[patch V4 part 1 33/36] x86,tracing: Robustify ftrace_nmi_enter()

Thomas Gleixner
2020-05-05T14:14:21Z

From: Peter Zijlstra <peterz@infradead.org>

ftrace_nmi_enter()
trace_hwlat_callback()
trace_clock_local()
sched_clock()
paravirt_sched_clock()
native_sched_clock()

All must not be traced or kprobed, it will be called from do_debug()
before the kprobe handler.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
arch/x86/include/asm/paravirt.h | 2 +-
arch/x86/kernel/tsc.c | 4 ++--
include/linux/ftrace_irq.h | 4 ++--
kernel/trace/trace_clock.c | 3 ++-
kernel/trace/trace_hwlat.c | 2 +-
5 files changed, 8 insertions(+), 7 deletions(-)

--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -17,7 +17,7 @@
#include <linux/cpumask.h>
#include <asm/frame.h>

-static inline unsigned long long paravirt_sched_clock(void)
+static __always_inline unsigned long long paravirt_sched_clock(void)
{
return PVOP_CALL0(unsigned long long, time.sched_clock);
}
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -207,7 +207,7 @@ static void __init cyc2ns_init_secondary
/*
* Scheduler clock - returns current time in nanosec units.
*/
-u64 native_sched_clock(void)
+noinstr u64 native_sched_clock(void)
{
if (static_branch_likely(&__use_tsc)) {
u64 tsc_now = rdtsc();
@@ -240,7 +240,7 @@ u64 native_sched_clock_from_tsc(u64 tsc)
/* We need to define a real function for sched_clock, to override the
weak default version */
#ifdef CONFIG_PARAVIRT
-unsigned long long sched_clock(void)
+noinstr unsigned long long sched_clock(void)
{
return paravirt_sched_clock();
}
--- a/include/linux/ftrace_irq.h
+++ b/include/linux/ftrace_irq.h
@@ -7,7 +7,7 @@ extern bool trace_hwlat_callback_enabled
extern void trace_hwlat_callback(bool enter);
#endif

-static inline void ftrace_nmi_enter(void)
+static __always_inline void ftrace_nmi_enter(void)
{
#ifdef CONFIG_HWLAT_TRACER
if (trace_hwlat_callback_enabled)
@@ -15,7 +15,7 @@ static inline void ftrace_nmi_enter(void
#endif
}

-static inline void ftrace_nmi_exit(void)
+static __always_inline void ftrace_nmi_exit(void)
{
#ifdef CONFIG_HWLAT_TRACER
if (trace_hwlat_callback_enabled)
--- a/kernel/trace/trace_clock.c
+++ b/kernel/trace/trace_clock.c
@@ -22,6 +22,7 @@
#include <linux/sched/clock.h>
#include <linux/ktime.h>
#include <linux/trace_clock.h>
+#include <linux/kprobes.h>

/*
* trace_clock_local(): the simplest and least coherent tracing clock.
@@ -29,7 +30,7 @@
* Useful for tracing that does not cross to other CPUs nor
* does it go through idle events.
*/
-u64 notrace trace_clock_local(void)
+u64 noinstr trace_clock_local(void)
{
u64 clock;

--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -139,7 +139,7 @@ static void trace_hwlat_sample(struct hw
#define init_time(a, b) (a = b)
#define time_u64(a) a

-void trace_hwlat_callback(bool enter)
+noinstr void trace_hwlat_callback(bool enter)
{
if (smp_processor_id() != nmi_cpu)
return;