[PATCH 4/6] S390: Enable "maint set show-debug-regs"

Andreas Arnez
2016-09-15T12:02:05Z

Implement a new function for dumping the S390 "debug
registers" (actually, the PER info) and invoke it at appropriate places.
Respect the variable show_debug_regs and make it settable by the user.

gdb/ChangeLog:

* s390-linux-nat.c (gdbcmd.h): New include.
(s390_show_debug_regs): New function.
(s390_stopped_by_watchpoint): Call it, if show_debug_regs is set.
(s390_prepare_to_resume): Likewise.
(_initialize_s390_nat): Register the command "maint set
show-debug-regs".
---
gdb/s390-linux-nat.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)

diff --git a/gdb/s390-linux-nat.c b/gdb/s390-linux-nat.c
index b549246..c5d9bd3 100644
--- a/gdb/s390-linux-nat.c
+++ b/gdb/s390-linux-nat.c
@@ -28,6 +28,7 @@
#include "gregset.h"
#include "regset.h"
#include "nat/linux-ptrace.h"
+#include "gdbcmd.h"

#include "s390-linux-tdep.h"
#include "elf/common.h"
@@ -565,6 +566,37 @@ s390_linux_new_fork (struct lwp_info *parent, pid_t child_pid)
parent_state->watch_areas);
}

+/* Dump PER state. */
+
+static void
+s390_show_debug_regs (int tid, const char *where)
+{
+ per_struct per_info;
+ ptrace_area parea;
+
+ parea.len = sizeof (per_info);
+ parea.process_addr = (addr_t) &per_info;
+ parea.kernel_addr = offsetof (struct user_regs_struct, per_info);
+
+ if (ptrace (PTRACE_PEEKUSR_AREA, tid, &parea, 0) < 0)
+ perror_with_name (_("Couldn't retrieve debug regs"));
+
+ debug_printf ("PER (debug) state for %d -- %s\n"
+ " cr9-11: %lx %lx %lx\n"
+ " start, end: %lx %lx\n"
+ " code/ATMID: %x address: %lx PAID: %x\n",
+ tid,
+ where,
+ per_info.control_regs.words.cr[0],
+ per_info.control_regs.words.cr[1],
+ per_info.control_regs.words.cr[2],
+ per_info.starting_addr,
+ per_info.ending_addr,
+ per_info.lowcore.words.perc_atmid,
+ per_info.lowcore.words.address,
+ per_info.lowcore.words.access_id);
+}
+
static int
s390_stopped_by_watchpoint (struct target_ops *ops)
{
@@ -574,6 +606,9 @@ s390_stopped_by_watchpoint (struct target_ops *ops)
ptrace_area parea;
int result;

+ if (show_debug_regs)
+ s390_show_debug_regs (s390_inferior_tid (), "stop");
+
/* Speed up common case. */
if (VEC_empty (s390_watch_area, state->watch_areas))
return 0;
@@ -653,6 +688,9 @@ s390_prepare_to_resume (struct lwp_info *lp)

if (ptrace (PTRACE_POKEUSR_AREA, tid, &parea, 0) < 0)
perror_with_name (_("Couldn't modify watchpoint status"));
+
+ if (show_debug_regs)
+ s390_show_debug_regs (tid, "resume");
}

/* Mark the PER info as changed, so the next resume will update it. */
@@ -882,4 +920,17 @@ _initialize_s390_nat (void)
linux_nat_set_prepare_to_resume (t, s390_prepare_to_resume);
linux_nat_set_forget_process (t, s390_forget_process);
linux_nat_set_new_fork (t, s390_linux_new_fork);
+
+ /* A maintenance command to enable showing the PER state. */
+ add_setshow_boolean_cmd ("show-debug-regs", class_maintenance,
+ &show_debug_regs, _("\
+Set whether to show the PER (debug) hardware state."), _("\
+Show whether to show the PER (debug) hardware state."), _("\
+Use \"on\" to enable, \"off\" to disable.\n\
+If enabled, the PER state is shown after it is changed by GDB,\n\
+and when the inferior triggers a breakpoint or watchpoint."),
+ NULL,
+ NULL,
+ &maintenance_set_cmdlist,
+ &maintenance_show_cmdlist);
}
--
2.5.0