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([2a02:390:741d:1:d4b2:8065:3bc7:d2eb]) by smtp.gmail.com with ESMTPSA id b74-v6sm22643429wma.8.2018.09.24.04.36.08 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Sep 2018 04:36:08 -0700 (PDT) Subject: Re: [PATCH] RISC-V: enable have_nonsteppable_watchpoint by default To: Andrew Burgess Cc: gdb-patches@sourceware.org References: <20180917103409.GJ5952@embecosm.com> From: Craig Blackmore Openpgp: preference=signencrypt Message-ID: <77978648-c391-0011-6c03-c7fd38429914@embecosm.com> Date: Mon, 24 Sep 2018 11:36:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180917103409.GJ5952@embecosm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-SW-Source: 2018-09/txt/msg00801.txt.bz2 On 17/09/18 11:34, Andrew Burgess wrote: > * Craig Blackmore [2018-09-16 01:13:08 +01= 00]: > >> 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. >>=20=20=20=20=20 >> 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 > >>=20=20=20=20=20 >> gdb/ChangeLog: >>=20=20=20=20=20 >> * 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 *fi= le, int from_tty, >> "to %s%s.\n"), value, additional_info); >> } >>=20=20 >> +static int riscv_have_nonsteppable_watchpoint =3D 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 =3D target_gdbarch (); >> + >> + set_gdbarch_have_nonsteppable_watchpoint (gdbarch, >> + riscv_have_nonsteppable_watchpoint); >> +} >> + >> /* The set and show lists for 'set riscv' and 'show riscv' prefixes. */ >>=20=20 >> static struct cmd_list_element *setriscvcmdlist =3D 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_f= rom_pc); >> set_gdbarch_sw_breakpoint_from_kind (gdbarch, riscv_sw_breakpoint_fro= m_kind); >> + set_gdbarch_have_nonsteppable_watchpoint (gdbarch, >> + riscv_have_nonsteppable_watchpoint); >>=20=20 >> /* 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 b= efore\n\ >> +the write is committed, in which case, GDB must step over the watchpoin= t\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); } =20 +/* Controls whether the debugger should step over hardware watchpoints bef= ore + checking if the watched variable has changed. If true, then the debugg= er + will step over the watchpoint. */ + +static int riscv_have_nonsteppable_watchpoint =3D 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 =3D 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. */ =20 static struct cmd_list_element *setriscvcmdlist =3D 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_k= ind); + set_gdbarch_have_nonsteppable_watchpoint (gdbarch, + riscv_have_nonsteppable_watchpoint); =20 /* 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 befo= re\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); }