This is the mail archive of the
gdb-patches@sourceware.org
mailing list for the GDB project.
Re: [PATCH] RISC-V: enable have_nonsteppable_watchpoint by default
On 17/09/18 11:34, Andrew Burgess wrote:
> * Craig Blackmore <craig.blackmore@embecosm.com> [2018-09-16 01:13:08 +0100]:
>
>> The RISC-V debug spec 0.13 recommends that write triggers fire before
>> the write is committed. If the target follows this behaviour, then
>> have_nonsteppable_watchpoint needs to be set to 1 so that GDB will step
>> over the watchpoint before checking if the value has changed.
>>
>> This patch adds a setshow for have_nonsteppable_watchpoint which defaults
>> to 1 to match the recommended behaviour. If a target does not follow
>> this timing, then 'set riscv have_nonsteppable_watchpoint 0' will need
>> to be issued on the command line.
> Thanks for this. Just a few minor formatting issues which I've
> pointed out below.
>
> Thanks,
> Andrew
>
>>
>> gdb/ChangeLog:
>>
>> * riscv-tdep.c (set_have_nonsteppable_watchpoint): add
>> callback for 'set riscv have_nonsteppable_watchpoint'
>> (riscv_gdbarch_init): initialise gdbarch setting for
>> have_nonesteppable_watchpoint
> Proper sentences in ChangeLogs please, capital letters and
> full-stops.
>
>> ---
>>
>> diff --git a/gdb/riscv-tdep.c b/gdb/riscv-tdep.c
>> index 254914c9c7..8f301d8b01 100644
>> --- a/gdb/riscv-tdep.c
>> +++ b/gdb/riscv-tdep.c
>> @@ -226,6 +226,20 @@ show_use_compressed_breakpoints (struct ui_file *file, int from_tty,
>> "to %s%s.\n"), value, additional_info);
>> }
>>
>> +static int riscv_have_nonsteppable_watchpoint = 1;
> You need to add a comment for this variable.
>
>> +
>> +/* The set callback for 'set riscv have-nonsteppable-watchpoint'. */
> Two whitespace after the full-stop and before the comment close please.
>
>> +
>> +static void
>> +set_have_nonsteppable_watchpoint (const char *args, int from_tty,
>> + struct cmd_list_element *c)
>> +{
>> + struct gdbarch *gdbarch = target_gdbarch ();
>> +
>> + set_gdbarch_have_nonsteppable_watchpoint (gdbarch,
>> + riscv_have_nonsteppable_watchpoint);
>> +}
>> +
>> /* The set and show lists for 'set riscv' and 'show riscv' prefixes. */
>>
>> static struct cmd_list_element *setriscvcmdlist = NULL;
>> @@ -2736,6 +2750,8 @@ riscv_gdbarch_init (struct gdbarch_info info,
>> set_gdbarch_return_value (gdbarch, riscv_return_value);
>> set_gdbarch_breakpoint_kind_from_pc (gdbarch, riscv_breakpoint_kind_from_pc);
>> set_gdbarch_sw_breakpoint_from_kind (gdbarch, riscv_sw_breakpoint_from_kind);
>> + set_gdbarch_have_nonsteppable_watchpoint (gdbarch,
>> + riscv_have_nonsteppable_watchpoint);
>>
>> /* Register architecture. */
>> set_gdbarch_num_regs (gdbarch, RISCV_LAST_REGNUM + 1);
>> @@ -2980,4 +2996,20 @@ can be used."),
>> show_use_compressed_breakpoints,
>> &setriscvcmdlist,
>> &showriscvcmdlist);
>> +
>> + add_setshow_boolean_cmd ("have-nonsteppable-watchpoint", no_class,
>> + &riscv_have_nonsteppable_watchpoint,
>> + _("\
>> +Set whether debugger must step over hardware watchpoints"),
>> + _("\
>> +Show whether debugger must step over hardware watchpoints"),
>> + _("\
>> +The RISC-V debug spec recommends that hardware write watchpoints fire before\n\
>> +the write is committed, in which case, GDB must step over the watchpoint\n\
>> +before checking the old and new values. Set this option to 1 (default) for\n\
> Two whitespace after full-stop again please.
>
>> +targets that follow this behaviour, otherwise set to 0."),
> As this is a boolean command can you replace references to 1 and 0
> both here and in the commit message with on and off.
>
>> + set_have_nonsteppable_watchpoint,
>> + NULL,
> You need to implement the show method too to allow for
> internationalisation.
>
>> + &setriscvcmdlist,
>> + &showriscvcmdlist);
>> }
>>
>>
Thanks for these comments, I have updated the patch accordingly.
---
The RISC-V debug spec 0.13 recommends that write triggers fire before the
write is committed. If the target follows this behaviour, then
have_nonsteppable_watchpoint needs to be set to 'on' so that GDB will step
over the watchpoint before checking if the value has changed.
This patch adds a setshow for have_nonsteppable_watchpoint which defaults
to 'on' to match the recommended behaviour. If a target does not follow
this timing, then 'set riscv have_nonsteppable_watchpoint off' will need
to be issued on the command line.
gdb/ChangeLog:
* riscv-tdep.c (set_have_nonsteppable_watchpoint): Add callback
for 'set riscv have_nonsteppable_watchpoint'.
(show_have_nonsteppable_watchpoint): Add callback for
'show riscv have_nonsteppable_watchpoint'.
(riscv_gdbarch_init): Initialise gdbarch setting for
have_nonesteppable_watchpoint.
---
diff --git a/gdb/riscv-tdep.c b/gdb/riscv-tdep.c
index 254914c..857c5d1 100644
--- a/gdb/riscv-tdep.c
+++ b/gdb/riscv-tdep.c
@@ -226,6 +226,36 @@ show_use_compressed_breakpoints (struct ui_file *file, int from_tty,
"to %s%s.\n"), value, additional_info);
}
+/* Controls whether the debugger should step over hardware watchpoints before
+ checking if the watched variable has changed. If true, then the debugger
+ will step over the watchpoint. */
+
+static int riscv_have_nonsteppable_watchpoint = 1;
+
+/* The set callback for 'set riscv have-nonsteppable-watchpoint'. */
+
+static void
+set_have_nonsteppable_watchpoint (const char *args, int from_tty,
+ struct cmd_list_element *c)
+{
+ struct gdbarch *gdbarch = target_gdbarch ();
+
+ set_gdbarch_have_nonsteppable_watchpoint (gdbarch,
+ riscv_have_nonsteppable_watchpoint);
+}
+
+/* The show callback for 'show riscv have-nonsteppable-watchpoint'. */
+
+static void
+show_have_nonsteppable_watchpoint (struct ui_file *file, int from_tty,
+ struct cmd_list_element *c,
+ const char *value)
+{
+ fprintf_filtered (file,
+ _("Debugger must step over hardware watchpoints is set to "
+ "%s.\n"), value);
+}
+
/* The set and show lists for 'set riscv' and 'show riscv' prefixes. */
static struct cmd_list_element *setriscvcmdlist = NULL;
@@ -2736,6 +2766,8 @@ riscv_gdbarch_init (struct gdbarch_info info,
set_gdbarch_return_value (gdbarch, riscv_return_value);
set_gdbarch_breakpoint_kind_from_pc (gdbarch, riscv_breakpoint_kind_from_pc);
set_gdbarch_sw_breakpoint_from_kind (gdbarch, riscv_sw_breakpoint_from_kind);
+ set_gdbarch_have_nonsteppable_watchpoint (gdbarch,
+ riscv_have_nonsteppable_watchpoint);
/* Register architecture. */
set_gdbarch_num_regs (gdbarch, RISCV_LAST_REGNUM + 1);
@@ -2980,4 +3012,20 @@ can be used."),
show_use_compressed_breakpoints,
&setriscvcmdlist,
&showriscvcmdlist);
+
+ add_setshow_boolean_cmd ("have-nonsteppable-watchpoint", no_class,
+ &riscv_have_nonsteppable_watchpoint,
+ _("\
+Set whether debugger must step over hardware watchpoints"),
+ _("\
+Show whether debugger must step over hardware watchpoints"),
+ _("\
+The RISC-V debug spec recommends that hardware write watchpoints fire before\n\
+the write is committed, in which case, GDB must step over the watchpoint\n\
+before checking the old and new values. Set this option to 'on' (default)\n\
+for targets that follow this behaviour, otherwise set to 'off'."),
+ set_have_nonsteppable_watchpoint,
+ show_have_nonsteppable_watchpoint,
+ &setriscvcmdlist,
+ &showriscvcmdlist);
}