 0644,

		.proc_handler   = sysctl_mem_sampling_enable,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_ONE,

	},

	{}

};



static struct ctl_table mem_sampling_dir_table[] = {

	{

		.procname = "kernel",

		.maxlen = 0,

		.mode = 0555,

		.child = ctl_table,

	},

	{}

};



static void __init check_mem_sampling_enable(void)

{

	bool mem_sampling_default = false;



	/* Parsed by setup_mem_sampling. override == 1 enables, -1 disables */

	if (mem_sampling_override)

		set_mem_sampling_state(mem_sampling_override == 1);

	else

		set_mem_sampling_state(mem_sampling_default);

}



static int __init mem_sampling_init(void)

{

	enum mem_sampling_type_enum mem_sampling_type = mem_sampling_get_type();



	switch (mem_sampling_type) {

	case MEM_SAMPLING_ARM_SPE:

		if (!arm_spe_enabled())

		if (!arm_spe_enabled()) {

			set_mem_sampling_state(false);

			return -ENODEV;

		}

		mem_sampling_ops.sampling_start		= arm_spe_start;

		mem_sampling_ops.sampling_stop		= arm_spe_stop;

		mem_sampling_ops.sampling_continue	= arm_spe_continue;
@@ -118,8 +209,13 @@ static int __init mem_sampling_init(void) 
	default:

		pr_info("unsupport hardware pmu type(%d), disable access hint!\n",

			mem_sampling_type);

		set_mem_sampling_state(false);

		return -ENODEV;

	}

	check_mem_sampling_enable();



	if (!register_sysctl_table(mem_sampling_dir_table))

		return -ENOMEM;



	return 0;

}