From 492ecee892c2a4ba6a14903d5d586ff750b7e805 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 25 Feb 2019 14:28:39 -0800 Subject: bpf: enable program stats JITed BPF programs are indistinguishable from kernel functions, but unlike kernel code BPF code can be changed often. Typical approach of "perf record" + "perf report" profiling and tuning of kernel code works just as well for BPF programs, but kernel code doesn't need to be monitored whereas BPF programs do. Users load and run large amount of BPF programs. These BPF stats allow tools monitor the usage of BPF on the server. The monitoring tools will turn sysctl kernel.bpf_stats_enabled on and off for few seconds to sample average cost of the programs. Aggregated data over hours and days will provide an insight into cost of BPF and alarms can trigger in case given program suddenly gets more expensive. The cost of two sched_clock() per program invocation adds ~20 nsec. Fast BPF progs (like selftests/bpf/progs/test_pkt_access.c) will slow down from ~10 nsec to ~30 nsec. static_key minimizes the cost of the stats collection. There is no measurable difference before/after this patch with kernel.bpf_stats_enabled=0 Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- include/linux/bpf.h | 9 +++++++++ include/linux/filter.h | 20 +++++++++++++++++++- kernel/bpf/core.c | 31 +++++++++++++++++++++++++++++-- kernel/bpf/syscall.c | 34 ++++++++++++++++++++++++++++++++-- kernel/bpf/verifier.c | 7 ++++++- kernel/sysctl.c | 34 ++++++++++++++++++++++++++++++++++ 6 files changed, 129 insertions(+), 6 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index de18227b3d95..a2132e09dc1c 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -16,6 +16,7 @@ #include #include #include +#include struct bpf_verifier_env; struct perf_event; @@ -340,6 +341,12 @@ enum bpf_cgroup_storage_type { #define MAX_BPF_CGROUP_STORAGE_TYPE __BPF_CGROUP_STORAGE_MAX +struct bpf_prog_stats { + u64 cnt; + u64 nsecs; + struct u64_stats_sync syncp; +}; + struct bpf_prog_aux { atomic_t refcnt; u32 used_map_cnt; @@ -389,6 +396,7 @@ struct bpf_prog_aux { * main prog always has linfo_idx == 0 */ u32 linfo_idx; + struct bpf_prog_stats __percpu *stats; union { struct work_struct work; struct rcu_head rcu; @@ -559,6 +567,7 @@ void bpf_map_area_free(void *base); void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr); extern int sysctl_unprivileged_bpf_disabled; +extern int sysctl_bpf_stats_enabled; int bpf_map_new_fd(struct bpf_map *map, int flags); int bpf_prog_new_fd(struct bpf_prog *prog); diff --git a/include/linux/filter.h b/include/linux/filter.h index f32b3eca5a04..7e5e3db11106 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -533,7 +533,24 @@ struct sk_filter { struct bpf_prog *prog; }; -#define BPF_PROG_RUN(filter, ctx) ({ cant_sleep(); (*(filter)->bpf_func)(ctx, (filter)->insnsi); }) +DECLARE_STATIC_KEY_FALSE(bpf_stats_enabled_key); + +#define BPF_PROG_RUN(prog, ctx) ({ \ + u32 ret; \ + cant_sleep(); \ + if (static_branch_unlikely(&bpf_stats_enabled_key)) { \ + struct bpf_prog_stats *stats; \ + u64 start = sched_clock(); \ + ret = (*(prog)->bpf_func)(ctx, (prog)->insnsi); \ + stats = this_cpu_ptr(prog->aux->stats); \ + u64_stats_update_begin(&stats->syncp); \ + stats->cnt++; \ + stats->nsecs += sched_clock() - start; \ + u64_stats_update_end(&stats->syncp); \ + } else { \ + ret = (*(prog)->bpf_func)(ctx, (prog)->insnsi); \ + } \ + ret; }) #define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN @@ -764,6 +781,7 @@ void bpf_prog_free_jited_linfo(struct bpf_prog *prog); void bpf_prog_free_unused_jited_linfo(struct bpf_prog *prog); struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags); +struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flags); struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size, gfp_t gfp_extra_flags); void __bpf_prog_free(struct bpf_prog *fp); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index ef88b167959d..1c14c347f3cf 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -78,7 +78,7 @@ void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, uns return NULL; } -struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags) +struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flags) { gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | gfp_extra_flags; struct bpf_prog_aux *aux; @@ -104,6 +104,26 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags) return fp; } + +struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags) +{ + gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | gfp_extra_flags; + struct bpf_prog *prog; + + prog = bpf_prog_alloc_no_stats(size, gfp_extra_flags); + if (!prog) + return NULL; + + prog->aux->stats = alloc_percpu_gfp(struct bpf_prog_stats, gfp_flags); + if (!prog->aux->stats) { + kfree(prog->aux); + vfree(prog); + return NULL; + } + + u64_stats_init(&prog->aux->stats->syncp); + return prog; +} EXPORT_SYMBOL_GPL(bpf_prog_alloc); int bpf_prog_alloc_jited_linfo(struct bpf_prog *prog) @@ -231,7 +251,10 @@ struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size, void __bpf_prog_free(struct bpf_prog *fp) { - kfree(fp->aux); + if (fp->aux) { + free_percpu(fp->aux->stats); + kfree(fp->aux); + } vfree(fp); } @@ -2069,6 +2092,10 @@ int __weak skb_copy_bits(const struct sk_buff *skb, int offset, void *to, return -EFAULT; } +DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key); +EXPORT_SYMBOL(bpf_stats_enabled_key); +int sysctl_bpf_stats_enabled __read_mostly; + /* All definitions of tracepoints related to BPF. */ #define CREATE_TRACE_POINTS #include diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ec7c552af76b..31cf66fc3f5c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1283,24 +1283,54 @@ static int bpf_prog_release(struct inode *inode, struct file *filp) return 0; } +static void bpf_prog_get_stats(const struct bpf_prog *prog, + struct bpf_prog_stats *stats) +{ + u64 nsecs = 0, cnt = 0; + int cpu; + + for_each_possible_cpu(cpu) { + const struct bpf_prog_stats *st; + unsigned int start; + u64 tnsecs, tcnt; + + st = per_cpu_ptr(prog->aux->stats, cpu); + do { + start = u64_stats_fetch_begin_irq(&st->syncp); + tnsecs = st->nsecs; + tcnt = st->cnt; + } while (u64_stats_fetch_retry_irq(&st->syncp, start)); + nsecs += tnsecs; + cnt += tcnt; + } + stats->nsecs = nsecs; + stats->cnt = cnt; +} + #ifdef CONFIG_PROC_FS static void bpf_prog_show_fdinfo(struct seq_file *m, struct file *filp) { const struct bpf_prog *prog = filp->private_data; char prog_tag[sizeof(prog->tag) * 2 + 1] = { }; + struct bpf_prog_stats stats; + bpf_prog_get_stats(prog, &stats); bin2hex(prog_tag, prog->tag, sizeof(prog->tag)); seq_printf(m, "prog_type:\t%u\n" "prog_jited:\t%u\n" "prog_tag:\t%s\n" "memlock:\t%llu\n" - "prog_id:\t%u\n", + "prog_id:\t%u\n" + "run_time_ns:\t%llu\n" + "run_cnt:\t%llu\n", prog->type, prog->jited, prog_tag, prog->pages * 1ULL << PAGE_SHIFT, - prog->aux->id); + prog->aux->id, + stats.nsecs, + stats.cnt); } #endif diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1b9496c41383..0e4edd7e3c5f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7320,7 +7320,12 @@ static int jit_subprogs(struct bpf_verifier_env *env) subprog_end = env->subprog_info[i + 1].start; len = subprog_end - subprog_start; - func[i] = bpf_prog_alloc(bpf_prog_size(len), GFP_USER); + /* BPF_PROG_RUN doesn't call subprogs directly, + * hence main prog stats include the runtime of subprogs. + * subprogs don't have IDs and not reachable via prog_get_next_id + * func[i]->aux->stats will never be accessed and stays NULL + */ + func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER); if (!func[i]) goto out_free; memcpy(func[i]->insnsi, &prog->insnsi[subprog_start], diff --git a/kernel/sysctl.c b/kernel/sysctl.c index ba4d9e85feb8..86e0771352f2 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -224,6 +224,9 @@ static int proc_dostring_coredump(struct ctl_table *table, int write, #endif static int proc_dopipe_max_size(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos); +static int proc_dointvec_minmax_bpf_stats(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); #ifdef CONFIG_MAGIC_SYSRQ /* Note: sysrq code uses its own private copy */ @@ -1230,6 +1233,15 @@ static struct ctl_table kern_table[] = { .extra2 = &one, }, #endif + { + .procname = "bpf_stats_enabled", + .data = &sysctl_bpf_stats_enabled, + .maxlen = sizeof(sysctl_bpf_stats_enabled), + .mode = 0644, + .proc_handler = proc_dointvec_minmax_bpf_stats, + .extra1 = &zero, + .extra2 = &one, + }, #if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) { .procname = "panic_on_rcu_stall", @@ -3260,6 +3272,28 @@ int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int write, #endif /* CONFIG_PROC_SYSCTL */ +static int proc_dointvec_minmax_bpf_stats(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + int ret, bpf_stats = *(int *)table->data; + struct ctl_table tmp = *table; + + if (write && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + tmp.data = &bpf_stats; + ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); + if (write && !ret) { + *(int *)table->data = bpf_stats; + if (bpf_stats) + static_branch_enable(&bpf_stats_enabled_key); + else + static_branch_disable(&bpf_stats_enabled_key); + } + return ret; +} + /* * No sense putting this after each symbol definition, twice, * exception granted :-) -- cgit v1.2.3 From 5f8f8b93aeb8371c54af08bece2bd04bc2d48707 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 25 Feb 2019 14:28:40 -0800 Subject: bpf: expose program stats via bpf_prog_info Return bpf program run_time_ns and run_cnt via bpf_prog_info Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann --- include/uapi/linux/bpf.h | 2 ++ kernel/bpf/syscall.c | 5 +++++ 2 files changed, 7 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index bcdd2474eee7..2e308e90ffea 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2813,6 +2813,8 @@ struct bpf_prog_info { __u32 jited_line_info_rec_size; __u32 nr_prog_tags; __aligned_u64 prog_tags; + __u64 run_time_ns; + __u64 run_cnt; } __attribute__((aligned(8))); struct bpf_map_info { diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 31cf66fc3f5c..174581dfe225 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2152,6 +2152,7 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog, struct bpf_prog_info __user *uinfo = u64_to_user_ptr(attr->info.info); struct bpf_prog_info info = {}; u32 info_len = attr->info.info_len; + struct bpf_prog_stats stats; char __user *uinsns; u32 ulen; int err; @@ -2191,6 +2192,10 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog, if (err) return err; + bpf_prog_get_stats(prog, &stats); + info.run_time_ns = stats.nsecs; + info.run_cnt = stats.cnt; + if (!capable(CAP_SYS_ADMIN)) { info.jited_prog_len = 0; info.xlated_prog_len = 0; -- cgit v1.2.3 From b1eca86db68b48f59b9f195c8b4f8114d2a9918c Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 25 Feb 2019 14:28:41 -0800 Subject: tools/bpf: sync bpf.h into tools sync bpf.h into tools directory Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- tools/include/uapi/linux/bpf.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index bcdd2474eee7..2e308e90ffea 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -2813,6 +2813,8 @@ struct bpf_prog_info { __u32 jited_line_info_rec_size; __u32 nr_prog_tags; __aligned_u64 prog_tags; + __u64 run_time_ns; + __u64 run_cnt; } __attribute__((aligned(8))); struct bpf_map_info { -- cgit v1.2.3 From 88ad472b8a4ad2292d11835652462fd9f745245e Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 25 Feb 2019 14:28:42 -0800 Subject: tools/bpftool: recognize bpf_prog_info run_time_ns and run_cnt $ bpftool p s 1: kprobe tag a56587d488d216c9 gpl run_time_ns 79786 run_cnt 8 loaded_at 2019-02-22T12:22:51-0800 uid 0 xlated 352B not jited memlock 4096B $ bpftool --json --pretty p s [{ "id": 1, "type": "kprobe", "tag": "a56587d488d216c9", "gpl_compatible": true, "run_time_ns": 79786, "run_cnt": 8, "loaded_at": 1550866971, "uid": 0, "bytes_xlated": 352, "jited": false, "bytes_memlock": 4096 } ] Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- tools/bpf/bpftool/Documentation/bpftool-prog.rst | 4 +++- tools/bpf/bpftool/prog.c | 7 +++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst index 12bc1e2d4b46..9386bd6e0396 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst @@ -171,7 +171,7 @@ EXAMPLES :: - 10: xdp name some_prog tag 005a3d2123620c8b gpl + 10: xdp name some_prog tag 005a3d2123620c8b gpl run_time_ns 81632 run_cnt 10 loaded_at 2017-09-29T20:11:00+0000 uid 0 xlated 528B jited 370B memlock 4096B map_ids 10 @@ -184,6 +184,8 @@ EXAMPLES "type": "xdp", "tag": "005a3d2123620c8b", "gpl_compatible": true, + "run_time_ns": 81632, + "run_cnt": 10, "loaded_at": 1506715860, "uid": 0, "bytes_xlated": 528, diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index db978c8d76a8..0c35dd543d49 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -214,6 +214,10 @@ static void print_prog_json(struct bpf_prog_info *info, int fd) info->tag[4], info->tag[5], info->tag[6], info->tag[7]); jsonw_bool_field(json_wtr, "gpl_compatible", info->gpl_compatible); + if (info->run_time_ns) { + jsonw_uint_field(json_wtr, "run_time_ns", info->run_time_ns); + jsonw_uint_field(json_wtr, "run_cnt", info->run_cnt); + } print_dev_json(info->ifindex, info->netns_dev, info->netns_ino); @@ -277,6 +281,9 @@ static void print_prog_plain(struct bpf_prog_info *info, int fd) fprint_hex(stdout, info->tag, BPF_TAG_SIZE, ""); print_dev_plain(info->ifindex, info->netns_dev, info->netns_ino); printf("%s", info->gpl_compatible ? " gpl" : ""); + if (info->run_time_ns) + printf(" run_time_ns %lld run_cnt %lld", + info->run_time_ns, info->run_cnt); printf("\n"); if (info->load_time) { -- cgit v1.2.3