Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2022-06-17

We've added 12 non-merge commits during the last 4 day(s) which contain
a total of 14 files changed, 305 insertions(+), 107 deletions(-).

The main changes are:

1) Fix x86 JIT tailcall count offset on BPF-2-BPF call, from Jakub Sitnicki.

2) Fix a kprobe_multi link bug which misplaces BPF cookies, from Jiri Olsa.

3) Fix an infinite loop when processing a module's BTF, from Kumar Kartikeya Dwivedi.

4) Fix getting a rethook only in RCU available context, from Masami Hiramatsu.

5) Fix request socket refcount leak in sk lookup helpers, from Jon Maxwell.

6) Fix xsk xmit behavior which wrongly adds skb to already full cq, from Ciara Loftus.

* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  rethook: Reject getting a rethook if RCU is not watching
  fprobe, samples: Add use_trace option and show hit/missed counter
  bpf, docs: Update some of the JIT/maintenance entries
  selftest/bpf: Fix kprobe_multi bench test
  bpf: Force cookies array to follow symbols sorting
  ftrace: Keep address offset in ftrace_lookup_symbols
  selftests/bpf: Shuffle cookies symbols in kprobe multi test
  selftests/bpf: Test tail call counting with bpf2bpf and data on stack
  bpf, x86: Fix tail call count offset calculation on bpf2bpf call
  bpf: Limit maximum modifier chain length in btf_check_type_tags
  bpf: Fix request_sock leak in sk lookup helpers
  xsk: Fix generic transmit when completion queue reservation fails
====================

Link: https://lore.kernel.org/r/20220617202119.2421-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 25 insertions, 4 deletions

diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
index 24d3cf109140..01ee6c8c8382 100644
--- a/samples/fprobe/fprobe_example.c
+++ b/samples/fprobe/fprobe_example.c
@@ -21,6 +21,7 @@
 #define BACKTRACE_DEPTH 16
 #define MAX_SYMBOL_LEN 4096
 struct fprobe sample_probe;
+static unsigned long nhit;
 
 static char symbol[MAX_SYMBOL_LEN] = "kernel_clone";
 module_param_string(symbol, symbol, sizeof(symbol), 0644);
@@ -28,6 +29,8 @@ static char nosymbol[MAX_SYMBOL_LEN] = "";
 module_param_string(nosymbol, nosymbol, sizeof(nosymbol), 0644);
 static bool stackdump = true;
 module_param(stackdump, bool, 0644);
+static bool use_trace = false;
+module_param(use_trace, bool, 0644);
 
 static void show_backtrace(void)
 {
@@ -40,7 +43,15 @@ static void show_backtrace(void)
 
 static void sample_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs)
 {
-	pr_info("Enter <%pS> ip = 0x%p\n", (void *)ip, (void *)ip);
+	if (use_trace)
+		/*
+		 * This is just an example, no kernel code should call
+		 * trace_printk() except when actively debugging.
+		 */
+		trace_printk("Enter <%pS> ip = 0x%p\n", (void *)ip, (void *)ip);
+	else
+		pr_info("Enter <%pS> ip = 0x%p\n", (void *)ip, (void *)ip);
+	nhit++;
 	if (stackdump)
 		show_backtrace();
 }
@@ -49,8 +60,17 @@ static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_r
 {
 	unsigned long rip = instruction_pointer(regs);
 
-	pr_info("Return from <%pS> ip = 0x%p to rip = 0x%p (%pS)\n",
-		(void *)ip, (void *)ip, (void *)rip, (void *)rip);
+	if (use_trace)
+		/*
+		 * This is just an example, no kernel code should call
+		 * trace_printk() except when actively debugging.
+		 */
+		trace_printk("Return from <%pS> ip = 0x%p to rip = 0x%p (%pS)\n",
+			(void *)ip, (void *)ip, (void *)rip, (void *)rip);
+	else
+		pr_info("Return from <%pS> ip = 0x%p to rip = 0x%p (%pS)\n",
+			(void *)ip, (void *)ip, (void *)rip, (void *)rip);
+	nhit++;
 	if (stackdump)
 		show_backtrace();
 }
@@ -112,7 +132,8 @@ static void __exit fprobe_exit(void)
 {
 	unregister_fprobe(&sample_probe);
 
-	pr_info("fprobe at %s unregistered\n", symbol);
+	pr_info("fprobe at %s unregistered. %ld times hit, %ld times missed\n",
+		symbol, nhit, sample_probe.nmissed);
 }
 
 module_init(fprobe_init)