hw-breakpoints: Use struct perf_event_attr to define kernel breakpoints
Kernel breakpoints are created using functions in which we pass
breakpoint parameters as individual variables: address, length
and type.
Although it fits well for x86, this just does not scale across
architectures that may support this api later as these may have
more or different needs. Pass in a perf_event_attr structure
instead because it is meant to evolve as much as possible into
a generic hardware breakpoint parameter structure.
Reported-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1259294154-5197-2-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index 5da472e..a03daed 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -28,6 +28,13 @@
.pinned = 1, \
};
+static inline void hw_breakpoint_init(struct perf_event_attr *attr)
+{
+ attr->type = PERF_TYPE_BREAKPOINT;
+ attr->size = sizeof(*attr);
+ attr->pinned = 1;
+}
+
static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
{
return bp->attr.bp_addr;
@@ -59,19 +66,13 @@
* Kernel breakpoints are not associated with any particular thread.
*/
extern struct perf_event *
-register_wide_hw_breakpoint_cpu(unsigned long addr,
- int len,
- int type,
+register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
perf_callback_t triggered,
- int cpu,
- bool active);
+ int cpu);
extern struct perf_event **
-register_wide_hw_breakpoint(unsigned long addr,
- int len,
- int type,
- perf_callback_t triggered,
- bool active);
+register_wide_hw_breakpoint(struct perf_event_attr *attr,
+ perf_callback_t triggered);
extern int register_perf_hw_breakpoint(struct perf_event *bp);
extern int __register_perf_hw_breakpoint(struct perf_event *bp);
@@ -100,18 +101,12 @@
perf_callback_t triggered,
struct task_struct *tsk) { return NULL; }
static inline struct perf_event *
-register_wide_hw_breakpoint_cpu(unsigned long addr,
- int len,
- int type,
+register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
perf_callback_t triggered,
- int cpu,
- bool active) { return NULL; }
+ int cpu) { return NULL; }
static inline struct perf_event **
-register_wide_hw_breakpoint(unsigned long addr,
- int len,
- int type,
- perf_callback_t triggered,
- bool active) { return NULL; }
+register_wide_hw_breakpoint(struct perf_event_attr *attr,
+ perf_callback_t triggered) { return NULL; }
static inline int
register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
static inline int
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 2a47514..cf5ee16 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -339,42 +339,16 @@
}
EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
-static struct perf_event *
-register_kernel_hw_breakpoint_cpu(unsigned long addr,
- int len,
- int type,
- perf_callback_t triggered,
- int cpu,
- bool active)
-{
- DEFINE_BREAKPOINT_ATTR(attr);
-
- attr.bp_addr = addr;
- attr.bp_len = len;
- attr.bp_type = type;
-
- if (!active)
- attr.disabled = 1;
-
- return perf_event_create_kernel_counter(&attr, cpu, -1, triggered);
-}
-
/**
* register_wide_hw_breakpoint - register a wide breakpoint in the kernel
- * @addr: is the memory address that triggers the breakpoint
- * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
- * @type: the type of the access to the memory (read/write/exec)
+ * @attr: breakpoint attributes
* @triggered: callback to trigger when we hit the breakpoint
- * @active: should we activate it while registering it
*
* @return a set of per_cpu pointers to perf events
*/
struct perf_event **
-register_wide_hw_breakpoint(unsigned long addr,
- int len,
- int type,
- perf_callback_t triggered,
- bool active)
+register_wide_hw_breakpoint(struct perf_event_attr *attr,
+ perf_callback_t triggered)
{
struct perf_event **cpu_events, **pevent, *bp;
long err;
@@ -386,8 +360,7 @@
for_each_possible_cpu(cpu) {
pevent = per_cpu_ptr(cpu_events, cpu);
- bp = register_kernel_hw_breakpoint_cpu(addr, len, type,
- triggered, cpu, active);
+ bp = perf_event_create_kernel_counter(attr, cpu, -1, triggered);
*pevent = bp;
diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index c538b15..ddfa0fd 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -42,9 +42,7 @@
struct trace_ksym {
struct perf_event **ksym_hbp;
- unsigned long ksym_addr;
- int type;
- int len;
+ struct perf_event_attr attr;
#ifdef CONFIG_PROFILE_KSYM_TRACER
unsigned long counter;
#endif
@@ -71,7 +69,7 @@
rcu_read_lock();
hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) {
- if ((entry->ksym_addr == hbp_hit_addr) &&
+ if ((entry->attr.bp_addr == hbp_hit_addr) &&
(entry->counter <= MAX_UL_INT)) {
entry->counter++;
break;
@@ -192,14 +190,15 @@
if (!entry)
return -ENOMEM;
- entry->type = op;
- entry->ksym_addr = addr;
- entry->len = HW_BREAKPOINT_LEN_4;
+ hw_breakpoint_init(&entry->attr);
+
+ entry->attr.bp_type = op;
+ entry->attr.bp_addr = addr;
+ entry->attr.bp_len = HW_BREAKPOINT_LEN_4;
ret = -EAGAIN;
- entry->ksym_hbp = register_wide_hw_breakpoint(entry->ksym_addr,
- entry->len, entry->type,
- ksym_hbp_handler, true);
+ entry->ksym_hbp = register_wide_hw_breakpoint(&entry->attr,
+ ksym_hbp_handler);
if (IS_ERR(entry->ksym_hbp)) {
ret = PTR_ERR(entry->ksym_hbp);
@@ -236,12 +235,12 @@
mutex_lock(&ksym_tracer_mutex);
hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
- ret = trace_seq_printf(s, "%pS:", (void *)entry->ksym_addr);
- if (entry->type == HW_BREAKPOINT_R)
+ ret = trace_seq_printf(s, "%pS:", (void *)entry->attr.bp_addr);
+ if (entry->attr.bp_type == HW_BREAKPOINT_R)
ret = trace_seq_puts(s, "r--\n");
- else if (entry->type == HW_BREAKPOINT_W)
+ else if (entry->attr.bp_type == HW_BREAKPOINT_W)
ret = trace_seq_puts(s, "-w-\n");
- else if (entry->type == (HW_BREAKPOINT_W | HW_BREAKPOINT_R))
+ else if (entry->attr.bp_type == (HW_BREAKPOINT_W | HW_BREAKPOINT_R))
ret = trace_seq_puts(s, "rw-\n");
WARN_ON_ONCE(!ret);
}
@@ -317,9 +316,9 @@
ret = -EINVAL;
hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
- if (entry->ksym_addr == ksym_addr) {
+ if (entry->attr.bp_addr == ksym_addr) {
/* Check for malformed request: (6) */
- if (entry->type != op)
+ if (entry->attr.bp_type != op)
changed = 1;
else
goto out;
@@ -328,13 +327,12 @@
}
if (changed) {
unregister_wide_hw_breakpoint(entry->ksym_hbp);
- entry->type = op;
+ entry->attr.bp_type = op;
ret = 0;
if (op > 0) {
entry->ksym_hbp =
- register_wide_hw_breakpoint(entry->ksym_addr,
- entry->len, entry->type,
- ksym_hbp_handler, true);
+ register_wide_hw_breakpoint(&entry->attr,
+ ksym_hbp_handler);
if (IS_ERR(entry->ksym_hbp))
ret = PTR_ERR(entry->ksym_hbp);
else
@@ -489,7 +487,7 @@
entry = hlist_entry(stat, struct trace_ksym, ksym_hlist);
- access_type = entry->type;
+ access_type = entry->attr.bp_type;
switch (access_type) {
case HW_BREAKPOINT_R:
@@ -505,7 +503,7 @@
seq_puts(m, " NA ");
}
- if (lookup_symbol_name(entry->ksym_addr, fn_name) >= 0)
+ if (lookup_symbol_name(entry->attr.bp_addr, fn_name) >= 0)
seq_printf(m, " %-36s", fn_name);
else
seq_printf(m, " %-36s", "<NA>");
diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
index ee7f9fb..2952550 100644
--- a/samples/hw_breakpoint/data_breakpoint.c
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -51,13 +51,13 @@
static int __init hw_break_module_init(void)
{
int ret;
- unsigned long addr;
+ DEFINE_BREAKPOINT_ATTR(attr);
- addr = kallsyms_lookup_name(ksym_name);
+ attr.bp_addr = kallsyms_lookup_name(ksym_name);
+ attr.bp_len = HW_BREAKPOINT_LEN_4;
+ attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
- sample_hbp = register_wide_hw_breakpoint(addr, HW_BREAKPOINT_LEN_4,
- HW_BREAKPOINT_W | HW_BREAKPOINT_R,
- sample_hbp_handler, true);
+ sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler);
if (IS_ERR(sample_hbp)) {
ret = PTR_ERR(sample_hbp);
goto fail;