scftorture: Count single_rpc offline failures in statistics outputgrafted

scf_torture_stats_print() aggregates each invoker thread's counters
into a local scf_statistics structure before printing, but the
n_single_rpc_ofl field is missing from the aggregation loop.  As a
result, the "single_rpc_ofl" value printed in the statistics line is
always zero, even when smp_call_function_single() invocations for the
RPC test have failed due to offline CPUs and been counted by the
invoker threads.

Add the missing accumulation so that the printed value reflects the
actual counts.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

3 files changed, 243 insertions, 0 deletions

diff --git a/samples/kprobes/Makefile b/samples/kprobes/Makefile
new file mode 100644
index 000000000..e77459271
--- /dev/null
+++ b/samples/kprobes/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# builds the kprobes example kernel modules;
+# then to use one (as root):  insmod <module_name.ko>
+
+obj-$(CONFIG_SAMPLE_KPROBES) += kprobe_example.o
+obj-$(CONFIG_SAMPLE_KRETPROBES) += kretprobe_example.o
diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
new file mode 100644
index 000000000..53ec6c8b8
--- /dev/null
+++ b/samples/kprobes/kprobe_example.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Here's a sample kernel module showing the use of kprobes to dump a
+ * stack trace and selected registers when kernel_clone() is called.
+ *
+ * For more information on theory of operation of kprobes, see
+ * Documentation/trace/kprobes.rst
+ *
+ * You will see the trace data in /var/log/messages and on the console
+ * whenever kernel_clone() is invoked to create a new process.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+
+static char symbol[KSYM_NAME_LEN] = "kernel_clone";
+module_param_string(symbol, symbol, KSYM_NAME_LEN, 0644);
+
+/* For each probe you need to allocate a kprobe structure */
+static struct kprobe kp = {
+	.symbol_name	= symbol,
+};
+
+/* kprobe pre_handler: called just before the probed instruction is executed */
+static int __kprobes handler_pre(struct kprobe *p, struct pt_regs *regs)
+{
+#ifdef CONFIG_X86
+	pr_info("<%s> p->addr = 0x%p, ip = %lx, flags = 0x%lx\n",
+		p->symbol_name, p->addr, regs->ip, regs->flags);
+#endif
+#ifdef CONFIG_PPC
+	pr_info("<%s> p->addr = 0x%p, nip = 0x%lx, msr = 0x%lx\n",
+		p->symbol_name, p->addr, regs->nip, regs->msr);
+#endif
+#ifdef CONFIG_MIPS
+	pr_info("<%s> p->addr = 0x%p, epc = 0x%lx, status = 0x%lx\n",
+		p->symbol_name, p->addr, regs->cp0_epc, regs->cp0_status);
+#endif
+#ifdef CONFIG_ARM64
+	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, pstate = 0x%lx\n",
+		p->symbol_name, p->addr, (long)regs->pc, (long)regs->pstate);
+#endif
+#ifdef CONFIG_ARM
+	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, cpsr = 0x%lx\n",
+		p->symbol_name, p->addr, (long)regs->ARM_pc, (long)regs->ARM_cpsr);
+#endif
+#ifdef CONFIG_RISCV
+	pr_info("<%s> p->addr = 0x%p, pc = 0x%lx, status = 0x%lx\n",
+		p->symbol_name, p->addr, regs->epc, regs->status);
+#endif
+#ifdef CONFIG_S390
+	pr_info("<%s> p->addr, 0x%p, ip = 0x%lx, flags = 0x%lx\n",
+		p->symbol_name, p->addr, regs->psw.addr, regs->flags);
+#endif
+#ifdef CONFIG_LOONGARCH
+	pr_info("<%s> p->addr = 0x%p, era = 0x%lx, estat = 0x%lx\n",
+		p->symbol_name, p->addr, regs->csr_era, regs->csr_estat);
+#endif
+
+	/* A dump_stack() here will give a stack backtrace */
+	return 0;
+}
+
+/* kprobe post_handler: called after the probed instruction is executed */
+static void __kprobes handler_post(struct kprobe *p, struct pt_regs *regs,
+				unsigned long flags)
+{
+#ifdef CONFIG_X86
+	pr_info("<%s> p->addr = 0x%p, flags = 0x%lx\n",
+		p->symbol_name, p->addr, regs->flags);
+#endif
+#ifdef CONFIG_PPC
+	pr_info("<%s> p->addr = 0x%p, msr = 0x%lx\n",
+		p->symbol_name, p->addr, regs->msr);
+#endif
+#ifdef CONFIG_MIPS
+	pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
+		p->symbol_name, p->addr, regs->cp0_status);
+#endif
+#ifdef CONFIG_ARM64
+	pr_info("<%s> p->addr = 0x%p, pstate = 0x%lx\n",
+		p->symbol_name, p->addr, (long)regs->pstate);
+#endif
+#ifdef CONFIG_ARM
+	pr_info("<%s> p->addr = 0x%p, cpsr = 0x%lx\n",
+		p->symbol_name, p->addr, (long)regs->ARM_cpsr);
+#endif
+#ifdef CONFIG_RISCV
+	pr_info("<%s> p->addr = 0x%p, status = 0x%lx\n",
+		p->symbol_name, p->addr, regs->status);
+#endif
+#ifdef CONFIG_S390
+	pr_info("<%s> p->addr, 0x%p, flags = 0x%lx\n",
+		p->symbol_name, p->addr, regs->flags);
+#endif
+#ifdef CONFIG_LOONGARCH
+	pr_info("<%s> p->addr = 0x%p, estat = 0x%lx\n",
+		p->symbol_name, p->addr, regs->csr_estat);
+#endif
+}
+
+static int __init kprobe_init(void)
+{
+	int ret;
+	kp.pre_handler = handler_pre;
+	kp.post_handler = handler_post;
+
+	ret = register_kprobe(&kp);
+	if (ret < 0) {
+		pr_err("register_kprobe failed, returned %d\n", ret);
+		return ret;
+	}
+	pr_info("Planted kprobe at %p\n", kp.addr);
+	return 0;
+}
+
+static void __exit kprobe_exit(void)
+{
+	unregister_kprobe(&kp);
+	pr_info("kprobe at %p unregistered\n", kp.addr);
+}
+
+module_init(kprobe_init)
+module_exit(kprobe_exit)
+MODULE_DESCRIPTION("sample kernel module showing the use of kprobes");
+MODULE_LICENSE("GPL");
diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
new file mode 100644
index 000000000..65d6dcafd
--- /dev/null
+++ b/samples/kprobes/kretprobe_example.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * kretprobe_example.c
+ *
+ * Here's a sample kernel module showing the use of return probes to
+ * report the return value and total time taken for probed function
+ * to run.
+ *
+ * usage: insmod kretprobe_example.ko func=<func_name>
+ *
+ * If no func_name is specified, kernel_clone is instrumented
+ *
+ * For more information on theory of operation of kretprobes, see
+ * Documentation/trace/kprobes.rst
+ *
+ * Build and insert the kernel module as done in the kprobe example.
+ * You will see the trace data in /var/log/messages and on the console
+ * whenever the probed function returns. (Some messages may be suppressed
+ * if syslogd is configured to eliminate duplicate messages.)
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+#include <linux/ktime.h>
+#include <linux/sched.h>
+
+static char func_name[KSYM_NAME_LEN] = "kernel_clone";
+module_param_string(func, func_name, KSYM_NAME_LEN, 0644);
+MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
+			" function's execution time");
+
+/* per-instance private data */
+struct my_data {
+	ktime_t entry_stamp;
+};
+
+/* Here we use the entry_handler to timestamp function entry */
+static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	struct my_data *data;
+
+	if (!current->mm)
+		return 1;	/* Skip kernel threads */
+
+	data = (struct my_data *)ri->data;
+	data->entry_stamp = ktime_get();
+	return 0;
+}
+NOKPROBE_SYMBOL(entry_handler);
+
+/*
+ * Return-probe handler: Log the return value and duration. Duration may turn
+ * out to be zero consistently, depending upon the granularity of time
+ * accounting on the platform.
+ */
+static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	unsigned long retval = regs_return_value(regs);
+	struct my_data *data = (struct my_data *)ri->data;
+	s64 delta;
+	ktime_t now;
+
+	now = ktime_get();
+	delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
+	pr_info("%s returned %lu and took %lld ns to execute\n",
+			func_name, retval, (long long)delta);
+	return 0;
+}
+NOKPROBE_SYMBOL(ret_handler);
+
+static struct kretprobe my_kretprobe = {
+	.handler		= ret_handler,
+	.entry_handler		= entry_handler,
+	.data_size		= sizeof(struct my_data),
+	/* Probe up to 20 instances concurrently. */
+	.maxactive		= 20,
+};
+
+static int __init kretprobe_init(void)
+{
+	int ret;
+
+	my_kretprobe.kp.symbol_name = func_name;
+	ret = register_kretprobe(&my_kretprobe);
+	if (ret < 0) {
+		pr_err("register_kretprobe failed, returned %d\n", ret);
+		return ret;
+	}
+	pr_info("Planted return probe at %s: %p\n",
+			my_kretprobe.kp.symbol_name, my_kretprobe.kp.addr);
+	return 0;
+}
+
+static void __exit kretprobe_exit(void)
+{
+	unregister_kretprobe(&my_kretprobe);
+	pr_info("kretprobe at %p unregistered\n", my_kretprobe.kp.addr);
+
+	/* nmissed > 0 suggests that maxactive was set too low. */
+	pr_info("Missed probing %d instances of %s\n",
+		my_kretprobe.nmissed, my_kretprobe.kp.symbol_name);
+}
+
+module_init(kretprobe_init)
+module_exit(kretprobe_exit)
+MODULE_DESCRIPTION("sample kernel module showing the use of return probes");
+MODULE_LICENSE("GPL");