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perf, bpf: Introduce PERF_RECORD_KSYMBOL 

For better performance analysis of dynamically JITed and loaded kernel
functions, such as BPF programs, this patch introduces
PERF_RECORD_KSYMBOL, a new perf_event_type that exposes kernel symbol
register/unregister information to user space.

The following data structure is used for PERF_RECORD_KSYMBOL.

    /*
     * struct {
     *      struct perf_event_header        header;
     *      u64                             addr;
     *      u32                             len;
     *      u16                             ksym_type;
     *      u16                             flags;
     *      char                            name[];
     *      struct sample_id                sample_id;
     * };
     */

Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@fb.com
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20190117161521.1341602-2-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Song Liu 2019-01-17 08:15:13 -08:00 committed by Arnaldo Carvalho de Melo
parent 5620196951
commit 76193a9452
3 changed files with 130 additions and 2 deletions
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8
include/linux/perf_event.h
View File

@ -1122,6 +1122,10 @@ static inline void perf_event_task_sched_out(struct task_struct *prev,
}
extern void perf_event_mmap(struct vm_area_struct *vma);
extern void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len,
bool unregister, const char *sym);
extern struct perf_guest_info_callbacks *perf_guest_cbs;
extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
@ -1342,6 +1346,10 @@ static inline int perf_unregister_guest_info_callbacks
(struct perf_guest_info_callbacks *callbacks) { return 0; }
static inline void perf_event_mmap(struct vm_area_struct *vma) { }
typedef int (perf_ksymbol_get_name_f)(char *name, int name_len, void *data);
static inline void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len,
bool unregister, const char *sym) { }
static inline void perf_event_exec(void) { }
static inline void perf_event_comm(struct task_struct *tsk, bool exec) { }
static inline void perf_event_namespaces(struct task_struct *tsk) { }

26
include/uapi/linux/perf_event.h
View File

@ -372,7 +372,8 @@ struct perf_event_attr {
context_switch : 1, /* context switch data */
write_backward : 1, /* Write ring buffer from end to beginning */
namespaces : 1, /* include namespaces data */
__reserved_1 : 35;
ksymbol : 1, /* include ksymbol events */
__reserved_1 : 34;
union {
__u32 wakeup_events; /* wakeup every n events */
@ -963,9 +964,32 @@ enum perf_event_type {
*/
PERF_RECORD_NAMESPACES = 16,
/*
* Record ksymbol register/unregister events:
*
* struct {
* struct perf_event_header header;
* u64 addr;
* u32 len;
* u16 ksym_type;
* u16 flags;
* char name[];
* struct sample_id sample_id;
* };
*/
PERF_RECORD_KSYMBOL = 17,
PERF_RECORD_MAX, /* non-ABI */
};
enum perf_record_ksymbol_type {
PERF_RECORD_KSYMBOL_TYPE_UNKNOWN = 0,
PERF_RECORD_KSYMBOL_TYPE_BPF = 1,
PERF_RECORD_KSYMBOL_TYPE_MAX /* non-ABI */
};
#define PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER (1 << 0)
#define PERF_MAX_STACK_DEPTH 127
#define PERF_MAX_CONTEXTS_PER_STACK 8

98
kernel/events/core.c
View File

@ -385,6 +385,7 @@ static atomic_t nr_namespaces_events __read_mostly;
static atomic_t nr_task_events __read_mostly;
static atomic_t nr_freq_events __read_mostly;
static atomic_t nr_switch_events __read_mostly;
static atomic_t nr_ksymbol_events __read_mostly;
static LIST_HEAD(pmus);
static DEFINE_MUTEX(pmus_lock);
@ -4235,7 +4236,7 @@ static bool is_sb_event(struct perf_event *event)
if (attr->mmap || attr->mmap_data || attr->mmap2 ||
attr->comm || attr->comm_exec ||
attr->task ||
attr->task || attr->ksymbol ||
attr->context_switch)
return true;
return false;
@ -4305,6 +4306,8 @@ static void unaccount_event(struct perf_event *event)
dec = true;
if (has_branch_stack(event))
dec = true;
if (event->attr.ksymbol)
atomic_dec(&nr_ksymbol_events);
if (dec) {
if (!atomic_add_unless(&perf_sched_count, -1, 1))
@ -7653,6 +7656,97 @@ static void perf_log_throttle(struct perf_event *event, int enable)
perf_output_end(&handle);
}
/*
* ksymbol register/unregister tracking
*/
struct perf_ksymbol_event {
const char *name;
int name_len;
struct {
struct perf_event_header header;
u64 addr;
u32 len;
u16 ksym_type;
u16 flags;
} event_id;
};
static int perf_event_ksymbol_match(struct perf_event *event)
{
return event->attr.ksymbol;
}
static void perf_event_ksymbol_output(struct perf_event *event, void *data)
{
struct perf_ksymbol_event *ksymbol_event = data;
struct perf_output_handle handle;
struct perf_sample_data sample;
int ret;
if (!perf_event_ksymbol_match(event))
return;
perf_event_header__init_id(&ksymbol_event->event_id.header,
&sample, event);
ret = perf_output_begin(&handle, event,
ksymbol_event->event_id.header.size);
if (ret)
return;
perf_output_put(&handle, ksymbol_event->event_id);
__output_copy(&handle, ksymbol_event->name, ksymbol_event->name_len);
perf_event__output_id_sample(event, &handle, &sample);
perf_output_end(&handle);
}
void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len, bool unregister,
const char *sym)
{
struct perf_ksymbol_event ksymbol_event;
char name[KSYM_NAME_LEN];
u16 flags = 0;
int name_len;
if (!atomic_read(&nr_ksymbol_events))
return;
if (ksym_type >= PERF_RECORD_KSYMBOL_TYPE_MAX ||
ksym_type == PERF_RECORD_KSYMBOL_TYPE_UNKNOWN)
goto err;
strlcpy(name, sym, KSYM_NAME_LEN);
name_len = strlen(name) + 1;
while (!IS_ALIGNED(name_len, sizeof(u64)))
name[name_len++] = '\0';
BUILD_BUG_ON(KSYM_NAME_LEN % sizeof(u64));
if (unregister)
flags |= PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER;
ksymbol_event = (struct perf_ksymbol_event){
.name = name,
.name_len = name_len,
.event_id = {
.header = {
.type = PERF_RECORD_KSYMBOL,
.size = sizeof(ksymbol_event.event_id) +
name_len,
},
.addr = addr,
.len = len,
.ksym_type = ksym_type,
.flags = flags,
},
};
perf_iterate_sb(perf_event_ksymbol_output, &ksymbol_event, NULL);
return;
err:
WARN_ONCE(1, "%s: Invalid KSYMBOL type 0x%x\n", __func__, ksym_type);
}
void perf_event_itrace_started(struct perf_event *event)
{
event->attach_state |= PERF_ATTACH_ITRACE;
@ -9912,6 +10006,8 @@ static void account_event(struct perf_event *event)
inc = true;
if (is_cgroup_event(event))
inc = true;
if (event->attr.ksymbol)
atomic_inc(&nr_ksymbol_events);
if (inc) {
/*