diff options
Diffstat (limited to 'gdb/x86-linux-nat.c')
| -rw-r--r-- | gdb/x86-linux-nat.c | 59 |
1 files changed, 28 insertions, 31 deletions
diff --git a/gdb/x86-linux-nat.c b/gdb/x86-linux-nat.c index c0cd3a6..b49ef8f 100644 --- a/gdb/x86-linux-nat.c +++ b/gdb/x86-linux-nat.c @@ -65,7 +65,7 @@ u_debugreg_offset (int regnum) /* Support for debug registers. */ -/* Get debug register REGNUM value from only the one LWP of PTID. */ +/* Get debug register REGNUM value from the LWP specified by PTID. */ static unsigned long x86_linux_dr_get (ptid_t ptid, int regnum) @@ -85,7 +85,7 @@ x86_linux_dr_get (ptid_t ptid, int regnum) return value; } -/* Set debug register REGNUM to VALUE in only the one LWP of PTID. */ +/* Set debug register REGNUM to VALUE in the LWP specified by PTID. */ static void x86_linux_dr_set (ptid_t ptid, int regnum, unsigned long value) @@ -101,18 +101,19 @@ x86_linux_dr_set (ptid_t ptid, int regnum, unsigned long value) perror_with_name (_("Couldn't write debug register")); } -/* Return the inferior's debug register REGNUM. */ +/* Return the address stored in the current inferior's debug register + REGNUM. */ static CORE_ADDR x86_linux_dr_get_addr (int regnum) { - /* DR6 and DR7 are retrieved with some other way. */ gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR); return x86_linux_dr_get (current_lwp_ptid (), regnum); } -/* Return the inferior's DR7 debug control register. */ +/* Return the value stored in the current inferior's debug control + register. */ static unsigned long x86_linux_dr_get_control (void) @@ -120,7 +121,8 @@ x86_linux_dr_get_control (void) return x86_linux_dr_get (current_lwp_ptid (), DR_CONTROL); } -/* Get DR_STATUS from only the one LWP of INFERIOR_PTID. */ +/* Return the value stored in the current inferior's debug status + register. */ static unsigned long x86_linux_dr_get_status (void) @@ -128,18 +130,16 @@ x86_linux_dr_get_status (void) return x86_linux_dr_get (current_lwp_ptid (), DR_STATUS); } -/* Callback for iterate_over_lwps. Update the debug registers of - LWP. */ +/* Callback for iterate_over_lwps. Mark that our local mirror of + LWP's debug registers has been changed, and cause LWP to stop if + it isn't already. Values are written from our local mirror to + the actual debug registers immediately prior to LWP resuming. */ static int update_debug_registers_callback (struct lwp_info *lwp, void *arg) { - /* The actual update is done later just before resuming the lwp, we - just mark that the registers need updating. */ lwp_set_debug_registers_changed (lwp, 1); - /* If the lwp isn't stopped, force it to momentarily pause, so we - can update its debug registers. */ if (!lwp_is_stopped (lwp)) linux_stop_lwp (lwp); @@ -147,7 +147,8 @@ update_debug_registers_callback (struct lwp_info *lwp, void *arg) return 0; } -/* Set DR_CONTROL to CONTROL in all LWPs of the current inferior. */ +/* Store CONTROL in the debug control registers of all LWPs of the + current inferior. */ static void x86_linux_dr_set_control (unsigned long control) @@ -157,7 +158,7 @@ x86_linux_dr_set_control (unsigned long control) iterate_over_lwps (pid_ptid, update_debug_registers_callback, NULL); } -/* Set address REGNUM (zero based) to ADDR in all LWPs of the current +/* Store ADDR in debug register REGNUM of all LWPs of the current inferior. */ static void @@ -170,8 +171,8 @@ x86_linux_dr_set_addr (int regnum, CORE_ADDR addr) iterate_over_lwps (pid_ptid, update_debug_registers_callback, NULL); } -/* Called when resuming a thread. - If the debug regs have changed, update the thread's copies. */ +/* Called prior to resuming a thread. Updates the thread's debug + registers if the values in our local mirror have been changed. */ static void x86_linux_prepare_to_resume (struct lwp_info *lwp) @@ -185,16 +186,12 @@ x86_linux_prepare_to_resume (struct lwp_info *lwp) = x86_debug_reg_state (ptid_get_pid (ptid)); int i; - /* On Linux kernel before 2.6.33 commit - 72f674d203cd230426437cdcf7dd6f681dad8b0d - if you enable a breakpoint by the DR_CONTROL bits you need to have - already written the corresponding DR_FIRSTADDR...DR_LASTADDR registers. - - Ensure DR_CONTROL gets written as the very last register here. */ - - /* Clear DR_CONTROL first. In some cases, setting DR0-3 to a - value that doesn't match what is enabled in DR_CONTROL - results in EINVAL. */ + /* Prior to Linux kernel 2.6.33 commit + 72f674d203cd230426437cdcf7dd6f681dad8b0d, setting DR0-3 to + a value that did not match what was enabled in DR_CONTROL + resulted in EINVAL. To avoid this we zero DR_CONTROL before + writing address registers, only writing DR_CONTROL's actual + value once all the addresses are in place. */ x86_linux_dr_set (ptid, DR_CONTROL, 0); ALL_DEBUG_ADDRESS_REGISTERS (i) @@ -203,14 +200,12 @@ x86_linux_prepare_to_resume (struct lwp_info *lwp) x86_linux_dr_set (ptid, i, state->dr_mirror[i]); /* If we're setting a watchpoint, any change the inferior - had done itself to the debug registers needs to be - discarded, otherwise, x86_stopped_data_address can get - confused. */ + has made to its debug registers needs to be discarded + to avoid x86_stopped_data_address getting confused. */ clear_status = 1; } - /* If DR_CONTROL is supposed to be zero, we've already set it - above. */ + /* If DR_CONTROL is supposed to be zero then it's already set. */ if (state->dr_control_mirror != 0) x86_linux_dr_set (ptid, DR_CONTROL, state->dr_control_mirror); @@ -222,6 +217,8 @@ x86_linux_prepare_to_resume (struct lwp_info *lwp) x86_linux_dr_set (ptid, DR_STATUS, 0); } +/* Called when a new thread is detected. */ + static void x86_linux_new_thread (struct lwp_info *lwp) { |