From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v4 05/27] x86: Replace ist_enter() with nmi_enter() Date: Wed, 26 Feb 2020 11:27:58 +0100 Message-ID: <20200226102758.GV18400@hirez.programming.kicks-ass.net> References: <20200221133416.777099322@infradead.org> <20200221134215.328642621@infradead.org> <20200221202246.GA14897@hirez.programming.kicks-ass.net> <20200224104346.GJ14946@hirez.programming.kicks-ass.net> <20200224112708.4f307ba3@gandalf.local.home> <20200224163409.GJ18400@hirez.programming.kicks-ass.net> <20200224114754.0fb798c1@gandalf.local.home> <20200224213139.GO11457@worktop.programming.kicks-ass.net> <20200224170231.3807931d@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200224170231.3807931d@gandalf.local.home> Sender: linux-kernel-owner@vger.kernel.org To: Steven Rostedt Cc: Andy Lutomirski , LKML , linux-arch , Ingo Molnar , Joel Fernandes , Greg KH , gustavo@embeddedor.com, Thomas Gleixner , paulmck@kernel.org, Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Tony Luck , Frederic Weisbecker , Dan Carpenter , Masami Hiramatsu List-Id: linux-arch.vger.kernel.org On Mon, Feb 24, 2020 at 05:02:31PM -0500, Steven Rostedt wrote: > The other is for the hwlat detector that measures the time it was in an > NMI, as NMIs appear as a hardware latency too. Yeah,.. I hate that one. But I ended up with this patch. And yes, I know some of those notrace annotations are strictly unnessecary due to Makefile crap, but having them is _SO_ much easier. --- Subject: x86,tracing: Robustify ftrace_nmi_enter() From: Peter Zijlstra Date: Mon Feb 24 23:40:29 CET 2020 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) --- arch/x86/include/asm/paravirt.h | 2 +- arch/x86/kernel/tsc.c | 7 +++++-- include/linux/ftrace_irq.h | 4 ++-- kernel/trace/trace_clock.c | 2 ++ kernel/trace/trace_hwlat.c | 4 +++- 5 files changed, 13 insertions(+), 6 deletions(-) --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -17,7 +17,7 @@ #include #include -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 @@ -14,6 +14,7 @@ #include #include #include +#include #include #include @@ -207,7 +208,7 @@ static void __init cyc2ns_init_secondary /* * Scheduler clock - returns current time in nanosec units. */ -u64 native_sched_clock(void) +notrace u64 native_sched_clock(void) { if (static_branch_likely(&__use_tsc)) { u64 tsc_now = rdtsc(); @@ -228,6 +229,7 @@ u64 native_sched_clock(void) /* No locking but a rare wrong value is not a big deal: */ return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); } +NOKPROBE_SYMBOL(native_sched_clock); /* * Generate a sched_clock if you already have a TSC value. @@ -240,10 +242,11 @@ 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) +notrace unsigned long long sched_clock(void) { return paravirt_sched_clock(); } +NOKPROBE_SYMBOL(sched_clock); bool using_native_sched_clock(void) { --- 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 #include #include +#include /* * trace_clock_local(): the simplest and least coherent tracing clock. @@ -44,6 +45,7 @@ u64 notrace trace_clock_local(void) return clock; } +NOKPROBE_SYMBOL(trace_clock_local); EXPORT_SYMBOL_GPL(trace_clock_local); /* --- a/kernel/trace/trace_hwlat.c +++ b/kernel/trace/trace_hwlat.c @@ -43,6 +43,7 @@ #include #include #include +#include #include "trace.h" static struct trace_array *hwlat_trace; @@ -137,7 +138,7 @@ 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) +notrace void trace_hwlat_callback(bool enter) { if (smp_processor_id() != nmi_cpu) return; @@ -156,6 +157,7 @@ void trace_hwlat_callback(bool enter) if (enter) nmi_count++; } +NOKPROBE_SYMBOL(trace_hwlat_callback); /** * get_sample - sample the CPU TSC and look for likely hardware latencies From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from merlin.infradead.org ([205.233.59.134]:52134 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726425AbgBZK2p (ORCPT ); Wed, 26 Feb 2020 05:28:45 -0500 Date: Wed, 26 Feb 2020 11:27:58 +0100 From: Peter Zijlstra Subject: Re: [PATCH v4 05/27] x86: Replace ist_enter() with nmi_enter() Message-ID: <20200226102758.GV18400@hirez.programming.kicks-ass.net> References: <20200221133416.777099322@infradead.org> <20200221134215.328642621@infradead.org> <20200221202246.GA14897@hirez.programming.kicks-ass.net> <20200224104346.GJ14946@hirez.programming.kicks-ass.net> <20200224112708.4f307ba3@gandalf.local.home> <20200224163409.GJ18400@hirez.programming.kicks-ass.net> <20200224114754.0fb798c1@gandalf.local.home> <20200224213139.GO11457@worktop.programming.kicks-ass.net> <20200224170231.3807931d@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200224170231.3807931d@gandalf.local.home> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Steven Rostedt Cc: Andy Lutomirski , LKML , linux-arch , Ingo Molnar , Joel Fernandes , Greg KH , gustavo@embeddedor.com, Thomas Gleixner , paulmck@kernel.org, Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Tony Luck , Frederic Weisbecker , Dan Carpenter , Masami Hiramatsu Message-ID: <20200226102758.JgO0kKWak5SFuyOxl2swRUxcXMTh7bwxAnetHWQ4Sl4@z> On Mon, Feb 24, 2020 at 05:02:31PM -0500, Steven Rostedt wrote: > The other is for the hwlat detector that measures the time it was in an > NMI, as NMIs appear as a hardware latency too. Yeah,.. I hate that one. But I ended up with this patch. And yes, I know some of those notrace annotations are strictly unnessecary due to Makefile crap, but having them is _SO_ much easier. --- Subject: x86,tracing: Robustify ftrace_nmi_enter() From: Peter Zijlstra Date: Mon Feb 24 23:40:29 CET 2020 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) --- arch/x86/include/asm/paravirt.h | 2 +- arch/x86/kernel/tsc.c | 7 +++++-- include/linux/ftrace_irq.h | 4 ++-- kernel/trace/trace_clock.c | 2 ++ kernel/trace/trace_hwlat.c | 4 +++- 5 files changed, 13 insertions(+), 6 deletions(-) --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -17,7 +17,7 @@ #include #include -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 @@ -14,6 +14,7 @@ #include #include #include +#include #include #include @@ -207,7 +208,7 @@ static void __init cyc2ns_init_secondary /* * Scheduler clock - returns current time in nanosec units. */ -u64 native_sched_clock(void) +notrace u64 native_sched_clock(void) { if (static_branch_likely(&__use_tsc)) { u64 tsc_now = rdtsc(); @@ -228,6 +229,7 @@ u64 native_sched_clock(void) /* No locking but a rare wrong value is not a big deal: */ return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); } +NOKPROBE_SYMBOL(native_sched_clock); /* * Generate a sched_clock if you already have a TSC value. @@ -240,10 +242,11 @@ 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) +notrace unsigned long long sched_clock(void) { return paravirt_sched_clock(); } +NOKPROBE_SYMBOL(sched_clock); bool using_native_sched_clock(void) { --- 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 #include #include +#include /* * trace_clock_local(): the simplest and least coherent tracing clock. @@ -44,6 +45,7 @@ u64 notrace trace_clock_local(void) return clock; } +NOKPROBE_SYMBOL(trace_clock_local); EXPORT_SYMBOL_GPL(trace_clock_local); /* --- a/kernel/trace/trace_hwlat.c +++ b/kernel/trace/trace_hwlat.c @@ -43,6 +43,7 @@ #include #include #include +#include #include "trace.h" static struct trace_array *hwlat_trace; @@ -137,7 +138,7 @@ 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) +notrace void trace_hwlat_callback(bool enter) { if (smp_processor_id() != nmi_cpu) return; @@ -156,6 +157,7 @@ void trace_hwlat_callback(bool enter) if (enter) nmi_count++; } +NOKPROBE_SYMBOL(trace_hwlat_callback); /** * get_sample - sample the CPU TSC and look for likely hardware latencies