Commit 3c502e7a authored by Jason Wessel's avatar Jason Wessel Committed by Frederic Weisbecker

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: default avatarJason 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: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 6c0aca28
...@@ -33,6 +33,8 @@ enum bp_type_idx { ...@@ -33,6 +33,8 @@ enum bp_type_idx {
#ifdef CONFIG_HAVE_HW_BREAKPOINT #ifdef CONFIG_HAVE_HW_BREAKPOINT
extern int __init init_hw_breakpoint(void);
static inline void hw_breakpoint_init(struct perf_event_attr *attr) static inline void hw_breakpoint_init(struct perf_event_attr *attr)
{ {
memset(attr, 0, sizeof(*attr)); memset(attr, 0, sizeof(*attr));
...@@ -108,6 +110,8 @@ static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp) ...@@ -108,6 +110,8 @@ static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
#else /* !CONFIG_HAVE_HW_BREAKPOINT */ #else /* !CONFIG_HAVE_HW_BREAKPOINT */
static inline int __init init_hw_breakpoint(void) { return 0; }
static inline struct perf_event * static inline struct perf_event *
register_user_hw_breakpoint(struct perf_event_attr *attr, register_user_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered, perf_overflow_handler_t triggered,
......
...@@ -620,7 +620,7 @@ static struct pmu perf_breakpoint = { ...@@ -620,7 +620,7 @@ static struct pmu perf_breakpoint = {
.read = hw_breakpoint_pmu_read, .read = hw_breakpoint_pmu_read,
}; };
static int __init init_hw_breakpoint(void) int __init init_hw_breakpoint(void)
{ {
unsigned int **task_bp_pinned; unsigned int **task_bp_pinned;
int cpu, err_cpu; int cpu, err_cpu;
...@@ -655,6 +655,5 @@ static int __init init_hw_breakpoint(void) ...@@ -655,6 +655,5 @@ static int __init init_hw_breakpoint(void)
return -ENOMEM; return -ENOMEM;
} }
core_initcall(init_hw_breakpoint);
...@@ -31,6 +31,7 @@ ...@@ -31,6 +31,7 @@
#include <linux/kernel_stat.h> #include <linux/kernel_stat.h>
#include <linux/perf_event.h> #include <linux/perf_event.h>
#include <linux/ftrace_event.h> #include <linux/ftrace_event.h>
#include <linux/hw_breakpoint.h>
#include <asm/irq_regs.h> #include <asm/irq_regs.h>
...@@ -6295,6 +6296,8 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) ...@@ -6295,6 +6296,8 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
void __init perf_event_init(void) void __init perf_event_init(void)
{ {
int ret;
perf_event_init_all_cpus(); perf_event_init_all_cpus();
init_srcu_struct(&pmus_srcu); init_srcu_struct(&pmus_srcu);
perf_pmu_register(&perf_swevent); perf_pmu_register(&perf_swevent);
...@@ -6302,4 +6305,7 @@ void __init perf_event_init(void) ...@@ -6302,4 +6305,7 @@ void __init perf_event_init(void)
perf_pmu_register(&perf_task_clock); perf_pmu_register(&perf_task_clock);
perf_tp_register(); perf_tp_register();
perf_cpu_notifier(perf_cpu_notify); perf_cpu_notifier(perf_cpu_notify);
ret = init_hw_breakpoint();
WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
} }
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