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-rw-r--r--samples/fprobe/fprobe_example.c29
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)