diff mbox series

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

Message ID 20210206065741.59188-6-alexei.starovoitov@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series bpf: Misc improvements | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
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 zhuyifei@google.com rdna@fb.com
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit fail Errors and warnings before: 12238 this patch: 12239
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 fail Errors and warnings before: 12886 this patch: 12887
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Alexei Starovoitov Feb. 6, 2021, 6:57 a.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

kernel test robot Feb. 6, 2021, 8:55 a.m. UTC | #1 
Hi Alexei,

I love your patch! Perhaps something to improve:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/0day-ci/linux/commits/Alexei-Starovoitov/bpf-Misc-improvements/20210206-150251
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: openrisc-randconfig-p001-20210206 (attached as .config)
compiler: or1k-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/8d71f0650d2551940d9fc39a723d6595ab604715
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Alexei-Starovoitov/bpf-Misc-improvements/20210206-150251
        git checkout 8d71f0650d2551940d9fc39a723d6595ab604715
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=openrisc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   kernel/bpf/syscall.c: In function 'bpf_prog_get_stats':
>> kernel/bpf/syscall.c:1740:21: warning: variable 'tmisses' set but not used [-Wunused-but-set-variable]
    1740 |   u64 tnsecs, tcnt, tmisses;
         |                     ^~~~~~~


vim +/tmisses +1740 kernel/bpf/syscall.c

  1730	
  1731	static void bpf_prog_get_stats(const struct bpf_prog *prog,
  1732				       struct bpf_prog_stats *stats)
  1733	{
  1734		u64 nsecs = 0, cnt = 0, misses = 0;
  1735		int cpu;
  1736	
  1737		for_each_possible_cpu(cpu) {
  1738			const struct bpf_prog_stats *st;
  1739			unsigned int start;
> 1740			u64 tnsecs, tcnt, tmisses;
  1741	
  1742			st = per_cpu_ptr(prog->stats, cpu);
  1743			do {
  1744				start = u64_stats_fetch_begin_irq(&st->syncp);
  1745				tnsecs = st->nsecs;
  1746				tcnt = st->cnt;
  1747				tmisses = st->misses;
  1748			} while (u64_stats_fetch_retry_irq(&st->syncp, start));
  1749			nsecs += tnsecs;
  1750			cnt += tcnt;
  1751			misses += misses;
  1752		}
  1753		stats->nsecs = nsecs;
  1754		stats->cnt = cnt;
  1755		stats->misses = misses;
  1756	}
  1757	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff mbox series

Patch

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 9927e14ce021..707f86560a43 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..a5b8af378c33 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 += misses;
 	}
 	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 {