The perf_event overflow handler does not receive any caller-derived
argument, so many callers need to resort to looking up the perf_event
in their local data structure. This is ugly and doesn't scale if a
single callback services many perf_events.
Fix by adding a context parameter to perf_event_create_kernel_counter()
(and derived hardware breakpoints APIs) and storing it in the perf_event.
The field can be accessed from the callback as event->overflow_handler_context.
All callers are updated.
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
---
v2: drop context from the callback signature; the callback can access it
via the perf_event parameter.
arch/arm/kernel/ptrace.c | 3 ++-
arch/powerpc/kernel/ptrace.c | 2 +-
arch/sh/kernel/ptrace_32.c | 3 ++-
arch/x86/kernel/kgdb.c | 2 +-
arch/x86/kernel/ptrace.c | 3 ++-
drivers/oprofile/oprofile_perf.c | 2 +-
include/linux/hw_breakpoint.h | 10 ++++++++--
include/linux/perf_event.h | 4 +++-
kernel/events/core.c | 21 +++++++++++++++------
kernel/events/hw_breakpoint.c | 10 +++++++---
kernel/watchdog.c | 2 +-
samples/hw_breakpoint/data_breakpoint.c | 2 +-
12 files changed, 44 insertions(+), 20 deletions(-)
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 9726006..4911c94 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -479,7 +479,8 @@ static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)
attr.bp_type = type;
attr.disabled = 1;
- return register_user_hw_breakpoint(&attr, ptrace_hbptriggered, tsk);
+ return register_user_hw_breakpoint(&attr, ptrace_hbptriggered, NULL,
+ tsk);
}
static int ptrace_gethbpregs(struct task_struct *tsk, long num,
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index cb22024..5249308 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -973,7 +973,7 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
&attr.bp_type);
thread->ptrace_bps[0] = bp = register_user_hw_breakpoint(&attr,
- ptrace_triggered, task);
+ ptrace_triggered, NULL, task);
if (IS_ERR(bp)) {
thread->ptrace_bps[0] = NULL;
ptrace_put_breakpoints(task);
diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index 3d7b209..930312f 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -91,7 +91,8 @@ static int set_single_step(struct task_struct *tsk, unsigned long addr)
attr.bp_len = HW_BREAKPOINT_LEN_2;
attr.bp_type = HW_BREAKPOINT_R;
- bp = register_user_hw_breakpoint(&attr, ptrace_triggered, tsk);
+ bp = register_user_hw_breakpoint(&attr, ptrace_triggered,
+ NULL, tsk);
if (IS_ERR(bp))
return PTR_ERR(bp);
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 5f9ecff..473ab53 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -638,7 +638,7 @@ void kgdb_arch_late(void)
for (i = 0; i < HBP_NUM; i++) {
if (breakinfo[i].pev)
continue;
- breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
+ breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL);
if (IS_ERR((void * __force)breakinfo[i].pev)) {
printk(KERN_ERR "kgdb: Could not allocate hw"
"breakpoints\nDisabling the kernel debugger\n");
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 807c2a2..28092ae 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -715,7 +715,8 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
attr.bp_type = HW_BREAKPOINT_W;
attr.disabled = 1;
- bp = register_user_hw_breakpoint(&attr, ptrace_triggered, tsk);
+ bp = register_user_hw_breakpoint(&attr, ptrace_triggered,
+ NULL, tsk);
/*
* CHECKME: the previous code returned -EIO if the addr wasn't
diff --git a/drivers/oprofile/oprofile_perf.c b/drivers/oprofile/oprofile_perf.c
index 9046f7b..59acf9e 100644
--- a/drivers/oprofile/oprofile_perf.c
+++ b/drivers/oprofile/oprofile_perf.c
@@ -79,7 +79,7 @@ static int op_create_counter(int cpu, int event)
pevent = perf_event_create_kernel_counter(&counter_config[event].attr,
cpu, NULL,
- op_overflow_handler);
+ op_overflow_handler, NULL);
if (IS_ERR(pevent))
return PTR_ERR(pevent);
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index d1e55fe..6ae9c63 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -73,6 +73,7 @@ static inline unsigned long hw_breakpoint_len(struct perf_event *bp)
extern struct perf_event *
register_user_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
+ void *context,
struct task_struct *tsk);
/* FIXME: only change from the attr, and don't unregister */
@@ -85,11 +86,13 @@ modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr);
extern struct perf_event *
register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
+ void *context,
int cpu);
extern struct perf_event * __percpu *
register_wide_hw_breakpoint(struct perf_event_attr *attr,
- perf_overflow_handler_t triggered);
+ perf_overflow_handler_t triggered,
+ void *context);
extern int register_perf_hw_breakpoint(struct perf_event *bp);
extern int __register_perf_hw_breakpoint(struct perf_event *bp);
@@ -115,6 +118,7 @@ static inline int __init init_hw_breakpoint(void) { return 0; }
static inline struct perf_event *
register_user_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
+ void *context,
struct task_struct *tsk) { return NULL; }
static inline int
modify_user_hw_breakpoint(struct perf_event *bp,
@@ -122,10 +126,12 @@ modify_user_hw_breakpoint(struct perf_event *bp,
static inline struct perf_event *
register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
+ void *context,
int cpu) { return NULL; }
static inline struct perf_event * __percpu *
register_wide_hw_breakpoint(struct perf_event_attr *attr,
- perf_overflow_handler_t triggered) { return NULL; }
+ perf_overflow_handler_t triggered,
+ void *context) { return NULL; }
static inline int
register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
static inline int
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index e0786e3..40264b5 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -855,6 +855,7 @@ struct perf_event {
u64 id;
perf_overflow_handler_t overflow_handler;
+ void *overflow_handler_context;
#ifdef CONFIG_EVENT_TRACING
struct ftrace_event_call *tp_event;
@@ -978,7 +979,8 @@ extern struct perf_event *
perf_event_create_kernel_counter(struct perf_event_attr *attr,
int cpu,
struct task_struct *task,
- perf_overflow_handler_t callback);
+ perf_overflow_handler_t callback,
+ void *context);
extern u64 perf_event_read_value(struct perf_event *event,
u64 *enabled, u64 *running);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9efe710..6dd4819 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6150,7 +6150,8 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
struct task_struct *task,
struct perf_event *group_leader,
struct perf_event *parent_event,
- perf_overflow_handler_t overflow_handler)
+ perf_overflow_handler_t overflow_handler,
+ void *context)
{
struct pmu *pmu;
struct perf_event *event;
@@ -6208,10 +6209,13 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
#endif
}
- if (!overflow_handler && parent_event)
+ if (!overflow_handler && parent_event) {
overflow_handler = parent_event->overflow_handler;
+ context = parent_event->overflow_handler_context;
+ }
event->overflow_handler = overflow_handler;
+ event->overflow_handler_context = context;
if (attr->disabled)
event->state = PERF_EVENT_STATE_OFF;
@@ -6478,7 +6482,8 @@ SYSCALL_DEFINE5(perf_event_open,
}
}
- event = perf_event_alloc(&attr, cpu, task, group_leader, NULL, NULL);
+ event = perf_event_alloc(&attr, cpu, task, group_leader, NULL,
+ NULL, NULL);
if (IS_ERR(event)) {
err = PTR_ERR(event);
goto err_task;
@@ -6663,7 +6668,8 @@ err_fd:
struct perf_event *
perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
struct task_struct *task,
- perf_overflow_handler_t overflow_handler)
+ perf_overflow_handler_t overflow_handler,
+ void *context)
{
struct perf_event_context *ctx;
struct perf_event *event;
@@ -6673,7 +6679,8 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
* Get the target context (task or percpu):
*/
- event = perf_event_alloc(attr, cpu, task, NULL, NULL, overflow_handler);
+ event = perf_event_alloc(attr, cpu, task, NULL, NULL,
+ overflow_handler, context);
if (IS_ERR(event)) {
err = PTR_ERR(event);
goto err;
@@ -6957,7 +6964,7 @@ inherit_event(struct perf_event *parent_event,
parent_event->cpu,
child,
group_leader, parent_event,
- NULL);
+ NULL, NULL);
if (IS_ERR(child_event))
return child_event;
get_ctx(child_ctx);
@@ -6984,6 +6991,8 @@ inherit_event(struct perf_event *parent_event,
child_event->ctx = child_ctx;
child_event->overflow_handler = parent_event->overflow_handler;
+ child_event->overflow_handler_context
+ = parent_event->overflow_handler_context;
/*
* Precalculate sample_data sizes
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 086adf2..b7971d6 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -431,9 +431,11 @@ int register_perf_hw_breakpoint(struct perf_event *bp)
struct perf_event *
register_user_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
+ void *context,
struct task_struct *tsk)
{
- return perf_event_create_kernel_counter(attr, -1, tsk, triggered);
+ return perf_event_create_kernel_counter(attr, -1, tsk, triggered,
+ context);
}
EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
@@ -502,7 +504,8 @@ EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
*/
struct perf_event * __percpu *
register_wide_hw_breakpoint(struct perf_event_attr *attr,
- perf_overflow_handler_t triggered)
+ perf_overflow_handler_t triggered,
+ void *context)
{
struct perf_event * __percpu *cpu_events, **pevent, *bp;
long err;
@@ -515,7 +518,8 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr,
get_online_cpus();
for_each_online_cpu(cpu) {
pevent = per_cpu_ptr(cpu_events, cpu);
- bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered);
+ bp = perf_event_create_kernel_counter(attr, cpu, NULL,
+ triggered, context);
*pevent = bp;
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 3d0c56a..0aaa41f 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -371,7 +371,7 @@ static int watchdog_nmi_enable(int cpu)
/* Try to register using hardware perf events */
wd_attr = &wd_hw_attr;
wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
- event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);
+ event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
if (!IS_ERR(event)) {
printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
goto out_save;
diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
index 0636539..2b85831 100644
--- a/samples/hw_breakpoint/data_breakpoint.c
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -60,7 +60,7 @@ static int __init hw_break_module_init(void)
attr.bp_len = HW_BREAKPOINT_LEN_4;
attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
- sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler);
+ sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler, NULL);
if (IS_ERR((void __force *)sample_hbp)) {
ret = PTR_ERR((void __force *)sample_hbp);
goto fail;
--
1.7.5.3
--
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