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

Masami Hiramatsu
2020-05-08T06:20:13Z

On Tue, 05 May 2020 15:16:35 +0200
Thomas Gleixner <tglx@linutronix.de> wrote:

> 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.
>

Looks good to me.

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you,

> 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;
>

--
Masami Hiramatsu <mhiramat@kernel.org>