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Subject[PATCH v3 3/5] register_wide_hw_breakpoint(): modify to accept step_needed arg
Date
arch like ARM64 expects 'step_needed = 1'  in order to use default
single step handler. Therefore, modify register_wide_hw_breakpoint()
implementation,so that we can set this field in struct hw_perf_event to
be used later by arch specific code.

Other arch will not have any affect as they do not use it so far.

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
arch/x86/kernel/kgdb.c | 2 +-
include/linux/hw_breakpoint.h | 4 ++--
kernel/events/hw_breakpoint.c | 4 +++-
samples/hw_breakpoint/data_breakpoint.c | 3 ++-
4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 8e36f249646e..19b24c50a952 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -674,7 +674,7 @@ 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, NULL);
+ breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL, 0);
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/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index b9ac9629bf74..8cbc8ded6d50 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -71,7 +71,7 @@ register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
extern struct perf_event * __percpu *
register_wide_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
- void *context);
+ void *context, int step);

extern int register_perf_hw_breakpoint(struct perf_event *bp);
extern int __register_perf_hw_breakpoint(struct perf_event *bp);
@@ -110,7 +110,7 @@ register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
static inline struct perf_event * __percpu *
register_wide_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
- void *context) { return NULL; }
+ void *context, int step) { return NULL; }
static inline int
register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
static inline int
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 3f8cb1e14588..0dcb175276b2 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -492,13 +492,14 @@ EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
* register_wide_hw_breakpoint - register a wide breakpoint in the kernel
* @attr: breakpoint attributes
* @triggered: callback to trigger when we hit the breakpoint
+ * @step: tells if framework can use default arch step handler
*
* @return a set of per_cpu pointers to perf events
*/
struct perf_event * __percpu *
register_wide_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
- void *context)
+ void *context, int step)
{
struct perf_event * __percpu *cpu_events, *bp;
long err = 0;
@@ -512,6 +513,7 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr,
for_each_online_cpu(cpu) {
bp = perf_event_create_kernel_counter(attr, cpu, NULL,
triggered, context);
+ bp->hw.step_needed = step;
if (IS_ERR(bp)) {
err = PTR_ERR(bp);
break;
diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
index ef7f32291852..f64e59f9fbc6 100644
--- a/samples/hw_breakpoint/data_breakpoint.c
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -60,7 +60,8 @@ 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, NULL);
+ sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler,
+ NULL, 1);
if (IS_ERR((void __force *)sample_hbp)) {
ret = PTR_ERR((void __force *)sample_hbp);
goto fail;
--
2.9.4
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