This patch resets the bit in dr6 after the corresponding exception is handled in code. Signed-off-by: K.Prasad --- arch/x86/kernel/hw_breakpoint.c | 13 +++++++++++-- arch/x86/kernel/kgdb.c | 6 ++++++ arch/x86/kernel/kprobes.c | 9 ++++++++- arch/x86/kernel/traps.c | 4 ++-- arch/x86/mm/kmmio.c | 8 +++++++- 5 files changed, 34 insertions(+), 6 deletions(-) Index: linux-2.6-tip.hbkpt/arch/x86/kernel/hw_breakpoint.c =================================================================== --- linux-2.6-tip.hbkpt.orig/arch/x86/kernel/hw_breakpoint.c +++ linux-2.6-tip.hbkpt/arch/x86/kernel/hw_breakpoint.c @@ -314,8 +314,12 @@ int __kprobes hw_breakpoint_handler(stru { int i, cpu, rc = NOTIFY_STOP; struct hw_breakpoint *bp; - /* The DR6 value is stored in args->err */ - unsigned long dr7, dr6 = args->err; + unsigned long dr7, dr6; + unsigned long *dr6_p; + + /* The DR6 value is pointed by args->err */ + dr6_p = (unsigned long *)ERR_PTR(args->err); + dr6 = *dr6_p; /* Do an early return if no trap bits are set in DR6 */ if ((dr6 & DR_TRAP_BITS) == 0) @@ -352,6 +356,11 @@ int __kprobes hw_breakpoint_handler(stru rc = NOTIFY_DONE; } /* + * Reset the 'i'th TRAP bit in dr6 to denote completion of + * exception handling + */ + (*dr6_p) &= ~(DR_TRAP0 << i); + /* * bp can be NULL due to lazy debug register switching * or due to the delay between updates of hbp_kernel_pos * and this_hbp_kernel. Index: linux-2.6-tip.hbkpt/arch/x86/kernel/kgdb.c =================================================================== --- linux-2.6-tip.hbkpt.orig/arch/x86/kernel/kgdb.c +++ linux-2.6-tip.hbkpt/arch/x86/kernel/kgdb.c @@ -43,6 +43,7 @@ #include #include +#include #include #include @@ -434,6 +435,11 @@ single_step_cont(struct pt_regs *regs, s "resuming...\n"); kgdb_arch_handle_exception(args->trapnr, args->signr, args->err, "c", "", regs); + /* + * Reset the BS bit in dr6 (pointed by args->err) to + * denote completion of processing + */ + (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; return NOTIFY_STOP; } Index: linux-2.6-tip.hbkpt/arch/x86/kernel/kprobes.c =================================================================== --- linux-2.6-tip.hbkpt.orig/arch/x86/kernel/kprobes.c +++ linux-2.6-tip.hbkpt/arch/x86/kernel/kprobes.c @@ -54,6 +54,7 @@ #include #include #include +#include void jprobe_return_end(void); @@ -967,8 +968,14 @@ int __kprobes kprobe_exceptions_notify(s ret = NOTIFY_STOP; break; case DIE_DEBUG: - if (post_kprobe_handler(args->regs)) + if (post_kprobe_handler(args->regs)) { + /* + * Reset the BS bit in dr6 (pointed by args->err) to + * denote completion of processing + */ + (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; ret = NOTIFY_STOP; + } break; case DIE_GPF: /* Index: linux-2.6-tip.hbkpt/arch/x86/kernel/traps.c =================================================================== --- linux-2.6-tip.hbkpt.orig/arch/x86/kernel/traps.c +++ linux-2.6-tip.hbkpt/arch/x86/kernel/traps.c @@ -550,8 +550,8 @@ dotraplinkage void __kprobes do_debug(st /* Store the virtualized DR6 value */ tsk->thread.debugreg6 = dr6; - if (notify_die(DIE_DEBUG, "debug", regs, dr6, error_code, - SIGTRAP) == NOTIFY_STOP) + if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code, + SIGTRAP) == NOTIFY_STOP) return; /* It's safe to allow irq's after DR6 has been saved */ Index: linux-2.6-tip.hbkpt/arch/x86/mm/kmmio.c =================================================================== --- linux-2.6-tip.hbkpt.orig/arch/x86/mm/kmmio.c +++ linux-2.6-tip.hbkpt/arch/x86/mm/kmmio.c @@ -540,8 +540,14 @@ kmmio_die_notifier(struct notifier_block struct die_args *arg = args; if (val == DIE_DEBUG && (arg->err & DR_STEP)) - if (post_kmmio_handler(arg->err, arg->regs) == 1) + if (post_kmmio_handler(arg->err, arg->regs) == 1) { + /* + * Reset the BS bit in dr6 (pointed by args->err) to + * denote completion of processing + */ + (*(unsigned long *)ERR_PTR(arg->err)) &= ~DR_STEP; return NOTIFY_STOP; + } return NOTIFY_DONE; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/