From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27159 invoked by alias); 13 Dec 2016 20:58:40 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 27077 invoked by uid 89); 13 Dec 2016 20:58:39 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,RCVD_IN_SORBS_SPAM,SPF_PASS autolearn=ham version=3.3.2 spammy=H*r:sk:gdb@sou, antoine, Antoine, canonical X-HELO: mail-io0-f174.google.com Received: from mail-io0-f174.google.com (HELO mail-io0-f174.google.com) (209.85.223.174) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 13 Dec 2016 20:58:28 +0000 Received: by mail-io0-f174.google.com with SMTP id d9so5508998ioe.0 for ; Tue, 13 Dec 2016 12:58:28 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=A47vjiNbxSMnqHXxkmryfKYMUVoH7nbwT77ePhdopYU=; b=aNjDLyad8wsnv3UKlVy/pIdD0ELP/vuDrM9Wt8iQWXr3KXCNGlphM4gQGPUvDR3mSj Hdv58n4crGpENgdAEldyTR6xZb2uDVZBF6GPA5I6ROK6Yvsah0TMZaWXSW6Egpvh3vfb tyF1hC714iQMbCx7lAFU/AjTTFViWXV2bJYAM2MquhX07tFrWVhI5MwqlfhkAlxx6f9L wGrB042bxT2zGwJ69tggIXnlJQ+lYIK9Duo2CL5hOGptXph6TFOkvTnNNPRmKbSeN6xs zODVqutaHvLh52fB+W4v9a9qbk8iE2PnP0kM8LHQN241r5avIbyuLZK5oRtveDb8B50U aqHg== X-Gm-Message-State: AKaTC01oa0zsfz8QzO6Vw7dj+BL6U1H4/1JO0wGK6uZbIjSqxRx36wAdV0oMSsFMKFhOE+1X96fvbkQ3HNgZdQ== X-Received: by 10.107.179.195 with SMTP id c186mr81265940iof.35.1481662707084; Tue, 13 Dec 2016 12:58:27 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.173.17 with HTTP; Tue, 13 Dec 2016 12:58:26 -0800 (PST) In-Reply-To: References: From: Tim Newsome Date: Tue, 13 Dec 2016 20:58:00 -0000 Message-ID: Subject: Re: read target register to decide breakpoint size To: Antoine Tremblay Cc: gdb Content-Type: text/plain; charset=UTF-8 X-IsSubscribed: yes X-SW-Source: 2016-12/txt/msg00018.txt.bz2 I finally got around to implementing this, but gdb still insists on calling breakpoint_kind_from_pc, where I don't have access to a regcache object (I think). Eg. ``` #0 riscv_breakpoint_kind_from_pc (gdbarch=0xcc8a90, pcptr=0x7fffffffde68) at riscv-tdep.c:184 #1 0x0000000000541301 in default_breakpoint_from_pc (gdbarch=0xcc8a90, pcptr=, lenptr=0x7fffffffde64) at arch-utils.c:847 #2 0x00000000004b40b3 in program_breakpoint_here_p (gdbarch=, address=2147550320) at breakpoint.c:9113 #3 0x00000000004b424c in bp_loc_is_permanent (loc=0xdd57b0) at breakpoint.c:9156 #4 add_location_to_breakpoint (b=b@entry=0xda9aa0, sal=sal@entry=0x7fffffffdf70) at breakpoint.c:9093 #5 0x00000000004b5169 in init_raw_breakpoint (ops=0xb4d200 , bptype=bp_breakpoint, sal=..., gdbarch=0xcc8a90, b=0xda9aa0) at breakpoint.c:7586 #6 init_breakpoint_sal (b=b@entry=0xda9aa0, gdbarch=gdbarch@entry=0xcc8a90, location=location@entry=0xda8f30, filter=filter@entry=0x0, cond_string=0x0, extra_string=0x0, type=bp_breakpoint, disposition=disp_donttouch, thread=-1, task=0, ignore_count=0, ops=0xb4d200 , from_tty=1, enabled=1, flags=0, display_canonical=0, internal=, sals=...) at breakpoint.c:9300 #7 0x00000000004bb490 in create_breakpoint_sal (display_canonical=0, flags=0, internal=0, enabled=1, from_tty=1, ops=0xb4d200 , ignore_count=0, task=0, thread=-1, disposition=disp_donttouch, type=bp_breakpoint, extra_string=0x0, cond_string=0x0, filter=0x0, location=0xda8f30, gdbarch=0xcc8a90, sals=...) at breakpoint.c:9436 #8 create_breakpoints_sal (gdbarch=0xcc8a90, canonical=0x7fffffffe170, cond_string=0x0, extra_string=0x0, type=bp_breakpoint, disposition=disp_donttouch, thread=-1, task=0, ignore_count=0, ops=0xb4d200 , from_tty=1, enabled=1, internal=0, flags=0) at breakpoint.c:9490 #9 0x00000000004bbbfc in create_breakpoint (gdbarch=0xcc8a90, location=location@entry=0xda3af0, cond_string=cond_string@entry=0x0, thread=-1, thread@entry=0, extra_string=, extra_string@entry=0xda3ad6 "", parse_extra=parse_extra@entry=1, tempflag=0, type_wanted=bp_breakpoint, ignore_count=0, pending_break_support=AUTO_BOOLEAN_AUTO, ops=0xb4d200 , from_tty=1, enabled=1, internal=0, flags=0) at breakpoint.c:9912 #10 0x00000000004bc099 in break_command_1 (arg=0xda3ad6 "", flag=, from_tty=1) at breakpoint.c:10020 ... ``` Is there some way I can check the misa register of my target from default_breakpoint_from_pc, or have gdb not call default_breakpoint_from_pc and use breakpoint_kind_from_current_state instead? Thank you, Tim On Mon, Nov 21, 2016 at 10:00 AM, Tim Newsome wrote: > Thanks, Antoine! That's exactly what I was looking for. > > Tim > > On Mon, Nov 21, 2016 at 8:36 AM, Antoine Tremblay > wrote: >> >> >> Tim Newsome writes: >> >> > I'm still working on RISC-V support for gdb. Any given RISC-V core may >> > support a compressed instruction set (2 bytes per instruction as >> > opposed to 4). There are corresponding 2-byte and 4-byte breakpoint >> > instructions. On cores that support the compressed instruction set it >> > is safe to just always use the 2-byte version, and there is a register >> > I can read to tell me whether the compressed instruction set is >> > supported. What I would like to do is read (and cache) that register >> > when breakpoint size is determined. That seems more robust than making >> > a decision based on ELF info, which may not reflect what is actually >> > being executed. >> > >> > Is that a good idea? Are there examples of operations that read target >> > registers to complete? >> >> Yes actually you can check how ARM does it, it has the same kind of >> problem with 3 breakpoints you can set for thumb, thumb2 and arm >> instruction sets. >> >> See arm-tdep.c:arm_sw_breakpoint_from_kind and >> arm_breakpoint_kind_from_current_state >> >> This is called in breakpoint.c:breakpoint_kind and it can use a register >> to make the decision from the current state of that register. >> >> So possibly just implementing the sw_breakpoint_from_kind and >> breakpoint_kind_from_current state would be ok your you. >> >> Regards, >> Antoine Tremblay