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Merge branch 'bpf-perf'

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Kaixu Xia says:

====================
bpf: Introduce the new ability of eBPF programs to access hardware PMU counter

This patchset is base on the net-next:
 git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
commit 9dc20a6496.

Previous patch v6 url:
https://lkml.org/lkml/2015/8/4/188

changes in V7:
 - rebase the whole patch set to net-next tree(9dc20a64);
 - split out the core perf APIs into Patch 1/5;
 - change the return value of function perf_event_attrs()
   from struct perf_event * to const struct perf_event * in
   Patch 1/5;
 - rename the function perf_event_read_internal() to perf_event_
   read_local() and rewrite it in Patch 1/5;
 - rename the function check_func_limit() to check_map_func
   _compatibility() and remove the unnecessary pass pointer to
   a pointer in Patch 4/5;

changes in V6:
 - make the Patch 1/4 commit message more meaning and readable;
 - remove the unnecessary comment in Patch 2/4 and make it clean;
 - declare the function perf_event_release_kernel() in include/
   linux/perf_event.h to fix the build error when CONFIG_PERF_EVENTS
   isn't configured in Patch 2/4;
 - add function perf_event_attrs() to get the struct perf_event_attr
   in Patch 2/4.
 - move the related code from kernel/trace/bpf_trace.c to kernel/
   events/core.c and add function perf_event_read_internal() to
   avoid poking inside of the event outside of perf code in Patch 3/4;
 - generial the func & map match-pair with an array in Patch 3/4;

changes in V5:
 - move struct fd_array_map_ops* fd_ops to bpf_map;
 - move array perf event decrement refcnt function to
   map_free;
 - fix the NULL ptr of perf_event_get();
 - move bpf_perf_event_read() to kernel/bpf/bpf_trace.c;
 - get rid of the remaining struct bpf_prog;
 - move the unnecessay cast on void *;

changes in V4:
 - make the bpf_prog_array_map more generic;
 - fix the bug of event refcnt leak;
 - use more useful errno in bpf_perf_event_read();

changes in V3:
 - collapse V2 patches 1-3 into one;
 - drop the function map->ops->map_traverse_elem() and release
   the struct perf_event in map_free;
 - only allow to access bpf_perf_event_read() from programs;
 - update the perf_event_array_map elem via xchg();
 - pass index directly to bpf_perf_event_read() instead of
   MAP_KEY;

changes in V2:
 - put atomic_long_inc_not_zero() between fdget() and fdput();
 - limit the event type to PERF_TYPE_RAW and PERF_TYPE_HARDWARE;
 - Only read the event counter on current CPU or on current
   process;
 - add new map type BPF_MAP_TYPE_PERF_EVENT_ARRAY to store the
   pointer to the struct perf_event;
 - according to the perf_event_map_fd and key, the function
   bpf_perf_event_read() can get the Hardware PMU counter value;

Patch 5/5 is a simple example and shows how to use this new eBPF
programs ability. The PMU counter data can be found in
/sys/kernel/debug/tracing/trace(trace_pipe).(the cycles PMU
value when 'kprobe/sys_write' sampling)

  $ cat /sys/kernel/debug/tracing/trace_pipe
  $ ./tracex6
       ...
       syslog-ng-548   [000] d..1    76.905673: : CPU-0   681765271
       syslog-ng-548   [000] d..1    76.905690: : CPU-0   681787855
       syslog-ng-548   [000] d..1    76.905707: : CPU-0   681810504
       syslog-ng-548   [000] d..1    76.905725: : CPU-0   681834771
       syslog-ng-548   [000] d..1    76.905745: : CPU-0   681859519
       syslog-ng-548   [000] d..1    76.905766: : CPU-0   681890419
       syslog-ng-548   [000] d..1    76.905783: : CPU-0   681914045
       syslog-ng-548   [000] d..1    76.905800: : CPU-0   681935950
       syslog-ng-548   [000] d..1    76.905816: : CPU-0   681958299
              ls-690   [005] d..1    82.241308: : CPU-5   3138451
              sh-691   [004] d..1    82.244570: : CPU-4   7324988
           <...>-699   [007] d..1    99.961387: : CPU-7   3194027
           <...>-695   [003] d..1    99.961474: : CPU-3   288901
           <...>-695   [003] d..1    99.961541: : CPU-3   383145
           <...>-695   [003] d..1    99.961591: : CPU-3   450365
           <...>-695   [003] d..1    99.961639: : CPU-3   515751
           <...>-695   [003] d..1    99.961686: : CPU-3   579047
       ...

The detail of patches is as follow:

Patch 1/5 add the necessary core perf APIs perf_event_attrs(),
perf_event_get(),perf_event_read_local() when accessing events
counters in eBPF programs

Patch 2/5 rewrites part of the bpf_prog_array map code and make it
more generic;

Patch 3/5 introduces a new bpf map type. This map only stores the
pointer to struct perf_event;

Patch 4/5 implements function bpf_perf_event_read() that get the
selected hardware PMU conuter;

Patch 5/5 gives a simple example.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2015-08-09 22:50:06 -07:00
commit d74a790d52
14 changed files with 373 additions and 53 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
arch/x86/net/bpf_jit_comp.c
View file

@ -246,7 +246,7 @@ static void emit_prologue(u8 **pprog)
* goto out;
* if (++tail_call_cnt > MAX_TAIL_CALL_CNT)
* goto out;
* prog = array->prog[index];
* prog = array->ptrs[index];
* if (prog == NULL)
* goto out;
* goto *(prog->bpf_func + prologue_size);
@ -284,9 +284,9 @@ static void emit_bpf_tail_call(u8 **pprog)
EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */
EMIT2_off32(0x89, 0x85, -STACKSIZE + 36); /* mov dword ptr [rbp - 516], eax */
/* prog = array->prog[index]; */
/* prog = array->ptrs[index]; */
EMIT4_off32(0x48, 0x8D, 0x84, 0xD6, /* lea rax, [rsi + rdx * 8 + offsetof(...)] */
offsetof(struct bpf_array, prog));
offsetof(struct bpf_array, ptrs));
EMIT3(0x48, 0x8B, 0x00); /* mov rax, qword ptr [rax] */
/* if (prog == NULL)

10
include/linux/bpf.h
View file

@ -10,6 +10,7 @@
#include <uapi/linux/bpf.h>
#include <linux/workqueue.h>
#include <linux/file.h>
#include <linux/perf_event.h>
struct bpf_map;
@ -24,6 +25,10 @@ struct bpf_map_ops {
void *(*map_lookup_elem)(struct bpf_map *map, void *key);
int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
int (*map_delete_elem)(struct bpf_map *map, void *key);
/* funcs called by prog_array and perf_event_array map */
void *(*map_fd_get_ptr) (struct bpf_map *map, int fd);
void (*map_fd_put_ptr) (void *ptr);
};
struct bpf_map {
@ -142,13 +147,13 @@ struct bpf_array {
bool owner_jited;
union {
char value[0] __aligned(8);
struct bpf_prog *prog[0] __aligned(8);
void *ptrs[0] __aligned(8);
};
};
#define MAX_TAIL_CALL_CNT 32
u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);
void bpf_prog_array_map_clear(struct bpf_map *map);
void bpf_fd_array_map_clear(struct bpf_map *map);
bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
@ -185,6 +190,7 @@ extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
extern const struct bpf_func_proto bpf_map_update_elem_proto;
extern const struct bpf_func_proto bpf_map_delete_elem_proto;
extern const struct bpf_func_proto bpf_perf_event_read_proto;
extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
extern const struct bpf_func_proto bpf_tail_call_proto;

10
include/linux/perf_event.h
View file

@ -641,6 +641,8 @@ extern int perf_event_init_task(struct task_struct *child);
extern void perf_event_exit_task(struct task_struct *child);
extern void perf_event_free_task(struct task_struct *task);
extern void perf_event_delayed_put(struct task_struct *task);
extern struct perf_event *perf_event_get(unsigned int fd);
extern const struct perf_event_attr *perf_event_attrs(struct perf_event *event);
extern void perf_event_print_debug(void);
extern void perf_pmu_disable(struct pmu *pmu);
extern void perf_pmu_enable(struct pmu *pmu);
@ -659,6 +661,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr,
void *context);
extern void perf_pmu_migrate_context(struct pmu *pmu,
int src_cpu, int dst_cpu);
extern u64 perf_event_read_local(struct perf_event *event);
extern u64 perf_event_read_value(struct perf_event *event,
u64 *enabled, u64 *running);
@ -979,6 +982,12 @@ static inline int perf_event_init_task(struct task_struct *child) { return 0; }
static inline void perf_event_exit_task(struct task_struct *child) { }
static inline void perf_event_free_task(struct task_struct *task) { }
static inline void perf_event_delayed_put(struct task_struct *task) { }
static inline struct perf_event *perf_event_get(unsigned int fd) { return ERR_PTR(-EINVAL); }
static inline const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
{
return ERR_PTR(-EINVAL);
}
static inline u64 perf_event_read_local(struct perf_event *event) { return -EINVAL; }
static inline void perf_event_print_debug(void) { }
static inline int perf_event_task_disable(void) { return -EINVAL; }
static inline int perf_event_task_enable(void) { return -EINVAL; }
@ -1011,6 +1020,7 @@ static inline void perf_event_enable(struct perf_event *event) { }
static inline void perf_event_disable(struct perf_event *event) { }
static inline int __perf_event_disable(void *info) { return -1; }
static inline void perf_event_task_tick(void) { }
static inline int perf_event_release_kernel(struct perf_event *event) { return 0; }
#endif
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_NO_HZ_FULL)

2
include/uapi/linux/bpf.h
View file

@ -114,6 +114,7 @@ enum bpf_map_type {
BPF_MAP_TYPE_HASH,
BPF_MAP_TYPE_ARRAY,
BPF_MAP_TYPE_PROG_ARRAY,
BPF_MAP_TYPE_PERF_EVENT_ARRAY,
};
enum bpf_prog_type {
@ -270,6 +271,7 @@ enum bpf_func_id {
*/
BPF_FUNC_skb_get_tunnel_key,
BPF_FUNC_skb_set_tunnel_key,
BPF_FUNC_perf_event_read, /* u64 bpf_perf_event_read(&map, index) */
__BPF_FUNC_MAX_ID,
};

137
kernel/bpf/arraymap.c
View file

@ -150,15 +150,15 @@ static int __init register_array_map(void)
}
late_initcall(register_array_map);
static struct bpf_map *prog_array_map_alloc(union bpf_attr *attr)
static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
{
/* only bpf_prog file descriptors can be stored in prog_array map */
/* only file descriptors can be stored in this type of map */
if (attr->value_size != sizeof(u32))
return ERR_PTR(-EINVAL);
return array_map_alloc(attr);
}
static void prog_array_map_free(struct bpf_map *map)
static void fd_array_map_free(struct bpf_map *map)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
int i;
@ -167,21 +167,21 @@ static void prog_array_map_free(struct bpf_map *map)
/* make sure it's empty */
for (i = 0; i < array->map.max_entries; i++)
BUG_ON(array->prog[i] != NULL);
BUG_ON(array->ptrs[i] != NULL);
kvfree(array);
}
static void *prog_array_map_lookup_elem(struct bpf_map *map, void *key)
static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
{
return NULL;
}
/* only called from syscall */
static int prog_array_map_update_elem(struct bpf_map *map, void *key,
void *value, u64 map_flags)
static int fd_array_map_update_elem(struct bpf_map *map, void *key,
void *value, u64 map_flags)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct bpf_prog *prog, *old_prog;
void *new_ptr, *old_ptr;
u32 index = *(u32 *)key, ufd;
if (map_flags != BPF_ANY)
@ -191,57 +191,75 @@ static int prog_array_map_update_elem(struct bpf_map *map, void *key,
return -E2BIG;
ufd = *(u32 *)value;
prog = bpf_prog_get(ufd);
if (IS_ERR(prog))
return PTR_ERR(prog);
new_ptr = map->ops->map_fd_get_ptr(map, ufd);
if (IS_ERR(new_ptr))
return PTR_ERR(new_ptr);
if (!bpf_prog_array_compatible(array, prog)) {
bpf_prog_put(prog);
return -EINVAL;
}
old_prog = xchg(array->prog + index, prog);
if (old_prog)
bpf_prog_put_rcu(old_prog);
old_ptr = xchg(array->ptrs + index, new_ptr);
if (old_ptr)
map->ops->map_fd_put_ptr(old_ptr);
return 0;
}
static int prog_array_map_delete_elem(struct bpf_map *map, void *key)
static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct bpf_prog *old_prog;
void *old_ptr;
u32 index = *(u32 *)key;
if (index >= array->map.max_entries)
return -E2BIG;
old_prog = xchg(array->prog + index, NULL);
if (old_prog) {
bpf_prog_put_rcu(old_prog);
old_ptr = xchg(array->ptrs + index, NULL);
if (old_ptr) {
map->ops->map_fd_put_ptr(old_ptr);
return 0;
} else {
return -ENOENT;
}
}
static void *prog_fd_array_get_ptr(struct bpf_map *map, int fd)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct bpf_prog *prog = bpf_prog_get(fd);
if (IS_ERR(prog))
return prog;
if (!bpf_prog_array_compatible(array, prog)) {
bpf_prog_put(prog);
return ERR_PTR(-EINVAL);
}
return prog;
}
static void prog_fd_array_put_ptr(void *ptr)
{
struct bpf_prog *prog = ptr;
bpf_prog_put_rcu(prog);
}
/* decrement refcnt of all bpf_progs that are stored in this map */
void bpf_prog_array_map_clear(struct bpf_map *map)
void bpf_fd_array_map_clear(struct bpf_map *map)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
int i;
for (i = 0; i < array->map.max_entries; i++)
prog_array_map_delete_elem(map, &i);
fd_array_map_delete_elem(map, &i);
}
static const struct bpf_map_ops prog_array_ops = {
.map_alloc = prog_array_map_alloc,
.map_free = prog_array_map_free,
.map_alloc = fd_array_map_alloc,
.map_free = fd_array_map_free,
.map_get_next_key = array_map_get_next_key,
.map_lookup_elem = prog_array_map_lookup_elem,
.map_update_elem = prog_array_map_update_elem,
.map_delete_elem = prog_array_map_delete_elem,
.map_lookup_elem = fd_array_map_lookup_elem,
.map_update_elem = fd_array_map_update_elem,
.map_delete_elem = fd_array_map_delete_elem,
.map_fd_get_ptr = prog_fd_array_get_ptr,
.map_fd_put_ptr = prog_fd_array_put_ptr,
};
static struct bpf_map_type_list prog_array_type __read_mostly = {
@ -255,3 +273,60 @@ static int __init register_prog_array_map(void)
return 0;
}
late_initcall(register_prog_array_map);
static void perf_event_array_map_free(struct bpf_map *map)
{
bpf_fd_array_map_clear(map);
fd_array_map_free(map);
}
static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
{
struct perf_event *event;
const struct perf_event_attr *attr;
event = perf_event_get(fd);
if (IS_ERR(event))
return event;
attr = perf_event_attrs(event);
if (IS_ERR(attr))
return (void *)attr;
if (attr->type != PERF_TYPE_RAW &&
attr->type != PERF_TYPE_HARDWARE) {
perf_event_release_kernel(event);
return ERR_PTR(-EINVAL);
}
return event;
}
static void perf_event_fd_array_put_ptr(void *ptr)
{
struct perf_event *event = ptr;
perf_event_release_kernel(event);
}
static const struct bpf_map_ops perf_event_array_ops = {
.map_alloc = fd_array_map_alloc,
.map_free = perf_event_array_map_free,
.map_get_next_key = array_map_get_next_key,
.map_lookup_elem = fd_array_map_lookup_elem,
.map_update_elem = fd_array_map_update_elem,
.map_delete_elem = fd_array_map_delete_elem,
.map_fd_get_ptr = perf_event_fd_array_get_ptr,
.map_fd_put_ptr = perf_event_fd_array_put_ptr,
};
static struct bpf_map_type_list perf_event_array_type __read_mostly = {
.ops = &perf_event_array_ops,
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
};
static int __init register_perf_event_array_map(void)
{
bpf_register_map_type(&perf_event_array_type);
return 0;
}
late_initcall(register_perf_event_array_map);

2
kernel/bpf/core.c
View file

@ -450,7 +450,7 @@ static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
tail_call_cnt++;
prog = READ_ONCE(array->prog[index]);
prog = READ_ONCE(array->ptrs[index]);
if (unlikely(!prog))
goto out;

2
kernel/bpf/syscall.c
View file

@ -72,7 +72,7 @@ static int bpf_map_release(struct inode *inode, struct file *filp)
/* prog_array stores refcnt-ed bpf_prog pointers
* release them all when user space closes prog_array_fd
*/
bpf_prog_array_map_clear(map);
bpf_fd_array_map_clear(map);
bpf_map_put(map);
return 0;

48
kernel/bpf/verifier.c
View file

@ -238,6 +238,14 @@ static const char * const reg_type_str[] = {
[CONST_IMM] = "imm",
};
static const struct {
int map_type;
int func_id;
} func_limit[] = {
{BPF_MAP_TYPE_PROG_ARRAY, BPF_FUNC_tail_call},
{BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_read},
};
static void print_verifier_state(struct verifier_env *env)
{
enum bpf_reg_type t;
@ -837,6 +845,28 @@ static int check_func_arg(struct verifier_env *env, u32 regno,
return err;
}
static int check_map_func_compatibility(struct bpf_map *map, int func_id)
{
bool bool_map, bool_func;
int i;
if (!map)
return 0;
for (i = 0; i <= ARRAY_SIZE(func_limit); i++) {
bool_map = (map->map_type == func_limit[i].map_type);
bool_func = (func_id == func_limit[i].func_id);
/* only when map & func pair match it can continue.
* don't allow any other map type to be passed into
* the special func;
*/
if (bool_map != bool_func)
return -EINVAL;
}
return 0;
}
static int check_call(struct verifier_env *env, int func_id)
{
struct verifier_state *state = &env->cur_state;
@ -912,21 +942,9 @@ static int check_call(struct verifier_env *env, int func_id)
return -EINVAL;
}
if (map && map->map_type == BPF_MAP_TYPE_PROG_ARRAY &&
func_id != BPF_FUNC_tail_call)
/* prog_array map type needs extra care:
* only allow to pass it into bpf_tail_call() for now.
* bpf_map_delete_elem() can be allowed in the future,
* while bpf_map_update_elem() must only be done via syscall
*/
return -EINVAL;
if (func_id == BPF_FUNC_tail_call &&
map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
/* don't allow any other map type to be passed into
* bpf_tail_call()
*/
return -EINVAL;
err = check_map_func_compatibility(map, func_id);
if (err)
return err;
return 0;
}

78
kernel/events/core.c
View file

@ -3212,6 +3212,59 @@ static inline u64 perf_event_count(struct perf_event *event)
return __perf_event_count(event);
}
/*
* NMI-safe method to read a local event, that is an event that
* is:
* - either for the current task, or for this CPU
* - does not have inherit set, for inherited task events
* will not be local and we cannot read them atomically
* - must not have a pmu::count method
*/
u64 perf_event_read_local(struct perf_event *event)
{
unsigned long flags;
u64 val;
/*
* Disabling interrupts avoids all counter scheduling (context
* switches, timer based rotation and IPIs).
*/
local_irq_save(flags);
/* If this is a per-task event, it must be for current */
WARN_ON_ONCE((event->attach_state & PERF_ATTACH_TASK) &&
event->hw.target != current);
/* If this is a per-CPU event, it must be for this CPU */
WARN_ON_ONCE(!(event->attach_state & PERF_ATTACH_TASK) &&
event->cpu != smp_processor_id());
/*
* It must not be an event with inherit set, we cannot read
* all child counters from atomic context.
*/
WARN_ON_ONCE(event->attr.inherit);
/*
* It must not have a pmu::count method, those are not
* NMI safe.
*/
WARN_ON_ONCE(event->pmu->count);
/*
* If the event is currently on this CPU, its either a per-task event,
* or local to this CPU. Furthermore it means its ACTIVE (otherwise
* oncpu == -1).
*/
if (event->oncpu == smp_processor_id())
event->pmu->read(event);
val = local64_read(&event->count);
local_irq_restore(flags);
return val;
}
static u64 perf_event_read(struct perf_event *event)
{
/*
@ -8574,6 +8627,31 @@ void perf_event_delayed_put(struct task_struct *task)
WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
}
struct perf_event *perf_event_get(unsigned int fd)
{
int err;
struct fd f;
struct perf_event *event;
err = perf_fget_light(fd, &f);
if (err)
return ERR_PTR(err);
event = f.file->private_data;
atomic_long_inc(&event->refcount);
fdput(f);
return event;
}
const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
{
if (!event)
return ERR_PTR(-EINVAL);
return &event->attr;
}
/*
* inherit a event from parent task to child task:
*/

31
kernel/trace/bpf_trace.c
View file

@ -158,6 +158,35 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
return &bpf_trace_printk_proto;
}
static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
{
struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct perf_event *event;
if (unlikely(index >= array->map.max_entries))
return -E2BIG;
event = (struct perf_event *)array->ptrs[index];
if (!event)
return -ENOENT;
/*
* we don't know if the function is run successfully by the
* return value. It can be judged in other places, such as
* eBPF programs.
*/
return perf_event_read_local(event);
}
const struct bpf_func_proto bpf_perf_event_read_proto = {
.func = bpf_perf_event_read,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_CONST_MAP_PTR,
.arg2_type = ARG_ANYTHING,
};
static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
{
switch (func_id) {
@ -183,6 +212,8 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func
return bpf_get_trace_printk_proto();
case BPF_FUNC_get_smp_processor_id:
return &bpf_get_smp_processor_id_proto;
case BPF_FUNC_perf_event_read:
return &bpf_perf_event_read_proto;
default:
return NULL;
}

4
samples/bpf/Makefile
View file

@ -12,6 +12,7 @@ hostprogs-y += tracex2
hostprogs-y += tracex3
hostprogs-y += tracex4
hostprogs-y += tracex5
hostprogs-y += tracex6
hostprogs-y += lathist
test_verifier-objs := test_verifier.o libbpf.o
@ -25,6 +26,7 @@ tracex2-objs := bpf_load.o libbpf.o tracex2_user.o
tracex3-objs := bpf_load.o libbpf.o tracex3_user.o
tracex4-objs := bpf_load.o libbpf.o tracex4_user.o
tracex5-objs := bpf_load.o libbpf.o tracex5_user.o
tracex6-objs := bpf_load.o libbpf.o tracex6_user.o
lathist-objs := bpf_load.o libbpf.o lathist_user.o
# Tell kbuild to always build the programs
@ -37,6 +39,7 @@ always += tracex2_kern.o
always += tracex3_kern.o
always += tracex4_kern.o
always += tracex5_kern.o
always += tracex6_kern.o
always += tcbpf1_kern.o
always += lathist_kern.o
@ -51,6 +54,7 @@ HOSTLOADLIBES_tracex2 += -lelf
HOSTLOADLIBES_tracex3 += -lelf
HOSTLOADLIBES_tracex4 += -lelf -lrt
HOSTLOADLIBES_tracex5 += -lelf
HOSTLOADLIBES_tracex6 += -lelf
HOSTLOADLIBES_lathist += -lelf
# point this to your LLVM backend with bpf support

2
samples/bpf/bpf_helpers.h
View file

@ -31,6 +31,8 @@ static unsigned long long (*bpf_get_current_uid_gid)(void) =
(void *) BPF_FUNC_get_current_uid_gid;
static int (*bpf_get_current_comm)(void *buf, int buf_size) =
(void *) BPF_FUNC_get_current_comm;
static int (*bpf_perf_event_read)(void *map, int index) =
(void *) BPF_FUNC_perf_event_read;
/* llvm builtin functions that eBPF C program may use to
* emit BPF_LD_ABS and BPF_LD_IND instructions

26
samples/bpf/tracex6_kern.c Normal file
View file

@ -0,0 +1,26 @@
#include <linux/version.h>
#include <uapi/linux/bpf.h>
#include "bpf_helpers.h"
struct bpf_map_def SEC("maps") my_map = {
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(u32),
.max_entries = 32,
};
SEC("kprobe/sys_write")
int bpf_prog1(struct pt_regs *ctx)
{
u64 count;
u32 key = bpf_get_smp_processor_id();
char fmt[] = "CPU-%d %llu\n";
count = bpf_perf_event_read(&my_map, key);
bpf_trace_printk(fmt, sizeof(fmt), key, count);
return 0;
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;

68
samples/bpf/tracex6_user.c Normal file
View file

@ -0,0 +1,68 @@
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <sys/ioctl.h>
#include <linux/perf_event.h>
#include <linux/bpf.h>
#include "libbpf.h"
#include "bpf_load.h"
#define SAMPLE_PERIOD 0x7fffffffffffffffULL
static void test_bpf_perf_event(void)
{
int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
int *pmu_fd = malloc(nr_cpus * sizeof(int));
unsigned long value;
int i;
struct perf_event_attr attr_insn_pmu = {
.freq = 0,
.sample_period = SAMPLE_PERIOD,
.inherit = 0,
.type = PERF_TYPE_HARDWARE,
.read_format = 0,
.sample_type = 0,
.config = 0,/* PMU: cycles */
};
for (i = 0; i < nr_cpus; i++) {
pmu_fd[i] = perf_event_open(&attr_insn_pmu, -1/*pid*/, i/*cpu*/, -1/*group_fd*/, 0);
if (pmu_fd[i] < 0)
printf("event syscall failed\n");
bpf_update_elem(map_fd[0], &i, &pmu_fd[i], BPF_ANY);
ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0);
}
system("ls");
system("pwd");
system("sleep 2");
for (i = 0; i < nr_cpus; i++)
close(pmu_fd[i]);
close(map_fd);
free(pmu_fd);
}
int main(int argc, char **argv)
{
char filename[256];
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
if (load_bpf_file(filename)) {
printf("%s", bpf_log_buf);
return 1;
}
test_bpf_perf_event();
return 0;
}