diff options
| -rw-r--r-- | i386/i386/db_interface.c | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/i386/i386/db_interface.c b/i386/i386/db_interface.c index b442b86..b3fac0b 100644 --- a/i386/i386/db_interface.c +++ b/i386/i386/db_interface.c @@ -63,6 +63,8 @@ /* Whether the kernel uses any debugging register. */ static boolean_t kernel_dr; #endif +/* Whether the current debug registers are zero. */ +static boolean_t zero_dr; void db_load_context(pcb_t pcb) { @@ -74,13 +76,20 @@ void db_load_context(pcb_t pcb) return; } #endif + /* Else set user debug registers, if any */ + unsigned int *dr = pcb->ims.ids.dr; + boolean_t will_zero_dr = !dr[0] && !dr[1] && !dr[2] && !dr[3] && !dr[7]; + + if (!(zero_dr && will_zero_dr)) + { + set_dr0(dr[0]); + set_dr1(dr[1]); + set_dr2(dr[2]); + set_dr3(dr[3]); + set_dr7(dr[7]); + zero_dr = will_zero_dr; + } - /* Else set user debug registers */ - set_dr0(pcb->ims.ids.dr[0]); - set_dr1(pcb->ims.ids.dr[1]); - set_dr2(pcb->ims.ids.dr[2]); - set_dr3(pcb->ims.ids.dr[3]); - set_dr7(pcb->ims.ids.dr[7]); #if MACH_KDB splx(s); #endif @@ -163,7 +172,9 @@ void db_dr ( if (kernel_dr) { if (!ids.dr[0] && !ids.dr[1] && !ids.dr[2] && !ids.dr[3]) { /* Not used any more, switch back to user debugging registers */ + set_dr7 (0); kernel_dr = FALSE; + zero_dr = TRUE; db_load_context(current_thread()->pcb); } } |