perf,hw_breakpoint: Initialize hardware api earlier
When using early debugging, the kernel does not initialize the
hw_breakpoint API early enough and causes the late initialization of
the kernel debugger to fail. The boot arguments are:
earlyprintk=vga ekgdboc=kbd kgdbwait
Then simply type "go" at the kdb prompt and boot. The kernel will
later emit the message:
kgdb: Could not allocate hwbreakpoints
And at that point the kernel debugger will cease to work correctly.
The solution is to initialize the hw_breakpoint at the same time that
all the other perf call backs are initialized instead of using a
core_initcall() initialization which happens well after the kernel
debugger can make use of hardware breakpoints.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Ingo Molnar <mingo@elte.hu>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4CD3396D.1090308@windriver.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 517d827..05b7d8c 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -31,6 +31,7 @@
#include <linux/kernel_stat.h>
#include <linux/perf_event.h>
#include <linux/ftrace_event.h>
+#include <linux/hw_breakpoint.h>
#include <asm/irq_regs.h>
@@ -6295,6 +6296,8 @@
void __init perf_event_init(void)
{
+ int ret;
+
perf_event_init_all_cpus();
init_srcu_struct(&pmus_srcu);
perf_pmu_register(&perf_swevent);
@@ -6302,4 +6305,7 @@
perf_pmu_register(&perf_task_clock);
perf_tp_register();
perf_cpu_notifier(perf_cpu_notify);
+
+ ret = init_hw_breakpoint();
+ WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
}