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perf,hw_breakpoint: Initialize hardware api earlier

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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>
This commit is contained in:
Jason Wessel
2010-11-04 17:33:01 -05:00
committed by Frederic Weisbecker
parent 6c0aca288e
commit 3c502e7a02
3 changed files with 11 additions and 2 deletions
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4
include/linux/hw_breakpoint.h
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@ -33,6 +33,8 @@ enum bp_type_idx {
#ifdef CONFIG_HAVE_HW_BREAKPOINT
extern int __init init_hw_breakpoint(void);
static inline void hw_breakpoint_init(struct perf_event_attr *attr)
{
memset(attr, 0, sizeof(*attr));
@ -108,6 +110,8 @@ static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
#else /* !CONFIG_HAVE_HW_BREAKPOINT */
static inline int __init init_hw_breakpoint(void) { return 0; }
static inline struct perf_event *
register_user_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,