Processing of debug exceptions (in do_debug()) can stop if it originated from a hw-breakpoint exception (return NOTIFY_STOP). For certain cases such as a) user-space breakpoints with pending SIGTRAP signal delivery (as in the case of ptrace induced breakpoints) and b) exceptions due to multiple causes (other than breakpoints) we will continue to process the exception (by returning NOTIFY_DONE). Signed-off-by: K.Prasad --- arch/x86/kernel/hw_breakpoint.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) Index: linux-2.6-tip.bugfix_perf_hbkpt/arch/x86/kernel/hw_breakpoint.c =================================================================== --- linux-2.6-tip.bugfix_perf_hbkpt.orig/arch/x86/kernel/hw_breakpoint.c +++ linux-2.6-tip.bugfix_perf_hbkpt/arch/x86/kernel/hw_breakpoint.c @@ -502,8 +502,6 @@ static int __kprobes hw_breakpoint_handl rcu_read_lock(); bp = per_cpu(bp_per_reg[i], cpu); - if (bp) - rc = NOTIFY_DONE; /* * Reset the 'i'th TRAP bit in dr6 to denote completion of * exception handling @@ -522,7 +520,13 @@ static int __kprobes hw_breakpoint_handl rcu_read_unlock(); } - if (dr6 & (~DR_TRAP_BITS)) + /* + * Further processing in do_debug() is needed for a) user-space + * breakpoints (to generate signals) and b) when the system has + * taken exception due to multiple causes + */ + if ((current->thread.debugreg6 & DR_TRAP_BITS) || + (dr6 & (~DR_TRAP_BITS))) rc = NOTIFY_DONE; set_debugreg(dr7, 7); -- 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/