Commit b6c5a71d authored by Paul Mackerras's avatar Paul Mackerras Committed by Ingo Molnar
Browse files

perf_counter: abstract wakeup flag setting in core to fix powerpc build 



Impact: build fix for powerpc

Commit bd753921015e7905 ("perf_counter: software counter event
infrastructure") introduced a use of TIF_PERF_COUNTERS into the core
perfcounter code.  This breaks the build on powerpc because we use
a flag in a per-cpu area to signal wakeups on powerpc rather than
a thread_info flag, because the thread_info flags have to be
manipulated with atomic operations and are thus slower than per-cpu
flags.

This fixes the by changing the core to use an abstracted
set_perf_counter_pending() function, which is defined on x86 to set
the TIF_PERF_COUNTERS flag and on powerpc to set the per-cpu flag
(paca->perf_counter_pending).  It changes the previous powerpc
definition of set_perf_counter_pending to not take an argument and
adds a clear_perf_counter_pending, so as to simplify the definition
on x86.

On x86, set_perf_counter_pending() is defined as a macro.  Defining
it as a static inline in arch/x86/include/asm/perf_counters.h causes
compile failures because <asm/perf_counters.h> gets included early in
<linux/sched.h>, and the definitions of set_tsk_thread_flag etc. are
therefore not available in <asm/perf_counters.h>.  (On powerpc this
problem is avoided by defining set_perf_counter_pending etc. in
<asm/hw_irq.h>.)

Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 7bb497bd

arch/powerpc/include/asm/hw_irq.h

+11 −3
Original line number Diff line number Diff line
@@ -142,10 +142,17 @@ static inline unsigned long get_perf_counter_pending(void) 
	return x;

}



static inline void set_perf_counter_pending(int x)

static inline void set_perf_counter_pending(void)

{

	asm volatile("stb %0,%1(13)" : :

		"r" (x),

		"r" (1),

		"i" (offsetof(struct paca_struct, perf_counter_pending)));

}



static inline void clear_perf_counter_pending(void)

{

	asm volatile("stb %0,%1(13)" : :

		"r" (0),

		"i" (offsetof(struct paca_struct, perf_counter_pending)));

}
@@ -158,7 +165,8 @@ static inline unsigned long get_perf_counter_pending(void) 
	return 0;

}



static inline void set_perf_counter_pending(int x) {}

static inline void set_perf_counter_pending(void) {}

static inline void clear_perf_counter_pending(void) {}

static inline void perf_counter_do_pending(void) {}

#endif /* CONFIG_PERF_COUNTERS */

arch/powerpc/kernel/irq.c

+3 −8
Original line number Diff line number Diff line
@@ -104,13 +104,6 @@ static inline notrace void set_soft_enabled(unsigned long enable) 
	: : "r" (enable), "i" (offsetof(struct paca_struct, soft_enabled)));

}



#ifdef CONFIG_PERF_COUNTERS

notrace void __weak perf_counter_do_pending(void)

{

	set_perf_counter_pending(0);

}

#endif



notrace void raw_local_irq_restore(unsigned long en)

{

	/*
@@ -142,8 +135,10 @@ notrace void raw_local_irq_restore(unsigned long en) 
			iseries_handle_interrupts();

	}



	if (get_perf_counter_pending())

	if (get_perf_counter_pending()) {

		clear_perf_counter_pending();

		perf_counter_do_pending();

	}



	/*

	 * if (get_paca()->hard_enabled) return;

arch/powerpc/kernel/perf_counter.c

+1 −2
Original line number Diff line number Diff line
@@ -653,7 +653,6 @@ void perf_counter_do_pending(void) 
	struct cpu_hw_counters *cpuhw = &__get_cpu_var(cpu_hw_counters);

	struct perf_counter *counter;



	set_perf_counter_pending(0);

	for (i = 0; i < cpuhw->n_counters; ++i) {

		counter = cpuhw->counter[i];

		if (counter && counter->wakeup_pending) {
@@ -811,7 +810,7 @@ static void perf_counter_interrupt(struct pt_regs *regs) 
			perf_counter_do_pending();

			irq_exit();

		} else {

			set_perf_counter_pending(1);

			set_perf_counter_pending();

		}

	}

}

arch/x86/include/asm/perf_counter.h

+3 −0
Original line number Diff line number Diff line
@@ -84,6 +84,9 @@ union cpuid10_edx { 
#define MSR_ARCH_PERFMON_FIXED_CTR2			0x30b

#define X86_PMC_IDX_FIXED_BUS_CYCLES			(X86_PMC_IDX_FIXED + 2)



#define set_perf_counter_pending()	\

		set_tsk_thread_flag(current, TIF_PERF_COUNTERS);



#ifdef CONFIG_PERF_COUNTERS

extern void init_hw_perf_counters(void);

extern void perf_counters_lapic_init(int nmi);

kernel/perf_counter.c

+1 −1
Original line number Diff line number Diff line
@@ -1433,7 +1433,7 @@ static void perf_swcounter_interrupt(struct perf_counter *counter, 


	if (nmi) {

		counter->wakeup_pending = 1;

		set_tsk_thread_flag(current, TIF_PERF_COUNTERS);

		set_perf_counter_pending();

	} else

		wake_up(&counter->waitq);

}

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