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Merge tag 'trace-ipi-tracepoints' of git://git.kernel.org/pub/scm/lin…
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…ux/kernel/git/rostedt/linux-trace

Pull IPI tracepoints for ARM from Steven Rostedt:
 "Nicolas Pitre added generic tracepoints for tracing IPIs and updated
  the arm and arm64 architectures.  It required some minor updates to
  the generic tracepoint system, so it had to wait for me to implement
  them"

* tag 'trace-ipi-tracepoints' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ARM64: add IPI tracepoints
  ARM: add IPI tracepoints
  tracepoint: add generic tracepoint definitions for IPI tracing
  tracing: Do not do anything special with tracepoint_string when tracing is disabled
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Linus Torvalds committed Aug 10, 2014
2 parents fc335c1 + 45ed695 commit c23190c
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Showing 5 changed files with 214 additions and 88 deletions.
70 changes: 42 additions & 28 deletions arch/arm/kernel/smp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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"),
Expand All @@ -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;
Expand All @@ -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)
{
Expand Down Expand Up @@ -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:
Expand Down Expand Up @@ -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);
}

Expand Down
65 changes: 39 additions & 26 deletions arch/arm64/kernel/smp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,9 @@
#include <asm/tlbflush.h>
#include <asm/ptrace.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
Expand Down Expand Up @@ -313,8 +316,6 @@ void __init smp_prepare_boot_cpu(void)
set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
}

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

/*
* Enumerate the possible CPU set from the device tree and build the
* cpu logical map array containing MPIDR values related to logical
Expand Down Expand Up @@ -469,32 +470,15 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
}
}

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

void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
{
smp_cross_call = fn;
__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_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 (smp_cross_call)
smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
}
#endif

static const char *ipi_types[NR_IPI] = {
#define S(x,s) [x - IPI_RESCHEDULE] = s
static const char *ipi_types[NR_IPI] __tracepoint_string = {
#define S(x,s) [x] = s
S(IPI_RESCHEDULE, "Rescheduling interrupts"),
S(IPI_CALL_FUNC, "Function call interrupts"),
S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
Expand All @@ -503,12 +487,18 @@ static const char *ipi_types[NR_IPI] = {
S(IPI_IRQ_WORK, "IRQ work 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;

for (i = 0; i < NR_IPI; i++) {
seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i + IPI_RESCHEDULE,
seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
prec >= 4 ? " " : "");
for_each_online_cpu(cpu)
seq_printf(p, "%10u ",
Expand All @@ -528,6 +518,24 @@ 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_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 (__smp_cross_call)
smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
}
#endif

static DEFINE_RAW_SPINLOCK(stop_lock);

/*
Expand Down Expand Up @@ -559,8 +567,10 @@ 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 >= IPI_RESCHEDULE && ipinr < IPI_RESCHEDULE + NR_IPI)
__inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_RESCHEDULE]);
if ((unsigned)ipinr < NR_IPI) {
trace_ipi_entry(ipi_types[ipinr]);
__inc_irq_stat(cpu, ipi_irqs[ipinr]);
}

switch (ipinr) {
case IPI_RESCHEDULE:
Expand Down Expand Up @@ -605,6 +615,9 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
break;
}

if ((unsigned)ipinr < NR_IPI)
trace_ipi_exit(ipi_types[ipinr]);
set_irq_regs(old_regs);
}

Expand Down
34 changes: 0 additions & 34 deletions include/linux/ftrace_event.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -571,40 +571,6 @@ do { \
__trace_printk(ip, fmt, ##args); \
} while (0)

/**
* tracepoint_string - register constant persistent string to trace system
* @str - a constant persistent string that will be referenced in tracepoints
*
* If constant strings are being used in tracepoints, it is faster and
* more efficient to just save the pointer to the string and reference
* that with a printf "%s" instead of saving the string in the ring buffer
* and wasting space and time.
*
* The problem with the above approach is that userspace tools that read
* the binary output of the trace buffers do not have access to the string.
* Instead they just show the address of the string which is not very
* useful to users.
*
* With tracepoint_string(), the string will be registered to the tracing
* system and exported to userspace via the debugfs/tracing/printk_formats
* file that maps the string address to the string text. This way userspace
* tools that read the binary buffers have a way to map the pointers to
* the ASCII strings they represent.
*
* The @str used must be a constant string and persistent as it would not
* make sense to show a string that no longer exists. But it is still fine
* to be used with modules, because when modules are unloaded, if they
* had tracepoints, the ring buffers are cleared too. As long as the string
* does not change during the life of the module, it is fine to use
* tracepoint_string() within a module.
*/
#define tracepoint_string(str) \
({ \
static const char *___tp_str __tracepoint_string = str; \
___tp_str; \
})
#define __tracepoint_string __attribute__((section("__tracepoint_str")))

#ifdef CONFIG_PERF_EVENTS
struct perf_event;

Expand Down
44 changes: 44 additions & 0 deletions include/linux/tracepoint.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -249,6 +249,50 @@ extern void syscall_unregfunc(void);

#endif /* CONFIG_TRACEPOINTS */

#ifdef CONFIG_TRACING
/**
* tracepoint_string - register constant persistent string to trace system
* @str - a constant persistent string that will be referenced in tracepoints
*
* If constant strings are being used in tracepoints, it is faster and
* more efficient to just save the pointer to the string and reference
* that with a printf "%s" instead of saving the string in the ring buffer
* and wasting space and time.
*
* The problem with the above approach is that userspace tools that read
* the binary output of the trace buffers do not have access to the string.
* Instead they just show the address of the string which is not very
* useful to users.
*
* With tracepoint_string(), the string will be registered to the tracing
* system and exported to userspace via the debugfs/tracing/printk_formats
* file that maps the string address to the string text. This way userspace
* tools that read the binary buffers have a way to map the pointers to
* the ASCII strings they represent.
*
* The @str used must be a constant string and persistent as it would not
* make sense to show a string that no longer exists. But it is still fine
* to be used with modules, because when modules are unloaded, if they
* had tracepoints, the ring buffers are cleared too. As long as the string
* does not change during the life of the module, it is fine to use
* tracepoint_string() within a module.
*/
#define tracepoint_string(str) \
({ \
static const char *___tp_str __tracepoint_string = str; \
___tp_str; \
})
#define __tracepoint_string __attribute__((section("__tracepoint_str")))
#else
/*
* tracepoint_string() is used to save the string address for userspace
* tracing tools. When tracing isn't configured, there's no need to save
* anything.
*/
# define tracepoint_string(str) str
# define __tracepoint_string
#endif

/*
* The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
* (void). "void" is a special value in a function prototype and can
Expand Down
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