Re: [PATCH v2 3/5] ARM: add IPI tracepoints

From: Daniel Lezcano
Date: Mon Jul 28 2014 - 01:34:57 EST


On 07/25/2014 10:05 PM, Nicolas Pitre wrote:
The strings used to list IPIs in /proc/interrupts are reused for tracing
purposes.

While at it, prevent a negative ipinr from escaping the range check
in handle_IPI().

Signed-off-by: Nicolas Pitre <nico@xxxxxxxxxx>
Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>

---
arch/arm/kernel/smp.c | 70 ++++++++++++++++++++++++++++++---------------------
1 file changed, 42 insertions(+), 28 deletions(-)

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 7c4fada440..9388a3d479 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -47,6 +47,9 @@
#include <asm/mach/arch.h>
#include <asm/mpu.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/ipi.h>
+
/*
* as from 2.5, kernels no longer have an init_tasks structure
* so we need some other way of telling a new secondary core
@@ -430,38 +433,15 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
}
}

-static void (*smp_cross_call)(const struct cpumask *, unsigned int);
+static void (*__smp_cross_call)(const struct cpumask *, unsigned int);

void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
{
- if (!smp_cross_call)
- smp_cross_call = fn;
-}
-
-void arch_send_call_function_ipi_mask(const struct cpumask *mask)
-{
- smp_cross_call(mask, IPI_CALL_FUNC);
-}
-
-void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
-{
- smp_cross_call(mask, IPI_WAKEUP);
-}
-
-void arch_send_call_function_single_ipi(int cpu)
-{
- smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
+ if (!__smp_cross_call)
+ __smp_cross_call = fn;
}

-#ifdef CONFIG_IRQ_WORK
-void arch_irq_work_raise(void)
-{
- if (is_smp())
- smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
-}
-#endif
-
-static const char *ipi_types[NR_IPI] = {
+static const char *ipi_types[NR_IPI] __tracepoint_string = {
#define S(x,s) [x] = s
S(IPI_WAKEUP, "CPU wakeup interrupts"),
S(IPI_TIMER, "Timer broadcast interrupts"),
@@ -473,6 +453,12 @@ static const char *ipi_types[NR_IPI] = {
S(IPI_COMPLETION, "completion interrupts"),
};

+static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
+{
+ trace_ipi_raise(target, ipi_types[ipinr]);
+ __smp_cross_call(target, ipinr);
+}
+
void show_ipi_list(struct seq_file *p, int prec)
{
unsigned int cpu, i;
@@ -499,6 +485,29 @@ u64 smp_irq_stat_cpu(unsigned int cpu)
return sum;
}

+void arch_send_call_function_ipi_mask(const struct cpumask *mask)
+{
+ smp_cross_call(mask, IPI_CALL_FUNC);
+}
+
+void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
+{
+ smp_cross_call(mask, IPI_WAKEUP);
+}
+
+void arch_send_call_function_single_ipi(int cpu)
+{
+ smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
+}
+
+#ifdef CONFIG_IRQ_WORK
+void arch_irq_work_raise(void)
+{
+ if (is_smp())
+ smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
+}
+#endif
+
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
void tick_broadcast(const struct cpumask *mask)
{
@@ -556,8 +565,10 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
unsigned int cpu = smp_processor_id();
struct pt_regs *old_regs = set_irq_regs(regs);

- if (ipinr < NR_IPI)
+ if ((unsigned)ipinr < NR_IPI) {
+ trace_ipi_entry(ipi_types[ipinr]);
__inc_irq_stat(cpu, ipi_irqs[ipinr]);
+ }

switch (ipinr) {
case IPI_WAKEUP:
@@ -612,6 +623,9 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
cpu, ipinr);
break;
}
+
+ if ((unsigned)ipinr < NR_IPI)
+ trace_ipi_exit(ipi_types[ipinr]);
set_irq_regs(old_regs);
}




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