[PATCH] x86,kgdb: Fix hw breakpoint regression
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From: Jason Wessel on 28 Jul 2010 16:50 HW breakpoints events stopped working correctly with kgdb as a result of commit: 018cbffe6819f6f8db20a0a3acd9bab9bfd667e4 (Merge commit 'v2.6.33' into perf/core). The regression occurred because the behavior changed for setting NOTIFY_STOP as the return value to the die notifier if the breakpoint was known to the HW breakpoint API. Because kgdb is using the HW breakpoint API to register HW breakpoints slots, it must also now implement the overflow_handler call back else kgdb does not get to see the events from the die notifier. The kgdb_ll_trap function will be changed to be general purpose code which can allow an easy way to implement the hw_breakpoint API overflow call back. Signed-off-by: Jason Wessel <jason.wessel(a)windriver.com> Acked-by: Dongdong Deng <dongdong.deng(a)windriver.com> Acked-by: Frederic Weisbecker <fweisbec(a)gmail.com> --- arch/x86/kernel/kgdb.c | 12 ++++++++++-- 1 files changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 4f4af75..4030ce5 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -572,10 +572,10 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd) return NOTIFY_STOP; } -#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP int kgdb_ll_trap(int cmd, const char *str, struct pt_regs *regs, long err, int trap, int sig) { + unsigned long flags; struct die_args args = { .regs = regs, .str = str, @@ -588,9 +588,10 @@ int kgdb_ll_trap(int cmd, const char *str, if (!kgdb_io_module_registered) return NOTIFY_DONE; + local_irq_save(flags); return __kgdb_notify(&args, cmd); + local_irq_restore(flags); } -#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */ static int kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) @@ -625,6 +626,12 @@ int kgdb_arch_init(void) return register_die_notifier(&kgdb_notifier); } +static void kgdb_hw_overflow_handler(struct perf_event *event, int nmi, + struct perf_sample_data *data, struct pt_regs *regs) +{ + kgdb_ll_trap(DIE_DEBUG, "debug", regs, 0, 0, SIGTRAP); +} + void kgdb_arch_late(void) { int i, cpu; @@ -655,6 +662,7 @@ void kgdb_arch_late(void) for_each_online_cpu(cpu) { pevent = per_cpu_ptr(breakinfo[i].pev, cpu); pevent[0]->hw.sample_period = 1; + pevent[0]->overflow_handler = kgdb_hw_overflow_handler; if (pevent[0]->destroy != NULL) { pevent[0]->destroy = NULL; release_bp_slot(*pevent); -- 1.6.4.rc1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |