ANDROID: cpufreq: track per-task time in state

Add time in state data to task structs, and create
/proc/<pid>/time_in_state files to show how long each individual task
has run at each frequency.
Create a CONFIG_CPU_FREQ_TIMES option to enable/disable this tracking.

Bug: 72339335
Bug: 127641090
Test: Read /proc/<pid>/time_in_state
Change-Id: Ia6456754f4cb1e83b2bc35efa8fbe9f8696febc8
Signed-off-by: Connor O'Brien <connoro@google.com>
[astrachan: Folded the following changes into this patch:
            a6d3de6a7fba ("ANDROID: Reduce use of #ifdef CONFIG_CPU_FREQ_TIMES")
            b89ada5d9c09 ("ANDROID: Fix massive cpufreq_times memory leaks")]
Signed-off-by: Alistair Strachan <astrachan@google.com>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7e9f07bf..b51e81e 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -94,6 +94,7 @@
 #include <linux/sched/stat.h>
 #include <linux/flex_array.h>
 #include <linux/posix-timers.h>
+#include <linux/cpufreq_times.h>
 #include <trace/events/oom.h>
 #include "internal.h"
 #include "fd.h"
@@ -3006,6 +3007,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_LIVEPATCH
 	ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
 #endif
+#ifdef CONFIG_CPU_FREQ_TIMES
+	ONE("time_in_state", 0444, proc_time_in_state_show),
+#endif
 };
 
 static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
@@ -3384,6 +3388,9 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_LIVEPATCH
 	ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
 #endif
+#ifdef CONFIG_CPU_FREQ_TIMES
+	ONE("time_in_state", 0444, proc_time_in_state_show),
+#endif
 };
 
 static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)