hw-breakpoints: Use overflow handler instead of the event callback

struct perf_event::event callback was called when a breakpoint
triggers. But this is a rather opaque callback, pretty
tied-only to the breakpoint API and not really integrated into perf
as it triggers even when we don't overflow.

We prefer to use overflow_handler() as it fits into the perf events
rules, being called only when we overflow.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
index 29525500df00..c69cbe9b2426 100644
--- a/samples/hw_breakpoint/data_breakpoint.c
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -41,7 +41,9 @@ module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
 MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
                         " write operations on the kernel symbol");
 
-static void sample_hbp_handler(struct perf_event *temp, void *data)
+static void sample_hbp_handler(struct perf_event *bp, int nmi,
+                               struct perf_sample_data *data,
+                               struct pt_regs *regs)
 {
         printk(KERN_INFO "%s value is changed\n", ksym_name);
         dump_stack();
@@ -51,8 +53,9 @@ static void sample_hbp_handler(struct perf_event *temp, void *data)
 static int __init hw_break_module_init(void)
 {
         int ret;
-        DEFINE_BREAKPOINT_ATTR(attr);
+        struct perf_event_attr attr;
 
+        hw_breakpoint_init(&attr);
         attr.bp_addr = kallsyms_lookup_name(ksym_name);
         attr.bp_len = HW_BREAKPOINT_LEN_4;
         attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;