// SPDX-License-Identifier: GPL-2.0
#include <linux/version.h>
#include <linux/ptrace.h>
#include <uapi/linux/bpf.h>
#include <bpf/bpf_helpers.h>
/*
* The CPU number, cstate number and pstate number are based
* on 96boards Hikey with octa CA53 CPUs.
*
* Every CPU have three idle states for cstate:
* WFI, CPU_OFF, CLUSTER_OFF
*
* Every CPU have 5 operating points:
* 208MHz, 432MHz, 729MHz, 960MHz, 1200MHz
*
* This code is based on these assumption and other platforms
* need to adjust these definitions.
*/
#define MAX_CPU 8
#define MAX_PSTATE_ENTRIES 5
#define MAX_CSTATE_ENTRIES 3
static int cpu_opps[] = { 208000, 432000, 729000, 960000, 1200000 };
/*
* my_map structure is used to record cstate and pstate index and
* timestamp (Idx, Ts), when new event incoming we need to update
* combination for new state index and timestamp (Idx`, Ts`).
*
* Based on (Idx, Ts) and (Idx`, Ts`) we can calculate the time
* interval for the previous state: Duration(Idx) = Ts` - Ts.
*
* Every CPU has one below array for recording state index and
* timestamp, and record for cstate and pstate saperately:
*
* +--------------------------+
* | cstate timestamp |
* +--------------------------+
* | cstate index |
* +--------------------------+
* | pstate timestamp |
* +--------------------------+
* | pstate index |
* +--------------------------+
*/
#define MAP_OFF_CSTATE_TIME 0
#define MAP_OFF_CSTATE_IDX 1
#define MAP_OFF_PSTATE_TIME 2
#define MAP_OFF_PSTATE_IDX 3
#define MAP_OFF_NUM 4
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, u32);
__type(value, u64);
__uint(max_entries, MAX_CPU * MAP_OFF_NUM);
} my_map SEC(".maps");
/* cstate_duration records duration time for every idle state per CPU */
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, u32);
__type(value, u64);
__uint(max_entries, MAX_CPU * MAX_CSTATE_ENTRIES);
} cstate_duration SEC(".maps");
/* pstate_duration records duration time for every operating point per CPU */
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, u32);
__type(value, u64);
__uint(max_entries, MAX_CPU * MAX_PSTATE_ENTRIES);
} pstate_duration SEC(".maps");
/*
* The trace events for cpu_idle and cpu_frequency are taken from:
* /sys/kernel/tracing/events/power/cpu_idle/format
* /sys/kernel/tracing/events/power/cpu_frequency/format
*
* These two events have same format, so define one common structure.
*/
struct cpu_args {
u64 pad;
u32 state;
u32 cpu_id;
};
/* calculate pstate index, returns MAX_PSTATE_ENTRIES for failure */
static u32 find_cpu_pstate_idx(u32 frequency)
{
u32 i;
for (i = 0; i < sizeof(cpu_opps) / sizeof(u32); i++) {
if (frequency == cpu_opps[i])
return i;
}
return i;
}
SEC("tracepoint/power/cpu_idle")
int bpf_prog1(struct cpu_args *ctx)
{
u64 *cts, *pts, *cstate, *pstate, prev_state, cur_ts, delta;
u32 key, cpu, pstate_idx;
u64 *val;
if (ctx->cpu_id > MAX_CPU)
return 0;
cpu = ctx->cpu_id;
key = cpu * MAP_OFF_NUM + MAP_OFF_CSTATE_TIME;
cts = bpf_map_lookup_elem(&my_map, &key);
if (!cts)
return 0;
key = cpu * MAP_OFF_NUM + MAP_OFF_CSTATE_IDX;
cstate = bpf_map_lookup_elem(&my_map, &key);
if (!cstate)
return 0;
key = cpu * MAP_OFF_NUM + MAP_OFF_PSTATE_TIME;
pts = bpf_map_lookup_elem(&my_map, &key);
if (!pts)
return 0;
key = cpu * MAP_OFF_NUM + MAP_OFF_PSTATE_IDX;
pstate = bpf_map_lookup_elem(&my_map, &key);
if (!pstate)
return 0;
prev_state = *cstate;
*cstate = ctx->state;
if (!*cts) {
*cts = bpf_ktime_get_ns();
return 0;
}
cur_ts = bpf_ktime_get_ns();
delta = cur_ts - *cts;
*cts = cur_ts;
/*
* When state doesn't equal to (u32)-1, the cpu will enter
* one idle state; for this case we need to record interval
* for the pstate.
*
* OPP2
* +---------------------+
* OPP1 | |
* ---------+ |
* | Idle state
* +---------------
*
* |<- pstate duration ->|
* ^ ^
* pts cur_ts
*/
if (ctx->state != (u32)-1) {
/* record pstate after have first cpu_frequency event */
if (!*pts)
return 0;
delta = cur_ts - *pts;
pstate_idx = find_cpu_pstate_idx(*pstate);
if (pstate_idx >= MAX_PSTATE_ENTRIES)
return 0;
key = cpu * MAX_PSTATE_ENTRIES + pstate_idx;
val = bpf_map_lookup_elem(&pstate_duration, &key);
if (val)
__sync_fetch_and_add((long *)val, delta);
/*
* When state equal to (u32)-1, the cpu just exits from one
* specific idle state; for this case we need to record
* interval for the pstate.
*
* OPP2
* -----------+
* | OPP1
* | +-----------
* | Idle state |
* +---------------------+
*
* |<- cstate duration ->|
* ^ ^
* cts cur_ts
*/
} else {
key = cpu * MAX_CSTATE_ENTRIES + prev_state;
val = bpf_map_lookup_elem(&cstate_duration, &key);
if (val)
__sync_fetch_and_add((long *)val, delta);
}
/* Update timestamp for pstate as new start time */
if (*pts)
*pts = cur_ts;
return 0;
}
SEC("tracepoint/power/cpu_frequency")
int bpf_prog2(struct cpu_args *ctx)
{
u64 *pts, *cstate, *pstate, cur_ts, delta;
u32 key, cpu, pstate_idx;
u64 *val;
cpu = ctx->cpu_id;
key = cpu * MAP_OFF_NUM + MAP_OFF_PSTATE_TIME;
pts = bpf_map_lookup_elem(&my_map, &key);
if (!pts)
return 0;
key = cpu * MAP_OFF_NUM + MAP_OFF_PSTATE_IDX;
pstate = bpf_map_lookup_elem(&my_map, &key);
if (!pstate)
return 0;
key = cpu * MAP_OFF_NUM + MAP_OFF_CSTATE_IDX;
cstate = bpf_map_lookup_elem(&my_map, &key);
if (!cstate)
return 0;
*pstate = ctx->state;
if (!*pts) {
*pts = bpf_ktime_get_ns();
return 0;
}
cur_ts = bpf_ktime_get_ns();
delta = cur_ts - *pts;
*pts = cur_ts;
/* When CPU is in idle, bail out to skip pstate statistics */
if (*cstate != (u32)(-1))
return 0;
/*
* The cpu changes to another different OPP (in below diagram
* change frequency from OPP3 to OPP1), need recording interval
* for previous frequency OPP3 and update timestamp as start
* time for new frequency OPP1.
*
* OPP3
* +---------------------+
* OPP2 | |
* ---------+ |
* | OPP1
* +---------------
*
* |<- pstate duration ->|
* ^ ^
* pts cur_ts
*/
pstate_idx = find_cpu_pstate_idx(*pstate);
if (pstate_idx >= MAX_PSTATE_ENTRIES)
return 0;
key = cpu * MAX_PSTATE_ENTRIES + pstate_idx;
val = bpf_map_lookup_elem(&pstate_duration, &key);
if (val)
__sync_fetch_and_add((long *)val, delta);
return 0;
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;
