diff mbox series

[v2,bpf-next,5/7] bpf: Count the number of times recursion was prevented

Message ID 20210206170344.78399-6-alexei.starovoitov@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series bpf: Misc improvements | expand

Checks

Context Check Description
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netdev/fixes_present success Link
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netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 11 maintainers not CCed: quentin@isovalent.com songliubraving@fb.com kafai@fb.com john.fastabend@gmail.com yhs@fb.com ast@kernel.org netdev@vger.kernel.org andrii@kernel.org kpsingh@kernel.org toke@redhat.com zhuyifei@google.com
netdev/source_inline success Was 0 now: 0
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netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 12238 this patch: 12238
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch warning CHECK: Unnecessary parentheses around 'prog->active' CHECK: Unnecessary parentheses around prog->active WARNING: line length of 87 exceeds 80 columns
netdev/build_allmodconfig_warn success Errors and warnings before: 12886 this patch: 12886
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netdev/stable success Stable not CCed

Commit Message

Alexei Starovoitov Feb. 6, 2021, 5:03 p.m. UTC 
From: Alexei Starovoitov <ast@kernel.org>

Add per-program counter for number of times recursion prevention mechanism
was triggered and expose it via show_fdinfo and bpf_prog_info.
Teach bpftool to print it.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 include/linux/filter.h         |  1 +
 include/uapi/linux/bpf.h       |  1 +
 kernel/bpf/syscall.c           | 14 ++++++++++----
 kernel/bpf/trampoline.c        | 18 ++++++++++++++++--
 tools/bpf/bpftool/prog.c       |  5 +++++
 tools/include/uapi/linux/bpf.h |  1 +
 6 files changed, 34 insertions(+), 6 deletions(-)

Comments

Andrii Nakryiko Feb. 8, 2021, 8:58 p.m. UTC | #1 
On Sat, Feb 6, 2021 at 9:06 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> From: Alexei Starovoitov <ast@kernel.org>
>
> Add per-program counter for number of times recursion prevention mechanism
> was triggered and expose it via show_fdinfo and bpf_prog_info.
> Teach bpftool to print it.
>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> ---

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>  include/linux/filter.h         |  1 +
>  include/uapi/linux/bpf.h       |  1 +
>  kernel/bpf/syscall.c           | 14 ++++++++++----
>  kernel/bpf/trampoline.c        | 18 ++++++++++++++++--
>  tools/bpf/bpftool/prog.c       |  5 +++++
>  tools/include/uapi/linux/bpf.h |  1 +
>  6 files changed, 34 insertions(+), 6 deletions(-)
>

[...]

>  static void print_prog_json(struct bpf_prog_info *info, int fd)
> @@ -446,6 +448,9 @@ static void print_prog_header_plain(struct bpf_prog_info *info)
>         if (info->run_time_ns)
>                 printf(" run_time_ns %lld run_cnt %lld",
>                        info->run_time_ns, info->run_cnt);
> +       if (info->recursion_misses)
> +               printf(" recursion_misses %lld",
> +                      info->recursion_misses);

no need for wrapping the line

>         printf("\n");
>  }
>
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index c001766adcbc..c547ad1ffe43 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -4501,6 +4501,7 @@ struct bpf_prog_info {
>         __aligned_u64 prog_tags;
>         __u64 run_time_ns;
>         __u64 run_cnt;
> +       __u64 recursion_misses;
>  } __attribute__((aligned(8)));
>
>  struct bpf_map_info {
> --
> 2.24.1
>
diff mbox series

Patch

diff --git a/include/linux/filter.h b/include/linux/filter.h
index d6c740eac056..4c9850b35744 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -543,6 +543,7 @@  struct bpf_binary_header {
 struct bpf_prog_stats {
 	u64 cnt;
 	u64 nsecs;
+	u64 misses;
 	struct u64_stats_sync syncp;
 } __aligned(2 * sizeof(u64));
 
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c001766adcbc..c547ad1ffe43 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4501,6 +4501,7 @@  struct bpf_prog_info {
 	__aligned_u64 prog_tags;
 	__u64 run_time_ns;
 	__u64 run_cnt;
+	__u64 recursion_misses;
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index f7df56a704de..c859bc46d06c 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1731,25 +1731,28 @@  static int bpf_prog_release(struct inode *inode, struct file *filp)
 static void bpf_prog_get_stats(const struct bpf_prog *prog,
 			       struct bpf_prog_stats *stats)
 {
-	u64 nsecs = 0, cnt = 0;
+	u64 nsecs = 0, cnt = 0, misses = 0;
 	int cpu;
 
 	for_each_possible_cpu(cpu) {
 		const struct bpf_prog_stats *st;
 		unsigned int start;
-		u64 tnsecs, tcnt;
+		u64 tnsecs, tcnt, tmisses;
 
 		st = per_cpu_ptr(prog->stats, cpu);
 		do {
 			start = u64_stats_fetch_begin_irq(&st->syncp);
 			tnsecs = st->nsecs;
 			tcnt = st->cnt;
+			tmisses = st->misses;
 		} while (u64_stats_fetch_retry_irq(&st->syncp, start));
 		nsecs += tnsecs;
 		cnt += tcnt;
+		misses += tmisses;
 	}
 	stats->nsecs = nsecs;
 	stats->cnt = cnt;
+	stats->misses = misses;
 }
 
 #ifdef CONFIG_PROC_FS
@@ -1768,14 +1771,16 @@  static void bpf_prog_show_fdinfo(struct seq_file *m, struct file *filp)
 		   "memlock:\t%llu\n"
 		   "prog_id:\t%u\n"
 		   "run_time_ns:\t%llu\n"
-		   "run_cnt:\t%llu\n",
+		   "run_cnt:\t%llu\n"
+		   "recursion_misses:\t%llu\n",
 		   prog->type,
 		   prog->jited,
 		   prog_tag,
 		   prog->pages * 1ULL << PAGE_SHIFT,
 		   prog->aux->id,
 		   stats.nsecs,
-		   stats.cnt);
+		   stats.cnt,
+		   stats.misses);
 }
 #endif
 
@@ -3438,6 +3443,7 @@  static int bpf_prog_get_info_by_fd(struct file *file,
 	bpf_prog_get_stats(prog, &stats);
 	info.run_time_ns = stats.nsecs;
 	info.run_cnt = stats.cnt;
+	info.recursion_misses = stats.misses;
 
 	if (!bpf_capable()) {
 		info.jited_prog_len = 0;
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 226f613ab289..83b77883bd77 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -381,6 +381,16 @@  void bpf_trampoline_put(struct bpf_trampoline *tr)
 	mutex_unlock(&trampoline_mutex);
 }
 
+static void notrace inc_misses_counter(struct bpf_prog *prog)
+{
+	struct bpf_prog_stats *stats;
+
+	stats = this_cpu_ptr(prog->stats);
+	u64_stats_update_begin(&stats->syncp);
+	stats->misses++;
+	u64_stats_update_end(&stats->syncp);
+}
+
 /* The logic is similar to BPF_PROG_RUN, but with an explicit
  * rcu_read_lock() and migrate_disable() which are required
  * for the trampoline. The macro is split into
@@ -396,8 +406,10 @@  u64 notrace __bpf_prog_enter(struct bpf_prog *prog)
 
 	rcu_read_lock();
 	migrate_disable();
-	if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1))
+	if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1)) {
+		inc_misses_counter(prog);
 		return 0;
+	}
 	if (static_branch_unlikely(&bpf_stats_enabled_key)) {
 		start = sched_clock();
 		if (unlikely(!start))
@@ -442,8 +454,10 @@  u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog)
 	rcu_read_lock_trace();
 	migrate_disable();
 	might_fault();
-	if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1))
+	if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1)) {
+		inc_misses_counter(prog);
 		return 0;
+	}
 	if (static_branch_unlikely(&bpf_stats_enabled_key)) {
 		start = sched_clock();
 		if (unlikely(!start))
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 1fe3ba255bad..2e1cd12589c5 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -368,6 +368,8 @@  static void print_prog_header_json(struct bpf_prog_info *info)
 		jsonw_uint_field(json_wtr, "run_time_ns", info->run_time_ns);
 		jsonw_uint_field(json_wtr, "run_cnt", info->run_cnt);
 	}
+	if (info->recursion_misses)
+		jsonw_uint_field(json_wtr, "recursion_misses", info->recursion_misses);
 }
 
 static void print_prog_json(struct bpf_prog_info *info, int fd)
@@ -446,6 +448,9 @@  static void print_prog_header_plain(struct bpf_prog_info *info)
 	if (info->run_time_ns)
 		printf(" run_time_ns %lld run_cnt %lld",
 		       info->run_time_ns, info->run_cnt);
+	if (info->recursion_misses)
+		printf(" recursion_misses %lld",
+		       info->recursion_misses);
 	printf("\n");
 }
 
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index c001766adcbc..c547ad1ffe43 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4501,6 +4501,7 @@  struct bpf_prog_info {
 	__aligned_u64 prog_tags;
 	__u64 run_time_ns;
 	__u64 run_cnt;
+	__u64 recursion_misses;
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {