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>

2 files changed, 8 insertions, 6 deletions

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index d42f65ac4927..05d5fec64a94 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -362,8 +362,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
                 return ret;
         }
 
-        if (bp->callback)
-                ret = arch_store_info(bp);
+        ret = arch_store_info(bp);
 
         if (ret < 0)
                 return ret;
@@ -519,7 +518,7 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
                         break;
                 }
 
-                (bp->callback)(bp, args->regs);
+                perf_bp_event(bp, args->regs);
 
                 rcu_read_unlock();
         }
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index dbb395572ae2..b361d28061d0 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -555,7 +555,9 @@ static int genregs_set(struct task_struct *target,
         return ret;
 }
 
-static void ptrace_triggered(struct perf_event *bp, void *data)
+static void ptrace_triggered(struct perf_event *bp, int nmi,
+                             struct perf_sample_data *data,
+                             struct pt_regs *regs)
 {
         int i;
         struct thread_struct *thread = &(current->thread);
@@ -599,7 +601,7 @@ ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
 {
         int err;
         int gen_len, gen_type;
-        DEFINE_BREAKPOINT_ATTR(attr);
+        struct perf_event_attr attr;
 
         /*
          * We shoud have at least an inactive breakpoint at this
@@ -721,9 +723,10 @@ static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
 {
         struct perf_event *bp;
         struct thread_struct *t = &tsk->thread;
-        DEFINE_BREAKPOINT_ATTR(attr);
+        struct perf_event_attr attr;
 
         if (!t->ptrace_bps[nr]) {
+                hw_breakpoint_init(&attr);
                 /*
                  * Put stub len and type to register (reserve) an inactive but
                  * correct bp